水分胁迫下钾对岸杂一号(Cynodon dactylon(L.)Pars.)光合作用的影响

Effect of Potassium on Photosynthesis in Cynodon Dactylon (L.) Pars. Under Water Stress

研究了两种浓度PEG—6000造成的水分胁迫下,钾对C_4型牧草良种岸杂一号狗牙根光合作用的影响,同时探讨了光合作用的气孔限制问题。试验结果表明,-2.5bar胁迫下,高钾使气孔阻力变化更加明显,而叶肉细胞的羧化活性并未受到影响;-4.7bar胁迫下,气孔因素对光合速率的影响,高K^+处理大于低K^+处理,且高K^+可减轻净光合速率的降低,还可维持相对较大的共质体体积,推测这可能是高K^+部分地逆转水分胁迫抑制光合作用的机制之一。因此认为,C_s的大小并不总是光合作用的主要限制因素。

Effect of potassium on photosynthesis in a C_4 species (coastcross No.1 bermuda grass) under two levels of water stress induced by PEG--6000 were studied. Net photosynthetic rate (Pn) measurements were made using a LI--6200 portable gas analysis was carried out. The result demonstrated that under the slight water stress changes of stomatal resistance are more obvious in the high K^+ treatment. Stomatal limitation of photosynthesis in the high K^+ treatment was greater than those in the low K^+ treatment, and high K reduced water stress inhibition on photosynthesis under the medium water stress. Moreover, high K maintained the relatively greater symplast volume. This may be one mechanism of the partial reverse effect of high K on water stress inhibition of photosynthesis. In addition, discussion proposed that stomatal conductance limit Pn in some cases. However, it is always the predominant limiting factor of photosynthesis though parallel changes in Pn and Cs are often observed.