1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Optimization of soil environment and crop response for magnesium nutrition in ultisol(Department of Soil Science and Agricultural Chemistry College of Horticulture, Vellanikkara, 2019) Soniya, V P; Bhindhu, P SItem Major nutrient disorders of banana (var. nendran) in vaikom block(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 2018) Greeshma Suresh; Sailaja Kumari, M SThe research programme entitled “Major nutrient disorders of banana (var. Nendran) in Vaikom block” was carried out in various locations of banana growing areas in Vaikom, during 2015–2017. The study was conducted with the objective of finding out nutrient disorders of banana through a preliminary field survey followed by analysis of soil and plant for nutrient contents. The reasons for low yield and productivity of banana in the area of study were also investigated to identify the nutritional causes behind it. As part of the study, a survey was conducted to identify the major banana growing tracts of Vaikom region and soil samples were collected randomly from six locations in six panchayats of Vaikom block where visible symptoms were observed and nutrient deficiencies were suspected. Soil samples were collected during the first month after planting before fertilizer application from Chembu, Maravanthuruth, Udayanapuram, T. V. Puram, Vechoor and Thalayazham panchayaths. The samples were analyzed for physicochemical parameters like pH, electrical conductivity, organic carbon, available nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulphur (S), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and boron (B). The index leaf tissues of banana were also collected from the study locations during the fourth month after planting and were analyzed for major and micro nutrients. Results on soil acidity showed that the intensity of acidity varied from very strongly acidic to slightly acidic. About 13.33 per cent soils were very strongly acidic, 17.78 per cent strongly acidic, 41.11 per cent moderately acidic and 27.77 per cent slightly acidic. The electrical conductivity was found to be normal in these tracts at the time of sampling. High organic carbon status was observed in 35.56 per cent of the samples. Available phosphorus was adequate in the soils, but nitrogen and potassium were found to be deficient. About 48.8 per cent of soil samples were deficient in potassium and visible symptoms were prominent in the fields with necrosis of leaves starting from the leaf margin and extenting towards the midrib. Deficiency of calcium and magnesium was acute in the soils where field symptoms were observed. Calcium deficiency appeared as yellow-white parallel streaks in the leaf lamina parallel to the midrib accompanied by severe crinkling of leaves. Soil and plant analysis data revealed that micronutrient deficiencies were also widespread in the region. The symptoms of boron deficiency were prominent in the study area where plants showed delayed unfolding of leaves. Uneven and brittle leaf surface with ‘ladder like’ symptoms were also noticed in these plants. Nutrient management practices followed by the farmers in Vaikom block influenced the fertility status of soils to a certain extent. Majority of the farmers were unaware of the scientific nutrient management practices and rarely applied secondary and micro nutrients. As banana is a nutrient exhaustive crop and continuous cultivation in the same piece of land resulted in severe nutrient mining. These factors might have led to the poor yields obtained in these areas. It was concluded that the nutrient disorders observed in field were due to deficiency of both major and micro nutrients. Multi- nutrient deficiencies identified in the banana growing areas might be the major reason for decline in productivity. Scientific nutrient management based on soil and plant health can alleviate the nutrient deficiencies and enhance the crop yield.Item Characterisation of coconut palms (Cocos Nucifera L.) showing general yellowing(Department of Plantation Crops and Spices, College of Agriculture, Vellayani, 2017) Aparna, K; Sreekala, G SThe study on “Characterisation of coconut palms (Cocos nucifera L.) showing general yellowing” was undertaken in selected coconut palms coming under Thiruvallam of Thiruvananthapuram district from March 2016 to March 2017. The objective was to evaluate the field characteristics and nutritional status of soil and coconut palms showing general yellowing and to formulate a management strategy. Coconut palms of variety WCT showing general yellowing which advance from lower to upper whorls of leaves were identified from farmer’s field of Thiruvallam. Fifteen palms showing uniform pattern of general yellowing and five healthy palms were selected from five farmer’s fields. Field, soil, plant and management practices followed by farmers were studied in the selected palms to identify the pre disposing factors leading to general yellowing. Observations on morphological and yield characteristics of selected coconut palms were recorded for one year at 60 days interval. Soil and plant samples were collected and analysed for macro and micronutrients. Based on soil test results the quantity of deficient macro nutrients were calculated and applied as per package of practices recommendation of Kerala Agricultural University. The soil and plant sample was again analysed six months after the application of fertilisers. Data generated on field characterization revealed the type of soils as red loam soils with good drainage in all the selected coconut palms. High soil organic matter was seen in all the healthy coconut palms while eighty percentage of coconut palms showing general yellowing were under medium status of organic matter. Of the coconut palms showing general yellowing, fifty three percent belonged to the age group of 31-35.The disease and pest incidence in the healthy palms was only twenty percent while it was more than fifty percent in palms showing general yellowing. The morphological, physiological and yield parameters of selected palms indicated significant variation in number of leaves showing yellowing, chlorophyll content, membrane integrity, relative water content, number of bunches, number of female flowers per bunch of inflorescence, number of nuts set per bunch, weight of nut, weight of copra and oil content in coconut palms showing general yellowing compared to healthy palms. However after the application of nutrients significant increase in chlorophyll a content, total chlorophyll content, membrane integrity and relative water content was noticed in coconut palms showing general yellowing. The soil and leaf nutrient analysis revealed a significant variation in N, P, K, Ca, Mg, S and B content between coconut palms showing general yellowing and healthy palms. However, observations made at six months after the application of manures and fertilisers revealed a significant increase in soil pH, organic carbon, N, P, K, Ca, Mg, B and Cl in the soil and N,P,K of index leaf of coconut palms showing general yellowing. There was no significant variation in the S, Fe, Mn, Zn and Cu before and after the application of manures and fertilisers. The present study based on nutritional status and visual symptoms revealed that low soil nutrient status of N, P, K, Ca and Mg have resulted in the general yellowing in coconut. The application of fertilisers as per average management recommended by KAU (2016) could only enhance the soil N, P, K and Mg status to medium level while for calcium it still remained in low status. Thus a higher dose of N, P, K, Ca and Mg are required for the palms showing general yellowing to substantially improve the nutritional status of the palm.