1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Industrial waste based nano mineral fertilizer for yield enhancement in aerobic rice (Oryza sativa L.)(Department of Agronomy, College of Agriculture,Vellayani, 2026) Kavvampalli Mahadev; Susha, V SThe research entitled “Industrial waste based nano mineral fertilizer for yield enhancement in aerobic rice (Oryza sativa L.)” was conducted during 2023-2025 at College of Agriculture, Vellayani. The research programme was aimed at synthesis of nano slag, characterization of slag and nano slag and evaluation of nano slag based mineral fertilizer on growth and yield of aerobic rice. Nano slag was synthesized using high energy ball mill and SEM (Scanning Electron Microscope) analysis of the nano slag depicted angular, cube-like particles with a rough surface texture and often clustered together. The average particle size observed was 160 nm. X- ray diffraction spectra exhibited a broadened peak at 30º and 35º (2ϴ) indicating the presence of well-defined crystalline phase dominated by magnesium-rich periclase (MgO), calcium ferrite (CaFe2O4), lime (CaO), and (SiO2), along with fractions of manganese oxide and phosphate-associated minerals. FTIR (Fourier-transform infrared spectroscopy) spectra of nano slag revealed the presence of siloxane bond (Si-O-Si) corresponding to peaks at 711-602 cm-1 and 985-875 cm-1. X- ray fluorescence (XRF) analysis of the slag sample revealed that the material predominantly comprised of CaO (50.60%), Fe2O3 (15.40%), SiO2 (10.70%), MgO (1.71%), P2O5 (1.79%) and MnO (0.41%). The field experiment was carried out at the Instructional Farm, College of Agriculture, Vellayani, from March 26/03/25 to July 06/07/25, with KAU Manuratna as the test variety. The experiment was laid out in randomized complete block design with ten treatments replicated thrice. The treatments were a combination of two factors and a control, first factor being phosphorus fertilization (p), viz., p1-No Phosphorus fertilizer, p2- 50% RDP and p3-100% RDP, second factor, nano slag (n) viz., n1- without nano slag, n2- nano slag at 3 t ha-1 and n3- nano slag at 5 t ha-1) and control C- KAU (POP). FYM (Farm Yard Manure), N and K nutrients were applied uniformly as per KAU POP. Results of the experiment revealed that phosphorus fertilization and nano slag had a significant effect on the growth and yield attributes of aerobic rice. The treatment combination p3n3 (100% RDP + 5 t ha⁻¹ nano slag) resulted in taller plants at 30 DAS, 45 DAS and 60 DAS (55.77cm, 71.67 cm and 89.10 cm), with p2n3 (50% RDP + 5 t ha⁻¹ nano slag) being statistically on par at 30 and 60 DAS, and p3n2 (100% RDP + 3 t ha⁻¹ nano slag) at 60 DAS. The lower plant height was observed in p1n1 (0% RDP without nano slag). The highest number of tillers m-2 (310.33, 426.10 and 508.54 m-2 respectively) was noted in p3n3 (100% RDP + 5 t ha⁻¹ nano slag) at 30 DAS, 45 DAS and 60 DAS. Leaf Area Index (LAI) was recorded higher in p3n3 (3.24, 3.69 and 4.19 respectively) at 30 DAS, 45 DAS and 60 DAS and was on par with p2n3 at 60 DAS. The Higher dry matter production (5428 kg ha-1) was recorded in p3n3 and was found to be on par with p2n3. Yield observations indicated that p3n3 (100% RDP + 5 t ha⁻¹ nano slag) resulted in higher number of productive tillers m-2 (435.58), Significantly higher number of grains per panicle (143.69), higher grain yield (3380 kg ha-1) and straw yield (4705 kg ha-1) and was found to be on par with p2n3 (50% RDP + 5 t ha⁻¹ nano slag) in all the yield parameters. The treatment combinations were compared with control treatment (KAU POP) by contrast analysis and found that p2n3 and p3n3 were on par with control in both grain and straw yield. Nutrient content and uptake also showed a significant variation across the treatment combinations. Higher uptake of N, P and K was recorded in p3n3 (75.641, 26.115 and 93.12 kg ha-1 respectively) and with respect to P and K, it was found to be on par with p2n3 (24.76 and 92.54 kg ha-1 respectively). The treatment p3n3 (100% RDP + 5 t ha⁻¹ nano slag) resulted in significantly higher content of Ca, Mg and Si in straw and grain and was found to be on par with p2n3. Micronutrient content of Mn and Cu in straw and grain were higher in p3n3 (100% RDP + 5 t ha⁻¹ nano slag), whereas Fe and Zn content were higher in p2n2 (50% RDP + 3 t ha⁻¹ nano slag). Among soil properties, Cation Exchange Capacity (CEC) was significantly higher (5.73, (c mol (p+) kg -1) in p1n3 (0% RDP + 5 t ha⁻¹ nano slag) and was found to be on par with p2n3(50% RDP + 5 t ha⁻¹ nano slag). However, pH was recorded higher (5.97) in p3n3 (100% RDP + 5 t ha⁻¹ nano slag). When compared against the control (KAU POP) p1n3, p2n3 and p3n3 were found to be on par. Soil Available N, P, K (248.50, 29.11, 189.93 kg ha-1 respectively), Ca, Mg and Si (283.56, 43.89 mg kg-1and 43.64 kg ha-1 respectively) were significantly highest in p3n3 (100% RDP + 5 t ha⁻¹ nano slag). The chlorophyll content at 30 DAS showed no significant variation among the treatments whereas at 60 DAS it was found to be significantly higher in p3n3 (3.04 mg g-1). Dehydrogenase enzyme activity at 60 DAS was significantly higher in p3n3 (54.98 μg TPF g-1soil-1d-1) and it was found to be comparable with p2n3 (54.97 μg TPF g-1soil- 1d-1) and p3n2 (54.81 μg TPF g-1soil-1d-1). Among different treatment combinations p3n3 recorded significantly higher bacterial and fungal count (7.75 and 5.34 log cfu g-1 respectively). In bacterial count it was found to be on par with p2n3 (7.76 log cfu g-1), whereas in fungal count it was on par with p1n3 (5.31 log cfu g-1). Economics of the study revealed that although gross income was higher (1,41,825 ₹ ha⁻¹) in p3n3 (100% RDP + 5 t ha⁻¹ nano slag), the higher net income (45,600 ₹) and BC ratio (1.48) were achieved with p2n3 (50% RDP + 5 t ha⁻¹ nano slag). From the experiment it was concluded that application of 50% Recommended Dose of Phosphorus along with 5 t ha⁻¹ nano slag proved to be equally effective as 100% RDP + 5 t ha⁻¹ nano slag in enhancing crop growth, yield, and profitability of aerobic rice. Nano slag produced from industrial waste slag also substituted the entire lime requirement for aerobic rice enhancing soil pH, nutrient availability and supply of Si and micronutrients such as Fe, Zn, Cu, and Mn.Item Water stress mitigation in upland rice through bacterial seed priming(Department of Agronomy, College of Agriculture, Vellayani, 2025) Jinsiya Jabin, E KThe study entitled ‘Water stress mitigation in upland rice through bacterial seed priming’ was conducted at the College of Agriculture, Vellayani, during 2023-2025. The objective of the study was to assess the influence of bacterial seed priming on upland rice under different levels of moisture stress during summer taken up as lab study, pot culture and field experiment. in vitro screening of beneficial bacteria for imparting drought tolerance in rice variety Prathyasa was conducted by a roll-towel assay laid out in completely randomized design (CRD) with 6×4 treatments, replicated four times. The factors were biopriming (b0- without biopriming, b1- B. pumilus VLY 17, b2- B. amyloliquefaciens VLY 24, b3- B. velezensis PCSE 10, b4- consortium and b5- hydropriming) and moisture stress levels (m₀ – without stress, m₁ – PEG 6000 at 5% (mild stress), m₂ – PEG 6000 at 10% (moderate stress), and m₃ – PEG 6000 at 20% (severe stress).The seeds were primed by soaking in respective bacterial cultures at concentration of 108 CFU mL-1 for 12 hours followed by shade drying. Both biopriming and moisture stress levels significantly influenced the germination indices, root parameters and growth attributes of rice seedlings. Under moderate stress, germination percentage and shoot length were significantly higher when bioprimed with B. pumilus, B. amyloliquefaciens, and the bacterial consortium; and were superior to the unprimed control. However, under severe stress, seeds primed with B. pumilus recorded the highest root-to-shoot ratio compared to the unprimed and hydroprimed control. The second experiment was a pot culture on ‘Screening of beneficial bacteria for drought tolerance in rice’ for identifying the most effective bacterial culture conferring drought tolerance. The experiment was laid out in CRD with two factors viz., biopriming (b0-without biopriming, b1 - B. pumilus, b2 - B. amyloliquefaciens, b3 - B velezensis, b4- consortium) and irrigation intervals [i1 - irrigated to field capacity, i₂ - irrigation completely withdrawn at 40 days after sowing (DAS)] with the rice variety Prathyasa. Seed primed with B. pumilus produced the tallest plants (85.22 cm at 60 DAS), the highest number of leaves (16.08 at 50 DAS) and dry matter production (39.23 g per plant at 50 DAS). At 50 DAS and 60 DAS, the highest rooting depth (27.65 and 32.48 cm), root volume (14.25 and 16.01 cm³), and root dry weight (13.25 and 16.29 g) were observed in B. pumilus primed plants, outperforming the unprimed control under complete irrigation withdrawal at 40 DAS. Lower malondialdehyde content, and the highest superoxide dismutase activity at 60 DAS were also noted in plants primed with B. pumilus. Based on PCA with a cut-off score of 0.75, B. pumilus was identified as the promising bioinoculant for priming and was subsequently selected for field validation under different levels of moisture stress. A field experiment was laid out in a randomized complete block design with 2 × 2 × 2 treatments replicated thrice, with the upland rice variety Prathyasa during March to June 2025. The factors included biopriming (b₀-without biopriming and b₁-with B. pumilus), irrigation interval (i₁ - at 30 mm CPE and i₂ - at 40 mm CPE), and depth of irrigation (d₁ -to a depth of 1.5 cm and d₂ - to a depth of 3.0 cm). The stress levels were categorized as ideal (i1d2), moderate (i2d2), severe (i1d1) and extremely severe (i2d1). The crop was raised as per KAU Package of Practices Recommendations for short-duration rice. Among the growth parameters, B. pumilus priming resulted in the tallest plants (83.47 cm), highest leaf area index (2.78) at 60 DAS, and the highest dry matter accumulation (3538 kg ha⁻¹) at harvest under extremely severe moisture stress compared to the control. Plants of bioprimed seeds produced the highest productive tillers (198.53 m⁻²), grains per panicle (82.33), grain yield (2163 kg ha⁻¹), and straw yield (2445 kg ha⁻¹), along with the lowest spikelet sterility (16.03%) under severe moisture stress, outperforming the unprimed control. Under extremely severe moisture stress, plants of bioprimed seeds recorded the highest proline content (90.04 and 65.08 μg g⁻¹ FW), and the highest relative leaf water content (78.93 and 73.70%) at panicle initiation (PI) and flowering, respectively, compared to the unprimed control. Similarly, under moderate stress, plants of bioprimed seeds maintained the highest cell membrane stability index and chlorophyll stability index at PI and flowering, respectively. Bioprimed plants exhibited the highest water use efficiency and water productivity at all stress levels compared to the unprimed control. They recorded the highest nutrient uptake under extremely severe stress, with nitrogen, phosphorus, and potassium uptake values of 51.75 kg ha⁻¹, 11.45 kg ha⁻¹, and 85.12 kg ha⁻¹, respectively. The study identified seed biopriming with the bacterial isolate Bacillus pumilus VLY 17 as an effective strategy for mitigating moisture stress in upland rice during summer as assessed based on growth, yield, physiological parameters and water-use efficiency.Item Production potential and nutrient dynamics in K-efficient cassava+ legume intercropping systems(Department of Agronomy, college of Agriculture, Vellayani, 2025-08-07) Amala Mary George; Sheeba Rabecca IsaacThe research work entitled “Production potential and nutrient dynamics in K- efficient cassava + legume intercropping systems” was conducted at College of Agriculture, Vellayani during 2019-2025. The major objectives were to standardize the nutrient management practice for K efficient cassava in cassava + legume intercropping systems, to assess the biological efficiency of intercropping systems and to appraise the decomposition dynamics and nutrient mineralization of legume biomass/ residues and the changes in soil properties. The study was conducted as two experiments - i) to evaluate different nutrient management practices in cassava variety Sree Pavithra under intercropping systems and ii) to study the decomposition dynamics and nutrient release from legume biomass/ residues. The first experiment was laid out in farmer’s field at AEU 8 in randomized block design with ten treatments and three replications during the period August 2022 to May 2023. The treatments included T1 : 100 % recommended dose of fertilizers (RDF), T2 :100 % RD of N and P + 50 % K, T3 : 100 % RD of N and P + 25 % K, T4 : 100 % RD of N and P + 0 % K, T5 : 50 % RDF, T6 : 50 % RDF + PGPR Mix I liquid, T7 : 50 % RD of N and P + 25 % K, T8 : 50 % RD of N and P + 25 % K + PGPR Mix I liquid, T9 : 50 % RD of N and P + 0 % K and T10 : 50 % RD of N and P + 0 % K + PGPR Mix I liquid. In situ green manuring of cowpea was done before planting cassava and allowed to decompose for 3 weeks. The RDF adopted in cassava was 100:50:100 kg NPK ha-1. PGPR Mix I was applied at 50 mL L-1, thrice, basal, at 2 and 4 MAP. The grain legumes, cowpea (Shubra) and red gram (APK 1) were evaluated as intercrops in two separate layouts. A control treatment without fertilizer application was also maintained. The intercrops were fertilized separately as per the nutrient recommendations. Other cultural practices were followed as per the recommendations for the crops. The results indicated that nutrient management practices had significant influence on growth characters, yield and nutrient uptake in cassava. Under cowpea intercropping, yield attributes (number of tubers, mean tuber weight, tuber girth) and tuber yields (50.04 t ha-1) were higher in T10, on par with T8 and T6. These treatments also recorded higher and comparable DMP and nutrient uptake. Among quality characters, crude protein content alone recorded significant differences in response to the nutrient management practice adopted. In cowpea, higher number of pods (11.67) and pod yield per plant (13.25 g) were observed in T5 and was on par with T7 and T9. Seed yield (428.68 kg ha-1) was higher in T7, on par with T2, T5 and T9. Competitive indices (LER and LEC) worked out revealed yield advantages with intercropping in all the treatments except control. The highest CEY (52.23 t ha-1) was obtained in T8 (50 % RD N and P + 25 % K + PGPR Mix I liquid). Application of PGPR Mix I (T6, T8 and T10), influenced the organic C fractions in soil favourably. Total microbial counts enumerated in these treatments were also higher and comparable. The post harvest available status of K in soil alone varied significantly and was the highest in T6. Among the nutrient management practices adopted in cassava when intercropped with cowpea, the maximum net income (₹ 458142 ha-1) were realized in T10 (50 % RD N and P + 0 % K + PGPR Mix I liquid). In cassava + red gram intercropping, the highest number of tubers per plant (12.0), mean tuber weight (0.96 kg), tuber weight per plant (9 kg), tuber yield (44.44 t ha-1), DMP and nutrient uptake were recorded in T10, on par with T6 and T8. Crude protein content (2.96 %) in tuber was significantly higher in T6. The growth and yield of red gram were significantly affected by the nutrient management practices evaluated in cassava. The number of pods per plant (28.33) was the highest in T4. Average pod weight, pod yield per plant, number of seeds, seed yield, DMP and nutrient uptakes were higher and comparable in T2, T4, T5, T7 and T9. The LER computed recorded values > 1 in treatments T6, T8 and T10, and LEC values less than 0.25 in all treatments indicating that intercropping with red gram was not advantageous. Treatment T10 recorded the highest CEY (44.96 t ha-1). Soil organic C fractions were higher and comparable in T10, T8 and T6. The available NPK status in soil declined with intercropping, and comparatively higher contents were recorded in treatments involving PGPR application and 100 percent RDF. Microbial activity was favourably influenced by PGPR application, with higher counts in T10, T8 and T6. Economic analysis of the cassava + red gram intercropping system revealed the highest net income (₹ 329379 ha-1) in treatment T10 (50 % RD N and P + 0 % K + PGPR Mix I liquid), among the nutrient management practices studied. Experiment II was conducted as two parts - i) field experiment on the decomposition dynamics and nutrient release from legume biomass/ residues and ii) incubation study on C and N mineralization from legume biomass/ residues. The experiment for the decomposition study was laid out at farmer’s field in AEU 8 during November 2022 to December 2023, in completely randomized design adopting the standard litter bag technique with twelve treatments (leaves, stem, roots and whole plant of green manure cowpea, grain cowpea and red gram respectively) replicated thrice. Among the three legumes, decomposition was most rapid in green manure cowpea, followed by grain cowpea and red gram, and among the plant tissues, it was the slowest in red gram roots (23 fortnights), followed by grain cowpea roots (14 fortnights). The higher decay rate (1.99 g fortnight-1) recorded in grain cowpea leaves was on par with green manure cowpea leaves (1.89 g fortnight-1). Half life values were the lowest for the same treatments. Changes in the nutrient and biochemical parameters revealed decline in N, P, K, Mg, cellulose and phenol contents at the end of decomposition, whereas Ca, micronutrients (Fe, Cu, Mn, Zn) and lignin, accumulated. Nutrient release, irrespective of the plant tissues were the highest for K (93-99 %), followed by N and P, and remained the lowest for Zn. Correlation analysis revealed the significant influence of lignin, C: N ratio and N content on the decay rates. The C and N mineralisation from the biomass were ascertained in the incubation experiment for 120 days, from February to May 2023. The experimental design and treatments were same as in the decomposition study. Total C mineralized followed the order green manure cowpea > grain cowpea > red gram. Among the plant parts, leaves/ stem had higher C mineralization, and roots, the lowest. Mineralisable N contents in the early stages of decomposition were high, the ammoniacal form accounting for the major proportion, but declined as the duration of incubation increased. The NH4+ and NO3- contents analysed at fortnightly intervals revealed the mineralization to occur within 45-60 days after incubation. Considering the yield and economics, in situ green manuring of cowpea, application of 12.5 t FYM, 50 kg N, 25 kg P along with soil application of PGPR Mix I at 50 mL L-1 thrice, basal, at 2 and 4 MAP, can be recommended as the suitable nutrient management practice for K efficient cassava variety Sree Pavithra, under intercropping with the grain legume, cowpea or red gram. Grain cowpea intercropping was more advantageous than red gram, based on the competitive indices assessed in medium K soils. Decay rates and nutrient mineralization were the highest in green manure cowpea, and among the plant tissues, leaves were the most amenable to decomposition. The soil chemical and biological properties were also favourably influenced with legume residue incorporation.Item Soil Moisture deficit irrigation for water stress management in tomoto (solanum lycopersicum L.)(Department of Agronomy, College of Agriculture, Vellayani, 2025-10-25) Sruthi Liz Thomas; Bindhu J SThe project entitled “Soil moisture deficit irrigation for water stress management in tomato (Solanum lycopersicum L.)” was conducted at Instructional Farm, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala, during 2019-2025. The objectives of the study were standardization of irrigation schedule and agronomic management strategies for tomato under soil moisture deficit irrigation, standardization of nutrient source for fertigation and to find out the effect of foliar nutrition of calcium. The study also aimed to develop a suitable statistical model to explain the relationship between deficit irrigation, crop yield and quality with weather parameters. The study comprised of two experiments. The first experiment was laid out in split plot design with sixteen treatment combinations replicated four times during rabi and summer seasons of 2022-23. The main plot treatments were four irrigation levels: I100 - Irrigation to 100 % of FC (I1), I75 - Irrigation to 75% of FC (I2), I50/75 - Irrigation to 50 % of FC up to flowering stage, and 75% of FC at reproductive and maturation stage(I3),and I50 - Irrigation to 50 % of FC (I4), The subplot treatments were four combinations of two planting materials (P) and two mulching materials (M): p1m1-seedling tomato x silver- black plastic mulch, p1m2- seedling tomato x coir geotextile mulch, p2m1-tomato graft x silver-black plastic mulch and p2m2- tomato graft x coir geotextile mulch. The variety Vellayani Vijai was used as seedling and for graft Vellayani Vijai was grafted on to brinjal var Haritha (rootstock). The irrigation was given through drip irrigation based on soil moisture status as per treatments. Fertigation was provided based on recommended dose of fertilizer at 75:40:25 kg N: P2O5: K2O ha-1, modified to 68:10:18 kg ha-1 based on soil test values (KAU, 2024). Irrigation levels, planting and mulching materials significantly influenced the growth parameters of tomato during rabi and summer. Among the irrigation levels, taller plants were observed in I1 and it was on par with I2 except at 90 DAT (days after transplanting) and at harvest. Deeper roots with higher root volume were observed in I4 and was on par with I3. Among, the planting and mulching material combination, P2M1 and P2M2 resulted in higher root length, volume and weight during both the seasons. Irrigation to 100% FC (I1) resulted in higher cell membrane stability, relative water content and stomatal conductance and was on par with I2 in both the seasons except stomatal conductance during summer. Proline and malondialdehyde content in leaves exhibited the highest value in I4. Among planting and mulching materials, higher cell membrane stability and relative water content were observed in P2M1 and P2M2. The highest stomatal conductance was observed in p2m1. Among the interactions, the stomatal conductance was higher in i1p2m1 and was on par with i2p2m1 during summer. The treatment i1p2m1 recorded the highest chlorophyll content at flowering during summer. The yield attributes were significantly influenced by irrigation levels, and planting and mulching material. Quality parameters viz., ascorbic acid content, titrable acidity, total soluble solids and lycopene content were higher in I4. The yield of tomato in I1 and I2 were 26 and 24 per cent higher over I4 during rabi. In summer, I2 recorded higher yield (1314 g plant-1) which was on par with I1 (1254 g plant-1) and was significantly superior over I3 and I4. Among the planting and mulching materials, grafted tomato with plastic mulch was found superior over others. Among the interactions, i1p2m1 and i2p2m1 recorded higher yield. Nutrient uptake was also influenced by treatments and the highest uptake was recorded in I1 and P2M1. The results on post experimental soil analysis after each season revealed that there was a significant variation in soil enzymes, and available N, P and K in response to different irrigation levels, planting and mulching materials. Available N was the highest in I1, while available P and K were highest in I2. Among the treatment combinations, i2p2m1 recorded the highest net returns (₹ 9,13,458 ha-1 and ₹ 8,62,849 ha-1) during rabi and summer, respectively while the highest B:C ratio of 3.37 and 3.62 were recorded in i2p1m1 and i1p1m1 in rabi and summer, respectively. Crop co-efficient of tomato varied from 0.60 to 1.11 during the study. Seasonal consumptive use varied with irrigation levels and the highest value was recorded in I1. The highest water use efficiency of 93 and 84 kg ha mm-1 were recorded in i2p2m1 in rabi and summer, respectively. The agro meteorological parameters such as growing degree days (GDD), for vegetative phenophase varied from 397 oC d (I3 and I4) to 441 oC d (I1 and I2) and for reproductive stage from 1287 oC d to 1368 oC d. The heliothermal units (HTU), photothermal units (PTU) were the lowest in i4p1m1 and i4p1m2 and heat use efficiency (HUE) was the highest in i2p2m1. Based on the findings, alternate-day drip irrigation at 75% of field capacity in grafted tomato cultivated under plastic mulch can be recommended as an agronomically efficient practice for achieving higher productivity, superior fruit quality, and enhanced economic profitability. A robust statistical framework, MANOVA (Multivariate Analysis of Variance) model was developed to elucidate the complex relationship between deficit irrigation and multiple crop responses including yield and quality parameters. Complimenting this, a regression model was also developed and projected the long-term yield trend with weather parameters. The data set generated from experiment I were used and the model established a positive relationship between irrigation to 75 per cent FC and 100 per cent FC for higher yield and quality. Rainfall was the single weather parameter which affect the yield of tomato when simulated for ten years. The best soil moisture level (I2- Irrigation to 75% of FC), planting material (graft) and mulching material (plastic mulch) in experiment 1 were selected for experiment II which was laid out in split plot design with twelve treatment combinations and four replications during rabi of 2023-24. The main plot treatments were four nutrient sources (S): S1-100% NPK fertigation through water soluble fertilizer (WSF), S2-100% NPK fertigation through conventional fertilizer (CF), S3- 50 % NPK (WSF) + 50 % NPK (CF) and S4-100% NPK through soil (CF)) and the three sub plot treatments were Ca fertilization (F): F0- No Ca fertilization, F1- foliar application of 0.5% CAN at 1 MAT and F2-foliar application of 0.5 % CAN at 1 and 2 MAT. The objectives were to standardize nutrient sources for fertigation and to find out the effect of foliar nutrition of Ca for productivity enhancement in grafted tomato with polythene mulch. Nutrients based on RDF modified on soil test values (63:10:18 kg N: P2O5: K2O per ha) was applied through fertigation in 30 splits at 4 days interval. The sources of fertilizers for WSF were 19:19:19, 12:61:00, 13:00:45 and urea, and CF were urea, SSP and MOP. The results revealed that 100 % NPK fertigation through WSF (S1) resulted in taller plants, more number of primary branches and higher stem girth, and was on par with S2. The highest leaf area and dry matter production were observed in S1. The physiological parameters also varied with treatments. Fertigation treatments took less number of days (39 to 41) for 50 per cent flowering. The flower clusters per plant were higher in S1 and was on par with S2. The yield attributes viz., fruits per truss, fruit set percentage, average fruit weight, yield per plant were higher in S1 and superior quality parameters were also observed with S1. The results revealed that application of nutrients through 100 % WSF (S1) or 50% through WSF or CF (S3) recorded 28.6 per cent and 18.8 per cent increased fruit yield over soil application. The foliar application of 0.5 % CAN at 1 and 2 MAT had significant influence on growth, yield and quality of grafted tomato. The foliar application of calcium (F1 and F2) produced more flower clusters per plant. Fruits per truss (6.24), fruit diameter (11.30 cm) and average fruit weight (41 g) were the highest in S1. Flower clusters and fruit diameter were significantly higher in F2 and was on par with F1. Fruits per truss (5.82) and fruit weight (39.66 g) were the highest in F2. The quality parameters viz., ascorbic acid, pH, TSS, titrable acidity and lycopene varied with nutrient sources and Ca nutrition. The total water requirement was 491.1 mm and the highest WUE (water use efficiency) were recorded in s1f2. The highest FUE (247 kg kg-1) was observed in s1f1. The highest nutrient recovery of 18 per cent and 75 per cent for N and P nutrients were observed in s1f0 over soil application. The highest uptake of N, P, K and Ca at harvest were observed in S1 and for calcium it was on par with S2. Among calcium nutrition, F2 recorded the highest uptake. Among the interactions, the highest N uptake was in s1f0 and for K uptake, s1f2 and s1f1 were on par and for Ca, the highest uptake was in s1f2. Available nutrient status of soil after the experiment varied with the treatments. The nutrient sources had a significant influence on soil reaction (pH). Available N and P were significantly higher in S1 and available K was higher in S3 and was on par with S1. Among Ca nutrition, available N was higher in F2 and was on par with F1, whereas available K and Ca were the highest in F2. Nutrient recovery of N varied from 8.13 per cent (S) to 17.96 per cent (s1f0) over soil application and the highest recovery of P and K were observed in s1f0 (74.59 and 64.77 per cent, respectively). The highest net returns were recorded in s1f1. From the study, it could be concluded that alternate-day drip irrigation at 75% field capacity under plastic mulch significantly enhanced the yield, quality, and profitability of grafted tomato. Multivariate analysis (MANOVA) confirmed strong associations between deficit irrigation, yield and quality of tomato, while regression modeling identified rainfall as the most influential weather variable affecting long-term yield. Additionally, fertigation with water-soluble fertilizers in 30 equal splits at four-day intervals, supplemented with foliar application of 0.5 % calcium ammonium nitrate at one and two months after transplanting, further improved plant growth and fruit quality.Item Seed invigouration and weed management for enhancing productivity in aerobic rice (Oryza sativa L.)(Department of Agronomy, College of Agriculture , Vellayani, 2025) Aswin Mohan; Sheeja, K RajThe experiment entitled “Seed inviguoration and weed management for enhancing productivity in aerobic rice (Oryza sativa L.) was conducted at College of Agriculture, Vellayani, Kerala during the period 2022-2024. The investigation pertaining to the study comprised two experiments. A pot culture experiment was conducted to assess the seed invigouration potential of liquid organic manures and field experiment to study the effect of seed invigouration and weed management regimes for higher productivity in aerobic rice. Pot culture experiment was conducted in September 2023 at the College of Agriculture, Vellayani. The experiment followed a completely randomized design (CRD) with 18 treatments in three replications. Treatments included beejamrit, jeevamrit, panchagavya, and vermiwash at 2.5 per cent, 3 per cent, 5 per cent, and 6 per cent concentrations, along with hydropriming and no priming. Seeds of Prathyasa variety were primed for 16 h and dried to original moisture before sowing. Seed priming with liquid organic manures significantly influenced seed germination parameters, seedling attributes, and vigor indices in rice. Among the treatments, beejamrit at 6 per cent concentration recorded higher germination percentage (90.0%), while beejamrit 5 per cent achieved the highest germination rate index (21.6). However, vermiwash 5 per cent proved superior in terms of overall germination performance, registering the highest germination index (125.3), greater speed of germination, and mean daily germination (2.1 no. d-1). In addition, the coefficient of rate of germination was higher in vermiwash 3 per cent (21.4). The shortest mean germination time (5.2 d) was observed with panchagavya 3 per cent. Beejamrit 6 per cent resulted in higher seedling vigor index I (3123) which was statistically on par with vermiwash at 3 per cent, 5 per cent, and 6 per cent, as well as panchagavya 5 per cent. In terms of seedling vigor index II, the higher value was observed with vermiwash 6 per cent (6.64), and was on par with vermiwash 5 per cent(6.49). Based on the total scores, seed priming with 5 per cent and 3 per cent vermiwash concentrations which scored the highest scores of 253 and 237, respectively, were selected for further evaluation under field condition The field experiment was conducted at the organic farm of Department of Agronomy from January to May 2024, in randomized block design (RBD) with three factors. The first factor was two levels of seed priming [vermiwash 3 per cent (p1) and vermiwash 5 per cent (p2)] and a control (unprimed seeds). The second factor consisted of various weed management regimes [wheel hoe weeding (WHW) performed three times at 15, 30, and 45 DAS (r1), live mulching with cowpea followed by WHW at 45 DAS (r2), Gliricidia maculata leaf mulching at 10 t ha-1 followed by WHW at 30 and 45 DAS (r3), hand weeding (HW) thrice at 15, 30, and 45 DAS (r4), and weedy check (r5)]. The Prathyasa variety of rice was used for the study. Seeds were sown using a seed drill, and cowpea seeds were sown for live mulching at 7 DAS of rice and was uprooted and spread at 45 DAS during wheel hoe weeding. Similarly, Gliricidia maculata leaf mulching was also done on 7 DAS. At 15, 45, and 60 DAS, the treatment combination p2r5 resulted in taller plants. However, at 30 DAS and harvest, p1r3 and p2r3 produced taller plants, respectively. Tillers m² were higher in p2r1 at 30 and 60 DAS, though it was on par with p2r3 at 30 DAS and p2r4 at 60 DAS. At 45 DAS, p2r4 produced a greater number of tillers m², and at harvest, p2r3 had a greater number of tillers m². Dry matter production per plant was found to be higher in p2r4 at 15 DAS, and at the remaining stages, p2r3 resulted in higher DMP per plant. The treatment combination p2r1 exhibited higher LAI at 30, 45, and 60 DAS. The chlorophyll content was higher in p2r1 at 15 DAS, p1r2 at 30 DAS, and in treatments p1r3, p2r1, p2r2 and p1r3 at 60 DAS. At 30 DAS - 45 DAS and 60 DAS - harvest, p2r3 resulted in higher crop growth rate (CGR) (4.74 g m² d⁻¹ and 11.96 g m² d⁻¹, respectively). However, at 45 DAS - 60 DAS, p3r3 exhibited the highest CGR (10.85 g m² d⁻¹). For 15 DAS - 30 DAS, p1r1 resulted in higher relative growth rate (RGR) (0.228 g g⁻¹ d⁻¹). However, at 45 DAS - 60 DAS, p3r3 resulted in significantly higher RGR (0.063 g g⁻¹ d⁻¹), and from 60 DAS - harvest, p1r5 showed the highest RGR (0.038 g g⁻¹ d⁻¹). The number of days to 50 per cent flowering ranged between 54 and 59 days across treatments, with the earliest flowering in seeds primed in p2r4 (vermiwash 5% + hand weeding thrice) (54 days). The treatment combination p2r2 had greater number of panicles m-2 (236 no. m-2) and 1000 grain weight, whereas, p2r4 had greater number of grains per panicle and p2r3 had higher panicle weight. The treatment combination, p2r3 resulted in significantly higher grain yield (2625 kg ha-1), straw yield and harvest index. Compared to p2r4 (unprimed seeds + hand weeding thrice), the percentage increase in grain yield observed in p3r3 (seeds primed in vermi wash 5 per cent concentration + G. maculata green leaf mulching with 10 t ha-1 fb WHW at 30 and 60 DAS) was 48.8 per cent. Weed infestation significantly reduced grain yield in aerobic rice. Among the treatment combinations, p3r5 recorded the highest weed index of 71.5 per cent. Among the quality parameters, the treatment combination, p3r1 resulted in higher starch content and was on par with all treatments except p1r1 and p3r4. At 15 DAS, p1r3 resulted in lower absolute density of BLW, however at 30 DAS, 45 DAS and 60 DAS, p2r4 registered lower absolute density of BLW. The absolute density of grasses was found to be lower in p2r2 and p3r5 at 15 DAS, p1r1 at 30 DAS, p2r1 at 45 DAS and p2r1 and p3r3 at 60 DAS. However, p1r3 resulted in lower total density of weeds at 15 DAS and p2r4 at the remaining stages. Weed dry weight was observed to be lower in p1r3 at 15 DAS and p2r4 at 30 DAS, 45 DAS and 60 DAS. Weed control efficiency also followed the same trend as that of weed dry matter. Nitrogen and P removal by weeds were observed to be lower in p2r4 at 30 DAS and 60 DAS. However, p2r4 showed lower K removal at 30 DAS and p3r4 at 60 DAS. The treatment combination, p2r2 resulted in higher N uptake by aerobic rice (72.6 kg ha-1) and it was followed by p2r3. However, p2r3 and p2r2 resulted in higher P uptake by aerobic rice (12.0 kg ha-1) and K uptake by p2r3 (48.4 kg ha-1). Interaction between seed priming and weed management regimes had significant effect only on organic carbon content and the treatment combination, p3r2 resulted in higher OC content (0.91%) and was on par with p2r3. Available P content of post experiment soil was found to higher in p2r2. The treatment combination, p2r3 resulted in higher gross return, net return (₹ 97070 ha-1) and B: C ratio (2.20) and it was followed by p2r2. The study demonstrated that seed priming with liquid organic manures— particularly vermiwash at 5 and 3 per cent concentrations—significantly enhanced germination, seedling vigour, and early growth parameters in rice. Both seed priming and weed management practices had a substantial impact on crop growth, physiological traits, nutrient uptake, yield, weed suppression, and economic returns. Among all treatments, seed priming with 5% vermiwash combined with green leaf manuring using Gliricidia maculata (10 t ha⁻¹), followed by wheel hoe weeding at 30 and 45 DAS, emerged as the most effective strategy for maximizing yield and profitability under aerobic rice cultivation.Item Conservation tillage and nano nitrogen nutrition in Chinese potato (Plectranthus rotundifolius (poir.) spreng.)(Department of Agronomy, College of Agriculture, Vellayani, 2024-04-27) Gopika, K T; Sheeba Rebecca IsaacThe study entitled "Conservation tillage and nano nitrogen nutrition in Chinese potato [Plectranthus rotundifolius (Poir.) Spreng]" was conducted at College of Agriculture, Vellayani during 2021-2023. The objective of the study was to assess the impact of conservation tillage and nano nitrogen nutrition on the growth, tuber yield and quality in Chinese potato, and carbon build up in the soil. The field experiment was executed during December 2022 to May 2023 at College of Agriculture, Vellayani. The experiment was laid out in split plot design with three methods of tillage [c1: Conventional tillage, c2: Reduced tillage (RT)+ surface incorporation of green manure (GM) cowpea and c3: RT+ surface retention of GM cowpea] as main plot treatments, and four N management practices [n1: 100% recommended dose of nitrogen (RDN) + nano urea, n2: 75% RDN+ nano urea, n3: 50% RDN+ nano urea and n4: 100% recommended dose of fertilizers (RDF)] as sub plot treatments, in three replications. In RT treatments, fodder cowpea variety Aiswarya was raised as green manure crop @ 20 kg seeds ha-1 and incorporated/ surface retained as mulch at flowering stage (45 DAS). Secondary ploughing in c2 and c3 plots was confined to the row zone alone. Cuttings of Chinese potato variety Suphala were planted at a spacing of 30 cm x 15 cm in all the plots. The NPK recommendation followed was 60: 60: 100 kg ha-1 (KAU, 2016). Nano urea (@ 0.4%) was sprayed 20 and 40 days after planting (DAP) as per treatments fixed. Other cultural operations were done in accordance with the KAU package recommendation for the crop. The treatment, c2 resulted in significantly taller plants at 90 and 120 DAP, higher number of branches per plant at 120 DAP and superior leaf area per plant at 30, 60 and 120 DAP. Among the subplot treatments, the significantly taller plants at 30 and 60 DAP, plant spread at 30, 60 and 90 DAP and number of branches at 30 DAP were recorded in n3. The treatment n1 recorded the highest leaf area at all the growth stages. Among the interactions, plants in c2n3 were significantly taller at 30 and 60 DAP, with the highest plant spread and leaf area at all stages of observation. The yield attributes and yield, number of tubers per plant (21.59), average tuber weight (12.13g) and marketable tuber yield (130.67 g per plant) were significantly the highest in c2. Tuber yield (16.20 t ha-1) was significantly higher in c3 and comparable with c2. In N management, n3 (50% RDN + nano urea) resulted in highest number of tubers and yield, and were the lowest in n4. Among the c x n interactions, c2n3 produced the highest tuber yield (17.74 t ha-1). Significantly higher chlorophyll contents were observed in c2 and was on par with c3. The chlorophyll content in n1 and n3 remained similar at 30 DAP and at 60 DAP, n1 was superior. The treatment combination c2n3 recorded the highest chlorophyll content at 60 DAP. Crop growth rate computed until 90 DAP, were significantly higher in c2 and during 90-120 DAP, in c3. It remained the highest in n1 upto 60 DAP and thereafter, n3 and n2 recorded the higher values. Leaf Area Index was higher in c2 but on par with c3. The highest LAI was recorded in c2n1 at all growth stages. No significant variations were found in days to start of senescence and biomass partitioning at the start of senescence due to tillage methods and interactions. Biomass accumulation followed the order tuber > stem > leaf, in all treatments. In tubers, significantly the highest biomass (66.4%) was recorded in n3. Nutrient uptake was higher for N and K in c2 and P uptake, in c3. With respect to N management, significantly higher N uptake was computed in n1 while P and K uptake were the highest in n3. Among interactions c2n3 was superior. Quality of tubers in terms of vitamin C and protein contents remained on par in c3 and c2 and among N management treatments, superior vitamin C content was observed in n3, and protein in n1. Starch content was the highest in n1 on par with n2. Among the treatment combinations, the highest starch and protein contents were observed in c2n1, and vitamin C in c2n3. The methods of tillage, N management and their interaction showed varied effects on soil nutrient status and were more pronounced for P, S and Zn. Conservation tillage methods (c2 and c3) elicited significant variations in soil C status. The highest TOC (11.80 g kg-1) and labile C (4.94 g kg-1) were recorded in c2 while non labile C (7.64 g kg-1) was the highest in c3. The C stock (5093 g m-2) was the highest in c3 and among interactions, c2n3 recorded the highest TOC. Soil microbial population and dehydrogenase activity were the highest in c2 and among c x n interactions, the combinations including c2 was superior. Economic analysis revealed c2n3 as the most profitable treatment combination for Chinese potato cultivation. The net income and BCR computed were ₹429657 ha-1 and 2.54 respectively. Based on the results of the study, in Chinese potato, the practice of raising GM cowpea sown @ 20 kg seeds ha-1, incorporation of biomass at flowering, planting stem cuttings in reduced tilled beds and nutrient management with 30 kg N (50% RDN), 60 kg P2O5, 100 kg K2O ha-1 + nano urea foliar spray (0.4%) at 20 DAP and 40 DAP, can be recommended as the most suitable conservation agriculture strategy. The C stock in soil was found to improve with conservation tillage practices.Item Performance of Maize (Zea mays L.) intercropping systems in lowlands(Department of Agronomy, College of Agriculture ,Vellayani, 2024-02-26) Meera, L Raj; Jacob JohnThe study entitled “Performance of maize (Zea mays L.) intercropping systems in lowlands” was undertaken at the College of Agriculture, Vellayani during 2021-2023. The objective was to evaluate different maize based intercropping systems in the summer fallow of double cropped lowland rice field in terms of weed dynamics, biological efficiency and economics. The field experiment was carried out at the Integrated Farming System Research Station (IFSRS), KAU, Karamana from January to May 2023 in Randomized Block Design with 10 treatments and three replications. The treatments comprised of T1: maize + bush cowpea (1:2), T2: maize + green gram (1:2), T3: maize + black gram (1:2), T4: maize + fodder cowpea (1:2), T5: sole crop of maize, T6: sole crop of bush cowpea, T7: sole crop of green gram, T8: sole crop of black gram, T9: sole crop of fodder cowpea and T10: fallow. Maize (var. TNAU maize hybrid Co-6) was raised as main crop and bush cowpea (var. PGCP-6), green gram (var.TM 96-2), black gram (var. VBN-6) and fodder cowpea (var. Aiswarya) were raised as intercrops. Maize was raised as per the recommendations of TNAU (CPG, 2005) and the intercrops as per KAU Package of Practice Recommendations (KAU, 2016). The results revealed that intercropping had significant effect on the growth and yield of the main crop and intercrops. Growth attributes of maize viz. plant height, number of leaves per plant, leaf area per plant and leaf area index (LAI) showed significant variation with intercropping. The treatment T5 resulted in taller plants, highest number of leaves per plant, leaf area per plant and LAI and it was followed by T1. Seed weight per cob (63.02 g), grain yield (4566 kg ha-1) and stover yield (13122 kg ha-1) were also highest in T5, which was followed by T3. Growth and yield attributes of intercrops were significantly reduced under intercropping systems. Sole crop of bush cowpea (T6), green gram (T7) and black gram (T8) recorded greatest plant height, number of branches per plant, leaf area per plant and LAI. Yield attributes like number of pods per plant, grain yield and haulm yield were also higher in sole cropping system. The plant height, number of branches per plant, leaf area per plant, leaf area index, leaf stem ratio, green fodder yield and dry fodder yield were higher in the sole crop of fodder cowpea (T9). Intercropping with maize profoundly reduced the weed count, weed dry matter production (DMP) and NPK removal by weeds. The lowest weed count was recorded in T9 at 30 DAS. At 60 DAS, lowest weed count was recorded in T3 and T1. The highest weed count was recorded in T10, both at 30 and 60 DAS. Lowest weed DMP was recorded in T1, 30 and 60 DAS. The weed smothering efficiency of maize + bush cowpea system was the highest among the different intercrops at 30 and 60 DAS (41.46 % and 59.04 % respectively). The N removal by weeds was lowest in T1(1.15 kg ha-1), which was on par with T4 (1.54 kg ha-1) at 30 DAS. At 60 DAS the lowest N removal was recorded in T1 (5.58 kg ha-1). P removal by weeds was lowest in T1 (0.62 kg ha-1, 0.64 kg ha-1) which was on par with T3 (1.78 kg ha-1,1.85 kg ha-1) both 30 DAS and 60 DAS respectively. K removal by weeds was lowest in T1 at 30 DAS (0.92 kg ha-1) and 60 DAS (2.22 kg ha-1). All the crops recorded higher values of NPK uptake under sole cropping of main crop and intercrops. The dehydrogenase activity was the highest in the maize + bush cowpea (T1) (175.52 µg TPF g-1 soil d-1) system compared to the others. The highest amount of available N in the soil found after the experiment was in T8 (472.29 kg ha-1) which was on par with T7 (397.23 kg ha-1) and T9 (397.23 kg ha-1). The highest amount of available P was found in T9 (71.00 kg ha-1) while available K was higher in T8 (168.64 kg ha-1). Analysis of the competitive indices of the intercropping system revealed that the land equivalent ratio (LER), monetary advantage index (MAI) and maize equivalent yield (MEY) were highest in the maize + black gram system (T3). The highest relative crowding coefficient and positive aggressivity value of maize indicated the dominance and competitive nature of maize over intercrops. The maize + black gram (T3) intercropping system recorded the highest net income (₹ 102262 ha-1) and B:C ratio (2.15). From the present study, it is inferred that in summer fallows of double cropped lowland, maize + black gram (1:2) system was more suitable in terms of maize equivalent yield, land equivalent ratio, monetary advantage index, net income and benefit cost ratio. Based on weed dry matter production, weed smothering efficiency and nutrient removal by weeds, the maize + bush cowpea (1:2) system was the best.Item Standardization of spacing and nitrogen management of multicut fodder sorghum(Sorghum bicolor x Sorghum sudanense)(Department of Agronomy,College of Agriculture , Vellayani, 2024-07-05) Bukke Sathish Kumar Naik; Usha, C ThomasThe study entitled “Standardization of spacing and nitrogen management of multicut fodder sorghum (Sorghum bicolor x Sorghum sudanense)” was undertaken at Instructional Farm, College of Agriculture, Vellayani, during 2021 to 2023. The key objective was to assess the influence of row to row spacing and nitrogen application on growth, yield, and quality aspects of multicut fodder sorghum. The field experiment was carried out at Instructional Farm, College of Agriculture, Vellayani, from November 2022 to August 2023. It was laid out in randomized block design with (3 x 3) + 1 treatments, replicated thrice. The treatment combinations included three levels each of row spacing (R) (r1- 20 cm, r2- 30 cm, r3- 40 cm) and nitrogen application (N) in seven equal splits (n1- 315 kg ha-1, n2- 245 kg ha-1, n3- 175 kg ha-1), compared against the control treatment (30 cm row spacing, nitrogen application- 315 kg ha-1 in seven equal splits, and MgSO4- 80 kg ha-1). Nitrogen was applied in seven splits- as basal, 20, and 40 days after sowing and after each cut. The variety used for the study was COFS-31, released from Tamil Nadu Agricultural University. A total of five cuts were taken during the study period. The treatment, r2 (30 cm row spacing) resulted in significantly taller plants with more leaves at harvest, the longest and broadest leaves, the highest leaf stem ratio, LAI at harvest, LAD, CGR, and RGR (at 30-60 DAS). The treatment, r3 (40 cm row spacing) resulted in the highest stem girth, and SLA (at harvest). Among the levels of nitrogen application, 315 kg N ha-1 (n1) recorded significantly taller plants with more leaves at harvest, the highest leaf length, leaf breadth, leaf stem ratio, stem girth, LAI, and SLA (at harvest), LAD, CGR, and RGR (at 30-60 DAS). Among the treatment combinations, r2n1 (30 cm row spacing + 315 kg N ha-1) resulted in taller plants (235.78 cm), with the highest CGR (30-60 DAS). It resulted in a higher leaf stem ratio (0.55) and was on par with r3n1 (0.53). The treatment combination, r1n1 resulted in the highest LAI (6.19) at harvest. The treatment combination, r3n1 resulted in the highest SLA at harvest. The control treatment was superior over all the treatment combinations concerning growth attributes. The treatments, r2 (30 cm row spacing), and n1 (315 kg N ha-1) resulted in the highest total green fodder yield (148.09 t ha-1 and 159.87 t ha-1 respectively) and dry fodder yield (34.56 t ha-1 and 37.36 t ha-1 respectively). Among the treatment combinations, r2n1 (30 cm row spacing + 315 kg N ha-1) resulted in the highest total green fodder yield (172.58 t ha-1) and dry fodder yield (40.60 t ha-1). The control treatment was superior over all the treatment combinations concerning green fodder yield (175.8 t ha-1) and dry fodder yield (41.52 t ha-1). The treatment, r2 (30 cm row spacing) significantly produced the highest chlorophyll content (1.94 mg g-1) at harvest. Among the levels of nitrogen application, 315 kg N ha-1 (n1) recorded significantly the highest chlorophyll content (1.95 mg g-1), and crude protein percent (9.03 %) at harvest. The control treatment did not show any significant influence on chlorophyll content and crude protein content over all the treatment combinations. The treatments, r2 (30 cm row spacing), and n1 (315 kg N ha-1) resulted in the highest NPK uptake. Among the treatment combinations, r2n1 (30 cm row spacing + 315 kg N ha-1) resulted in the highest NPK uptake. The control treatment was superior to all the treatment combinations concerning NPK uptake. The treatment, r3 (40 cm row spacing) resulted in significantly the highest soil available P and K, higher soil available N, and Mg which were on par with the treatment r1 (20 cm row spacing). The treatment, n3 (175 kg N ha-1) resulted in the highest soil available P, K, and Mg, with higher soil available N, and was on par with the treatment n2 (245 kg N ha-1). Among the treatment combinations, r3n3 (40 cm row spacing + 175 kg N ha-1) resulted in the highest soil available P, K, and higher soil available N which was on par with the treatment combinations r1n1, r1n2, r3n2. Among the treatment combinations, r3n3 (40 cm row spacing + 175 kg N ha-1) resulted in higher soil available Mg which was on par with the treatment combinations r1n3, and r3n2. The treatments, r2 (30 cm row spacing), and n1 (315 kg N ha-1) resulted in the highest benefit cost ratio (2.09 and 2.23 respectively). Among the treatment combinations, r2n1 (30 cm row spacing + 315 kg N ha-1) resulted in a higher benefit cost ratio (2.52) which was comparable with r3n1 (2.32). The control treatment was superior over all the treatment combinations in terms of benefit cost ratio (2.77). Based on the study, it could be inferred that multicut fodder sorghum is suitable for cultivation in Kerala when grown at a row spacing (30 cm) and nitrogen dose of 315 kg ha-1 y-1 (seven equal splits) along with FYM- 10 t ha-1, P2O5- 40 kg ha-1 y-1, K2O- 40 kg ha-1 y-1, and MgSO4- 80 kg ha-1 y-1.Item Conservation tillage and nano nitrogen nutrition in Chinese potato (Plectranthus rotundifolius (poir.) spreng.)(Department of Agronomy, College of Agriculture, Vellayani, 2024-04-27) Gopika, K T; Sheeba Rebecca IsaacThe study entitled "Conservation tillage and nano nitrogen nutrition in Chinese potato [Plectranthus rotundifolius (Poir.) Spreng]" was conducted at College of Agriculture, Vellayani during 2021-2023. The objective of the study was to assess the impact of conservation tillage and nano nitrogen nutrition on the growth, tuber yield and quality in Chinese potato, and carbon build up in the soil. The field experiment was executed during December 2022 to May 2023 at College of Agriculture, Vellayani. The experiment was laid out in split plot design with three methods of tillage [c1: Conventional tillage, c2: Reduced tillage (RT)+ surface incorporation of green manure (GM) cowpea and c3: RT+ surface retention of GM cowpea] as main plot treatments, and four N management practices [n1: 100% recommended dose of nitrogen (RDN) + nano urea, n2: 75% RDN+ nano urea, n3: 50% RDN+ nano urea and n4: 100% recommended dose of fertilizers (RDF)] as sub plot treatments, in three replications. In RT treatments, fodder cowpea variety Aiswarya was raised as green manure crop @ 20 kg seeds ha-1 and incorporated/ surface retained as mulch at flowering stage (45 DAS). Secondary ploughing in c2 and c3 plots was confined to the row zone alone. Cuttings of Chinese potato variety Suphala were planted at a spacing of 30 cm x 15 cm in all the plots. The NPK recommendation followed was 60: 60: 100 kg ha-1 (KAU, 2016). Nano urea (@ 0.4%) was sprayed 20 and 40 days after planting (DAP) as per treatments fixed. Other cultural operations were done in accordance with the KAU package recommendation for the crop. The treatment, c2 resulted in significantly taller plants at 90 and 120 DAP, higher number of branches per plant at 120 DAP and superior leaf area per plant at 30, 60 and 120 DAP. Among the subplot treatments, the significantly taller plants at 30 and 60 DAP, plant spread at 30, 60 and 90 DAP and number of branches at 30 DAP were recorded in n3. The treatment n1 recorded the highest leaf area at all the growth stages. Among the interactions, plants in c2n3 were significantly taller at 30 and 60 DAP, with the highest plant spread and leaf area at all stages of observation. The yield attributes and yield, number of tubers per plant (21.59), average tuber weight (12.13g) and marketable tuber yield (130.67 g per plant) were significantly the highest in c2. Tuber yield (16.20 t ha-1) was significantly higher in c3 and comparable with c2. In N management, n3 (50% RDN + nano urea) resulted in highest number of tubers and yield, and were the lowest in n4. Among the c x n interactions, c2n3 produced the highest tuber yield (17.74 t ha-1). Significantly higher chlorophyll contents were observed in c2 and was on par with c3. The chlorophyll content in n1 and n3 remained similar at 30 DAP and at 60 DAP, n1 was superior. The treatment combination c2n3 recorded the highest chlorophyll content at 60 DAP. Crop growth rate computed until 90 DAP, were significantly higher in c2 and during 90-120 DAP, in c3. It remained the highest in n1 upto 60 DAP and thereafter, n3 and n2 recorded the higher values. Leaf Area Index was higher in c2 but on par with c3. The highest LAI was recorded in c2n1 at all growth stages. No significant variations were found in days to start of senescence and biomass partitioning at the start of senescence due to tillage methods and interactions. Biomass accumulation followed the order tuber > stem > leaf, in all treatments. In tubers, significantly the highest biomass (66.4%) was recorded in n3. Nutrient uptake was higher for N and K in c2 and P uptake, in c3. With respect to N management, significantly higher N uptake was computed in n1 while P and K uptake were the highest in n3. Among interactions c2n3 was superior. Quality of tubers in terms of vitamin C and protein contents remained on par in c3 and c2 and among N management treatments, superior vitamin C content was observed in n3, and protein in n1. Starch content was the highest in n1 on par with n2. Among the treatment combinations, the highest starch and protein contents were observed in c2n1, and vitamin C in c2n3. The methods of tillage, N management and their interaction showed varied effects on soil nutrient status and were more pronounced for P, S and Zn. Conservation tillage methods (c2 and c3) elicited significant variations in soil C status. The highest TOC (11.80 g kg-1) and labile C (4.94 g kg-1) were recorded in c2 while non labile C (7.64 g kg-1) was the highest in c3. The C stock (5093 g m-2) was the highest in c3 and among interactions, c2n3 recorded the highest TOC. Soil microbial population and dehydrogenase activity were the highest in c2 and among c x n interactions, the combinations including c2 was superior. Economic analysis revealed c2n3 as the most profitable treatment combination for Chinese potato cultivation. The net income and BCR computed were ₹429657 ha-1 and 2.54 respectively. Based on the results of the study, in Chinese potato, the practice of raising GM cowpea sown @ 20 kg seeds ha-1, incorporation of biomass at flowering, planting stem cuttings in reduced tilled beds and nutrient management with 30 kg N (50% RDN), 60 kg P2O5, 100 kg K2O ha-1 + nano urea foliar spray (0.4%) at 20 DAP and 40 DAP, can be recommended as the most suitable conservation agriculture strategy. The C stock in soil was found to improve with conservation tillage practices.Item Management of submerged aquatic weeds by pond liming(Department of Agronomy, College of Agriculture, Vellanikkara, 2024-04-15) Sajjana Gandla GowthamThe aquatic weed infestations are proliferating at an alarming rate resulting in various adverse effects such as the water quality degradation, water flow disruption, reduced water storage capacity, and the establishment of habitats for vectors. Though physical or mechanical measures can be adopted for their control, it is not feasible due to practical difficulty or cost and drudgery involved. There is no registered herbicide for effectively managing aquatic macrophytes. Hence, a study entitled “Management of submerged aquatic weeds by pond liming” was conducted at the Department of Agronomy, College of Agriculture, Vellanikkara, Kerala Agricultural University, during 2022-23. The objective was to assess the efficiency of different liming materials against three common submerged aquatic weeds (Cabomba furcata, Lymnophila heterophylla, and Hydrilla verticillata), and its effects on water and sediment quality. The impact of different liming doses on phytotoxicity, chlorophyll degradation, water, and sediment quality over time was analysed through ANOVA, and the significant differences between treatments were studied using TUKEY's test. Correlation and regression studies on percentage control, phytotoxicity, chlorophyll degradation, water, and sediment quality were conducted to elucidate the trends over time. The experiment consisted of three tank studies and one field study. The tank studies were conducted to standardize the doses of various liming materials. The treatments in the first tank study were three different liming materials (calcite, quicklime, and dolomite) at varying doses of 50, 100, 200, 400, and 600 mg L-1. As these doses were found ineffective, in the second tank study, treatments included higher concentrations (0.8, 1.0, 1.2, and 1.4 g L-1) of calcite, quicklime, and dolomite. Only CaO was found effective in the second tank study. Hence varied doses of CaO @ 2, 4, 6, 8, and 10 g L-1 were included in the third tank study and higher doses were found more effective. In field study, varying doses of quicklime @ 2, 4, and 6 g L-1 was tested in lined irrigation channels of Kole lands infested with limnophila during May 2023.The total quantity of CaO to be applied was arrived at based on quantity of water in the waterbody. From the first and second tank studies, it was revealed that, calcite and dolomite were not effective in controlling the weeds whereas quicklime at 1.0 g L 1 and above was effective. However, there was a noticeable influence on pH and EC of water when calcite and dolomite was used. Conversely, the higher dose of quicklime resulted in considerable effect on both water and sediment quality. From the third experiment, the efficacy of quicklime on weeds was evident across all liming doses (2, 4, 6, 8, and 10 g L-1). Notable impacts on chlorophyll content and phytotoxicity were observed from 7 days after application. More than 50 per cent reduction in chlorophyll content was noted at higher doses after 14 days of liming. By 21 days, a substantial decrease from 0.98 mg g-1 to 0.07 mg g-1 was observed in cabomba and from 1.65 mg g-1 to 0.07 mg g-1 in hydrilla, achieving 85 per cent control. Similarly, in limnophila, chlorophyll content reduced from 0.83 mg g-1 to 0.15 mg g-1 with a 75 per cent control. In the field experiment, when applied in lined channels, quicklime applied @ 6 g L-1 of water in the channel resulted in complete weed control (100 %), while 4 g L-1 resulted in 50 per cent control only. The water quality parameters like pH, EC, carbonates, bicarbonates, alkalinity, total hardness, calcium, and Chemical Oxygen Demand (COD) were positively correlated with increasing doses of quicklime. However, all parameters except COD were in the acceptable range by 30 days after liming. pH values were in the range of 9.27-9.71 by 30 days at higher doses. Alkalinity, total hardness, carbonates, bicarbonates, and calcium increased by 15 days after application and thereby, a slight reduction was observed. Bicarbonates ranged from 2.83 meq L-1 to 9.0 meq L-1. Alkalinity was within the permissible limit (600 mg L-1) and ranged from 53.33 mg L-1 to 266.66 mg L-1 in treated tanks. In all the treatments COD was above the acceptable limit of 1 mg L-1. By 30 days after liming, nutrient content in both water and sediment parameters showed a negative correlation with the increasing dose of quicklime. In field study pH was within a narrow range of 6.47 to 6.87 by 21 days. The pH, EC, organic carbon, and calcium content of sediment were positively correlated with doses of quicklime. Whereas the available N, P, K, magnesium, iron, and manganese were negatively correlated. Organic carbon content linearly increased with increasing quicklime concentration in all the treatments and was in the medium range (0.50 % to 0.75 %). The current study revealed that the quicklime can effectively control submerged aquatic weeds with no regrowth. In tank study, chlorophyll degradation progressed with time and complete chlorophyll degradation was observed by 21 days after liming in higher doses starting from 6 g L-1 and by 30 days complete control was observed even at lower doses. However, in the field study, the lower doses of 2 and 4 g L-1 were less effective and the higher dose of 6 g L-1 resulted in complete chlorophyll degradation and death of weeds by 21 days. When quicklime was applied, there was an immediate hike in water quality parameters and over time, followed by a gradual decline and reached the acceptable range by 21 days after liming. Similarly, no adverse effects on aquatic fauna such as fishes and snails were observed. Hence, the study indicates the possibility of CaO application as an eco friendly and effective means for managing submerged freshwater aquatic weeds. However, the size and nature of the waterbody, weed density and volume of water contained are the three important factors which decides the practical feasibility of the technology. The present technology has to be extended to ponds and crop lands for a comprehensive investigation and validation of its effectiveness in managing submerged aquatic weeds and algae.