土壤干旱条件下保水剂对多年生黑麦草光合特性的影响

以多年生黑麦草（Lolium perenne Linn．）为研究对象，对土壤干旱条件下（土壤含水量12．6％、10．5％、8．4％和6．3％）使用保水剂后叶片光合特性的动态变化进行了分析。结果显示：随土壤含水量的降低和胁迫时间（12d）的延长，多年生黑麦草叶片的净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）和光能利用效率（LUE）呈逐渐下降的趋势；随土壤含水量的降低，胞间CO2浓度（Ci）逐渐升高、瞬时水分利用效率（WUE）逐渐降低，但随胁迫时间的延长Ci和WUE则呈现不同的变化趋势；总体上，在土壤含水量不同的条件下及不同的胁迫时间各指标均有显著差异（P〈0．05）。与未添加保水剂的各处理组相比，添加质量分数2％保水剂后多年生黑麦草叶片的Pn、Gs、WUE和LUE值均增大，而Ci和Tr值则降低，差异达显著水平（P〈0．05）。研究结果表明：合理使用保水剂能提高多年生黑麦草叶片的光合能力以及土壤的保水能力，增强多年生黑麦草对干旱环境的适应性。

Effect of water retaining agent on photosynthetic characteristics of Lolium perenne under soil drought

Taking Lolium perenne Linn. as the experimental object, dynamic change of photosynthetic characteristics of leaf under soil drought （water content 12.6% , 10.5% , 8.4% and 6.3% in soil） was analyzed after using water retaining agent. The results show that with reducing of water content in soil and prolonging of stress time, all of net photosynthetic rate （ Pn）, stomatal conductance （ Gs）, transpiration rate （Tr） and light use efficiency （LUE） of L. intercellular CO2 concentration （ Ci ） increases gradually with reducing of water content in soil, perenne leaf appear gradually decreasing trend, while gradually and water use efficiency （WUE） decreases but Ci and WUE appear different changing trends with prolonging of stress time. Generally, there are significant differences in all indexes among different conditions of water content in soil and among different stress times （P〈0.05）. Compared with all treatment groups without water retaining agent, after adding mass-ratio 2% water retaining agent, values of Pn, Gs, WUE and LUE in L. perenne leaf all increase while its Ci and Tr values all decrease, and their differences reach significant level （P〈0.05）. It is suggested that rationally applying of water retaining agent can enhance photosynthetic capable of L. perenne and water retention capacity of soil, and can improve adaptability of L. perenne to drought environment.