Major nutrient disorders of banana (var. nendran) in vaikom block

Abstract

The 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.