Differential response of pearl millet hybrids to water stress in relation to antioxidant enzymes and proline

Pearl millet [Pennisetum glaucum (L.) R. Br.] is an important crop of semi-arid tropics. Due to erratic rainfall, the crop is generally exposed to water stress at different stages, which decreases growth and yield of plants in many ways. In the present study the female parent ICMA 94555 was crossed with eight inbred male lines in summer, 2004. Hybrids were evaluated under terminal drought condition at three different stages, each at 10 days interval (i.e. at 60, 70 and 80 DAS) in Kharif, 2004 to assess the antioxidant enzymes activity and proline content. Terminal drought condition was created by withdrawing irrigation at 50 days after sowing. Among the eight hybrids tested, four hybrids viz., ICMA 94555 x J 2340, ICMA 94555 x J 2405, ICMA 94555 x J 108 and ICMA 94555 x J 2290 showed increased activities of superoxide dismutase (SOD) and non specific peroxidase (POX) at second and third stage, while catalase (CAT) and ascorbate peroxidase (APOX) activity increased only at second stage. The CAT and APOX activity in these four hybrids recorded 2-3 folds increase as compared to first stage. The results suggested that moisture stress affected the activity of antioxidant enzymes involved in detoxification of activated oxygen species and H₂O₂ differently. Proline content increased in all hybrids at second and third stage but these four hybrids showed 2-3 fold higher proline level as compared to first stage. Thus, these four hybrids indicated biochemical adaptability to tolerate water stress condition.