PhD Thesis
Permanent URI for this collectionhttp://localhost:4000/handle/123456789/48
Browse
62 results
Search Results
Item Irrigation and crop establishment techniques in Bajra Napier hybrid(Department of Agronomy, College of Agriculture, Vellayani, 2025-07-23) Greeshma, U; Usha C ThomasThe research entitled “Irrigation and crop establishment techniques in Bajra Napier hybrid” was conducted at Department of Agronomy, College of Agriculture, Vellayani, during 2022 to 2025. The major objectives of the study were standardization of irrigation levels for popular Bajra Napier hybrid varieties in Kerala and standardization of sett size, age and method of planting of Bajra Napier hybrid. The study was undertaken as two separate parts. Part 1 entitled “Standardization of irrigation levels for popular Bajra Napier hybrid varieties in Kerala” was conducted from March 2023 to August 2024 at Instructional Farm, College of Agriculture, Vellayani. The experiment was laid out in split plot design with 4 main plots (i1 - IW/CPE- 1.00, i2 - IW/CPE- 0.80, i3 - IW/CPE- 0.60 and i4 - Rainfed), 3 sub plots (v1 – Susthira, v2 – Suguna and v3 – CO-5) and three replications. Crop was irrigated to a depth of 2.5 cm. Initial 6 months was taken as establishment period and after that, observations were recorded for 12 months. The results revealed that irrigation scheduling at IW/CPE ratio of 1.0 significantly enhanced the growth attributes including mean plant height, number of tillers per hill, leaf stem ratio (1.85), leaf area, and leaf area index compared to lower irrigation levels. Among the varieties, CO-5 consistently recorded superior growth performance, achieving the highest mean plant height (208.07 cm), leaf stem ratio (1.69), leaf area (228.87 cm²), and leaf area index (12.13). The mean number of tillers per hill was the highest in Suguna (v2). Among the interactions, CO-5 irrigated at an IW/CPE of 1.0 (i1v3) yielded the highest growth values like mean leaf stem ratio, leaf area and leaf area index. The results on yield revealed that total green and dry fodder yield were the highest in irrigation at an IW/CPE of 1.0 (175.45 t ha-1 and 40.95 t ha-1, respectively). Variety CO-5 (v3) produced the highest total green fodder (186.74 t ha-1) and dry fodder yield (39.05 t ha-1). Among the treatment combinations, i2v3 (CO-5 at an IW/CPE of 0.8) recorded the higher total green fodder (206.06 t ha⁻¹) and dry fodder (51.26 t ha⁻¹) yield, and remained comparable with i1v3. Across all harvests, green fodder yield and dry fodder yield followed a declining trend from the first to the fifth cut, with consistently higher yields recorded under IW/CPE of 1.0 and CO-5 variety at each harvest. Root studies revealed that rainfed conditions encouraged deeper rooting (46.56 cm), whereas irrigation at IW/CPE 1.0 improved root biomass (318.83 g per plant), with CO-5 exhibiting superior root dry weight (389.08 g per plant). Among the interactions, the treatment combination of rainfed irrigation with variety CO-5 (i4v3) recorded the deepest roots (51.73 cm). Conversely, the highest root dry weight (503.83 g per plant) was recorded in the combination of IW/CPE 1.0 with CO-5 (i1v3). Biochemical analysis showed significantly higher chlorophyll content in treatments involving IW/CPE 1.0 and CO-5, although crude protein content remained unaffected by treatments. Lower crude fibre content was noticed in IW/CPE of 0.8 (29.91%) and was on on par with i1. Crude protein yield was the highest in i1v3 (IW/CPE of 1.0 in CO-5) recording the maximum crude protein yield of 4739 kg ha⁻¹, which was statistically on par with i2v3. Analysis of post-experiment soil showed no significant effect for interactions in soil pH, electrical conductivity, organic carbon and available N. However, available phosphorus was the highest under rainfed conditions (i4). Interaction between irrigation levels and varieties also influenced soil potassium status, with i1v3 (IW/CPE of 1.0 x CO-5 variety) recording the highest value. Nutrient uptake studies revealed that nitrogen, phosphorus, and potassium uptake closely followed the same trend as that of dry fodder yield, with the highest uptake under IW/CPE of 1.0 and in the variety CO-5, particularly in the treatment combination i1v3 (CO-5 at an IW/CPE of 1.0). The water use efficiency and economic water productivity was found to be higher in irrigation scheduling at IW/CPE ratio of 0.8 (45.67 kg ha-1 mm-1 and 161.55 ₹ ha-1 mm-1) and it was on par with IW/CPE ratio 1.0. Among varieties, CO-5 recorded higher WUE and economic water productivity. CO-5 irrigated at an IW/CPE of 0.8 recorded higher WUE and the highest economic water productivity. Economic analysis showed that CO-5 irrigated at an IW/CPE of 0.8 (i2v3) achieved the highest net returns (348655 ₹ ha-1) and B: C ratio (1.94). The part II of the study for “standardization of crop establishment methods in Bajra Napier hybrid” was conducted from June to October 2023 and the confirmatory trial was conducted from June – October 2024 at Instructional Farm, College of Agriculture, Vellayani. The experiment was laid out in randomized block design with 3 factors and at three levels each, replicated thrice. The treatments comprised three levels of nodes per cutting (n1 – Single noded cutting, n2 – Two noded cutting, n3 – Three noded cutting), three planting method (p1 – Horizontal planting, p2 - Vertical planting, p3 – Planting at 45 degree) and three stages of maturity (s1 – 3 months, s2 – 4 months, s3 – 5 months). The observations were recorded to two harvests and the variety used for the study was Susthira. The results revealed that growth, yield, establishment, and economics were significantly influenced by nodes per cutting, planting methods, stage of maturity and their interactions. Among the nodes per cutting, three noded cutting (n3) recorded tallest plants (170.93 and 227.72 cm respectively), mean number of tillers per hill (8.92 and 8.32 respectively), leaf stem ratio, leaf area, LAI (8.07 and 8.54 respectively), total green fodder yield (88.49 and 85.27 t ha-1 respectively) and total dry fodder yield (22.12 and 21.32 t ha-1 respectively) in first and second year. But the specific leaf area was the highest in single noded cutting (n1). Among the planting methods, horizontal planting (p1) recorded the highest mean number of tillers per hill, leaf stem ratio, LAI, mean specific leaf area, total green fodder yield (92.78 and 90.84 t ha-1 respectively), total dry fodder yield (23.19 and 22.71 t ha-1 respectively) and crude protein yield (2032 and 2131 kg ha-1 respectively) in first and second year. Among the stages of maturity, cuttings from 4 month old plants (s2) recorded the highest number of tillers per hill, leaf stem ratio, LAI, total green (85.91 and 86.30 t ha-1 respectively) and dry fodder yield (21.48 and 21.57 t ha-1 respectively) and crude protein yield (1892 and 2034 t ha-1 respectively) in first and second year. The lowest number of days for first harvest (75 days in both years) was observed in 4 month old cutting (s2). Horizontal planting of three noded cutting taken from 4 month old plants (n3p1s2) recorded the highest mean number of tillers per hill, mean leaf stem ratio, mean LAI, total green (156.46 and 155.80 t ha-1 respectively) and dry fodder yield (39.12 and 38.95 t ha-1 respectively) and crude protein yield in both years. Among the establishment characters, 4 month old cutting (s2) established earlier (10.33 and 10.52 respectively) in both years. The treatment combination n3p1s2 (horizontal planting of three noded cutting taken from 4 month old plants) recorded higher establishment percentage in first and second year. The economic analysis revealed that, horizontal planting of three noded cutting taken from 4 month old plants (n3p1s2) recorded the highest B: C ratio in first (3.91) and second (3.89) year. It could be concluded that, among the Bajra Napier hybrid screened, the variety CO-5 irrigated at an IW/CPE of 0.8 could be recommended for realizing higher green fodder yield, dry fodder yield, WUE, economic water productivity, net returns and B:C ratio. In Bajra Napier hybrid variety Susthira, horizontal planting of three noded cutting taken from 4 month old plants could be adjudged as the best establishment method for higher growth, yield, establishment and B:C ratio.Item Nitrogen use efficient varieties for enhanced productivity in rice (Oryza sativa L.)(Department of Agronomy, College of Agriculture, Vellayani, 2025-07-29) Merin Jose; Shalini Pillai, PThe research entitled “Nitrogen use efficient varieties for enhanced productivity in rice (Oryza sativa L.)” was conducted at the Department of Agronomy, College of Agriculture, Vellayani, during 2021 to 2025. The objectives of the study were to screen selected rice varieties for nitrogen use efficiency (NUE) based on germination and root characteristics, to evaluate the field performance of selected nitrogen-efficient rice varieties at graded doses of nitrogen (N), and to work out the economics. The study was conducted in three parts. The first part was a lab study wherein, 14 popular rice varieties released from Kerala Agricultural University (KAU) were screened for NUE based on germination characteristics. The experiment was laid out in completely randomized design (CRD) with 14 varieties and 5 media, replicated thrice. The treatments comprised seven short duration varieties (SDVs) viz., v1- Makom (MO 9), v2- Prathyasa (MO 21), v3- KAU Manuratna, v4- Jyothi (PTB 39), v5- Harsha (PTB 55), v6- Varsha (PTB 56) and v7- Kanchana (PTB 50) and seven medium duration varieties (MDVs) viz., v8- Bhadra (MO 4), v9- Uma (MO 16), v10- Sreyas (MO 22), v11- Pournami (MO 23), v12- KAU Manuvarna, v13- Athira (PTB 51) and v14- Aiswarya (PTB 52), and Modified Arnon Hoagland (AH) media [(m1- AH media with urea (7.5 mM), m2 - AH media with ammonium chloride (15 mM), m3- AH media without N source, m4- AH media and m5 - distilled water]. In general, the presence of urea or any other additional source of N tends to inhibit germination. However, this inhibitory effect was not observed in the case of Harsha (v5) and Varsha (v6), as both varieties took 39 h each to reach 50 per cent germination in distilled water and in AH media with urea. In the case of MDVs, the germination of all the varieties were inhibited. The SDVs, viz., Varsha (v6), Harsha (v5) and Prathyasa (v2) had longer shoots (10.25 cm ± 1.27 cm, 7.95 cm ± 0.52 cm and 6.63 cm ± 0.79 cm respectively) in the presence of urea as compared to distilled water. In the case of MDVs, Aiswarya (v14), Athira (v13), Sreyas (v10) and Uma (v9) produced longer shoots (9.20 cm ± 0.36 cm, 8.20 cm ± 0.39 cm, 8.13cm ± 0.85 cm and 6.53 cm ± 0.75 cm respectively) in the presence of urea as compared to distilled water. In the presence of urea, Varsha (v6) and Harsha (v5) recorded longer roots (9.13 cm ± 1.91 cm and 9.03 cm ± 2.78 cm). With respect to MDVs, Sreyas (v10) recorded longer roots (12 cm ± 0.28 cm) and this was on par (11.73 cm) with that under distilled water. Higher seedling dry weight (23.15 mg ± 2.25 mg) was recorded in Varsha (v6) which was on par with Kanchana (v7), Harsha (v5) and Jyothi (v4). In the presence of urea, Uma (v9) recorded higher seedling dry weight (23 mg ± 1.83 mg) which was on par with Aiswarya (v14), Sreyas (v10) and KAU Manuvarna (v12). Urease enzyme activity was found to be the highest (0.59 ± 0.01) mM NH4+ min-1 g-1 in Varsha (v6) followed by Harsha (v5). A similar trend was observed in urea and NH₄Cl, where Varsha (v6) recorded higher urease enzyme activity than Harsha (v5). In case of MDVs, urease enzyme activity was the highest (0.47 ± 0.01) mM NH4+ min-1 g-1 in Aiswarya (v14) followed by Sreyas (v10). Seedling vigour index I (SVI I) was higher in Varsha (v6) followed by Harsha (v5) and higher seedling vigour index II (SVI II) was recorded by Kanchana (v7), followed by Varsha (v6) and Harsha (v5). In case of MDVs, Aiswarya (v14) recorded higher SVI I (885.15), followed by Sreyas(v10) (717.28). Whereas, Sreyas (v10) recorded higher SVI II (2288.25) which was followed by Aiswarya (v14) (2278.50). The second part of the study comprised screening the 14 rice varieties in field, under two contrasting N levels. It was carried out in the wetlands of the Integrated Farming System Research Station (IFSRS), Karamana, during June to October 2023. The experiment was laid out in randomised block design (RBD) with the 14 varieties at two levels of nitrogen (n0- 0 % RDN and n1- 100 % RDN), replicated thrice. Among the SDVs, Harsha (v5) and Varsha (v6) and among MDVs, Sreyas (v10) and Aiswarya (v14) proved superior in terms of growth attributes including plant height, tillers m-2, rooting depth and root volume. The same trend was observed in yield attributes and yield. The lower percentage in yield reduction observed in Harsha (23.89%), Varsha (22.50%), Sreyas (27.89%) and Aiswarya (20.61%) at zero per cent RDN compared to 100 per cent RDN pointed towards their higher NUE. These varieties also exhibited higher root dry weight efficiency index (RDWEI) which is also an indicator of NUE. The Partial factor productivity of N (PFPN) also exhibited a similar trend. Based on the cumulative ranking of germination traits (part I) and RDWEI, yield and PFPN (part II) the varieties Harsha, Varsha, Sreyas and Aiswarya were chosen as promising candidates for further field evaluation aimed at validating their production potential, NUE and profitability. The third part of the study entitled ‘Field evaluation of nitrogen- efficient rice varieties’ was also conducted at IFSRS, Karamana from November 2023 to February 2024 (second crop 2023-’24 referred to as season I) and July to November 2024 (first crop 2024 ’25 referred to as season II). The field performance of the four nitrogen-efficient rice varieties chosen from part I and part II were assessed at graded levels of recommended dose of nitrogen (RDN). The experiment was laid out in split plot design with four main plots (n1- 100 % RDN, n2 - 75 % RDN, n3 - 50 % RDN and n4- absolute control) and four sub plots [v1- Harsha (PTB 55), v2- Varsha (PTB 56), v3- Sreyas (MO 22) and v4- Aiswarya (PTB 52)], replicated four times. The results revealed that during seasons I and II, while Harsha at 100% RDN (n1v1) recorded the highest grain yield (4567 kg ha-1 ± 64 kg ha-1 and 4703 kg ha-1 ± 35 kg ha-1 respectively), the yield of Varsha at 100% RDN (n1v2) (4507 kg ha-1 ± 81 kg ha-1 and 4720 kg ha-1 ± 89 kg ha-1) and 75 per cent RDN (n2v2) (4440 kg ha-1 ± 82 kg ha-1 and 4603 kg ha-1 ± 68 kg ha-1) were statistically comparable. The MDVs, Sreyas and Aiswarya also behaved in a similar manner with comparable yields at 100 per cent RDN and 75 per cent RDN. Chlorophyll content was significantly the highest at 100 % RDN in Harsha, Varsha and Sreyas throughout the growth stages. Whereas in Aiswarya, the chlorophyll content at 100 per cent RDN was statistically comparable to that at 75 per cent RDN. In terms of NUE indices, all the four varieties exhibited significantly higher PFPN and agronomic efficiency of nitrogen (AEN) at 50 per cent RDN. However, during season II AEN of both Varsha and Aiswarya at 50 per cent RDN and 75 per cent RDN were comparable. Harsha recorded the highest BCR (1.41± 0.02 and 1.45± 0.01) at 100% RDN (n1v1), while, Varsha recorded the same (1.42 ± 0.03 and 1.49 ± 0.02) at 75 per cent RDN (n2v2). Among the MDVs, Sreyas and Aiswarya recorded higher BCR at 75 per cent RDN. Screening of 14 popular rice varieties released from KAU based on germination characters, RDWEI and PFPN showed that the short duration varieties viz., Harsha (PTB 55) and Varsha (PTB 56) and the medium duration varieties viz., Sreyas (MO 22) and Aiswarya (PTB 55) could be considered as nitrogen efficient. Field evaluation of the nitrogen efficient varieties showed that while the productivity and profitability of Varsha could be sustained at 75 per cent RDN, the variety Harsha required 100 per cent RDN. The study also revealed that, the recommended dose of N (90 kg ha-1) for the nitrogen efficient MDVs, could be reduced by 25 per cent without compromising yield and profitability.Item Nano zinc nutrition in rice based cropping systems in high Phosphorus soils(Department of Agronomy, College of Agriculture,Vellayani, 2025-07-04) Boddu Archana; Bindhu, J SThe project entitled “Nano zinc nutrition in rice based cropping systems in high phosphorus soils” was conducted at College of Agriculture, Vellayani, Thiruvananthapuram, Kerala, during 2020-2025. The objectives of the study were to evaluate the response of rice to nano zinc in high P soils, study the residual effect of nano zinc nutrition on growth and yield of succeeding crops, study the P - Zn interactions and to identify the promising crop sequence in terms of system productivity and profitability. The study comprised three parts which were carried out at Integrated Farming System Research Station (IFSRS), Karamana, Thiruvananthapuram, Kerala during 2022-23. The first and second parts of the experiment were laid out in randomized complete block design with three replications using variety Uma (Mo 16) in virippu and mundakan seasons. The treatments comprised T1- [Soil application (SA) of ZnSO4 at 20 kg ha-1 (applied only in virippu season)], T2- [Nutri priming (NP) with nano Zn at 0.05%], T3- [NP with nano Zn at 0.05% + Foliar spray (FS) with nano Zn at 0.05% at maximum tillering (MT) stage], T4- [NP with ZnSO4 at 0.5%], T5- [NP with ZnSO4 at 0.5% + FS with nano Zn at 0.05% at MT stage], T6-[FS with nano Zn at 0.05% at MT and panicle initiation (PI) stages], T7- [FS with ZnSO4 at 0.5% at MT and PI stages], T8- [Control (Recommended Dose of Nutrients (RDN) without application of P and Zn)]. The RDN were 90:45:45 (N:P2O5:K2O) kg ha-1 modified as 64:22:53 kg ha-1 on soil test basis. The growth and yield attributes of rice were significantly influenced by nano zinc nutrition. Taller plants with the highest number of tillers per m2, higher leaf area per hill, leaf area index and dry matter production were recorded in T3 and was on par with T6 during both the seasons. The yield attributes viz., higher numbers of productive tillers per hill, grains per panicle, grain weight per panicle and lower sterility percentage were observed in T3 and was on par with T6 during both the seasons. The pooled mean over the seasons revealed that the grain yield (5161 kg ha-1) and straw yield (6148 kg ha-1) of rice were higher in T3 and was on par with T6. The grain yield increased by 78 and 69 per cent in T3 and T6, respectively over control. The nutrient uptake by plants at panicle initiation and harvest were significantly affected by zinc nutrition. The higher uptake of N, P, K, Ca and Zn by the rice plants at panicle initiation and harvest were observed in T3 which was comparable to T2 and T6 at panicle initiation and comparable to T6 at harvest during both virippu and mundakan. The nutrient use efficiency of P and Zn in terms of agronomic efficiency was the highest in T3 and T6, respectively during virippu and mundakan. The available nutrient status of the soil after each season was significantly influenced by nano zinc nutrition. The available N, P, K and Zn were higher in T3 and T6 during both virippu and mundakan. The dehydrogenase and phosphatase activities were significantly higher in T3 and were on par with T6. The highest net returns (₹ 76622 ha-1 and ₹ 86368 ha-1) and B:C ratio (1.74 and 1.82) were recorded in T3 during virippu and mundakan, respectively. The third part of the experiment was conducted during summer season to study the residual effect of nano zinc nutrition on growth and yield of succeeding crops. The experiment was laid out in strip plot design and was replicated thrice wherein, each individual plots of previous crop were divided to three sub plots and crops viz., grain cowpea (Kanakamony (PTB 1)) and bhindi (Anjitha) were grown in two sub plots and one sub plot was kept as fallow. The main plot treatments were residual nutrients of the previous seasons (N1 to N8) and the sub plot treatments were three crop sequences (C1- rice-rice-grain cowpea, C2- rice-rice-bhindi, C3- rice-rice-fallow). Growth, yield attributes and yield of summer crops viz., grain cowpea and bhindi were higher in N1. Available N, P, K, Zn, and soil enzyme activities were influenced by the residual nutrient status of the soil and crop sequences. Higher available N was observed in N6 and N5, available P, K and dehydrogenase activity were higher in N3, available Zn was the highest in N6, and phosphatase activity was higher in N1. Among the crop sequences, available P, Zn and dehydrogenase activity were the highest in C1. Among the interactions, the highest available Ca, available Zn and phosphatase activity were observed in n8c2, n3c1 and n1c1, respectively. The highest system yield (11504 kg ha-1) and system productivity (32 kg ha-1 day-1) were observed in N3 which was on par with N6. The crop sequence C2 recorded the highest system yield (10592 kg ha-1), while both C2 and C1 sequences showed higher system productivity. Among the interactions, n3c1 and n3c2 recorded the highest system yield (12100 and 12090 kg ha-1, respectively) and system productivity (33 kg ha-1 day-1, respectively). The highest energy efficiency, the lowest specific energy, the highest energy productivity and the highest energy intensity were recorded in N3. Among the crop sequences, C1 recorded the highest energy efficiency (7.42) and energy productivity was higher in C2 (0.62 kg MJ-1). Among the interactions, n3c3 recorded the highest energy efficiency. The data on nutrient balance showed a net gain of nitrogen in all treatments in C1 and C2, except N8. The rice-rice-fallow sequence showed a net gain in N3, and N6. Available phosphorus showed a net loss among all sequences and all treatments except N8. Potassium had a positive balance in the rice-rice-grain cowpea and rice-rice-bhindi in all treatments except N8. In rice-rice-fallow sequence, net gain of K was observed in N3 and N6. Zinc balance was positive in all the crop sequences and all the treatments except N1 and N7 which recorded net loss of Zn. Among the residual nutrients, the highest system net returns (₹ 173627 ha-1) and B:C ratio (1.49) were observed in N3 whereas, among crop sequences, rice-rice-bhindi (C2) showed the highest net returns (₹ 114127 ha-1) and B:C ratio (1.47). Among the treatment combinations, n3c2 recorded the highest net returns (₹ 182091 ha-1) and the highest B:C ratio (1.79) in n3c3. From the study, it can be concluded that nutri priming with nano zinc at 0.05% (50 ml ha-1) followed by foliar spray of nano zinc at 0.05% (250 ml ha-1) at maximum tillering stage along with soil test basis recommended dose of nutrients was effective way in enhancing the productivity and profitability of rice in high phosphorus soils. The growth and yield of grain cowpea and bhindi were the highest in residual nutrient with soil application of ZnSO4 at 20 kg ha-1 [applied only in virippu]. Rice-rice-bhindi was identified as the promising crop sequence in terms of system productivity and system profitability.Item Integrated management of purple nutsedge (Cyperus rotundus L.) in grain legumes(Department of Agronomy, College of Agriculture,Vellayani, 2025-06-20) Mena Sai Rajeswari Kalyani; Ameena, MThe study entitled ‘Integrated management of purple nutsedge (Cyperus rotundus L.) in grain legumes’ was conducted at the College of Agriculture, Vellayani, Thiruvananthapuram, Kerala, during 2020-2025. The objectives of the study were to standardize land preparation methods to deplete the tuber reserves of nutsedge, formulate an integrated management strategy for Cyperus rotundus in grain cowpea, assess the residual effect of the herbicides on successive crop, and evaluate the in vitro sensitivity of beneficial organisms to these herbicides. The investigation comprised of five experiments. The first experiment was conducted was conducted at Instructional Farm, College of Agriculture, Vellayani to evaluate the efficacy of land preparation methods to exhaust tuber reserve and nutsedge regeneration. The experiment was laid out in randomized complete block design (RCBD) with eight treatments replicated thrice. The treatments were: T1 [stale seed bed method (SSB) with halosulfuron methyl at 60 g ha-1], T2 [SSB with halosulfuron methyl at 67.5 g ha-1], T3 [SSB with halosulfuron methyl at 75 g ha-1], T4 [SSB with chlorimuron ethyl at 9 g ha-1], T5 [SSB with chlorimuron ethyl at 12 g ha-1], T6 [SSB with glyphosate at 1.5 kg ha-1], T7 [SSB with mechanical destruction] and T8 [SSB alone]. The herbicides were applied when the nutsedge plants were at three to four leaf stage. Results revealed that T6 resulted in lower final population, shoot dry weight, tuber dry weight and tuber viability of nutsedge at 6 weeks after spraying of herbicide (WASP) and comparable with T3 and T2. The treatments, T6, T3 and T2 resulted in higher weed control efficiency (88.52, 82.28 and 82.27 %, respectively) and lower regeneration count at 6 WASP (11.11, 13.33 and 15.56 m-2). The study confirmed that halosulfuron methyl at 67.5 g ha-1 was equally effective as glyphosate at 1.5 kg ha-1 in depleting the tuber reserves and regeneration count of C. rotundus under SSB and hence, this treatment was selected as the most effective land preparation method for raising grain cowpea. The second experiment ‘Integrated management of purple nutsedge’ was conducted in the locations having severe nutsedge infestation at Instructional Farm, College of Agriculture, Vellayani during first (kharif) and second crop (rabi) seasons of 2022-23. The experiment was laid out in RCBD with nine treatments replicated thrice. The treatments comprised of T1 (pre-emergence diclosulam at 12.5g ha-1), T2 (post directed application of chlorimuron ethyl at 9 g ha-1 at 20 DAS), T3 (post emergence haloxyfop R methyl at 100 g ha-1 at 20 DAS), T4 (T1 followed by (fb) wheel hoe weeding (WH) at 25 DAS), T5 (T2 fb WH at 40 DAS), T6 (T3 fb WH at 40 DAS), T7 (pre-emergence pretilachlor at 0.75 kg ha-1), T8 (hand weeding twice at 20 and 40 DAS) and T9 (weedy check). The grain cowpea variety DC-15 was raised as per KAU POP recommendations. The growth parameters of grain cowpea were significantly influenced by the weed management practices. The treatment T4 resulted in taller plants, higher branches per plant, green leaves per plant, leaf area index and dry matter production per plant at harvest and was comparable with T8 and T1 during both the seasons. The yield attributes viz., number of pods per plant, pod weight per plant, seed yield and haulm yield per plant were found to be higher in T4 during both the seasons. Pooled analysis over both seasons revealed that the highest seed yield was recorded in T4 (1717 kg ha-1) while the lowest in T9 (871 kg ha-1). The yield reduction due to weeds in cowpea was estimated to be 46.66 per cent during kharif and 50.56 per cent during rabi. The treatment T4 resulted in lower total weed population and dry weight resulting in higher weed control efficiency at 15 and 30 DAS during both kharif (90.96 and 84.50 %, respectively) and rabi seasons (78.84 and 82.67 %, respectively). Lower regeneration counts of C. rotundus at 45 DAS was noted in T4 (13.33 and 11.10 m-2) during both seasons, respectively. The N, P and K removal by weeds was found to be lower at 15 and 30 DAS in T4 during both seasons. Further, at just before spraying, T6 showed higher microbial and enzyme activity, while T8 noted the highest microbial and enzyme activity at 15 and 30 days after spraying, across both the seasons. Pre emergence diclosulam (12.5 g ha-1) fb WH at 25 DAS turned out to be the most economic nutsedge management strategy in cowpea with higher net income (₹ 41,894 and ₹ 19,081 ha-1) and B: C ratio (1.69 and 1.32) during kharif and rabi seasons, respectively and was comparable with T1. The third experiment ‘Screening of indicator plants’ was conducted in a net house with two test crops (finger millet and cucumber) and three herbicides (diclosulam, halosulfuron methyl and haloxyfop R methyl) to identify the most sensitive indicator plant for each herbicide. The experiment was laid out in completely randomised design (CRD) with eight treatments replicated thrice. Treatments comprised of different concentrations of the test herbicides (ppm) viz., T1 (0.01), T2 (0.05), T3 (0.1), T4 (0.5), T5 (1.0), T6 (10), T7 (100) and T8 (control). Results revealed that all the three tested herbicides had a significant impact on the growth of both the crops tested. As herbicide concentration increased, there was a corresponding decline in shoot length, root length, shoot and root dry weights of both test crops. Finger millet exhibited greater sensitivity to diclosulam and halosulfuron methyl than cucumber, with the highest R² values recorded for all parameters using cubic polynomial regression equations and hence selected as the successive crop for assessing residual herbicide effects. The fourth experiment ‘Assessing the residual effect of herbicides on succeeding crop’ was carried out after the harvest of cowpea using the finger millet variety VR-847. Hundred per cent seedling emergence without significant grain yield reduction was observed indicating no residual impact of the herbicides on successive crop. The fifth experiment ‘in vitro sensitivity of beneficial organisms’ was conducted to assess in vitro sensitivity of Trichodermaasperellum and Rhizobium sp. (RH-15) to three herbicides (diclosulam, halosulfuron methyl and haloxyfop R methyl). The experiment was laid out in CRD with eight treatments replicated thrice. The treatments comprised of different concentrations (ppm) of diclosulam (T1-20, T2- 25, T3- 30, T4- 35, T5- 40, T6- 45, T7- 50 and T8-control); halosulfuron methyl (T1-100, T2 120, T3- 140, T4- 160, T5- 180, T6- 200, T7- 220 and T8-control) and haloxyfop R methyl (T1-180, T2-200, T3- 220, T4- 240, T5- 260, T6- 280, T7- 300 and T8-control). Results revealed that diclosulam and haloxyfop R methyl had no significant effect on the radial growth of Trichodermaasperellum, with all concentrations showing uniform colony diameter of 9 cm and zero inhibition. In contrast, halosulfuron methyl significantly inhibited T. asperellum growth, ranging from 38.55 to 76.67 per cent. Further, Rhizobium sp. showed no zone of inhibition for any of the three herbicides, indicating no adverse effect on its growth. The study identified stale seedbed with halosulfuron methyl (67.5 g ha-1) followed by pre-emergence diclosulam (12.5 g ha-1) along with wheel hoe weeding at 25 DAS as the most effective and economical integrated management strategy for purple nutsedge in grain cowpea. The tested herbicides (diclosulam, halosulfuron methyl, and haloxyfop R methyl) had no adverse effects on soil health, enzyme activity, or residual impact and were compatible with Rhizobium sp. However, Trichodermaasperellum showed sensitivity to halosulfuron methyl.Item Nutrient management in cassava (Manihot esculenta Crantz) variety Vellayani Hraswa for southern laterites (Agro ecological unit 8)(Department of Agronomy, College of Agriculture ,Vellayani, 2024-06-01) Aparna, R A.Phosphorus transformation in acid sulphate rice soils of Kerala Acid sulphate soils are lowland soils situated below the mean sea level along the coastal tracts of Kottayam, Alappuzha, Thrissur and Malappuram districts of Kerala, spread in two agro-ecological units namely Kuttanad (AEU 4) and Kole lands (AEU 6). These soils are characterised by high levels of organic matter, low pH and toxicity of iron (Fe) and aluminium (Al) with wide variability in available phosphorus (P) content. Acid sulphate soils generally contain substantial quantities of Fe sulphide minerals or the oxidation reaction products of these sulphidic minerals and the protonated/non-protonated surfaces of Al/Fe hydroxides and oxides, resulting in P sorption and formation of the complexes, thus decreasing P availability in soil. However, the recent fertility evaluations across the state showed high available P status due to solubilization of the accumulated applied P. To develop an economically viable phosphorus nutrient management strategy, a pioneer study on P transformations in acid sulphate soils is highly required. The study aimed to understand seasonal variation of nutrients and transformations of phosphorus in acid sulphate soils. The investigation was conducted at Radiotracer laboratory, College of Agriculture, Vellanikkara, with four experiments viz., collection and characterization of soil samples from the acid sulphate soils of Kerala in two seasons, fractionation of phosphorus, adsorption study and an incubation study. In the first experiment, 125 representative soil samples from Kuttanad (AEU 4) (15 each from Upper Kuttanad, Lower Kuttanad, Vechur Kari, Purakkad Kari and Kayal lands) and Kole lands (25 each from Thrissur and Ponnani Kole) in pre-monsoon (April) and post-monsoon (November) were collected and characterised. The experiments on the fractionation and adsorption of phosphorus were done in thirty-five samples ie., five each from the seven selected locations with varying available P status. Phosphorus fractionation was carried out to quantify different fractions of phosphorus and their contribution to the available pool. The inorganic P fractions includes saloid bound P, Fe-P, Al-P, reductant soluble P and Ca-P. Adsorption study was carried out to work out the quantity/ intensity (Q/I) relationship of phosphorus and the pattern of adsorption in acid sulphate soils. Finally, an incubation experiment of 90 days duration was conducted to understand the effect of phosphatic fertilisers, lime and farmyard manure at different levels in low and high available P soils collected from Kuttanad and Kole lands. The treatment details of the incubation study were three levels of phosphatic fertilisers (as SSP - 0, 35 and 70 kg ha-1), two levels of lime (as CaO - without lime and lime as per POP recommendations) and two levels of farmyard manure (0 t ha-1 and 5 t ha-1). The observations were made on 30th, 60th and 90th days of incubation. Seasonal characterisation of soil samples during the two seasons revealed that among the collected samples, 50 per cent was sandy clay loam and 40 per cent was sandy loam in texture. The acidity characterisation of soil samples reaffirmed the extreme acidity condition of acid sulphate soils with 40 per cent of samples coming under extremely acidic class and 20 per cent under very strongly acidic. Among the collected soil samples, 37.60 per cent was low in available P, 23.20 per cent and 39.20 per cent under medium and high P respectively. The soil sample from Vechur Kari region showed the highest value of organic carbon (11.46 %). The available micronutrients viz., Fe and Mn showed very high concentrations. Among the acidity fractions, potential acidity was dominant followed by pH-dependent acidity in both seasons. Seasonal variation in electrochemical properties like pH and EC was noticed between two seasons. Ultra acidic soil reaction with high electrical conductivity was noticed during pre-monsoon period which reaffirm the salt water intrusion in these locations. Oxidation of pyrite mineral resulted in high amount of available sulphur as well as potential acidity during pre-monsoon. Reduced condition prevailing in the post monsoon resulted in high concentration of available iron. The fractionation study of phosphorus indicated that the per cent distribution of different phosphorus fractions followed the order, Fe- P > organic P > reductant soluble P > calcium P > aluminium P > saloid bound P. The contribution of dominant fraction (Fe-P) to the available P is mainly through saloid bound P. The phosphorus fixing capacity was significantly and positively correlated with clay, organic matter content, and negatively correlated with the available P. In the adsorption study, high buffer power indicated the ability of acid sulphate soils to replenish the depleted available P. Freundlich adsorption isotherm was found to be the best to explain P adsorption followed by Langmuir and Temkin adsorption isotherms. The Freundlich adsorption constant, KF was found to be correlated with organic matter which confirmed the fixation of phosphorus by organic matter in acid sulphate soils. In most of the soils, Langmuir adsorption constant (KL) increased with rise in temperature, indicates chemisorption behaviour of P adsorption. The incubation study affirmed that in soils with low available P, the addition of SSP at doses of 70 kg ha-1 and 35 kg ha-1 along with lime and FYM showed a significant increase in pH. In these soils, the addition of SSP (70 kg ha-1) along with lime and FYM registered the highest available P of 51.63 and 73.33 kg ha-1 respectively in Kuttanad and Kole soils at 60th day of incubation. In the same treatment, Fe bound P fraction was found to be highest with a decreasing trend towards 60th day of incubation, which increased after that. In the case of soils with high available P, the treatment combination with the addition of the highest dose of SSP (70 kg ha-1) along with lime and FYM showed the highest pH with an increasing trend towards 60th day. On the contrary to low P soils, in high P soils, the addition of SSP at 35 kg ha-1 along with lime and FYM registered the highest available P of 309.44 and 126.94 kg ha-1 respectively in Kuttanad and Kole at 30th day of incubation followed by a reduction towards 60th day of incubation. Phosphorus, a widely varying nutrient in acid sulphate soils is prone to high adsorption and fixation in soil depending upon the type of clay, organic matter content and amount of oxides and hydroxides of Fe and Al. There was no significant seasonal variation of P in soil samples from AEU 4 and AEU 6. In acid sulphate soils, the most dominant fraction, Fe-P contributed to available P mainly through saloid bound P, which is the water-soluble and loosely bound P fraction. The reduction of available P with the increase in P fixing capacity necessitates its estimation at least for the grouping of soils for the efficient management of phosphorus. In soils with high available P, addition of lower dose of SSP (35 kg ha-1) along with organic manure (FYM @ 5 t ha- 1) and lime (POP recommendations) is sufficient to enhance the P availability. Where as, in soils with low available P, addition of higher dose of SSP (70 kg ha-1) along with organic manure (FYM @ 5 t ha-1) and lime (POP recommendations) enhanced the P availability than its sole application. In this regard, field experiments in acid sulphate soils have to be conducted to confirm the results of incubation study in rice under natural system and more investigation is needed to know the interaction between organic matter and organic P fraction. As the organic matter plays the dual function in the environment- as a link and as a bottleneck for phosphorus availability, detailed study should be undertaken to know the complex formed by P fixation and its degree of crystallinity for developing better P management strategies in acid sulphate soils.Item Resilient rice based cropping systems for lowlands(Department of Agronomy, College of Agriculture, Vellayani, 2024-04-01) Jince mary, M Joy.; Jacob John; Rajasree, GThe study entitled “Resilient rice based cropping systems for lowlands” was carried out at the Department of Agronomy, College of Agriculture, Vellayani during the period from 2019-2023. The major objectives of the study were to evaluate the performance, in terms of yield and economics, of different rice based cropping systems in lowlands, investigate their impact on weed dynamics, soil health and carbon dioxide emission, and assess the residual effect on the succeeding virippu rice crop. The investigation comprised two experiments viz. Experiment I: Performance of different rice based cropping systems in lowlands and their impact on the weed dynamics, soil health and carbon dioxide emission and Experiment II: Residual effect of rice based cropping systems on the succeeding virippu rice crop. The field experiments were carried out at the Integrated Farming System Research Station, Karamana, during 2019-2020 in randomized block design with eleven cropping systems [rice-fallow-fallow (T1), rice-rice-fallow (T2), rice-dhaincha – cowpea (T3), (rice + dhaincha)- rice – green gram (T4), rice – cassava – amaranthus (T5), ricecassava- cowpea (T6), rice – para grass- fodder cowpea (T7), rice- fodder cowpea – fodder maize (T8), rice- bhindi – culinary melon (T9), rice – bhindi – yard long bean (T10) and rice – rice – amaranthus (T11)], each replicated thrice. In treatment T4, dhaincha was used for brown manuring. It was raised as an intercrop by sowing seeds @ 20 kg ha,-1 two days after transplanting rice and was later incorporated by spraying 2, 4- D @ 1.0 kg ha -1 at 50 per cent flowering stage (45 DAS). The varieties used were, Uma (rice), dhaincha local (dhaincha), Anaswara (cowpea), CO-8 (green gram), Vellayani Hraswa (cassava), Arun (amaranthus), local (paragrass), CO-8 (fodder cowpea), African Tall (fodder maize), Salkeerthi (bhindi), KAU Vishal (culinary melon) and Vellayani Jyothika (yard long bean). During virippu, the highest yield of rice was in T9 (5016 kg ha-1) and the lowest in T1 (3463 kg ha-1). Fodder cowpea produced the highest yield among the crops grown during mundakan (24434 kg ha-1) and summer (26620 kg ha-1). The rice equivalent yield (REY) in mundakan and summer seasons differed significantly among the systems. The REY in mundakan was the highest in T10 (16761 kg ha-1) which was on par with T9 (16419 kg ha-1). The least REY in mundakan was obtained from T3 and T7 (486 kg ha-1). The highest REY in summer was obtained from T10 (7348 kg ha-1) followed by T11 (6532 kg ha-1) which were on par. Rice - bhindi - yard long bean sequence (T10) produced the lowest weed dry matter at 20 DAS (46.95 g m-2) and 40 DAS (33.15 g m-2). Highest weed dry matter at 20 DAS (75.80 g m-2) and 40 DAS (87.32g m-2) was recorded in T1 at the end of the crop cycle. Treatment T10 had the highest weed smothering efficiency (WSE) at 20 DAS (38.07 %) and 40 DAS (63.20%) at the end of the crop cycle. Data on influence of physical properties of soil at the end of crop cycle among the cropping systems revealed that, the greatest decrease (8.09%) in bulk density over the initial value was observed in T9 while T1 showed an increase in bulk density (1.37%). The highest increase in water holding capacity was observed in T4 (8.59%) while T1 showed a decrease in water holding capacity by 7.43% over the initial value by the end of the crop cycle. Soil pH did not vary significantly among the cropping sequences. Significantly higher organic C (1.94%, 1.86%), labile C (2310 mg kg-1, 1614 mg kg-1) and water-soluble C (33.69 mg kg-1 , 21.70 mg kg-1) at 0-15 cm and 15-30 cm respectively were recorded in T9 at the end of the crop cycle. Results on available nutrient status in soil at the end of crop cycle revealed that, the highest available nitrogen was noticed in T10 (342.87 kg ha -1) while available P and K did not show any significant variation among the cropping systems. Exchangeable Ca was the highest in T5 (215.08 mg kg-1) while exchangeable Mg and available Fe did not show any significant variation among the cropping systems. Available Zn was the highest in T6 (3.697 mg kg-1). At the end of crop cycle, T10 (rice - bhindi - yard long bean), T5 (rice - cassava- amaranthus) and T6 (rice- cassava – cowpea) recorded the highest urease (91.07 mg g- 1 h-1), acid phosphatase (31.16 μg g-1 h-1) and dehydrogenase activity (34.51, μg g-1 h-1) respectively. Perusal of data on total nutrient uptake by crops at the end of crop cycle divulged that among the cropping systems, the highest N uptake (234.70 kg ha-1) was in T8 while highest P (54.92 kg ha -1) and K uptake (244.90 kg ha-1) were noticed in T6. T5 recorded highest Ca (114.20 kg ha -1) and Fe uptake (12.60 kg ha-1) while T3 and T7 recorded highest Mg (81.89 kg ha -1) and Zn uptake (17.62 kg ha-1) respectively. Total nutrients recycled through crop residues at the end of crop cycle showed that, T4 recorded the highest nitrogen recycled (19.52 kg ha -1) while T6 recorded the highest P recycled (5.13 kg ha -1) and T10 recorded the highest K (17.04 kg ha -1) recycled. Highest Ca (8.61 kg ha -1) and Zn (1.55 kg ha -1) were recycled by T9 while T7 recorded the highest Mg recycled (8.16 kg ha -1) and T3 (1.81 kg ha -1) recorded the highest Fe recycled. Data on total nutrients removed by weeds by the end of crop cycle revealed that T7 recorded the least N removal (18.07 kg ha -1) while T8 recorded lowest P removal (6.70 kg ha -1) and T10 recorded lowest K (19.85 kg ha -1), Mg (2.24 kg ha -1) and Zn removal (0.015 kg ha -1). T8 recorded the lowest Ca removal (0.72 kg ha -1) and T3 recorded the lowest Fe removal (0.077 kg ha -1). The removal of all nutrients assessed was highest in T1. Results from CO2 emission study revealed that in mundakan, T5 (281 ppm) and T6 (283 ppm), with cassava exhibited lower CO2 emissions. T5 (25.93 ºC) recorded the least and T4 recorded the highest (32.24 ºC) soil temperatures in mundakan season. T7 and T8 recorded significantly higher soil temperatures (37.80 ºC) and the least (34.03 ºC) was noticed in T1 in summer season. The highest soil moisture was recorded in T4 (23.43%) which was on par with most of the treatments and the lowest value of soil moisture was noticed in T1 (15.92%) during mundakan. The highest rice equivalent yield (28.93 t ha-1), maximum gross returns (₹ 9,01,865 ha-1) and net returns (₹ 5,45,705 ha-1) were obtained in T10 (rice - bhindi - yard long bean). The B:C ratio was the highest for T9 (rice – bhindi - culinary melon) (2.64) followed by T10 (rice - bhindi - yard long bean) (2.53). Based on data of three years, the highest stability index was recorded in rice –cassava – cowpea (T6) (0.95) while rice - bhindi - yard long bean (T10) sequence had the lowest (0.42). The second experiment revealed that rice crop following rice – cassava – amaranthus (T5) was superior in terms of number of grains per panicle (113), grain yield (3934 kg ha-1) and straw yield (4311.67 kg ha -1). Significantly higher weed dry weight was recorded in T1 (48.25 g m-2) and the lowest in T5 (9.86 g m-2) at 20 DAS. At 40 DAT, significantly higher weed dry weight was noticed in T1 (96.12 g m-2) while the lowest was in T4 (23.66 g m-2). The treatment T8 recorded the highest weed smothering efficiency (80%) which was on par with T5 (79.63%) and T4 (77.05%) at 20 DAT. At 40 DAT, T4 recorded significantly higher weed smothering efficiency (74.33%). Significantly highest NUE was in the treatment T5 (8.62) and the lowest in T1 (5.74). Available NUE was highest in T5 (9.72) followed by T6 (9.24) which were on par, while T1 (7.06) showed lowest value of available NUE. It could be concluded that, among different rice based cropping systems in lowlands, rice – bhindi – yard long bean (T10) performed better in terms of yield, economics, weed dynamics and soil health. Cropping systems with cassava during the mundakan season had lower CO2 emissions. Rice crop succeeding rice – cassava – amaranthus (T5) was superior in terms of number of grains per panicle (113), grain yield (3934 kg ha -1) and straw yield (4311 kg ha -1), NUE (8.61) and available NUE (9.72).Item Crop intensification and stress tolerance in hybrid napier(Department of Agronomy, College of Agriculture ,Vellanikkara, 2024-03-07) Akhila, C Thampi.; Prameela, PHybrid Napier (Pennisetum glaucum X Pennisetum purpureum) is a popular fodder grass among dairy farmers of Kerala due to its high production potential. However, there is a significant gap between fodder demand and supply, given the limited land availability in the State. Expanding fodder cultivation through crop intensification with the inclusion of fodder legumes in the existing cropping system is a viable option to boost fodder production and quality. Understanding the salt and flood tolerance of hybrid napier can help the farmers select suitable cultivars for coastal and flood-prone areas, to ensure fodder availability. In this context, an investigation entitled ‘Crop intensification and stress tolerance in hybrid napier’ was conducted at the Agronomy Farm, Department of Agronomy, College of Agriculture, Vellanikkara, Kerala from 2019 to 2021. The objectives were to assess the suitability of intercropping legumes with hybrid napier, its effect on growth, yield, quality, as well as soil health, and to study the response of a few popular hybrid napier cultivars to salinity stress and short-term flooding. The investigation comprised of three experiments (i) the production potential of hybrid napier-based legume intercropping systems (ii) tolerance of high-yielding hybrid napier cultivars to salinity stress and (iii) tolerance of high-yielding hybrid napier cultivars to short-term flooding. The field experiment on hybrid napier-based legume intercropping systems (HN+legume) was conducted during the two-year period from 2019 to 2021. It was laid out in randomized block design with four replications. The treatments consisted of hybrid napier in normal rows (60cm x 60cm) (T1), hybrid napier in paired rows (45/90cm) (T2), HN in paired rows + fodder cowpea (T3), HN in paired rows + stylosanthes (T4) and HN in paired rows + horse gram (T5). Three additional treatments of sole crops of fodder cowpea (T6), stylosanthes (Stylosanthes guianensis) (T7), and horse gram (T8) were included for comparison of production efficiency in the intercropping system under study. The results of the study indicate the possibility of intercropping hybrid napier planted in paired rows with legumes, in Kerala. Among the legumes, stylosanthes were the most suitable in terms of yield, net profit, and B-C ratio. Varieties IGFRI-3 and CO-3 were found inherently tolerant to mild levels of salinity stress compared to CO-5 and Suguna. Considering fodder yield, varieties CO-5 was found better suited to areas amenable to shortterm flooding (3-4 cm water depth, up to 15 days), and flooding immediately after harvesting was identified as the susceptible stage.Item Resource management for optimising tuberisation in Tannia (Xanthosoma sagittifolium(L.) Schott)(Department of Agronomy, College of Agriculture, Vellayani, 2024-04-08) Sreena, K S; Shalini Pillai, PThe research entitled ‘Resource management for optimising tuberisation in tannia (Xanthosoma sagittifolium (L.) Schott)’ was conducted at College of Agriculture, Vellayani, Thiruvananthapuram, during 2019-2023. The objectives of the study were to characterise the tannia growing soils of three agro-ecological units (AEUs), to study the tuberisation pattern of tannia, to assess the effect of soil amendments and nutrient management in tannia, and to work out the economics. The study was undertaken as three experiments. In the first experiment entitled “Characterisation of tannia growing soils” four physical properties, viz., soil texture, bulk density (BD), particle density (PD) and water holding capacity (WHC), 17 chemical properties viz., pH, exchangeable acidity, electrical conductivity (EC), cation exchange capacity (CEC), organic carbon (OC), N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, B and Al, and three biological properties, viz., soil respiratory activity (SRA), total microbial biomass carbon (TMBC) and dehydrogenase activity (DA) of tannia growing soils of three selected AEUs were analysed. The selected AEUs were AEU 8 (Southern Laterites), AEU 9 (South Central Laterites), and AEU 12 (Southern and Central Foothills). The experiment II (Tuberization pattern of tannia) and experiment III (Effect of soil amendments and nutrient management in tannia) were conducted in AEU 9, in a farmer’s field located at Kollam district, Kerala, during the period from February to December 2021. The second experiment was a pot study laid out in CRD with three treatments (t1: Kerala Agricultural University Package of Practices recommendation (KAU POP), t2: Farmer’s practice, t3: Absolute control) and six replications. The nutrient management followed in farmer’s practice was application of lime (350 kg ha-1) as soil amendment along with 25: 25: 50 kg NPK ha-1. The third experiment was laid out in RCBD with (4 x 3) + 1 treatments, replicated thrice. The treatments comprised combinations of soil amendments (a1: dolomite, a2: phosphogypsum, a3: compost + dolomite, and a4: compost + phosphogypsum) and nutrient management [n1: recommended dose of nutrients (RDN) + borax (10 kg ha-1) at 4 MAP + solubor (0.1%) at 5, 6 and 7 MAP, n2: RDN + ZnSO4 (20 kg ha-1) at 4 MAP + ZnSO4 (1%) at 5, 6 and 7 MAP and n3: RDN + borax (10 kg ha-1) + ZnSO4 (20 kg ha-1) at 4 MAP + solubor (0.1%) + ZnSO4 (1%) at 5,6 and 7 MAP], compared against a control (KAU POP). The soil of the experimental site was sandy loam in texture and strongly acidic in reaction (surface soil pH - 5.45; sub soil pH - 5.05). Cormel pieces (100 g) of a local variety were planted at a spacing of 90 cm x 90 cm. Compost, dolomite and phosphogypsum were applied at the rate of 1kg per plant, 80 g per plant and 50 g per plant respectively. Cluster analysis of the three selected AEUs was carried out to group similar panchayats based on their physical, chemical, and biological variation. In the case of physical properties, three clusters were identified. The cluster 1 was heterogenous, including panchayats with high influence of WHC, PD and BD and lesser influence of PD and BD and classified as “moderately suitable for tannia”. The cluster 2 comprised panchayats which had high influence of WHC and lesser influence of PD and BD This cluster was classified as “suitable for tannia”. Majority of panchayats in AEU 8 fell in cluster 3 which was named as “less suitable for tannia” with lesser influence of WHC and higher impact of PD and BD. Cluster analysis of the soil chemical properties revealed three optimum number of clusters. Cluster 1 was influenced with high values of EC, CEC, OC, K, Ca, Mg and S and lower values of pH, exchangeable acidity, Fe, Zn, B, and Al. It was categorised “suitable for tannia”. It was mostly found in AEU 8. The variable P was quite prevalent in the panchayats of AEU 8. Four panchayats of AEU 12 were also included in cluster 1. Regarding cluster 2, categorised as “moderately suitable for tannia” a significant proportion of panchayats within AEU 8 and AEU 9 were found to have elevated levels of exchangeable acidity, P, B, Fe, and K. High presence of exchangeable acidity, and P content were observed in Pallichal, Karumkulam and Venganoor of AEU 8, and Pooyappally of AEU 9. The variables, B and Fe were found to be high in AEU 8 and AEU 9. This cluster also comprised two panchayats of AEU 12, with high influence of available K. Cluster 3 included panchayats with higher influence of pH, Fe, Zn, B, and Al. It was categorised in “less suitable for tannia.” The panchayats covered in AEU 9 exhibited elevated pH, Fe, and B levels. Four panchayats of AEU 12 and one panchayat of AEU 9 had high influence Al and Zn. The study revealed that the tannia growing soils of the selected AEUs could be grouped into three categories (suitable, moderately suitable, and less suitable for tannia) based on the physico-chemical and biological properties of the soil. The Southern and Central Foothills (AEU 12) could be categorised as suitable for tannia, with the panchayat Amboori exhibiting soil properties favourable for cultivating tannia. The rate of tuber bulking in tannia was observed to reach its peak at 4 MAP to 5 MAP. Compared to farmer’s practice, KAU POP showed lesser reduction in the number of roots, root weight and root volume per plant from 6 MAP to harvest, resulting in higher yield. Supplementing KAU POP with basal application of compost (1 kg per plant) and phosphogypsum (50 g per plant), and top dressing with borax (10 kg ha-1) and ZnSO4 (20 kg ha-1) at 4 MAP followed by foliar application of solubor (0.1%), and ZnSO4 (1%) at 5 MAP, 6 MAP and 7 MAP could be recommended for realizing higher yield, starch content, longer shelf-life, and higher net returns of tannia in the South Central Laterites of Kerala.Item Agro- techniques for sesame (Sesamum indicum L.) under partial shade of coconut in southern laterites(Department of Agronomy, College of Agriculture, Vellayani, 2024-10-19) Arunima Babu, C S.; Sheeja, K RajThe study entitled ‘Agro-techniques for sesame (Sesamum indicum L.) under partial shade of coconut in Southern Laterites’ was undertaken at College of Agriculture, Vellayani during 2021-24, with the objectives to standardize the nutrient levels for sesame under partial shade of coconut in Southern Laterites, assess the response of promising sesame varieties to the identified optimum nutrient levels and evaluate the allelopathic effect of sesame on selected weeds and crops. Field experiments were conducted at Coconut Research Station (CRS), Balaramapuram, to identify the optimum nutrient levels for sesame in Southern Laterites during Rabi 2021-22 and 2022-23, using variety Thilak. The experiments were conducted in the inter row spaces of coconut palms aged more than 60 years planted at a spacing of 7.6 m × 7.6 m. It was laid out in central composite design (CCD), with 20 runs viz., T1:31:20:16 kg NPK ha-1, T2:64:20:16 kg NPK ha-1, T3:31:50:16 kg NPK ha-1, T4:64:50:16 kg NPK ha-1,T5:31:20:34 kg NPK ha-1, T6:64:20:34 kg NPK ha-1, T7:31:50:34 kg NPK ha-1, T8:64:50:34 kg NPK ha-1, T9:20:35:25 kg NPK ha- 1, T10:75:35:25 kg NPK ha-1, T11:48:10:25 kg NPK ha-1, T12:48:60:25 kg NPK ha-1, T13:48:35:10 kg NPK ha-1,T14:48:35:40 kg NPK ha-1 and T15 to T20 (represented the central points of CCD): 48:35:25 kg NPK ha-1, replicated thrice. The nutrient level for sesame in Southern Laterites was standardized by plotting response surface curves using the seed yield of sesame during both years. Remaining observations were statistically analysed using randomized block design (RBD) with fifteen treatments (T1-T14, same as that of CCD, T15: was taken as the average of treatments T15-T20 in CCD). The growth parameters viz., plant height, number of leaves per plant, number of branches per plant and dry matter production were significantly influenced by different nutrient levels. Results on growth attributes at harvest revealed that, T1 produced taller plants during 2021-22 and 2022-23. However, T1 was on par with T2 during 2021-22 and with T2 and T4 during 2022-23. During both years, the highest number of leaves per plant was observed in T1 at 60 DAS. However, T1 resulted in more number of branches per plant at harvest during 2021- 22 and was on par with T2. While, during 2022-23, T2 produced more number of branches per plant and was on par with T1. During both years, DMP was significantly higher in T1 at all stages of observation. Physiological parameters were also significantly influenced by nutrient levels. During both years at 60 DAS, T1 resulted in higher LAI. However, it was on par with T2 and T4, during 2021-22 and with T2 during 2022-23. Chlorophyll content at 60 DAS was significant only during 2021-22 and T2 resulted in higher chlorophyll content which was on par with T1 and T4. Crop growth rate varied significantly with nutrient levels. At 40 DAS-60 DAS, T1 resulted in higher CGR which was on par with T2, T4 and T7 during both years. Similarly, higher RGR was noted in T1 which was on par with T2, T4, T7 and T11 at 40 DAS-60 DAS. Greater number of seeds per capsule was observed in T1 which was on par with T2 during 2021-22 and with T2 and T4 during 2022-23. During both years, the highest number of capsules per plant (57.7 and 74.7, respectively) and seed yield (503.5 kg ha-1 and 554.7 kg ha-1, respectively) were observed in T1. Pooled analysis of seed yield also revealed the highest value in T1 (529.1 kg ha-1). Whereas, the haulm yield and harvest index in T1 and T2 were comparable during both years. The optimum NPK levels identified by plotting the response surface curves during 2021-22 were 35:26:7 kg NPK ha-1 and 34:21:3 kg NPK ha-1 and during 2022-23 was 34:35:3 kg NPK ha-1. Oil content in seed varied significantly only during 2021-22 with the treatment T1 resulting in significantly higher oil content. During 2021-22, higher crude protein content was observed in T1 which was on par with T2. While during 2022-23, T2 resulted in higher crude protein content which was on par with T1 and T4. Higher P, Mg and Fe content in the seeds were observed in T2 during both years. Calcium content in the seeds was significant only during 2022-23 and was higher in T1. Similarly, Zinc content in the seeds was significant only during 2021-22 and was higher in T1. Post experiment soil analysis revealed that T1 resulted in higher organic carbon content, available N and P in the soil during both years. Available K was higher in T1 during 2021-22 and in T2 during 2022-23. The N, P and K uptake by the crop were also significantly influenced by nutrient levels and were higher in T1. The results on economics of cultivation revealed the highest gross return, net return and B:C ratio in T1 during both years. Field experiment to validate the response of promising sesame varieties to the identified optimum nutrient levels was laid out in split plot design during 2023- 24 at CRS Balaramapuram. The main plot treatments included five nutrient levels viz., 35:26:7 kg NPK ha-1 (n1), 34:21:3 kg NPK ha-1 (n2), 34:35:3 kg NPK ha-1 (n3), 31:20:16 kg NPK ha-1 (n4) and 30:15:30 kg NPK ha-1 (n5) and the sub plot treatments comprised of six sesame varieties viz., Kayamkulam 1(v1), Thilathara (v2), Thilarani (v3), Thilak (v4), GT 10 (v5) and TMV 7(v6). The nutrient levels had significant influence on growth parameters. Among the nutrient levels, n2 produced the tallest plants at harvest. Similarly at 60 DAS, number of leaves and branches per plant were higher in n2. At harvest significantly higher DMP was observed in n2. Similarly at 60 DAS, n2 resulted in higher LAI and chlorophyll content which was on par with n1. At 60 DAS-harvest, n2 resulted in the highest CGR and RGR. Significantly more number of capsules per plant, seeds per capsule and higher seed yield were observed in n2. Higher haulm yield was also observed in n2 which was on par with n1. Among the quality parameters, higher P, Ca, Mg, Fe and Zn content in the seeds were observed in n2. Similarly, higher N, P and K uptake and available N, P and K in the soil were observed in n2. The results on economics of cultivation revealed that the highest gross return, net return and B:C ratio were observed in n2. Adoption of optimum nutrient level (34:21:3 kg NPK ha-1) reduced the consumption of K by 90 per cent, compared to KAU POP recommendation, which could be attributed to medium to high K status in the soil of Southern Laterites. The growth parameters varied among the tested sesame varieties. Among the varieties, the tallest plants were observed in v5 at harvest. At 60 DAS, greater number of leaves and branches per plant were recorded in v5 which was on par with v4. At harvest, the highest DMP was observed in v5 (19.71 g per plant). Similarly, at 60 DAS, v5 had higher LAI which was on par with v4. The chlorophyll content was the highest in v5 at 60 DAS. Significantly more number of capsules per plant (84.0), higher seed yield (1066.0 kg ha-1) and haulm yield (2502 kg ha-1) were recorded in v5. The variety v5 recorded higher P, Ca, Mg and Fe content in the seeds. Results on nutrient uptake and availability revealed that higher soil available N, P and K in the post-harvest soil and N, P and K uptake by the crop were observed in v5.The variety GT 10 resulted in the highest gross return, net return and B:C ratio. Interaction effect of nutrient levels over varieties revealed that at 60 DAS and harvest, taller plants were observed in n2v5. The treatment, n2v5 also recorded more number of leaves per plant at 60 DAS. At harvest, the highest DMP was observed in n2v5. Higher LAI and chlorophyll content at 60 DAS were observed in n2v5. Similarly, n2v5 produced greater number of capsules per plant, higher seed yield ha-1and haulm yield ha-1. The results on nutrient uptake revealed that n2v5 resulted in higher N and P uptake. The treatment n2v5 also resulted in the highest gross return, net return and B:C ratio. The interaction effect of varieties over nutrient levels revealed that at harvest, all varieties except v3 produced taller plants at nutrient level n2. While v3 produced taller plants at n3. At 60 DAS, all varieties except v3, produced greater number of leaves per plant at n2. While, v3 produced higher number of leaves per plant at n3. At 60 DAS and harvest, all varieties produced higher DMP, LAI and chlorophyll content at n2. Similarly, all varieties produced the highest number of capsules per plant and seed yield ha-1 at n2. All varieties except v3 produced higher haulm yield ha-1 at n2. However, v3 produced higher haulm yield ha-1 at n1. The results on post experiment soil analysis revealed that all varieties except v1 recorded higher available N at n2. While, v1 recorded higher available N at n1. All varieties recorded the highest N and P uptake at nutrient level n2. The results on economics of cultivation revealed that all varieties recorded the highest gross return, net return and B:C ratio at n2. The leachates of different sesame varieties had significant impact on germination and seedling growth of weeds viz., Alternanthera sessilis, Setaria barbata and Cyperus rotundus. Leachate of variety GT10 had significant inhibitory effect on the germination, seedling shoot length, root length, dry weight, SVI I and SVI II of all tested weeds. Similarly, the leachates of different sesame varieties had significant impact on germination and seedling growth of tested crops viz., cowpea and okra. Application of leachate of variety GT 10 resulted in the lowest germination percentage, seedling shoot length, root length, fresh weight, dry weight, SVI I and SVI II of cowpea and okra. While leachates had no significant effect on the germination and seedling growth of amaranthus. From the results of the study, it could be concluded that the optimum nutrient level for sesame under partial shade of coconut in Southern Laterites was 34:21:3 kg NPK ha-1. Among the tested sesame varieties, GT 10 was identified as the best variety for Southern Laterites. The variety GT 10 raised under partial shade of coconut gardens manured with 5 t ha-1 of FYM + 34:21:3 kg NPK ha-1 (full dose of P, K and 75 per cent N as basal application and 25 per cent N as foliar spray at 3 per cent concentration, 30 DAS) realized the highest seed yield, net return and B:C ratio. Application of leachate of variety GT 10 had significant inhibitory effect on the germination and growth of test weeds (Alternanthera sessilis, Setaria barbata and Cyperus rotundus) and test crops (cowpea and okra).Item Nutrient use efficient technologies for enhancing productivity of cowpea[VIGNA UNGUICULATA (L.) WALP.](Department of Agronomy, College of Agriculture ,Vellanikkara, 2024-09-24) Vidhu Priyadarshini, P T.; Anitha, SCowpea, a vital leguminous crop in the semi-arid regions of tropics and sub tropics, plays a key role in sustainable agriculture and nutritional security. However, the productivity of cowpea remains low in various regions of India. There is a critical need to enhance the productivity of cowpea with limited resources to achieve nutritional security for the growing population. The research program entitled, ‘Nutrient use efficient technologies for enhancing productivity of cowpea [Vigna unguiculata ( L.) Walp.]’ was conducted from October 2021 to May 2023 at Instructional Farm, College of Agriculture, Vellanikkara, with the objective, to enhance the nutrient use efficiency and yield of cowpea through fertilizer microdosing, nano NPK and designer seeds. The investigation consisted of three experiments viz., standardization of fertilizer microdosing and seed treatment for cowpea, standardisation of nano fertilizer dose and seed treatment for cowpea and on field evaluation of nutrient use efficient technologies in two different cowpea varieties (Anaswara and PGCP 6) and the field experiments were repeated for three seasons (summer 2022, rabi 2022 and summer 2023). The experiment on standardization of fertilizer microdosing and seed treatments for cowpea consisted of five levels of fertilizer microdosing (25%, 50%, 75% NPK as per POP, NPK as per POP, and absolute control) and three levels of seed treatments (designer seeds, rhizobium treated seeds, and untreated seeds). Among fertilizer microdosing levels, microdosing (50%) exhibited the best growth and yield parameters followed by microdosing (25%). The percentage increase in grain yield with microdosing (50%) was 19% compared to NPK as per POP. Nutrient uptake and soil nutrient availability were higher in microdosing (50%). Partial factor efficiency (PFE), agronomic efficiency (AE) and apparent recovery efficiency (ARE) of N, P and K were significantly higher in microdosing (25%). Among seed treatments, designer seeds demonstrated superiority in terms of growth, yield and nutrient use efficiency. Designer seeds resulted in earlier flowering and led to a 114 per cent increase in grain yield compared to untreated seeds. Regarding interaction effect of treatments, microdosing (50%) with designer seeds showed the best performance followed by microdosing (25%) with designer seeds. Based on these results, microdosing 50% with designer seeds and microdosing (25%) with designer seeds were selected for field study. The experiment on standardization of nano fertilizer dose and seed treatment for cowpea consisted of six levels of nano fertilizers (2/3, 1/2, 1/3, 1/4 NPK as per POP applied as nano fertilizer (NF), NPK as per POP and absolute control) and three levels of seed treatments (designer seeds, rhizobium treated seeds, and untreated seeds). Among nano fertilizers, 2/3 NPK as per POP applied as NF showed significantly higher growth and yield parameters. This treatment resulted in a 14% increase in grain yield compared to NPK as per POP and a 137% increase compared to the absolute control. Significantly higher PFE and AE of N, P and K were recorded in 1/4 NPK as per POP applied as NF. Among seed treatments, designer seeds demonstrated the highest efficiency in terms of growth, yield, and nutrient use efficiency. Considering interaction effect, the application of 2/3 NPK as per POP applied as NF along with designer seeds resulted in 50 per cent increase in grain yield, while 1/4 NPK as per POP applied as NF along with designer seeds led to a 48 per cent increase in yield compared to the recommended dose of NPK as per POP of KAU with untreated seeds. Based on these findings, 2/3 NPK as per POP applied as NF with designer seeds and 1/4 NPK as per POP applied as NF with designer seeds were selected for field study. Experiment on field evaluation of nutrient use efficient technologies, consists of eight treatments viz., best two treatments from experiment I viz., microdosing (25%) with designer seeds, microdosing (50%) with designer seeds, best two treatments from experiment II viz., 2/3 NPK as per POP applied as NF with designer seeds, 1/4 NPK as per POP applied as NF with designer seeds, STCR equation based NPK with designer seeds, soil test based NPK with designer seeds, NPK as per POP with designer seeds and absolute control. Results on field evaluation of nutrient use efficient technologies using cowpea variety Anaswara revealed that microdosing (50%) with designer seeds showed increased growth parameters viz., plant height, number of branches, dry matter production per plant, crop growth rate and relative growth rate. Significantly highest grain yield was recorded in microdosing (50%) with designer seeds. Despite reducing the fertilizer dose to 50%, this treatment resulted in a 16% yield increase compared to the NPK as per POP with designer seeds. Total chlorophyll content at different growth stages and protein content in grains were higher in 1/4 NPK as per POP applied as NF with designer seeds. Soil parameters did not exhibit a consistent trend across treatments. Regarding nutrient use efficiencies, significantly higher partial factor efficiency and agronomic efficiency of N, P and K were recorded in 1/4 NPK as per POP applied as NF with designer seeds. While considering the economics, microdosing (50%) with designer seeds showed higher net returns and a better B:C ratio. Despite the higher yield observed with 2/3 of NPK as per POP applied as NF with designer seeds, the elevated cost of nano fertilizers rendered it less profitable. The field evaluation of nutrient use efficient technologies using cowpea variety, PGCP 6 revealed that microdosing (50%) with designer seeds and 2/3 NPK as per POP applied as NF with designer seeds performed best in terms of growth and yield parameters. The highest yield was recorded in microdosing (50%) with designer seeds followed by 2/3 NPK as per POP applied as NF with designer seeds. Reducing the fertilizer quantity by 50 per cent from NPK as per POP with designer seeds, microdosing (50%) with designer seeds resulted in an 86 per cent increase in yield. Throughout the growth stages, consistently higher total chlorophyll content and protein content in grains were observed with 1/4 of NPK as per POP applied as NF with designer seeds. Soil parameters did not show a consistent trend across treatments. Significantly higher PFE and AE of N, P and K were recorded with 1/4 NPK as per POP applied as NF with designer seeds. In terms of economics, microdosing (50%) with designer seeds demonstrated higher net returns and better B:C ratio. Despite achieving a higher yield with 2/3 of NPK as per POP applied as NF with designer seeds, the high cost of nano fertilizers made this treatment less profitable. From the results of field experiments conducted for both cowpea varieties (Anaswara and PGCP 6), microdosing (50%) with designer seeds can be recommended as an economically viable and nutrient use efficient technology for enhancing cowpea productivity