[Effects of drought stress on performance of photosystem II in maize seedling stage]

Maize cultivar Shandan 609 was used to determine the effects of drought stress on photosystem II, dry matter accumulation, protective enzyme activity and proline content at seedling stage in pot experiment. Two drought treatments (moderate drought and severe drought) were tested. The results showed that dry matter accumulation, leaf area and plant height of cultivar shaandan 609 decreased significantly with the increasing drought stress. The less grouped PS II units (L-band > 0), severely damaged OEC (K-band > 0), and the inhibited acceptor side (ψo significantly decreased) resulted in the overall dropped performance of PS II (PI(ABS)). Under the condition of moderate and severe drought stress, the activities of superoxide, peroxidase, catalase and proline content increased significantly, which were 1.3, 1.1, 1.2, 5.8 and 1.1, 3.3, 1.5, 15.0 times of control (CK), respectively. Those results indicated that damage of PS II acceptor and donor side under drought stress led to the decline of PS II performance, which was likely to cause the decline of dry mater accumulation of maize cultivar Shandan 609, while protective enzymes and proline as protective substance in plant played a positive role in drought resistance.