小麦叶片CO_2/H_2O交换参数对不同供水条件的响应

Response of CO 2/H 2O Exchange Parameters of Wheat Leaves to Different Water Supply Condition

在大田不同供水条件下，于小麦孕穗期和灌浆期对小麦叶片气体交换参数的日变化进行了连续测定。结果表明，小麦叶片光合速率（Ｐｎ）、气孔导度（Ｇｓ）、蒸腾速率（Ｔｒ）以及叶肉细胞间隙ＣＯ２浓度（Ｃｉ）均有较明显的日变化。不同供水条件下，Ｐｎ的日变化趋势不同，充分供水时为典型的双峰曲线，中午有明显的“午休”现象；当非充分供水时，Ｐｎ午休现象明显，且持续时间长，第二高峰表现不明显。供水条件较好时，小麦叶片Ｇｓ日变化与Ｐｎ的日变化趋势相似，均为双峰曲线，而土壤供水不足时小麦叶片的Ｇｓ早晚高，中午低。充分供水的小麦叶片Ｔｒ在中午基本维持在较高的水平，与光合有效幅射（ＰＡＲ）和大气温度（Ｔａ）的日变化基本一致；供水不足时，小麦叶片Ｔｒ呈双峰型；土壤水分含量越高，Ｔｒ越大。光合作用的日变化受环境因素（土壤水分、光照、气温、湿度等）的影响，由Ｇｓ和叶肉细胞光合特性决定的。在上午以前Ｐｎ主要受气孔开张度控制，下午主要受叶绿体光合特性控制。

Daily change of gas exchange parameter of wheat leaves was measured under different water conditions, the result have showed that, the photosynthetic rate, stomatal conductance, transpiration rate, and intercelluar CO 2 concentration are obvious change in daily. The trend of this change was differ from different water supply and it was influenced by many environment factors, such as soil water status, light, air temperature, and air humidity et al., but mainly determinated by stomatal conductance and photosynthetic characteristic of chloroplast.