NaCl胁迫对两种番茄气孔特征、气体交换参数和生物量的影响

Effects of NaCl stress on stomatal traits,leaf gas exchange parameters,and biomass of two tomato cultivars

为探讨番茄叶片气孔特征、气体交换参数和生物量对盐胁迫的响应机理,以赛棚和阿拉姆番茄为试材,通过向水培营养液中添加NaCl(0.1 mol·L^(-1)),在人工气候箱条件下进行为期90 d的NaCl盐胁迫处理.结果表明:NaCl胁迫导致赛棚番茄叶片的气孔密度、气孔宽度、气孔面积和气孔面积指数显著降低,降幅分别为32%、45%、25%、49%,但没有改变阿拉姆番茄叶片的气孔特征参数.同时,NaCl胁迫还导致赛棚和阿拉姆叶片气孔规则分布的空间尺度分别减少30%和43%,且赛棚品种的单个气孔最小邻域距离在盐胁迫下增加20%.另外,赛棚和阿拉姆叶片的净光合速率(P_n)、气孔导度(g_s)和蒸腾速率(T_r)在盐胁迫下均显著下降,通过气孔限制值分析发现,盐胁迫导致赛棚番茄叶片光合速率下降主要是由气孔限制因素引起的,而阿拉姆叶片则以非气孔限制因素为主导作用.盐胁迫还导致赛棚和阿拉姆番茄生物量显著降低,且地下生物量的下降幅度大于地上生物量.综合分析表明,阿拉姆的抗盐能力高于赛棚.

To understand the mechanism underlying responses of stomatal traits, gas exchange parameters, and biomass of tomato plants to salt stress, two tomato cultivars (Shed and Alam) were treated by salt stress by adding NaCl (0.1 mol·L^-1) to nutrition medium in environmental growth chambers for 90 days. Our results showed that salt stress substantially decreased the stomatal density, stomatal width, stomatal area, and stomatal area index of Shed by 32%, 45%, 25%, and 49%, respectively. The stomatal traits of Alam were not affected by NaCl treatment. The spatial scales of the regular stomatal distribution pattern of Shed and Alam were significantly decreased by 30% and 43%, and the nearest neighbor distance Lhat (d) of shed cultivar was increased by 20% under salt stress. NaCl stress resulted in marginal declines in the net photosynthetic rates (Pn), stomatal conductance (gs), transpiration rates (Tr) of both cultivars. The decrease of the photosynthetic rate of Shed under salt stress resulted from stomatal limitation, whereas the Pn of Alam was subjected to non-stomatal constraints. NaCl stress substantially decreased the seedling biomass of both cultivars, and the decline of belowground biomass was higher than that of aboveground biomass. Overall, our results suggested that the Alam cultivar is more salt-tolerant than Shed.