Evaluation of Responses of Mung Bean (Vigna radiata) Genotypes to Drought Stress Using Different Stress Tolerance Indices

A field study was carried out in 2007 to determine the response of promising genotypes of Mung bean to late season drought stress at zabol climatic condition. The experiment was conducted in a randomized complete block design with three replications at two locations (with and without drought stress). Treatments were 6 different genotypes of Mung bean. All treatments in two fields were irrigated normally until 50% heading stage. The last irrigation in drought stress conditions was done at 50% heading stage and then plants were developed under stress conditions until harvesting. Comparisons of traits in both conditions showed that water stress have negatively affected plant growth. The stress conditions had the highest effects on yield and the least effects on number of slinked pod. For evaluation of drought stress tolerance indices such as mean productivity (MP)، geometric mean productivity (GMP)، stress tolerance index (STI)، tolerance index (TOL)، stress sensitivity index (SSI)، harmonic mean of productivity (HARM)، were used. According to these indices، genotype PUSA was the most tolerant and the genotypes MN22 and MN92 were the most sensitive genotypes to drought stress. Principal component analysis used to study the relationship between indices. Two first components could explain more than 99% of variations of indices. Also، biplot of PC1 and PC2 showed the genotype PUSA was the most tolerant and the genotypes MN22 and MN92 were the most sensitive genotypes to last season drought stress between evaluated genotypes of Mung bean in zabol climatic conditions.