1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Quantification and depth distribution analysis of carbon, nitrogen, and microbiomes in soils of Miyawaki forests in Kerala(Department of Soil Science, College of Agriculture, Vellayani, 2024-12-11) Sreelekshmi, M; Naveen LenoA study entitled “Quantification and depth distribution analysis of carbon, nitrogen and microbiomes in soils of Miyawaki forests in Kerala” was undertaken with the objectives of quantifying the levels of carbon and nitrogen in Miyawaki forest soils in Kerala, analysing the effect of increasing carbon sinks in achieving carbon sequestration and to investigate abundance of microbiomes in these soils. A preliminary survey was conducted to identify the locations where Miyawaki forests were established and is existent in the entire Kerala state. Altogether 58 Miyawaki forests have been established till date in Kerala. Five well established and oldest Miyawaki forests out of these were selected for further study. A survey was conducted during December 2023 in the selected study area and 20 georeferenced soil samples were collected from surface and subsurface layers from five Miyawaki forest and nearby undisturbed plots. The selected sites were located at Puliyarakonam, Peyad, Kanakakkunnu, Vilappilsala and Chalai. The soil samples were characterized for selected physical, chemical and biological attributes, carbon pools and nitrogen fractions. Various carbon indices like carbon pool index (CPI), lability index (CLI) and management index (CMI) were worked out. The carbon sequestration potential of each Miyawaki forest was also calculated. A metagenomic analysis of one sample each from Miyawaki forest and undisturbed plot was also conducted. A minimum data set (MDS) of indicators to assess soil quality index (SQI) was set up using Principal component analysis (PCA). The spatial variation in temperature within the confines of the Miyawaki forest as well as outside were recorded for a period of three months from March 2024 to May 2024 at two locations, viz., Puliyarakonam and Vilappilsala. The soils under study belong to sandy clay loam. The bulk density was found to be the lowest in the Miyawaki forest (1.15 Mg m-3) than the control. Other physical properties like water holding capacity (60.28%), soil moisture content (34.83%) and water stable aggregates (88.48%) were found to be higher in the surface soils of Miyawaki forest than the control plots. The soil acidity (pH 5.40) and EC (0.059 dSm-1) were found to be more in the Miyawaki forest. Soil biological properties like soil enzyme dehydrogenase activity (80.20 mg TPF g-1 soil 24 h-1), bacterial density (7.573 log cfu g-1), fungal count (5.507 log cfu g-1) and actinobacterial count (4.909 log cfu g-1) were also found to be higher in Miyawaki forest and decreased with depth. A higher total organic carbon of 10.31% was recorded in Miyawaki forest, which was observed to decrease with depth. Other carbon fractions like water soluble carbon (21.21 mg kg-1), labile carbon (4.51 mg g-1), particulate organic carbon (1.03%) and microbial biomass carbon (152.69 mg kg-1) were also observed to be higher in the Miyawaki forest when compared to the control plots. Total nitrogen content (0.36%) and available nitrogen (264.26 kg ha-1) was highest in Miyawaki forest. A higher C:N ratio was observed in Miyawaki forest (28.77) and was observed to increase with depth. The soil organic carbon stock (38.08 Mg ha-1) and carbon sequestration rates 9.05 Mg ha-1yr-1 were also found higher in Miyawaki forest soils compared to the control plots. A temperature difference up to 3.93°C and 4.21°C was observed between the mean maximum temperature between the inside and outside of Miyawaki forest during the summer months in Puliyarakonam and Vilappilsala respectively. No significant difference was observed for CPI, CLI, CMI, and SQI. The study on Miyawaki forests in Kerala reveal their substantial contribution to soil carbon storage and nutrient enrichment. The findings indicate that these forests not only enhance soil quality through increased organic carbon and nitrogen levels but also support a diverse microbiome, which is vital for soil health. Miyawaki forests in Kerala exhibit lower bulk density and higher water holding capacity compared to control plots, indicating improved soil structure and moisture retention. Additionally, the significant temperature regulation observed within the forests highlights their role in moderating local microclimates. Overall, the results underscore the potential of Miyawaki forests as effective carbon sinks and valuable ecological assets, advocating for their expansion as a strategy for carbon sequestration and soil restoration in the region. Further research is recommended to explore the long-term ecological impacts and management practices that can optimize these benefits.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 Expression profiling of genes associated with nitrogen use efficiency in rice varieties under organic and conventional management(Department of Molecular Biology and Biotechnology, College of Agriculture, Vellayani, 2024-05-02) Elizabeth Jose; KAU; Soni, K BThe study entitled “Expression profiling of genes associated with nitrogen use efficiency in rice varieties under organic and conventional management” was conducted in the Department of Molecular Biology and Biotechnology during 2019-2023. The objectives of the study were to identify differentially expressed genes associated with nitrogen use efficiency (NUE) in rice varieties under organic and conventional management and to find out the polymorphism in the gene sequences. A pot culture experiment was conducted in a completely randomized design with five replications. Four rice varieties namely Jaiva, Ezhome 2, Uma and Jyothi were compared under two nutrient management practices (KAU PoP, Adhoc Organic PoP of KAU) along with an absolute control. Under organic management, nutrients were applied on N equivalent basis. The observations on morphological, physiological, biochemical and yield parameters and expression of genes associated with NUE were taken at seedling, panicle initiation and grain filling stages. All rice varieties showed significantly taller plants, greater number of tillers per hill, higher grain and straw yields per hill with KAU PoP. Jaiva and Ezhome 2 showed a significantly greater number of productive tillers per hill (P=0.001 and P=0.02) under KAU PoP, and Ezhome 2 produced higher filled grains per panicle under organic PoP. Jyothi showed significantly higher root depth and root biomass per hill (46.34 cm, 18.6 g) under organic PoP. At the vegetative stage, all varieties except Jaiva and Uma, exhibited significantly higher photosynthetic rates under KAU PoP. The varieties Ezhome 2 and Uma showed higher leaf protein content under organic PoP. All rice varieties, except Ezhome 2, showed significantly higher amino acid content under KAU PoP. The nutrient management practices did not significantly affect the reducing sugar content in Jyothi, compared to other varieties which showed higher values under KAU PoP. All the varieties showed higher NUE with KAU PoP than organic PoP. Maximum NUE was seen in Jyothi (0.28 kg yield increase/g N applied) under KAU PoP. Variation in NUE under both nutrient management was found to be lesser in the variety Jaiva (23.8%). 195 Expression profiles of NUE-associated genes such as OsNRT1.1a, OsNRT1.1b, OsAMT1.1, OsAMT1.2, OsAMT1.3, OsNRT2.1, OsNAR2.1, OsGS1.1, OsNADH-GOGAT1 were analyzed at different stages of growth by performing RT-qPCR using SYBR Green dye and β-actin as the reference gene. At the three-week seedling stage, ammonium uptake and transporter genes OsAMT1.1, OsAMT1.2, and nitrate uptake and transporter gene OsNRT2.1 which are root-specific in nature, exhibited significantly higher expression under organic PoP in Jaiva and Jyothi. Jyothi also showed a significantly high expression of glutamine synthase gene, OsGS1.1 in the leaf and root tissues (0.72 and 8.28 folds respectively). OsNADH-GOGAT1, a gene associated with nitrogen assimilation exhibited significantly higher expression in the root tissues of all rice varieties, except Jaiva under organic PoP. At the panicle initiation stage, Uma and Jyothi showed comparatively higher expression of OsNRT1.1a, OsNRT1.1b, OsAMT1.1, OsAMT1.2, OSAMT1.3, OsNRT2.1, OsNAR2.1 and OsNADH-GOGAT1 under organic PoP. At the grain-filling stage, Uma showed significantly higher expression of OsAMT1.1 (3.19 folds), OsAMT1.2 (5.24 folds), OsAMT1.3 (7.65 folds), OsNAR2.1 (11.02 folds), OsNADH-GOGAT1 (2.2 folds) in root tissues under organic PoP. Jyothi, under organic management, showed significantly higher expression of the OsNRT2.1 gene (6.95 folds) in root tissues. In Jaiva, nitrogen assimilatory genes like OsGS1.1 and OsNADH-GOGAT1 showed higher expression in leaf and root tissues under PoP and for Jyothi, they were found elevated (P<0.005) under organic PoP. The full-length sequencing of differently expressed OsAMT1.1 of Jaiva yielded a sequence comprising 2671 bp. This is the initial comprehensive gene sequencing report for the OsAMT1.1 gene of an organic rice variety. It showed a similarity (99.7%) to that of NERICA L19 (O. sativa × O. glaberrima). Uma exhibited an insertion of 41 bp in the promoter region compared to the other three varieties. Furthermore, some single nucleotide polymorphisms were also identified in the promoter region of Jaiva, Ezhome, Uma and Jyothi. In conclusion, the present study explored the response of the key genes involved in the uptake, transport and assimilation of nitrate and ammonium under different nutrient management strategies in determining nitrogen use efficiency in rice varieties. 196 Jaiva and Jyothi exhibited superior efficiency in both nitrate and ammonium uptake, correlating with higher NUE and narrower yield gaps between organic and fertilizer-based management. In the initial stages of crop growth, an elevated expression of OsAMT1.1 and OsAMT1.2 was seen in Jaiva and Jyothi under organic management, whereas OsAMT1.3, which has a N-derepressible role was highly expressed in Uma under organic management. The variety, Uma was found to be less nitrogen-efficient and was highly influenced by ammoniacal fertilizer. Even though OsAMT1.1 and OsAMT1.2 were less expressed in the initial stages of Uma, a significant increase was observed in its later stages. OsNRT2.1 and its partner protein OsNAR2.1, which are important in regulating nitrate transport and signaling, were upregulated in Jaiva and Jyothi under organic PoP, influencing root development and contributing to superior agronomic use efficiency. The higher expression of OsGS1.1 in the seedling and grain filling stages of Jyothi under organic PoP contributed to grain development and filling, demonstrating better NUE and a reduced yield gap. Ezhome 2, by exhibiting higher OsGS1.1 expression at the seedling stage, displayed increased filled grains, emphasizing the significance of early gene expression in yield determination. Furthermore, OsNADH-GOGAT1's role in ammonia assimilation, productive tiller formation, and grain development was evident, with varieties like Ezhome 2 showcasing its positive impact on grain number and tiller productivity under organic PoP. The findings highlight the complexity of nitrogen response and metabolism in rice and emphasize the importance of nutrient management strategies in achieving optimal NUE and crop yield. The observed variations in the gene expression across different varieties and growth stages provide a foundation for further research and potential molecular interventions to enhance NUE in rice.Item Potential and prospects of fodder legumes in rice fallows(Department of Agronomy, College of Horticulture,Vellanikara, 1987) Meera Menon, V; Achuthan Nair, MAn experiment was conducted in the Agricultural Research Station , Mannuthy during third crop season of 1985-’86 and first crop season of 1986-’87 to evaluate the relative performance of fodder legumes in rice fallows and their residual effect on the succeeding crop of rice under graded levels of N. The experiment, replicated thrice, was laid out in a split plot design with seven treatments – six fodder legumes (sannhemp, soya bean, rice bean, velvet bean, cowpea and black gram and a fallow- as main plot treatments and two N levels (52.5 and 70 kg/ha) applied to kharif rice as sub-plot treatments. The results revealed that sannhemp gave a fodder yield of 21 t/ha in rice fallows which was significantly superior to all other treatments. An increase in soil organic carbon, total and available N was also noticed. Soil organic carbon and total N was highest in the cowpea cropped plot. Available N in the soil was highest in the velvet bean cropped plot and the fallow plot recorded the lowest values. Increased rice grain yield was recorded after legumes compared to fallow and the highest grain yield was recorded after velvet bean followed by that after sannhemp cowpea and black gram. Application of N at the recommended dose of 70 kg/ha produced superior yields compared to N at 52.5 kg/ha. Rice crop succeeding fodder legumes with 75% N produced grain yield comparable to that after fallow receiving 100% N. The net income and returns per rupee invested were highest after the sannhemp-rice sequence followed by the cowpea-rice sequence. The results proved that 25% N could be saved in the case of rice after legumes. The study also showed the superiority of sannhemp and cowpea in fodder yield and residual effect in the succeeding rice crop.Item Nutrient- moisture interaction under phasic stress irrigation of sweet potato in summer rice fallows(Department of Agronomy, College of Agriculture,Vellayani, 1994) Muraleedharan Nair, G; Muraleedharan Nair,VA field experiment on sweet potato was laid out in the rice field fallowed during summer season at the Instructional Farm, College of Agriculture, Vellayani. The study was intended to work out of the irrigation schedule and fertilizer practice for sweet potato grown as a catch crop during the summer season of 1990 and 1991. The experiment was designed to economise the use of irrigation water as well as fertilizers by inducing phasic stress at certain phases of plant growth which are considered critical for sweet potato. The field experiment was laid out in a strip plot design replicated thrice with irrigation in horizontal strips and fertility levels in vertical strips. Irrigation water at full CPE was given during tuber initiation phase (10-30 DAP), full CPE at tuber maturity phase (80-100 DAP) and full CPE at tuber initiation and tuber maturity phases. The crop received irrigation at ½ CPE during the rest of the period of plant growth. Nitrogen and potassium were applied @ 25, 50 and 75 kg ha-1 and a uniform dose of P2 O5 @ 50 kg ha-1 and lime @ 500 kg ha-1 were applied. A control plot that received NPK @ 75:50:75 kg ha-1 and FYM @ 10 t ha-1 was maintained for treatment comparison. Growth characters were recorded at an interval of 21 days from planting and it was observed that providing irrigation at full CPE during tuber initiation phase resulted in significant increase in vine length and number of leaves plant-1. Enhanced rate of application of Nitrogen promoted the growth of vines, number of branches plant-1 and number of leaves produced plant-1. Potassium did not exert any influence on these growth characters. Growth analysis studies showed that the LAI was maximum in plots that received irrigation at full CPE during tuber initiation phase. Nitrogen substantially influenced the LAI, higher levels being significantly superior to the lower levels. Higher levels of potassium also influenced the LAI. The NAR and specific leaf weight were the highest in plots that received irrigation at ½ CPE during tuber initiation phase. Both NAR and CGR were high in the early stage of plant growth and decreased towards harvest. Increased rates of nitrogen supply decreased the NAR and specific leaf weight whereas no definite trend could be observed on CGR> Higher levels of potassium had a favourable influence on NAR and CGR. The dry matter of leaves, shoots, fibrous roots and tubers were significantly enhances by providing full CPE during tuber initiation phase. Increasing the level of nitrogen, influenced the dry matter in the aerial parts. The influence of K on dry matter production was not consistent. Tuber bulking rate showed a positive trend under irrigation at full CPE during tuber initiation phase. Nitrogen levels at 50 and 75 kg ha-1 had an overlapping influence on tuber bulking rate and both remained superior to 25 kg ha-1. Scheduling of irrigation did not exert any influence on the length and girth of tuber. However, an increase in the length and a corresponding decrease in the girth were noticed at enhanced rates of nitrogen supply. The number of tubers plant-1 showed a significant improvement by providing irrigation at full CPE during tuber initiation phase. The total number of tubers plant-1 was increased by high rates of N, but did not influence the number of marketable tubers. Application of K at 50 kg ha-1 promoted the production of more tubers. Tuber yield was significantly influenced by irrigation wherein providing full CPE during tuber initiation phase resulted in superior yield of both total and marketable tubers. Tuber yield was maximum at 50 kg ha-1 each of nitrogen and potash. Vine yield was significantly enhanced by higher rates of applied nitrogen. The harvest index and utilization index were enhanced by the application of irrigation water at full CPE during tuber initiation phase. Application of N at 25 kg ha-1 resulted in the production of high starch content whereas the sugar content was increased upto the highest level of 75 kg ha-1. The uptake of nitrogen by vines and tubers showed a progressive increase by applying full CPE during tuber initiation phase. Application of higher levels of nitrogen invariably promoted the uptake of N, P and K by the plant. Application of potash at 50 or 75 kg ha-1 also resulted in higher uptake of potassium. The fertility status of the soil did not show a positive trend by scheduling of irrigation. The plots that received the lowest dose of nitrogen, invariably recorded the highest level of available phosphorus. Available potassium content was also high in plots that received higher rates of potash. Irrigation at full CPE during tuber initiation and/or tuber maturity phase recorded significantly higher water use efficiency and net returns as compared to including stress during tuber initiation phase. Nitrogen and potash both at 50 kg ha-1 recorded the maximum water use efficiency and net returns from sweet potato cultivation.Item Comparative efficiency of different phosphatic fertilizers in rainfed Nendran Banana(Department of Soil Science and Agricultural Chemistry, College of Agriculture,Vellanikara, 1990) Sheeja, V G; Harikrishnan Nair, KThough phosphorus is one of the key nutrients for plant growth, the consumption rate of phosphatic fertilizers in India is found to be comparatively low. The escalating cost of the imported raw material used for the manufacture of P fertilizers may be one of the possible reasons for the low intake. In this regard, the direct application of cheap native ground rockphosphate as a P source is a fruitful attempt especially in acid soils. The present investigation was conducted to compare the efficiency of different phosphatic fertilizers including rockphosphates in upland soils with ‘Nendran’ variety of banana as the test crop. The present study comprises of two aspects, field experiment and laboratory incubation study. The field experiment was conducted at two locations, viz. at the Instructional Farm attached to College of Agriculture, Vellayani and at Kattakada, in the cultivator’s field. The experiment was laid out in randomised block design with four treatments and five replications. The laboratory study was carried out in the soil, treated with different phosphatic fertilizers after incubation with organic matter under moist conditions to assess the influence of organic matter on the release of P from different P sources. The growth characters of banana plant such as height and girth of pseudostem, number of photosynthetically active leaves, leaf area and period taken for flowering were recorded and analysed upto shooting stages of the crop. The bunch characters like weight of bunch, length of bunch, number of fingers and hands bunch-1, and length and girth of finger were also recorded and analysed. Phosphorus application significantly influenced biometric characters of the crop while the differences between the various P sources were not statistically significant. In most of the growth and yield characters, comparatively higher efficiency was shown by plants treated with superphosphate, eventhough, it was statistically on par with the other sources in both locations. Thus, it indicates the possibility of using cheaper rockphosphates for meeting the phosphorus requirement of banana in upland soils of Kerala, rather than going in for the costly superphosphate. The effect of treatments on the drymatter production was significant at both locations. Phosphorus application significantly increased the P uptake. However the different P sources could not produce significant variation in the uptake of phosphorus in both locations. The phosphorus content in the leaf was found to be maximum from the late vegetative phase to shooting period of the plant growth. With respect to available and total P2o5 content in the soil, the differences between the various sources were not statistically significant though, addition of phosphorus increased the available as well as total P2o5 content of soil significantly over no P treatment. A significant positive correlation existed between the leaf P content and total P uptake. Similarly a significant positive correlation between yield as well as total drymatter content with P uptake was observed. The incubation study revealed that organic matter produced significant effect on the release of phosphorus from different P sources added to the soil under moist conditions. Upto 90 days of incubation, increased availability of phosphorus was recorded in all treatments, and the trend continued till 135 days. A gradual decline in the concentration of available P was noticed thereafter. However, a favourable influence of organic matter on the release of P from different sources has been brought out from this study. When the mean values of available P over all the periods were compared, maximum availability was recorded by soils incubated with organic matter and superphosphate. In general, various sources of P behaved similarly and were on par with respect to the release of phosphorus due to organic matter incubation.Item Suitability of Tunisia rock phosphate for direct application in acid rice soils of Kerala(Department of Soil Science and Agricultural Chemistry, College of Horticulture,Vellanikara, 1997) SanthoshKumar, V C; Mariam, K AA study was conducted at College of Horticulture during the period 1993-95 so as to assess the suitability of Tunisia rockphosphate for direct application in acid rice soils of Kerala as a source of P compared with single superphosphate (SSP) diammonium phosphate (DAP) and Mussoorie rockphosphate (MRP). In addition to above sources a control treatment (with no P fertilizer) and another treatment with SSP of the rate of 45 kg P2O5 ha-1) given twice (conventional practice) were also included. The P release from all the sources was monitored with an incubation experiment. In order to evaluate the residual effect of fertilizers two continuous pot culture experiments were undertaken using Triveni variety of rice. The acids soils of Kerala namely Kuttanad alluvium and laterites were used for the study. The soils showed variation in pH with submergence irrespective of the treatments. The different nutrients like N, K, Ca, Mg were higher in Kuttanad soil compared to laterite soil and was found to decrease with period of incubation. The available phosphorus content gradually increased with period of incubation and reached a peak .fit 60 to 90 days for water soluble phosphates and 90th to 120th day for rockphosphates. Comparing the two extractants, Mathew's triacid extracted more available P than that of Bray solution in both soil types. In general, Kuttanad alluvium recorded higher content of available nutrient as compared to laterite. The extent of fixation of P was higher in Kuttanad soil with Fe-P as dominant fraction while in laterite soil it was Al-P which was dominated. While evaluating pot culture experiment the different nutrients showed a decrease in soil and increase in uptake with the advancement of crop. Of the different soils Kuttanad alluvium registered a higher yield compared to laterite soil. It was found that TRP registered a comparable uptake of phosphorus and gave a comparable yield of grain and straw with other sources in laterite and Kuttanad alluvium. The residual effectiveness of rockphosphate was found to be higher than that of water soluble sources and TRP gave the highest. Of the two different type of soils Kuttanad soil showed a higher residual effectivenes and resulted in higher yield for 2nd crop while laterite soil registered a lower yield.Item Spatial arrangement & nutrient management of grain cowpea - Fodder maize intercropping in summer rice fallows(Department of Agronomy, College of Agriculture, Vellayani, 1990) Sunitha, S; Lekha SreekantanAn investigation was carried out during the summer season of 1988-'89 in the Instructional Farm attached to the College of Agriculture, Vellayani to determine the best crop arrangement for a grain cowpea + fodder maize intercropping system in summer rice fallows under different fertility levels. The different crop arrangements tried were pure crop of cowpea at normal row arrangement, pure crop of maize at normal row arrangement, cowpea and maize in alternate rows, paired row of cowpea with one row of maize in between and triple row of cowpea with one row of maize in between. The fertilizer levels tried were 100, 75 and 50 per cent of the recommended doses of nutrients of cowpea, maize and cowpea+ maize, depending on the crop arrangement and the area occupied by each crop. The experiment was laid out in split plot design with four replications. The crop arrangements were allotted to main plots and the fertility levels to the subplots. Plant height of cowpea was maximum in the crop arrangement where cowpea was alternated with one row of maize where as the pure crop of cowpea produced the maximum number of leaves. In the case of maize, plant height and number of leaves were maximum when cowpea and maize were grown in alternate rows. Pure crops of cowpea and maize recorded the highest for their respective LAI values at flowering. Plant height, number of leaves and LAI of both cowpea and maize were affected by different fertility levels. Higher doses of fertilizers were found to be the best. The crop arrangements did not show pronounced variation in the uptake of nutrients by cowpea except potassium. Potassium uptake by cowpea and maize were maximum for their respective sole crops. For maize, nitrogen and phosphorus uptake were maximum when grown in alternate rows with cowpea plants. Full dose of fertilizers recorded the highest uptake values. Number of pods per plant, length of pods, number of seeds per pod, hundred grain weight, pod yield as well as grain yield of cowpea were not affected by different crop arrangements or fertilizer levels. The fodder yield of maize was affected by different crop arrangements and the pure crop of maize was on par with the crop arrangement where cowpea and maize were alternately grown. Hundred per cent recommended dose of fertilizers recorded the highest value for fodder yield of maize. The treatment where cowpea and maize were grown in alternate rows resulted in the greatest protein content of cowpea grains. Seventy five percent dose of fertilizers resulted in the highest crude protein content of maize fodder. The various indices like LER, LEC, IER, net profit, benefit/cost ratio, return per rupee invested on labour and return per cropping day were found to be superior in the crop arrangement where cowpea and maize were grown in alternate rows and at full dose of fertilizers. Hundred per cent and seventy five per cent dose of fertilizers were on par with regard to LER, LEC, IER, net profit and benefit/ cost ratio. From a detailed analysis it is seen that cowpea alternated with one row of fodder maize under 75 per cent of the recommended level of nutrients, is the best in providing higher profit to the farmer.Item Nutritional requirement of pre-release sesamum culture 42-1 in garden land(Department of Agronomy, College of Agriculture, Vellayani, 1987) Raveendran Nair, P; Chandrasekharan, PA 4 raise to 3 fatorial experiment confounding NPK (3 df) totally in replication I and II was conducted under garden land condition at the Instructional Farm, College of Agriculture, Vellayani, during semirabi season 1984, to study the effect of graded doses of nitrogen (10, 30, 50 and 70 kg/ha), phosphorus (5, 15,25 and 35 kg P2O5/ha) and potassium (10, 30,50 and 70 kg K2O/ha) on the growth , yield , quality, content and uptake of mineral nutrients and also to work out the economics of production with the pre-release sesamum culture 42-1 (now released as Soorya or ACV-2). The study revealed that application of nitrogen significantly influenced growth , yield and yield attributing characters. Phosphorus and potassium produced significant influence on number of leaves and leaf area index on 40 and 60 days after sowing. Significant effect of phosphorus was also observed on number of branches, pod-seed ratio, bhusa yield, thousand seed weight and total dry matter production. Applied potassium significantly influenced the yield and yield attributing characters like number of pods , weight of pod per plant, pod seed ratio, seed yield and harvest index.Item Effect of different forms and levels of phosphorus on the growth, yield and composition of three yielding varieties of rice (IR 8, Taichung Native I and Culture 28)(Division of Agricultural Chemistry, Agricultural College and Research Institute, Vellayani, 1968) Jagadeeschandran Nair, M P; Koshy, M MTo study the effect of different forms and levels of phosphorus on the growth, yield and composition of three high yielding varieties of rice, a pot culture experiment was carried out in the Agricultural College and Research Institute, Vellayani, in a randomised block design with 39 treatments and 3 replications. The different forms of phosphorus used were superphosphate, ultrafos, defluorinated rock phosphate and Thomas phosphate. The levels of application were 0,25, 50 and 75 kg P2O5/ha. The rice varieties studied were Culture 28, IR 8 and Taichung Naive 1. The main findings of the experiment are summarised below: 1) The height of plants was a maximum for IR 8. This growth character was not influenced by the form of phosphorus used, but it increased significantly with increase in the rate of phosphorus application, 2) In the matter of tillers, Taichung Native 1 was superior to IR8 and Culture 28. Of the different forms of phosphorus applied, superphosphate and deflurinated rock phosphate produced the maximum number of tillers. As regards the effect of level, the number of tillers increased with increase in the level of phosphorus application.