气孔限制在植物叶片光合诱导中的作用

用三种不同的气体交换分析方法研究了玉米、大豆等叶片光合诱导期间的气孔限制作用。发现有利于气孔开放的因素如良好的土壤水分状况、较高的空气湿度等,能够缩短叶片的光合诱导期;CO_2饱和条件下,叶片的光合诱导期比在普通空气条件下的诱导期短得多;在光合诱导后期细胞间隙CO_2度达到稳态值以后,气孔导度的增加伴随着光合速率的提高和气孔限制值的下降。而气孔导度的降低则会引起光合速率的降低和气孔限制值的上升。诱导期存在气孔限制,并在后期占优势。

The Role of Stomatal Limitation in Photosynthetic Induction of Plant Leaves

Stomatal limitation during the photosyn-thetic induction of leaves of maize, soybean, etc.was studied by using three measurihg methodsof gas exchange. It was found that factors, suchas good water status of soil (Fig. 1) and highrelative humidity of air (Fig. 2) favouring theopening of stomata could shorten the inductionperiod of leaf photosynthesis. The inductionperiod was much shorter in saturating CO_2than that in normal air (Fig. 3, 4). The induc-tion dynamics of leaf photosynthesis had somecommon characteristics as follows (Fig. 5, 6).Photosynthetic rate increased gradually andteached a constant level within a period afterillumination. The change of stomatal conduc-tance was similar to that of photosynthetic rate.The intercellular CO_2 concentration first gra-dually decreased to a certain level and then re-mained nearly constant. However, it is note-worthy that the stomatal conductance andphotosynthetic rate did not reach constant levelimmediately when the intercellular CO_2 concen-tration did it. After the intercellular CO_2 con-centration reached a constant level in the latestage of induction the increase in stomatul con-ductance was accompanied by an increase inphotosynthetic rate and a decrease in stomatallimiting value, however the decline in stomatalconductance would cause a decrease in photosyn-thetic rate and an increase in stomatal limitingvalue (Fig. 7). These results indicate that cer-tain there was indeed stomatal limitation duringinduction of leaf photosynthesis, which was,however, predominant only in the late stage ofinduction.