1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Evaluation of plant growth promoting rhizobacteria for pokkali rice(Department of Agricultural Microbiology, College of Agriculture,Vellanikkara, 2023-02-17) Bony Cyriac.; Surendra Gopal, KPokkali rice farming is a time-honoured, environmentally beneficial, traditional and organic method of growing rice. Neither chemical fertilizers nor plant protection agents are used on the crop in this conventional rice farming technique. The present study was undertaken to evaluate a native plant growth promoting rhizobacteria (PGPR) consortia with an objective to screen PGPR for functional efficiency under in vitro and evaluate for plant growth promotion in Pokkali rice. Isolation, characterization and screening of plant growth promoting rhizobacteria such as nitrogen fixers, phosphate solubilizers, potassium solubilizers, fluorescent pseudomonads and Bacillus sp. were carried out from three Pokkali rice growing regions of Ernakulam district (Vytilla, Varapuzha and Kadamakudy). Maximum population of 4 x 103 , 4.66 x 103 and 16.67 x 103 cfu per g of soil were recorded for nitrogen fixers, phosphate solubilizers and Bacillus sp. respectively and fluorescent pseudomonads and potassium solubilizers were absent. A total of 25 predominant isolates were obtained of which 17 isolates belonged to Bacillus sp. and remaining 4 isolates each were nitrogen fixers and phosphate solubilizers. Cultural, morphological and biochemical characters of all the 25 isolates of rhizobacteria showed varied colony morphology and Gram reaction. These isolates were evaluated under in vitro for plant growth promotion activities (production of indole acetic acid, nitrogen fixation, phosphate and potassium solubilization), antagonistic mechanisms (NH3, HCN and siderophore production) and its activities against Xanthomonas oryzae. Quantity of IAA produced by rhizobacterial isolates ranged from 0.46 to 31.27 μg ml-1. Quantity of nitrogen fixed and phosphate solubilized by rhizobacterial isolates varied from 5.72 to 25.21 mg of N g-1 sucrose utilized and 1.98 to 53.19 μg ml-1, respectively. There was no significant difference between potassium solubilized by isolates. Among the rhizobacterial isolates all Bacillus sp. isolates and two isolates each of nitrogen fixers and phosphate solubilizers were found positive for ammonia production. In case of screening of isolates for siderophore production, isolate VYP1 produced moderate orange halo zone on CAS agar media. Isolates VYN1, VYN2, VRB1 and VRB3 recorded poor siderophore activity. Remaining all isolates in the study screened negative for siderophore production. All isolates in the study were found negative for HCN production. Antagonistic activities of isolates to inhibit the rice pathogen Xanthomonas oryzae was evaluated and twenty one isolates screened exhibited antagonistic response against pathogen in which Bacillus isolates KDB4 and KDB5 exhibited excellent antagonism against pathogen. Based on the plant growth promotion activities and antagonistic activities, four most efficient isolates each of nitrogen fixers, phosphate solubilizers and Bacillus sp. were selected for salinity tolerance studies. Among the isolates, nitrogen fixers and Bacillus sp. exhibited maximum salinity tolerance of 12% whereas, phosphate solubilizers exhibited salinity tolerance up to 4% salt concentration. After salinity tolerance studies, three most tolerant nitrogen fixers (VYN2, KDN1 and KDN2), phosphate solubilizers (VYP1, VRP1 and KDP1), and Bacillus sp. (VYB3, VYB6 and KDB1) were selected for compatibility studies. Three most promising PGPR based consortia, PGPR consortia1 (KDN2 + KDP1 + VYB6), PGPR consortia-2 (KDN1 + KDP1 + VYB6) and PGPR consortia-3 (KDN2 + VYP1 + KDB1) were formulated. The three most promising consortia were evaluated under pot culture experiment, along with KAU commercial formulation (PGPR Mix-1) and Organic Package of Practices Recommendations of KAU (2017), at RRS, Vytilla, with Pokkali rice (variety Vytilla-6) as the test crop. All the three native PGPR consortia (T1, T2 and T3) exhibited significant increase in plant height and plants treated with T1 (PGPR consortia 1- KDN2 + KDP1 + VYB6) and T2 (PGPR consortia 2 - KDN1 + KDP1 + VYB6) recorded significantly higher results. Higher number of grains per panicle, grain yield (g per pot) and theoretical grain yield (kg ha-1) were observed in PGPR consortia 1 consisting of isolates KDN2 (N-fixer) + KDP1 (P- solubilizer) + VYB6 (Bacillus sp.). Significantly higher test weight of seeds were observed in T1, T2 and T3 inoculated with native PGPR consortia compared to other treatments. However, the treatments did not have any significant effect on number of tillers, number of panicles per plant and the percentage of chaffy grains produced. The present study indicated that saline tolerant PGPR consortia-1 consisting of Enterobacter cloacae strain KDN2 (N-fixer) + Bacillus subtilis strain KDP1 (Psolubilizer) + Bacillus altitudinis strain VYB1 (Bacillus sp.) was the most promising biofertilizer in enhancing the production of Pokkali rice of Kerala. However, further evaluation of the most promising consortia needs to be done under field conditions to confirm the results.Item Studies on the biological effects of x-rays on chillies (Capsicum annuum L.)(Division of Agricultural Botany, Agricultural College & Research Institute, Vellayani, 1969) Kamaluddin Sahib, M; Kumara Pillai, PThis thesis work was oriented towards the study of the M1 parameters, and the chlorophyll mutation spectrum in the M2 generation of the X-ray irradiated seeds of K-1 variety of Chillies (Capsicum annuum L.) Dry paroline seeds of chillies were subjected to X-ray treatment at doses of 1000, 4000, 8000 and 15000 units employing a Superficial Therapy Medical X-ray unit. Germination tests showed higher percentage of germination in the control than in the treatments.Item Response of CO.7 ragi (Eleusine coracana) to phosphate and potash(Regional Post Graduate Training Centre, Agricultural College and Research Institute, Coimbatore, 1963) Ramakrishnan Nair, KWith a view to study the effect of graded doses of P2 O5 and K2O on the yield potential of popular high fertility Ragi, strain Co.7 field experiment was laid out in the Central farm, Agricultural College and Research Institute, Coimbatore during 1962-63(February). Three levels of P2O5 and K2O at 0 to 20 lb and 40 lb, alone and in combination with one level of nitrogen at 60 over a basal dressing of five tons of farm yard manure was found by analysis to have 0.38 percent P2O5 AND 0.22 percent K2O supplying 43 lb of P2O5 and 25 lb of K2O per acre.Item Investigations on the efficacy of biochar from tender coconut husk for enhanced crop production(Department of soil science and agricultural chemistry, College of agriculture, Vellayani, 2015) Mariya Dainy, M S; KAU; Usha, P BAn investigation was carried out at College of Agriculture, Vellayani to characterize biochar from tender coconut husk and to assess its effects on soil properties, growth and yield of yard long bean (Vigna unguiculata subsp. sesquipedalis). The experiment consisted of production and characterization of biochar, laboratory experiments on nutrient sorption- desorption studies, carbon dioxide emission studies and a field experiment. Biochar was produced from tender coconut husk by the process of pyrolysis and it was crushed, sieved and the 2 mm sieved samples were used for further studies. The produced biochar had an alkaline pH (9.13), high CEC (15.26 cmol kg-1) and C: N ratio (68.86). Electrical Conductivity, total C, N, P, K, Ca, Mg and S contents in the prepared biochar were 1.73 dS m-1, 72.3 per cent, 1.05 per cent, 0.38 per cent, 2.27 per cent, 0.40 per cent, 0.20 per cent and 0.27 per cent respectively. The produced biochar recorded very high water holding capacity (226 per cent), low bulk density (0.14 Mg m-3) and high Brunauer Emmett Teller surface area (157.93 m² g-1) A laboratory experiment was conducted to study the desorption and sorption of nutrients like N, P, K, Ca, Mg, S, Fe, Mn, Zn and Cu using biochar. 32.35 per cent NH4+, 75.65 per cent PO42-, 45.14 per cent K+, 46.00 per cent Ca2+, 23.45 per cent Mg2+, 74.38 per cent SO42-, 36.80 per cent Fe2+, 30.20 per cent Mn2+, 26.75 per cent Zn2+ and 26.72 per cent Cu2+ were found to be desorbed from biochar after 7 rinses using de-ionized water in 1:100 ratio. The highest per cent of nutrient desorbed was P (75.65 per cent), followed by S (74.38 per cent) and the lowest per cent of nutrients desorbed were Zn (26.75 per cent) and Cu (26.72 per cent) within 72 hours. Sorption experiments were performed using rinsed biochar at different concentrations of nutrients and at different time intervals in 1:100 ratio. The results of the study indicated that biochar could sorb 100 per cent NH4+, 90.70 per cent PO42-, 92.00 per cent K+, 87.00 per cent Ca2+, 86.15 per cent Mg2+ and 91.82 per cent SO42- when it was equilibrated with 100ppm solutions within 24hours. For micronutrients, when 50 mg l-1 Fe2+, Mn2+, Zn2+ and Cu2+ solutions were given, biochar could sorb 99.67 per cent, 100 per cent, 99.12 per cent and 99.12 per cent respectively. Biochar from tender coconut husk is a good sorber and slow releaser of nutrients. An incubation study was carried out to estimate and study the pattern of carbon dioxide emission by the application of biochar into soil and it was compared with that of common organic amendments viz. FYM and vermicompost. The experiment consisted of 7 treatments with 3 replications and the study revealed that the cumulative amount of carbon dioxide emitted was highest for FYM @ 2 per cent (1014.05 mg CO2 100 g-1) and biochar @ 2 per cent registered an emission of 87.17 mg CO2 100 g-1 after 6months of incubation. There observed 91.40 per cent reduction in CO2 emission when soil was incubated with biochar @ 2 per cent compared to 2 per cent FYM. A field experiment was carried out with biochar and other commonly used organic manures at different doses using yard long bean variety Vellayani Jyothika as the test crop during January 2013 to April 2013, at the Instructional farm, College of Agriculture, Vellayani. Yield (1358 g plant-1) and yield attributes like pod length (54.50 cm), pod girth (3.90 cm), number of pods per plant (51), nutrient uptake and B: C ratio were significantly superior for the treatment T8 which received biochar @ 20 t ha-1 with 2 per cent PGPR and NPK as per POP. Physical properties chemical properties of the soil were significantly improved by the application of biochar @ 30 t ha-1. Biochar application reduced the bulk density, increased water holding capacity, water stable aggregates, pH, Cation Exchange Capacity, organic carbon status and nutrient availability. From the investigations, it can be concluded that application of biochar @ 20 t ha-1 along with 2 per cent PGPR and NPK as per POP which resulted in the yield of 1358 g plant-1 (20.12 t ha-1) can be considered as the economically viable and the best treatment. Biochar from tender coconut husk can be used as a good soil amendment which can improve soil health and enhance crop production.