Effects of Drought Stress on Physiological Characteristics and Dry Matter Production in Maize Silking Stage

Maize cultivars Zhengdan 958 (drought-tolerance) and Shaandan 902 (drought-sensitive) were used to determine the responses of photosynthetic traits, protective enzyme activity and dry matter production at silking stage to in drought pool experiment. The results showed that under drought stress, the yield of drought-tolerant maize Zhengdan 958 reduced 39.10 percent compared with control, while drought-sensitive maize Shaandan 902 reduced 44.87 percent. At 15 d after anthesis, leaf ’ s net photosynthetic rate (Pn) and stomatal conductance (Gs) decreased significantly, whereas intercellular CO2 concentration (Ci) first decreased and then increased under drought stress in both cultivars. The quantum yield (ф PSⅡ ), photochemical quenching (qP) and non-photochemical quenching (qN) of photosystem II decreased under drought stress in leaves of both cultivars. Meanwhile, the superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) activities first increased then decreased while malondialdehyde (MDA) content increased under drought stress in both cultivars. In addition, drought stress significantly increased dry matter translocation, dry matter translocation efficiency, and contribution of pre-anthesis assimilates to grains, however, the effect was smaller in Zhengdan 958 than in Shaandan 902. Our results indicated that higher ability of oxidative enzyme defense system eliminates reactive oxygen, and the absorbed energy is effectively utilized, resulting in the greater photosynthesis capacity in Zhengdan 958, so extending the period of leaf’s photosynthesis and enhancing the contribution of pre-anthesis assimilates to grains, which may be one of the important roles in getting high yield of drought-tolerant maize Zhengdan 958 under drought conditions.