PG Thesis
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Item Investigations on the possible relationship fields in Kerala State between the nutritional status of soils and the incidence of Bunchy top disease of Bananas (Musa species)(Division of Agronomy, Agricultural College & Research Institute, Vellayani, 1963) Damodaran Nambiar, P K; Nair, C K NBanana plays a very decisive role in the economy of the country. This is more so in the case of Kerala which commands the largest acreage under this crop. Such an economic crop is threatned with annihilation by the deadly disease "Bunchy Top" and the modest estimate of the annual loss is calculated to be about six crores of rupees.Item Weed dynamics in acid saline pokkali ecosystem(Department of Agronomy, College of Horticulture, Vellanikkara, 2018) Jeen Shaji; Deepa ThomasPokkali is a unique and sustainable rice farming system in coastal saline soils of Kerala, where rice - prawn rotational system is the traditional system followed. Pokkali system though unique in the world, is vanishing due to many practical problems and socio - economic constraints. The weed flora of Pokkali rice fields is different from that of other rice ecosystems. Weeds survive and dominate in Pokkali ecosystem by developing morphological and anatomical adaptive mechanisms. Aquatic and semi aquatic weeds occur during the crop season and get dried up and decay in the off-season (high saline phase). Hence no weed management practices are taken up during the period of crop production. With time, deviations in soil fertility status and variations in many other climatic factors like mean rainfall and number of rainy days have been observed. As a result, the weed spectrum has also undergone changes. However, not many studies have been conducted on the weed spectrum or contributing factors to weed shifts in Pokkali areas. The present study entitled “Weed dynamics in acid saline Pokkali ecosystem” was conducted in three parts. The first part was survey in the five major Pokkali growing areas in Ernakulum and Alappuzha districts viz., Paravur, Palluruthy, Vypin, Kalamassery and Pattanakad blocks. Two panchayaths from each block were selected for surveying. The predominant weeds reported in the Pokkali ecosystem were Diplachne fusca and Eleocharis dulcis. A total of 36 weeds were identified from Pokkali ecosystem during low saline phase and that included the weed flora in the actual rice fields, bunds and water channels. The newly reported weeds of the ecosystem include Rhizophora mangle, Hygroryza aristata, Hydrilla verticillata, Najas graminea, Fuirena umbellata, Schoenoplectus lateriflorus, Hygrophila schulli, Cleome burmanii, Ipomoea sp., Digitaria sanguinalis, Lindernia sp., Sesbania sp., Pennisetum clandestinum, Cyperus exaltatus, C. javanicus, Achrostichum aureum, and Exoecaria agallocha. Echinochloa cruss-galli, a dominant weed reported in earlier weed surveys has now confined to a very few locations only and the frequency has now reduced from 80 per cent to 12.5 per cent When weeds in the field alone were considered, Vypin block was found to have highest species richness (S) and diversity index (H). Similarity coefficients between the blocks indicated that Pattanakad and Kalamassery blocks were highly similar, followed by Vypin and Paravur blocks. When total weeds in the ecosystem were considered, Palluruthy block was seen to have highest species richness and diversity indices. The second part was a pot culture study of three predominant weeds found during the survey. Experimental design was CRD with three dominant weeds at two salinity levels. Presence of micro-hairs and higher K+ / Na+ ratio were the tolerance mechanisms observed in D. fusca. For E. dulcis and S. zeylanica, higher K+ / Na+ ratio and presence of more aerenchymatous voids were observed. The third part was the field study to assess the extent of crop loss due to weed infestation in Pokkali system. Factorial RBD was the experimental design used with two rice varieties (Vyttila -6 and Chettivirippu) and three weed management practices (unweeded control, weeding at 20 DAT and weed free condition) as the two factors. From the biometric characters recorded it was observed that the plant height and tiller number per m2 were found significantly higher in weed free conditions. Yield attributes like panicles per m2 and grains per panicle were also found significantly higher in weed free plot. Grain yield in weed free treatment had 19 per cent yield advantage over the unweeded control check. However the increase in yield of weed free treatment over single weeding was only 4 per cent. The highest benefit - cost ratio was recorded in weed free treatments of both varieties. However, the ratio of single weeded treatment was found comparable with the weed free treatment. Thus, it can be concluded that a single weeding at 20 DAT is an inevitable practice which can be recommended to farmers for better returnsItem Nutritional requirements of winged bean [Psophocarpus tetragonolobus(L.)DC. ](Department of Agronomy, College of Agriculture, Vellayani, 1984) Brillin, C; Pushpangadan, KItem Carbon storage potential of intensive silvopasture systems in humid tropics of kerala(Academy of Climate Change Education and Research, Vellanikkara, 2016) Varsha, K M; Asha K RajItem Biomass production and root distribution pattern of selected acacias(Department of Silviculture and Agroforestry, College of Forestry, Vellanikkara, 2014) Mereena, M J; Jamaludheen, VItem Fertigation and mulching studies in yard long bean (Vigna unguiculata var-sesquipedalis (L.) verdcourt)(Department of Olericulture, College of horticulture, Vellanikkara, 2014) Mahasuma Puthuppalli; Salikutty JosephThe investigations on ‘Fertigation and mulching studies in yard long bean (Vigna unguiculata var. sesquipedalis (L.) Verdcourt)’ were carried out in the Department of Olericulture, College of Horticulture, Vellanikkara during January –May 2014. The study was conducted in the yard long bean variety Vellayani Jyothika to standardize the fertigation requirement and to assess the relative efficacy of fertigation and mulching over the conventional method. The experiment was laid out in strip plot design with two replications. There was a total of 17 treatments consisting of combinations of two irrigation levels (60 and 80 per cent pan evaporation (Ep) through drip irrigation) and four fertilizer levels (75, 100 and 125 per cent recommended dose of fertilizer (RDF) and 100 per cent RDF with water soluble fertilizer) with and without mulching and a control treatment (channel irrigation once in three days with 100 per cent RDF). The study revealed that irrigation, mulching and fertilizer levels had significant effect on vine length. Scheduling of irrigation at 80 per cent Ep resulted in significantly higher vine length. At higher levels of irrigation (80 per cent Ep) yield and number of pods per plant were higher whereas, length and weight of pods, and number of seeds per pod were not influenced by the levels of irrigation. Mulching significantly influenced yield and yield attributing characters like number of pods per plant, and length and weight of pods but had no influence on number of seeds per pod and protein content of pods. Plants receiving 125 per cent RDF resulted in significantly higher yield and yield attributing characters like number of pods per plant, number of seeds per pod, length and weight of pods compared to 75 and 100 per cent RDF. Per se and interaction effects of irrigation, mulching and fertilizer were not significant with respect to days to first flowering, first fruit set, first harvest, days from flowering to harvest, number of harvests, duration of the crop and protein content. Weed growth in terms of fresh and dry weight was not influenced by levels of irrigation while mulched plots recorded significantly lower weed growth than the unmulched plots. Among the fertilizer levels, 125 per cent RDF resulted in higher weed growth. Organic carbon content, available nitrogen, available phosphorus and available potassium on 45 DAS and at final harvest were the highest in treatments receiving 125 per cent RDF whereas, the highest pH and the lowest EC were recorded in 75 per cent RDF. Interactions between levels of irrigation, mulching and fertilizer when considered together, had significant effect on vine length, all yield attributes, weed growth and all soil parameters. The vine length, yield, yield attributes like length and weight of pods and soil nutrients were the highest when irrigation was given at 80 percent Ep along with mulching and 125 per cent RDF (I1M1F3). This was statistically on par with the treatment I2M1F3 in which irrigation was limited to 60 per cent Ep. An increase of 3.4 times was there in yield in the treatments I1M1F3 and I2M1F3 over conventional channel irrigation at 3 days interval with 100 per cent RDF (control). The highest BC ratio of 1.83 was obtained for the treatments I1M1F3 and I2M1F3 (60 and 80 per cent Ep with mulching, 125 per cent RDF). Irrigation at 60 or 80 per cent Ep along with 125 per cent RDF and mulching with white on black polythene was found to be the best treatments.Item Production protocol for organic tomato : (lycopersicon esculentum mill.).(Department of Agronomy, College of Agriculture, Vellayani, 2011) Abijith Kumar, V P; Girija Devi, LItem Biomass productivity of a forage crop based cropping systems involving C3 and C4 plants(Department of Agronomy, College of Agriculture, Vellayani, 1988) Jayakumar, M; Pillai, M R CAn investigation was undertaken at the College of Agriculture, Vellayani during 1987 to study the biomass productivity of guinea grass based cropping system involving C3 and C4 plants. The intercrops wars a C4 grass maize and a C3 legume cowpea. The intercrops were grown in different rows with and without sequential thinning. The experiment was laid out in Randomised Block Design with three replications. After harvesting intercrops guinea grass was allowed to grow without subsequent intercrops. Total biomass yields upto third out of guinea grass were subjected to evaluation.Item Sulphur status of major uplands of south Kerala(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 1991) Sheeba, S; Korah, P AA study has been made to determine the different forms and distribution of sulphur, and its relationship to relevant soil parameters in the major upland soils of South Kerala representing sandy, redloam, laterite midland, laterite midupland and forest soils. An attempt was made to study the plant available sulphur by conducting Neubauer technique using paddy as the test crop. Available sulphur in the soils was also estimated using different extractants. The results of the experiments were summarised and appropriate conclusions drawn.Item Nutritional requirement of arrow root as pure crop(Department of Agronomy, College of Agriculture, Vellayani, 1991) Remesan, K K; Oommen, MA field experiment was conducted in garden lands of Instructional Farm of College of Agriculture, Vellayani, to study the effect of N, P and K on growth, yield and quality of arrow root and uptake pattern of major nutrients. The treatments in the experiment consisted of four levels of nitrogen (0, 50,100 and 150 kg/ha N). Four levels of phosphorus (0, 25, 50 and 75 kg/ha P2O5) and four levels of potassium (0, 50, 100 and 150 kg/ha K2O). The experiment was laid out in 43 partially confounded factorial in RBD with two replications. Different growth attributes like height of plants, number of leaves, number of suckers per plant, leaf area index were maximum at higher levels of nitrogen and potassium. The total drymatter production was highest by the application of 150 kg N. 75 kg P2O5 and 150 kg K2O per hectare. The highest value of rhizome number, length of rhizome and girth of rhizome were obtained by the application of 100 kg/N, 75 kg P2O5 and 150 kg/ha K2O. Maximum mean rhizome weight was with 150 kg n/ha, 75 kg P2O5 and 150 kg K2O per hectare. Fresh weight of plants was maximum with highest levels of nitrogen, phosphorus and potassium. Rhizome yield was maximum when nitrogen, phosphorus and potassium were applied at the rate of 150, 75 and 150 kg/ha respectively. Highest levels of nitrogen, phosphorus and potassium increased the starch, yield and protein content of rhizome. Nitrogen nutrition increased the crude fibre content of rhizome, but potassium application decrease the fibre content. The plant uptake of nitrogen, phosphorus and potassium was maximum at highest level of these nutrients. Maximum benefits cost ratio and net return were obtained by the application of 150 kg/ha N, 75 kg/ha P2O5 and 150 kg/ha K2O.