1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Agrotechniques for enhancing root production in Desmodium gangeticum (L.) DC under partial shade(Department of Agronomy, College of Agriculture,Vellayani, 2019) Abhijith, S S; Anilkumar, A SThe study entitled “Agrotechniques for enhancing root production in Desmodium gangeticum (L.) DC. under partial shade” was undertaken during 2017-2019, in the Instructional farm, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala, with an objective to study the integrated effect of root endophyte fungus, planting density, source efficacy of nutrients, moisture stress and subsurface mulching on the growth, yield and quality constituents of Desmodium gangeticum (L.) DC. under partial shade. The field experiment was laid out in randomized block design with 12 treatments and three replications. The treatments were, T1 – Inoculation with Piriformospora indica (root endophyte) alone, T2 – T1 + Soil application of cow dung slurry (5% at monthly interval), T3 – T1 + Soil application of NPK (basal- @ 40:40:40 kg ha-1 year-1), T4 – T2 + Irrigation at 15 mm depth, T5 – T2 + Irrigation at 30 mm depth, T6 – T3 + Irrigation at 15 mm depth, T7 – T3 + Irrigation at 30 mm depth, T8 – T5 at high density planting (40 cm x 20 cm), T9 – T7 at high density planting, T10 – T8 under subsurface mulching with black polythene, T11 – T9 under subsurface mulching with black polythene and T12 – control at normal row planting (40 cm x 40 cm). Piriformospora indica was inoculated with the potting medium @ 10g fungal culture kg-1 of potting medium. Results of the experiment revealed that integrated management practices have significant effects on growth and yield attributes of D. gangeticum. The treatment T7 recorded the tallest plants at 3 and 4 months after transplanting (MAT) whereas, T9 was superior at 5, 6 and 7 MAT and at harvest. The treatment T7 registered the highest number of branches at all stages of growth. At 3 and 5 MAT, T6 recorded the highest leaf number whereas T7 was superior at 4, 6 and 7 MAT and at harvest. T5 registered the highest root number at 3 MAT but T10 was found superior at 5, 6 and 7 MAT and at harvest. At 2 MAT, T9 and at all other growth stages, T7 recorded the highest root spread. T5 at 3 MAT, T7 at 5 and 6 MAT and at harvest and T6 at 7 MAT registered the highest root volume. With respect to length of tap root, the treatments T9 at 3, 4, and 6 MAT and at harvest and T8 at 7 MAT were found superior. At 3 MAT, T5 revealed the highest girth of primary root but at 5, 6 and 7 MAT, T7 and at harvest T6 were found superior. The treatment, T7 registered the longest laterals at 5, 6 and 7 MAT and at harvest. The root fresh and dry weight showed a similar trend. The treatments T9 at 3 MAT, T6 at 5 and 7 MAT and T7 at 6 MAT and at harvest showed the highest fresh and dry root weight. The highest root yield at harvest was recorded by T8 which was on par with T9, T10 and T11. Chlorophyll content varied with different growth stages. T5 at 2 MAT, T6 at 5 MAT, T11 at 6 MAT and T9 at 4 and 7 MAT and at harvest registered the highest total chlorophyll content. Like chlorophyll content, RLWC also showed variations with respect to different growth stages. T2 at 3 and 4 MAT, T6 at 7 MAT and T7 at 5 and 6 MAT and at harvest recorded the highest values. At 5 and 7 MAT and at harvest T7, T5 and T6 respectively recorded the highest root-shoot ratio. The treatments T11 and T9 at 2 and 7 MAT and T8 at 3, 5 and 6 MAT and at harvest registered the highest leaf area index. Observations on crop growth rate showed the significance of T8 at 4 to 5 MAT, T6 at 6 to 7 MAT and T9 at 5 to 6 MAT and 7 MAT to harvest. With respect to relative growth rate, T4 at 2 to 3 MAT and T6 at 3 to 4, 4 to 5 and 6 to 7 MAT followed by T9 at 7 MAT to harvest were found superior. At 2 to 3 and 4 to 5 MAT, the treatments T11 and T10 respectively recorded the highest values for net assimilation rate. Ethanol extract of plant roots grown under control at normal row planting (40 cm x 40 cm) (T12) recorded the highest total alkaloids at harvest. Among seed parameters, only number of seeds per inflorescence was significantly influenced by the treatments at 6 MAT and it was the highest in T1. Soil moisture studies revealed the significance of T8 and T9 in enhancing soil moisture retention before and after irrigation. T4 on par with T6 registered the highest consumptive use, daily consumptive use and Kc. Crop water use efficiency was the highest for the treatment T8. T2 registered the highest field water use efficiency and water productivity. T9 recorded the highest up take of primary plant nutrients. After the experiment, organic carbon and available K status of soil were found superior in T3 and T10. Even though nursery seedlings exhibited P. indica root colonization at harvest, it was not clearly evident through microscopic investigation. Economic analysis of the system revealed the significance of T8 (₹ 47,902 ha-1) which was on par with T9 and T10 with respect to net income. The highest benefit-cost ratio was also registered by T8 which was significantly superior to all other treatments. It is concluded that high density planting of P. indica inoculated seedlings under partial shade followed by monthly application of cow dung slurry (5 %) and scheduling irrigation at 30 mm depth once in six days (T8) was found beneficial for enhancing leaf area index, root production, crop water use efficiency, net income (₹ 47,902 ha-1) and benefit-cost ratio (1.74).Item Microbial inoculants for enhancing degradation of biosolid waste in aerobic composting(Department of Agricultural Microbiology, College of Horticulture, Vellanikkara, 2019) Shilpa, P; Girija, DSolid waste management is a major challenge throughout the world, especially in urban areas, due to the rapid growth of population along with urbanization. Earlier, centralized management of biosolid waste was being practiced. However, due to problems in transportation and segregation, management at source is being promoted. Aerobic composting has been practiced from time immemorial for recycling of biosolid waste, using various processes and containers. Recently, more importance is being given to bio- composting, considering the efficiency of microorganisms in enhancing degradation of organic substrates by their multiple mode of action. Hence, this study was taken up to explore microorganisms which can enhance the process of aerobic composting of biosolid waste. Isolation of potential decomposing microorganisms was attempted from different compost samples including coir pith compost, kitchen waste compost and Oushadhi ayurvedic compost. A total of 14 isolates were obtained from different compost samples. All the isolates were assigned names depending upon the type of microorganism and the source from which they were isolated. Based on the ability to degrade the chemical components in selective medium, four isolates (BaBc-1, BaCp-1, BaOu-1 and AcOu-1) and four reference cultures (Bacillus subtilis, Bacillus niabensis, Gongronella butleri and Trichoderma asperellum) were selected for quantitative assay. Enzyme assay was carried out for selected isolates and the isolate G. butleri exhibited highest cellulase activity. BaBc-1, B. subtilis and BaOu-1 recorded significantly higher β- 1, 3 glucanase activity. Glucosidase activity was found to be significantly high in G. butleri, T. asperellum, BaBc-1 and B. subtilis. Significantly higher laccase, amylase and pectinase activity was recorded in BaOu-1, BaBc-1 and AcOu-1 respectively. Maximum protease activity was recorded in fungal isolates G. butleri and T. asperellum. Potential isolates were further subjected to cultural, morphological, biochemical and molecular characterization. The isolate BaBc-1 showed maximum homology to Bacillus subtilis, BaCp-1 to Bacillus cereus, BaOu-1 to Bacillus sp. and the actinomycete isolate AcOu-1 to Streptomyces roseofulvus. The compatible combinations of selected isolates with high enzyme activity were selected for formulation of microbial consortia and the consortia were evaluated for degrading vegetable waste under in vitro condition. All the inoculated treatments showed faster degradation compared to uninoculated control. Based on visual observations, per cent weight reduction, enzyme activity and microbial population on 21 DAI in flask culture, consortium II (B. subtilis BaBc-1+ T.asperellum+ Bacillus sp. BaOu-1) and consortium IV (B. subtilis+ G. butleri +B. subtilis BaBc-1) were selected for pilot scale experiment. The efficiency of selected consortia was evaluated in KAU smart biobin along with cow dung slurry and uninoculated treatment. In T1 (B. subtilis BaBc-1+ T.asperellum+ Bacillus sp. BaOu-1) compost formation was initiated within 17 days after inoculation. Based on the volume reduction, duration of composting process, yield of compost, microbial population and phytotoxicity of compost, consortium I (B. subtilis BaBc-1+ T.asperellum+ Bacillus sp. BaOu-1) was selected as best performing consortium in KAU smart biobin. Hence, this consortial formulation was selected for large scale experiment in Thumburmuzhi composting units. Cow dung was used as inoculum in positive control and uninoculated treatment served as negative control. The treatment T1 (B. subtilis BaBc-1+ T.asperellum+ Bacillus sp. BaOu-1) recorded maximum temperature (640C) during composting period, faster volume reduction and maximum microbial population in compost. Based on these results, T1 was found to be the best treatment in Thumburmuzhi composting unit. The study revealed that, consortial formulation of B. subtilis BaBc-1, T. asperellum and Bacillus sp. BaOu-1 could be exploited for enhancing degradation of biosolid waste in aerobic composting. This can be used in future for the management of agricultural and municipal solid waste. The plant growth promoting (PGP) activities of these isolates could be an added advantage in improving the growth and yield of plants.Item Evaluation of biofilm based microbial antagonists for the management of soil borne diseases and growth promotion in cowpea (Vigna unguiculata L. Walp)(Department of Agricultural Microbiology, College of Horticulture, Vellanikkara, 2018) Vinay Kumar, B; Surendra Gopal, K