Suitability of Multinutrient Extractants for Evaluation Of Available Soil Zinc for Tomato Nutrition Of Karnataka Soils

Abstract

Pot experiment was conducted at University of Agricultural Sciences, Bangalore, Karnataka, which received five treatments i.e., 0, 5, 10, 15, 20 kg ZnSO4/ha. Among all the treatments Recommended NPK + ZnSO4 @ 20 kg/ha recorded highest mean dry matter yields of tomato. The amount of zinc extracted by different extractants were in the following order as Mehlich-3 - Zn > 0.1 N HCl - Zn > AB-DTPA - Zn > 0.01 N EDTA - Zn > DTPA - Zn > 0.01 M EDTA + 1 N NH4OAc - Zn > 1 N NH4OAc (pH 4.6) - Zn > 1 N NH4OAc (pH 7) - Zn. Among the various extractants tried DTPA - Zn gave positive and higher significant correlation with Brays per cent Yield (r = 0.781). The next better extractants were Mehlich-3 (r = 0.726) and AB-DTPA (r = 0.576) which were also significantly positively correlated with Brays per cent yield. The critical limits of DTPA, Mehlich-3, AB-DTPA, tomato plant and tomato fruit by graphical method were 1.12, 2.15, 1.20, 34 and 58 mg/kg, respectively. Bangladesh J. Bot. 51(4): 655-662, 2022 (December)