PhD Thesis
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Item Studies on induced mutations in rice (Oryza sativa L.)(Division of genetics and plant breeding ,Agricultural college and research institute , Coimbatore., 1971) Gopinathan Nair, VItem Studies on the rice swarming caterpillar , Spodoptera mauritia boisduval in Kerala(Division of entomology ,Agricultural college and research institute ,Vellayani., 1967) Thomas, B; M R G K NairItem Nutrient dynamics if the rice based cropping systems(Department of soil Science and Agricultural Chemistry, College of agriculture, Vellayani, 1989) Sundaresan Nair, C; Subromonia Aiyer, RItem Factors governing response of rice to liming in Kerala soils(Department of soil science and Agricultural chemistry, College of Agriculture Vallayani , Trivandrum, 1986) Mary kutty, K C; Subramania Aiyer, RItem Optimization of agronomic resources for maximizing grain and mill yield of rice(Department of Agricultural Engineering, Indian Institute of Technology, Kharagpur, 1976) Kannan, Mukundan; Pande, H KItem Phosphorus management in a rice based cropping system(Department of Agronomy, College of Agriculture, Vellayani, 1989) Annamma George; Sasidhar, V KIn order to standardize an appropriate phosphorus management practice in a rice based cropping system involving rice-rice-cowpea/sesamum, field experiments were carried out in the rice fields of the Instructional Farm, College of Agriculture, Vellayani from June 1984 to September 1986. The experiment was laid out in a randomized block design with three replications. There were eight treatments. The treatments comprised of (1) continuous phosphorus application to all the three crops in the system (2) phosphorus application to the first and second crops of rice (3) phosphorus application to the first crop of rice and third crop of cowpea/sesamum (4) phosphorus application to the first crop of rice only (5) phosphorus application to the second crop of rice and third crop of cowpea/sesamum (6) phosphorus application to the second crop of rice only (7) phosphorus application to the third crop of cowpea/sesamum only (8) control plot with no addition of phosphorus to any of the crops in the system. The salient findings of the experiment are as follows: Phosphorus application had no significant influence on grain and straw yield of first crop of rice. But available nitrogen, available and total phosphorus and available potassium of the soil were increased with phosphorus application. Direct, residual and cumulative effects of phosphorus had no significant influence on grain and straw yield of second crop of rice. Phosphorus uptake could not show any variation due to the different treatments. Available and total phosphorus content of the soil were highest under cumulative phosphorus treatment. All the growth and yield attributes of third crop of cowpea and sesamum were increased by the direct and cumulative effects of phosphorus. Grain yield of cowpea was significantly increased by the direct application of phosphorus. Eventhough not significant the highest sesamum yield was accorded by the direct and cumulative application of phosphorus. Phosphorus uptake in all the growth stages of the crop was highest in direct phosphorus plots. Available and total phosphorus content of the soil was highest in continuous phosphorus applied plots. There was no significant influence on grain and straw yield of first crop of rice after cowpea and sesamum in the direct, residual and cumulative effects of phosphorus. Residual phosphorus was sufficient to maintain the available nitrogen status of the soil. Available phosphorus of the soil was increased by the direct, cumulative and continuous application of phosphorus and total phosphorus by continuous application of phosphorus. Balance sheet of available phosphorus revealed that the soil phosphorus level almost maintained, where phosphorus was applied only to the third crop of cowpea or sesamum. The highest net return and benefit-cost ratio for the rice-rice-cowpea and rice-rice-sesamum system was obtained when phosphorus was applied only to the third crop in the rice fallow and the residual effect being utilized by the succeeding rice crops.Item Nutrient dynamics in the rice based cropping systems(Division of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1989) Sundaresan Nair, C; Subramonia Aiyer, RThe experiment consisting of five cropping sequences viz. rice - rice – rice (A1), sweet potato – rice – rice (A2) cowpea – rice – rice (A3) daincha – rice – rice (A4) and fallow – rice – rice (A5) and six treatments with varying doses of N P and K were conducted to study the performance of the sequences in relation to the nutrients required for optimising the out put from the sequences. The field experiment was laid out at R.R.S., Pattambi in 1980 – 81 and the experiment was conducted for two consecutive years ie. For six seasons. The experiment was started with the summer crop of 1981, namely summer rice (Triveni), sweet potato, cowpea, daincha and a summer fallow wherein the land was ploughed twice and left as such without any crops. The component crops were raised with five treatment variations modified from the recommended doses for each crop. The biometric observations for the summer crops, virippu and mundakan crops were recorded. The indications were that treatments have a significant effect on summer crops virippu and mundakan rice crops of 1981 and 1982. The yield shows that both treatments and sequences have a significant effect. The sequence daincha – rice – rice and the cowpea – rice – rice sequence gave the highest yield. The chemical analyses of plant parts of the summer crops, virippu and mundakan rice crops of both 1981 and 1982 show that the treatments have no effect on the NPK content. The soil study shows that the cropping sequences have a significant effect on soil pH. A pH decrease was noticed in all the sequences, the highest decrease being in the rice – rice – rice sequence. The organic carbon level of the soil is also affected due to the cropping sequence. The rice – rice – rice sequence shows a maximum decrease in organic carbon level and the daincha – rice – rice – rice shows a gain in organic carbon level of the soil. The total nitrogen of the soil shows a decrease in all the sequences and maximum decrease was noticed in sweet potato – rice – rice sequence. The available nitrogen level also was influence both by the sequences and treatments. A decrease in available nitrogen was noted to be a maximum in the rice – rice – rice sequence. The total P and available P levels show an increase in all the sequences and were high in daincha – rice – rice and cowpea – rice – rice sequences. The treatments also have a significant effect in maintain the P level in soils. The total K status of the soil as well as the exchangeable status of K shows a decrease after two year of cropping. The nutrient uptake studies reveal that the maximum NPK uptake takes place in the sequences sweet potato – rice – rice followed by rice – rice – rice and cowpea- rice – rice – rice followed by rice – rice – rice and cowpea - rice – rice. The balance sheet of nutrients reveals that nitrogen and available phosphorus in all sequences show a decrease and increases with decrease in fertilizer levels. The balance sheet of K shows that the soil maintains K levels. The sequence daincha – rice – rice is the best in maintaining a high K status in the soil. An analysis of the economics of cropping sequences reveal that the sequence sweet potato – rice – rice with full recommended dose of fertilizers gave the highest net return, which was followed by Cowpea in – rice – rice and rice – rice – rice. From nutrient balance studies, yield and economic analysis it is clear that any attempt in reducing the quantity of fertilizer for the component crops of the sequences affects the yield, besides deleteriously affecting the fertility of the soils. Any decrease in the fertilizer doses in the sequences will not be economical. With a long range view of enhancing crop output from cropping sequences and maintaining soil fertility, it becomes necessary to enhance and maintain higher fertility levels.Item Influence of levels of nitrogen, methods of application and plant population on the performance of the high yielding rice variety Sabari(Department of Agronomy, College of Agriculture, Vellayani, 1989) Mohamed Kunju, U; Sadanandan, NItem Strain variation in Rhizoctonia solani Kuhn [Thanatephorus cucumeris (Frank) Donk] causing sheath blight of rice(Department of Plant Pathology, College of Agriculture, Vellayani, 1986) Vijayan, M; Chandrasekharan Nair, NItem Persistence and metabolism of phorate in rice plants and in different soil types of Kerala and its effect on non target organisms(Division of Agricultural Entomology, College of Agriculture, Vellayani, 1987) Naseema Beevi, S; Visalakshi, AThe uptake, persistence and metabolism of phorate in rice plants and in different types of soil, viz., alluvial, sandy and lateritic loam when applied at 3 doses and 3 growth stages of the crop were studied by conducting field experiments. In these studies, the insecticides was applied as granules at 3 doses of 1.0, 1.25 and 1.5 kg ai/ha at 20, 40 and 60 days after planting. The residues were estimated colorimetrically and by bioassay. The metabolites in plants and soil were separated by T.L.C and further estimated colorimetrically at intervals of 2,7 and 14 days after application. The ultimate residues of the insecticide in grain and straw also were determined.
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