硝酸镧对碱胁迫下黑麦草幼苗生长和光合生理的影响

在150 mmol·L^-1 NaHCO₃胁迫下，研究了不同浓度硝酸镧对黑麦草幼苗生长的影响及其对叶片光合生理响应的调节作用。结果表明，叶面喷施低浓度硝酸镧(0.05 mmol·L^-1)预处理显著减小了碱胁迫下黑麦草幼苗生物量、叶片叶绿素和类胡萝卜素含量、叶绿体希尔反应、光合电子传递、光合磷酸化、Mg²⁺ ATP酶、RuBP羧化酶活性和光合效率的下降幅度，却对光呼吸调节酶乙醇酸氧化酶活性无明显影响。而高浓度硝酸镧(0.5 mmol·L^-1)预处理不仅对碱胁迫没有缓解作用，反而加重了碱胁迫伤害。因此，适宜浓度硝酸镧可以通过改善光合功能从而缓解碱胁迫对黑麦草幼苗生长的抑制作用。

Effects of La(NO3)3 on Plant Growth and Leaf Photosynthetic Physiology of Ryegrass(Lolium pernne L.) Seedlings under Alkaline Stress

Effects of different concentrations of La(NO₃)₃ on growth of ryegrass seedlings and regulatory effect on photosynthetic physiological response in ryegrass leaves under 150 mmol·L^-1 NaHCO₃ stress were investigated. The ryegrass leaves were sprayed by low concentration(0.05 mmol·L^-1) of La(NO₃)₃ solution for 3 days before NaHCO₃ stress. The results showed that La(NO₃)₃ pretreatment significantly alleviated the decreases of the fresh and dry weights of ryegrass seedlings, the leaf chlorophyll and carotene contents, the activities of Hill reaction, electron transport, photophosphorylation, Mg²⁺ ATPase and RuBPCase in chloroplast, and photosynthetic rate by alkaline stress, but no effect on glycolic acid oxidase activity was observed. However, pretreatment of La(NO₃)₃ with high concentration(0.5 mmol·L^-1) had no alleviation effect on alkaline stress, instead, aggravated the injury by alkaline stress on ryegrass seedlings. These results suggested that the pretreatment of feasible concentration of La(NO₃)₃ could alleviate the inhibitory effect on the growth of ryegrass seedlings by alkaline stress via improving leaf photosynthetic function.