To evaluation of suitability of soil extractants for assessing boron availability to cauliflower (Brassica oleracea)

Abstract

A pot experiment was conducted during 2015-2016 with twenty two numbers of soils of varying soil characters for selecting the most suitable chemical extractant for determination of available boron and evaluation of critical limits of boron for cauliflower. The soils were extracted with hot water, hot 0.01M calcium chloride, 0.01M tartaric acid, 1.0M ammonium acetate, 0.5M potassium dihydrogen phosphate and 0.1M salicylic acid. The availability of boron was found to be varying with chemical extractants used. In terms of the efficiency of B extraction, the extractants followed the order in decreasing trend as hot 0.01M calcium chloride (HCC) > hot water (HW) > 0.1M salicylic acid (SA) >0.5M potassium dihydrogen phosphate (PDP) > 0.01 M tartaric acid (TA) >1.0M ammonium acetate (AA). Critical limits of extractable boron as determined by graphical procedure were 0.50, 0.66, 0.45, 0.38, 0.47, 0.50 mg kg-1 and by statistical procedure were 0.53, 0.66, 0.47, 0.38 0.47 and 0.50 mg kg-1 for hot water, hot 0.01M calcium chloride, 0.01 M tartaric acid, 1.0M ammonium acetate, 0.5M potassium dihydrogen phosphate and 0.1M salicylic acid, respectively. Both the methods showed very closer values of critical soil boron concentration. Among the extractants, 0.1M salicylic acid recorded the highest correlation with Bray’s percent yield, yield at control, B concentration at control and B uptake at control. Therefore, in view of high degree of correlation of soil test values with plant response parameters, 0.1M salicyclic acid was found to be the best extractant for assessing the available boron in soils of Assam. The critical level of boron concentration established by graphical and statistical procedures were 24.87 and 25.78 mg kg-1, respectively grown in soils of Assam in cauliflower plant on dry weight basis at 60 days growth period.