Effect of Drought Stress on Biochemical and Yield Parameters in Common Bean (Phaseolus vulgaris L.) Genotypes

Experiment was conducted to assess drought-tolerance in two common bean genotypes by inducing stress at flower initiation stage on the basis of inherent stress tolerance characters viz.total chlorophyll content, chlorophyll stability index, nitrate reductase activity, total free proline content and drought susceptibility index. Foliar spray of ABA, calcium and potassium was also applied to check whether they enhance drought tolerance by showing their impact on these parameters. Seeds of fifty common bean genotypes were evaluated for drought tolerance in laboratory by simulation with two PEG-6000 osmotic potential levels (−0.3 MPa and-0.5 MPa). Reduction in germination percentage, plumule and radicle length was observed in KR 84 and KR 257 genotypes. Pot trial revealed that drought stress at flower initiation stage significantly reduced total chlorophyll content, chlorophyll stability index, nitrate reductase activity and drought susceptibility index whereas total free proline content was significantly enhanced. Foliar application of ABA, calcium and potassium effectively ameliorated the negative effects of drought stress in both genotypes. Reduction in drought susceptibility index was also observed under these treatments as compared to stressed and non-treated plants. Foliar application of ABA, calcium and potassium effectively elevated various biochemical parameters, however these foliar treatments displayed lower accumulation of total free proline conferring lower drought sensitivity of genotypes after foliar application. Abscisic acid 20 ppm and CaCl₂ 0.5% were found to be most effective and surpassed other treatments.