外源SA对盐碱胁迫下葡萄幼苗生长与光系统的影响

Effects of Exogenous SA on Growth and Photosystems of Grape Seedlings under Saline-alkali Stress

水杨酸(SA)是植物体内的一种重要激素,在多种逆境下都发挥作用。本试验以中等耐盐碱葡萄品种‘Dechaunac(Seibel 9549)’水培幼苗为材料,研究外源水杨酸对葡萄幼苗在盐碱胁迫下的生长和光系统活性的影响。研究表明:葡萄幼苗在0.1mol·L^(-1) NaHCO3盐碱胁迫后,长势变差,株高、鲜质量下降,与对照相比,叶绿素含量、净光合速率、气孔导度、蒸腾速率均显著下降,而0.1mmol·L^(-1)外源SA处理能有效缓解这种下降。对光系统Ⅱ荧光参数的研究发现,盐碱胁迫后指标Wk显著升高,说明放氧复合体(OEC)有明显损伤;有活性反应中心(RC/CSo)数量下降;电子传递活性受到抑制(φEo显著下降),而SA处理能显著缓解对OEC和有活性反应中心的损伤,加快电子传递,同时也减缓盐碱胁迫对光系统Ⅰ的损伤。从以上结果得出结论:0.1mmol·L^(-1)外源SA处理能促进盐碱胁迫下葡萄幼苗的生长,是因为缓解了盐碱胁迫对光系统的损伤作用,促进了电子传递,从而提高光合速率。

Salicylic acid (SA) is an important hormone in plants, which can alleviate the damage of many kinds of adversity. In this study, the hydroponic seedlings of medium saline-tolerant grape variety‘Dechaunac (Seibel 9549)’ were used as materials and the effects of exogenous SA on the growth and photosystems of grape seedlings under saline-alkali stress were studied. The results showed that after the saline-alkali stress with 0.1 mol·L^-1 NaHCO 3 treated, the growth of grape seedlings became worse, plant height and fresh weight, chlorophyll content, net photosynthetic rate, stomatal conductance, transpiration rate were decreased significantly compared with the control. But the treatment with 0.1 mmol·L^-1 exogenous SA could effectively alleviate this decline. The fluorescence parameters of photosystemⅡunder saline-alkali stress were analyzed. It was found that Wk increased sharply, indicating the oxygen evolution complex (OEC)was damaged, density of RCs ( RC / CSo ) decreased clearly and electron transport activity inhibited (φEo decreased evidently). But SA treatment significantly alleviated the damage to OEC and reaction centers,and accelerated electron transfer rate and attenuate the damage of photosystemⅠ at the same time. From above results we arrived at a conclusion that the treatment with 0.1 mmol·L^-1 exogenous SA could promoted the growth of grape seedlings under salt-alkali stress because SA treatment could significantly alleviate the damage to photosystem and increased photosynthetic rate.