Effect of Drought Stresses at Different Growth Stages on Peanut Leaf Protective Enzyme Activities and Osmoregulation Substances Content

Abstract

Using Huayu 22 and Huayu 25 as experimental materials, the physiological and biochemical parameters at seedling stage, flowering-pining stage, and podding stage in peanut leaf were investigated under drought stress in pool cultivation with rainproof. The result showed that, the changes of antioxidant systems and the components of osmoregulation substances of two varieties were not entirely consistent during early drought stress stage. Leaf superoxide dismutase (SOD) and catalase (CAT) activities, soluble protein (Pr), free amino acid (AA) and proline (Pro) contents were significantly increased and then decreased under drought stress. With the prolonged stress, the protective enzyme activities and osmoregulation substances content decreased at the same time. The POD activity and soluble sugar content weakly responded to drought stress. The content of malondialdehyde (MDA) was significantly increased and then decreased with the stress prolonged, but its time lagged behind those of the protective enzyme activities. The MDA content in Huayu 22 leaf was higher than that in Huayu 25. After the drought stress, the activities of SOD, CAT, and soluble protein, free amino acid and proline contents were obviously increased at the end of drought stress at different growth stages. Among those stages, all the parameters were markedly increased at the flowering-pining stage, which is sensitive to water supply. The effects of drought stress on protective enzyme activities and osmoregulation substances of peanuts were weaker at seedling stage than at late growth stages. SOD and CAT were the key antioxidant enzymes to adapt dr ought stress in peanut. The ability of osmoregulation substances contributed to the regulation of drought stress in turn was: soluble sucrose free amino acid soluble protein proline. The drought tolerance of Huayu 25 was higher than that of Huayu 22.