Liu Wei, Ai Xi-Zhen, Liang Wen-Juan, Wang Hong-Tao, Liu Sheng-Xue, Zheng Nan
Ministry of Agriculture Key Laboratory of Horticultural Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an 271018, Shandong, China.
Ying Yong Sheng Tai Xue Bao. 2009 Feb;20(2):441-5.
In order to elucidate the regulation functions of salicylic acid (SA) on the photosynthesis of cucumber under low temperature and light intensity, the seedlings of cucumber 'Jinyou 3' under low temperature and light intensity were foliar-sprayed with different concentration SA, and the leaf gas exchange parameters, photochemical efficiency, MDA content, and antioxidant enzyme activities were measured. The results showed that under low temperature and light intensity, the leaf photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), actual photochemical efficiency of PS II (PhiPSII), and maximal photochemical efficiency of PS II (Fv/Fm) of the seedlings all decreased but the intercellular CO2 concentration (Ci) increased, suggesting that nonstomatal limitation was the main cause of the decrease of Pn under low temperature and light intensity stress. Low temperature and light intensity also led to the increase of leaf malondialdehyde (MDA) content and superoxide dismutase (SOD) activity, the decrease of catalase (CAT) activity, and the decrease after an initial increase of peroxidase (POD) activity. However, foliar-spraying 0.5-2.5 mmol x L(-1) of SA before the stress increased the leaf Pn, Gs, Tr, PhiPSII, Fv/Fm, and activities of SOD, POD and CAT while decreased the Ci and MDA content, suggesting that SA could regulate the leaf photosynthetic functions of cucumber seedlings, and enhance the seedlings resistance against low temperature and light intensity. The optimum concentration of SA for the foliar-spraying was 1 mmol x L(-1).
为了阐明水杨酸（SA）对低温弱光下黄瓜光合作用的调控作用，对低温弱光条件下的黄瓜‘津优3号’幼苗进行不同浓度SA的叶面喷施，并测定叶片气体交换参数、光化学效率、丙二醛（MDA）含量和抗氧化酶活性。结果表明，在低温弱光条件下，幼苗叶片的光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）、PSⅡ实际光化学效率（PhiPSII）和PSⅡ最大光化学效率（Fv/Fm）均下降，但胞间CO2浓度（Ci）升高，表明非气孔限制是低温弱光胁迫下Pn下降的主要原因。低温弱光还导致叶片丙二醛（MDA）含量增加、超氧化物歧化酶（SOD）活性升高、过氧化氢酶（CAT）活性降低以及过氧化物酶（POD）活性先升高后降低。然而，在胁迫前叶面喷施0.5 - 2.5 mmol·L-1的SA可提高叶片的Pn、Gs、Tr、PhiPSII、Fv/Fm以及SOD、POD和CAT的活性，同时降低Ci和MDA含量，表明SA可调节黄瓜幼苗叶片的光合功能，增强幼苗对低温弱光的抗性。叶面喷施SA的最佳浓度为1 mmol·L-1。
