1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Physiological and molecular studies in mitigating drought stress of Tomato (Solanum lycopersicum) by biochar with organic amendments(Department of Plant Biotechnology, College of Agriculture , Vellayani, 2022-11-09) Anjusha, P; Viji, M MThe study entitled “Physiological and molecular studies in mitigating drought stress of tomato (Solanum lycopersicum) by biochar with organic amendments” was conducted at College of Agriculture, Vellayani, Thiruvananthapuram, during 2021-2022. The primary objective of this study was to determine the physiological and molecular attributes of tomato grown under water stress as influenced by biochar with organic amendments. The experiment on tomato variety ‘Vellayani Vijay’ was conducted in a completely randomized design in pot culture with five replications. In order to assess the effect of biochar (BC) (0.5% w/w) and organic amendments such as vermicompost (VC) and farm yard manure (FYM) in mitigating the consequences of water stress, individual treatments viz. (Biochar (0.5% w/w), VC (50g/10kgsoil) and FYM (50g/10kg soil)) as well as combined treatments viz. ((Biochar+VC) and (Biochar+FYM)) were carried out along with T1 control (normal irrigated condition) and T7 control (water stress). The study consisted of 12 treatments, in which T1 to T6 were irrigated normally whereas treatments designated as T7 to T12 were subjected to 25% water stress. The present study was carried out using biochar derived from rice husk that was subjected to maximum pyrolysis temperature of 550°C in a cylindrical iron tank. Water stress of 25% was imposed by gravimetric method for a period of 80 days (after three weeks of sowing). The seedlings were maintained in protected condition for the first three weeks. Various morpho-physiological and yield parameters were evaluated at different critical stages of the crop, such as seedling stage, vegetative stage, flowering stage, fruiting stage and harvesting stage. Molecular studies were carried out at 50% flowering stage. Water stress had a negative impact on morphological, physiological and yield attributes of S. lycopersicum except total soluble solids, when compared to plants under normal irrigated condition. Biochar treatment was found to effectively mitigate the deleterious impacts of water stress. Plants treated with biochar outperformed the plants grown in both VC and FYM with regard to all the physiological and morphological parameters studied. However the best yield performance (yield and yield parameters) was obtained in the treatment with 124 biochar in combination with vermicompost. According to the results obtained it was clear that the combined application of biochar and vermicompost increased the relative water content, membrane stability index, chlorophyll stability index, photosynthetic rate, total protein content, stomatal conductance, transpiration rate, plant height and primary branches per plant under both water stress and normally irrigated conditions when compared to the non-treated controls. This indicates the ability of biochar to retain water and thereby increasing soil moisture content. Furthermore, under water stress, there was a significant improvement in the morphological traits such as, root weight (57.07%), shoot weight (33.33%), root: shoot ratio (17.91%), fruit number (43.54%), fruit size (69.93%), fruit weight (13.10%), total soluble solids (10.32%) and yield (62.42%). SlWRKY8 gene has an important role under drought stress conditions and is reported to have role in the regulation of ROS pathways and mitigating the detrimental effects in plants grown under water stress condition. In the present study, quantitative real time PCR amplification of SlWRKY8 gene in tomato leaves (taken at 50% flowering stage) showed an increase in the expression level of this gene in the treatments with combined application of biochar and vermicompost, both under water stress condition (T11) (3.24 fold) and normal irrigated condition (T5) (1.51 fold) compared to their respective controls (T7 and T1). This indicates that BC and VC combinations can be applied to tomato plants grown under water stress for the upregulation of SlWRKY8 genes which regulate the ABA signaling and helps in ABA-mediated stomatal closure in water stress condition. Taken together, the study demonstrate that, the combined application of vermicompost and biochar not only boost crop production, but also mitigate the destructive impacts of water stress by influencing physiological, morphological and molecular parameters of tomato.Item Sorption and movement of cyantraniliprole in sandy loam soils with and without organic amendments(Department of Soil Science and Agricultural Chemistry , Vellayani, 2021-10-08) Al Noufiya, S; Thomas GeorgeThe study entitled “Sorption and movement of cyantraniliprole in sandy loam soils with and without organic amendments” was conducted in the Department of Soil Science and Agricultural Chemistry and the laboratory attached to the All India Network Project (AINP) on Pesticide Residues, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala during 2019-21. The main objectives of the experiment were to study the adsorption, desorption, persistence and leaching of cyantraniliprole in sandy loam soils with and without addition of organic amendment at the rate of 0.5 per cent Farm Yard Manure (FYM). The soil was collected from the sandy belts of Kazhakkoottam, Thiruvananthapuram. The physical and chemical analysis of the soil revealed that the soil was moderately acidic, with 0.84 per cent organic matter, 11.80 per cent clay, 22.30 per cent silt and 65.90 per cent sand. Among the major nutrients, phosphorus content was found to be high; potassium was medium while the other nutrients were low. The method for estimation of cyantraniliprole residues in soil were validated by modified QuEChERS method and was found ideal. Liquid- liquid partitioning using dichloromethane was found suitable for cyantraniliprole residue estimation in water. The adsorption-desorption studies were carried out at 5 different concentrations of 20, 40, 60, 80 and 100 μg levels each both in normal soil and 0.5 per cent FYM amended soil in Completely Randomized Design (CRD) with ten treatments and three replications and was repeated by direct spiking also. The adsorption- desorption data fitted well in Freundlich adsorption isotherm. The distribution coefficient, K d (mean value) was found high in amended soil (2.55) than normal soil (2.40) which indicated increased sorption in relation to organic matter content. The K f values (adsorption coefficient) were 2.60 and 2.45 for amended and normal soil respectively, indicating a high sorption capacity for the amended soil. The desorption was carried out in three cycles, the percentage desorption was decreasing in each consecutive cycle. In all levels of concentration, desorption was slower than adsorption indicating a hysteresis effect. In the soil samples directly spikedwith cyantraniliprole also, the desorption percentages were found lower and formed a still higher hysteresis. Mobility of cyantraniliprole was assessed in CRD with eighteen treatments and three replications i.e., by loading 3 levels viz., 25, 50 and 75 μg concentrations of cyantraniliprole, separately on top of 200 g soil columns loaded in PVC pipes and followed by eluting with 40, 80 and 160 mL of water @ 0.4 ml min -1 . In all the treatments residues were obtained in 0-25 cm packed columns and also in the leachate. In the normal soil, cyantraniliprole moved down the soil column which resulted in residue levels ranging from 7.48-3.98, 19.27- 9.57 and 27.67- 13.41 μg at 25, 50 and 75 μg levels, respectively when eluted with different volumes of water. In the soil amended with 0.5 per cent FYM, the corresponding residues ranged from 10.41- 4.48, 21.08- 9.89 and 29.98- 14.19 μg at 25, 50 and 75 μg levels indicating a higher retention in soil. The persistence of cyantraniliprole in normal soil and amended soil under three soil moisture conditions (air dry, field capacity and saturated) were studied using the formulation of cyantraniliprole added at the rate of 1, 2 and 4 mg kg -1 in CRD with eighteen treatments and three replications. The half- life of cyantraniliprole was found highest in amended soil spiked with 4 mg kg -1 cyantraniliprole under air dry soil condition i.e., 32.44 days followed by the same under normal soil condition i.e., 30.45 days. In the persistence study, no metabolites of cyantraniliprole were detected. The study concluded that the adsorption coefficient was higher in FYM amended soil indicating stronger adsorption than normal soil and the desorption percentages were reduced in the same. Hysteresis effect was noticed in all the treatments indicating slower desorption than adsorption. The mobility of cyantraniliprole was found to be slightly higher in normal soil compared to the 0.5 per cent FYM amended soil and also indicates its moderate mobility behaviour. The dissipation was found to be the fastest under submerged condition followed by field capacity and air dry conditions.