硅对低温胁迫下冬小麦幼苗光合作用及相关生理特性的影响

采用水培试验，以抗寒性不同的两个小麦品种（临麦2号（Linmai 2）高抗；扬麦 5号（Yangmai 5）低抗）为材料，研究了不同硅处理（0、0.1和1.0 mmol/L）对低温胁迫条件下小麦幼苗光合作用、叶绿素和可溶性糖的影响。结果表明：低温胁迫条件下，小麦幼苗的光合作用显著受到抑制，扬麦5号的下降速率要大于临麦2号。施硅能够提高低温胁迫条件下小麦幼苗净光合速率（Pn）、气孔导度（Gs）、气孔限制值（Ls）、水分利用率（WUE）；蒸腾速率（Tr）在低温胁迫条件下降低，加硅处理后蒸腾速率下降。低温胁迫条件下两个小麦品种的叶绿素含量和叶绿素a/b的比值下降，可溶性糖含量显著升高；施硅能减缓低温胁迫对叶绿素含量、chl a/chl b和可溶性糖的影响。

Effect of Silicon on Photosynthesis and Its Related Physiological Parameters in Two Winter Wheat Cultivars Under Cold Stress

Two winter wheat (Tritium aestivum L.) cultivars, Linmai No.2 (resistant) and Yangmai No.5 (susceptible), were grown hydroponically to investigate the effects of exogenous silicon (Si) on photosynthetic and physiological parameters of the seedlings grown under cold stress. Wheat seedlings grown in nutrient solutions were treated with 0, 0.1or 1.0 mmol / L Si, and then were subjected to freezing stress. The results showed that the photosynthesis and photosynthetic efficiency of the seedlings were significantly inhibited under freezing stress, but significantly enhanced by added Si. In comparison with the control, freezing stress induced a decline in net photosynthetic rate (Pn), stomatal conductance (Cs), transpiration rate (Tr), stomatal limitation value (Ls) and water utiliy efficiency (WUE) in seedlings. However, exogenous Si significantly increased the Pn, Cs and Tr. The transpiration rate was decreased under freezing stress and even lower in Si-supplied cold treatment than in Si-deprived one. The content of chlorophyll, the value of chl a/chl b and the content of soluble sugar were decreased under freezing stress. Exogenous Si decreased the content of soluble sugar significantly in both cultivars, whereas it did not significantly increase the contents of chlorophyll or the value of chl a/chl b.