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小麦和大豆叶片的气孔不均匀关闭现象

孟庆伟, 邹琦, 许长成, 赵世杰

山东农业大学.山东, 泰安 271018

摘要

用~(14)CO_(2)放射自显影的方法研究了田间小麦和大豆叶片在水分胁迫下的气孔关闭状况。正常浇水的小麦和大豆叶片呈现出对~(14)CO_(2)的均匀吸收。在小麦与大豆叶片水势分别降至-1.75和-1.32 MPa的土壤干旱条件下，两种作物叶片都发生气孔不均匀关闭。离体叶片在空气中快速脱水易引起气孔不均匀关闭。正常供水小麦叶片在晴天中午明显的光合午休时，无CO_(2)的不均匀吸收。某些晴天中午，在大豆光合午休低谷时段观察到较明显的气孔不均匀关闭，用气体交换资料计算出的细胞间隙CO_(2)浓度并不随气孔导度的降低而下降,反而略有回升。

关键词： ~(14)CO_(2)放射自显影; 气孔不均匀关闭; 光合午休; 小麦; 大豆

Nonuniform stomatal closure in leaves of wheat and soybean

Meng Qingwei, Zou Qi, Xu Changcheng, Zhao Shijie

Shandong Agricultural University. Taian 271018, Shandong

Abstract

The occurrence of “patchy”pattern of CO_(2) uptake across the surface of leaves was examined in wheat and soybean under field conditions by ~(14)CO_(2) autoradiography. Well-watered leaves had uniform distribution of photosynthesis. Plant water deficits causing a leaf water potential depression to -1.75 MPa in wheat and -1.32 MPa in soybean resulted in nonuniform CO_(2) assimilation patterns. The leaf water potential at which nonuniform stomatal closure occurred in soybean was not as low as that in wheat. Nonuniform stomatal closure occurred when a leaf was subjected to a rapid dehydration in air for a few minutes.An increase in the calculated value of intercellular CO_(2) concentration was often observed.The increase probably resulted from an erroneous calculation due to “patchy” stomatal closure,but might also be caused by an enhanced photorespiration or respiration rates.When the photosynthetic rate of wheat flag leaves showed midday depression under field conditions on clear days,nonuniform stomatal closure was not observed.Soybean leaves,on the other hand,sometimes showed nonuniform stomatal closure when midday depression occurred with an increase of Ci. Higher VPD during midday period was probably the main factor causing nonuniform stomatal closure of soybean leaves. It is not certain whether the observed increase of intercellular CO_(2) concentration in soybean leaves was due to nonstomatal limitalion or an overestimation due to “patchy” stomatal closure, or both. It is suggested that,whenever nonuniform stomatal closure takes place,one should not infer the occurrence of nonstomatal limitation of photosynthesis from an increase of Ci.

Key words: ~(14)CO_(2) autoradiograph;Nonuniform atomatal closure;Midday depression of photosynthesis;Wheat;Soybean

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引用本文：

孟庆伟, 邹琦, 许长成, 赵世杰. 小麦和大豆叶片的气孔不均匀关闭现象[J]. 生理学报 1997; 49 (1): .

Meng Qingwei, Zou Qi, Xu Changcheng, Zhao Shijie. Nonuniform stomatal closure in leaves of wheat and soybean. Acta Physiol Sin 1997; 49 (1): (in Chinese with English abstract).