两种水分条件下夏玉米叶片气孔行为对光质的瞬时响应

Instantaneous Response of Leaf Stomatal Behavior to Light Quality under Two Irrigation Levels in Summer Maize

在灌水和不灌水(整个生长期不灌溉)两种水分条件下,利用LI-6400便携式光合测定仪,测定3个主要生育期(拔节期、抽雄期和灌浆期选择典型日)夏玉米(郑单958)第一个功能叶片的气孔导度(Gs)、净光合速率(Pn)和蒸腾速率(Tr)指标,据此计算叶片的瞬时水分利用效率(WUE),测定时设定了5种比例的红蓝光组合(即B/(R+B)分别为0、25%、50%、75%和100%),以对比分析不同红蓝光比对玉米叶片气孔行为的瞬时影响。结果表明:与不灌水相比,灌水处理的叶片平均Gs、Pn和Tr在抽雄期明显较高,但在拔节期和灌浆期差异不显著。不论何种水分处理,光合有效辐射为500μmol·m-2·s-1时,叶片Gs、Pn和Tr均表现为单色红光照射时最大,随着蓝光所占比例的增加,各指标均有不同程度的降低。从节水角度来看,高红光比例的光质有利于提高玉米叶片WUE。

The LI-6400 portable photosynthesis system was used to measure the stomatal conductance（Gs）, net photosynthetic rate（Pn） and transpiration（Tr） of the first functional leaf of summer maize（Zhengdan 958） under irrigation and no irrigation during three growth periods（jointing, tasselling and filling stages）. While measuring these physiological indicators, red to blue ratio was set at 0, 25%, 50%, 75% and 100% to analyze its effects on the stomatal behavior of summer maize. The instantaneous leaf water use efficiency was also calculated from measurements of these physiological indicators. The results showed that compared with no-irrigation, the mean values of Gs, Pn and Tr in leaves were significantly higher under the irrigation treatment at the tasselling stages, but the differences between both treatments were not significant at the jointing and filling stage. Under both two water treatments, the Gs, Pn and Tr were maximum under the pure red light and decreased with the increase of blue light proportion. Considering the water-saving effect, higher ratio of red to blue light can improve the WUE of maize leaves.