Evaluation of blackgram (Vigna mungo) genotypes for drought tolerance under field and in vitro conditions

Abstract

Blackgram a rainfed crop often experiences soil moisture deficit that reduces productivity to a large extent, could overcome by using a suitable drought resistant variety. Based on this, the present investigation was carried out during 2018 at Department of Genetics and Plant Breeding, Faculty of Agriculture, Annamalai University to study the drought tolerance in twenty-one blackgram genotypes. The selected genotypes (IC-343943, IC-343947, IC-343962, ABG-11013, KU-11680, TBG-104, VBG-10010, VBG-11011, VBG12005, VBG-12062, VBG-13017, ADT-5, RU-16-9, RU-16-13, RU-16-14, KGB-28, T-9, VBN(Bg)-4, VBN(Bg)-6, VBN(Bg)-7, MDU Local) were evaluated in the field condition for drought tolerance by imposing water stress during flowering and pod setting stages (4060 days after sowing) of the crop. The screening was also carried out in vitro by using PEG6000 at three concentrations viz., 0 bar, -3 bars and -6 bars to assess their seedling response under induced osmotic potential. Reduced growth was observed in all blackgram genotypes for all the characters except for the number of days to first flowering. Based on per se performance of genotypes under water-stressed field condition, the genotypes VBG12005, IC-343943 and IC-343947 were recommended as drought-tolerant genotypes for seed yield. In vitro condition, reduction in germination percentage, plumule and radicle length and biomass yield observed under increasing polyethylene glycol (PEG) induced water stress. In vitro screening of blackgram genotypes using PEG 6000 found that the genotypes VBG-11011, RU-16-9 and VBG-13017 expressed tolerance to drought at seed germination level. Thus, seedling stage screening for drought tolerance alone is not reliable as the tolerance mechanism may vary at different growth stages.