1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Characterization, conversion and evaluation of selected lignocellulosic biomass(Department of Soil science and Agricultural Chemistry, College of Agriculture, Vellayani, 2014) Anushma, S; Aparna, BThe study entitled “Characterization, conversion and evaluation of selected lignocellulosic biomass” was conducted during the period 2013-14 at the Department of Soil Science & Agricultural Chemistry, College of Agriculture, Vellayani. The main objectives of the study were the characterization of the lignocellulosic biomass from selected plant sources, assessment of various microbial and enzymatic sources for degrading the lignocellulosic biomass into compost and evaluation of the resultant compost for assessing its manurial value. The experiment was completed in three stages. Representative samples of water cabbage (L. flava), coir pith, water hyacinth (E. crassipes) , and farm wastes (dried leaves and pseudostem of banana) were collected and analysed for bio-chemical composition. Water cabbage recorded 2.74 per cent N, 0.30 per cent P, 0.33 per cent K, 16.98 C:N ratio, and no detectable levels of heavy metals except Ni (0.55 ppm) and inferred as the best substrate in terms of nutrient content followed by water hyacinth, farm wastes and coir pith respectively. The substrates were converted to composts using various inoculants viz. T. reesei, P. sajor-caju, Composting Inoculum and commercial enzyme cocktail (cellulase/pectinase and lactase) and physico- chemical and biological characteristics were analyzed. A mixture of water cabbage and Composting Inoculum) was concluded as the best in terms of nitrogen content , cellulase activity, maturity period, C:N ratio and no detectable levels of heavy metals except Ni (0.414 ppm) followed by the mixture of Water hyacinth and Composting Inoculum had comparable N, P , K, EC , C:N ratio, and heavy metal content below the detectable limit. Considering the effect of inoculants on different substrates, Composting Inoculum was concluded as the best in terms of moisture content, EC,N, P, K, dehydrogenase activity, cellulase activity, maturity period and C:N ratio. The resultant composts from the previous stage were evaluated for their performance as manure in a pot culture experiment with test crop amaranthus (variety - Arun). Application of 100 % N as compost water hyacinth and Composting Inoculum was noticed as the best treatment in terms of yield, plant height, number of branches, girth of stem, soil properties viz. water holding capacity, available N, available P, available K, available Mn, available Cu, bacteria population and plant content of micronutrients viz. Mn, Cu, and B. Major enzymes viz. dehydrogenase, urease and aryl sulphatase imposed significance on yield and yield attributes. Application of 100 % N as compost from water cabbage and Composting Inoculum was found to be good and on par with T13 in many of the characters. Application of various composts did not result any heavy metal accumulation in the soil Thus it was inferred from the study that water cabbage was the best substrate in terms of their chemical composition followed by water hyacinth. water cabbage + Composting Inoculum was recorded as the best compost followed by water hyacinth + Composting Inoculum. 100 % N as compost (water hyacinth + Composting Inoculum) was noticed as the best treatment in pot culture. With regards to inoculants used on different substrates,Composting Inoculum was found to be the most effective for composting the agrowastes.Item Management of water cabbage (Limnochairs flava (L.) buchenau) in wetland rice ecosystem(Department of Agronomy, College of Agriculture, Vellayani, 2012) Nishan, M A; Sansamma GeorgeAn investigaton entitled ‘Management of water cabbage (Limnocharis flava (L.) Buchenau) in wetland rice ecosystem’ was carried out in the wetland of the Instructional farm attached to the College of Agriculture, Vellayani from February 2011 to January 2012. The major objectives of the experiment were, to study the biology of water cabbage (Limnocharis flava (L.) Buchenau), to evaluate certain new generation herbicides for managing it and to assess the potential of the weed biomass as an organic source. For the study of weed biology (Part I), a part of the weed infested field was selected for the experiment and prepared thoroughly as in the case of rice cultivation and the sample plants were observed from their emergence onwards. The ontogeny of the weed, its vegetative, and reproductive characters and also their allelopathic influence on germination and early growth of rice were studied. The field experiment on weed management (Part II) was laid out in Randomised Block design with eight treatments replicated thrice. The treatments included azimsulfuron @20 and 30 g a.i. ha-1, bispyribac sodium @20 and 30 g a.i. ha-1), (metsulfuron methyl+ chlorimuron ethyl) @ 4 and 6 g a.i. ha-1 and 2, 4-D @ 1 kg a.i. ha-1 along with a weedy check as control. The potential for utilization of the weed biomass through vermicomposting (Part III) was also assessed during the investigation. The data on weed biology indicated that water cabbage had very efficient reproductive mechanism which explains the invasive nature of the weed. A single plant was found capable of producing more than one lakh seeds and about 90 per cent of them germinated under favourable conditions. The plants exhibited pseudovivipary, through production of ramets which gave an additional advantage for the plant to spread. Germination studies revealed that maximum weed seed germination occurred under direct sunlight in crowded condition in the wetland soil condition. Direct sunlight was found necessary for the seed germination. Allelopathic studies showed that the fresh leachate of water cabbage was found to exert a positive effect on the vigour index of rice seedlings while substantial reductions in seedling growth were observed when treated with decayed plant leachate. The results of the field study on weed control efficiency of the different herbicides indicated that 2, 4-D @1 kg a.i. ha-1 was most effective for controlling water cabbage. Among the new generation herbicides (metsulfuron methyl + chlorimuron ethyl) @ 6 g a.i. ha-1 and bispyribac sodium @ 30 g a.i. ha-1 were equally effective for controlling water cabbage. The results of soil microbial studies indicated that the soil treated with the herbicides had much higher microbial population than the untreated plots except in the case of bispyribac sodium. The cost of managing the weed by using new generation herbicide was found considerably lower than that by manual weeding. The chemical analysis of the vermicompost prepared from the weed biomass recorded favourable nutrient composition. The micronutrients and heavy metals were within the safe limits except for the copper content. More over, the luxuriantly growing weed biomass was promising for bioremediation, to remove pollutants from aquatic ecosystems.