辣椒幼苗叶片光合特性对低温、弱光及盐胁迫3重逆境的响应

以"中椒4号"辣椒为试材,研究了低温(18℃/10℃,昼/夜)、弱光(80μmol·m-2·s-1)及盐胁迫(70mmol·L-1NaCl)3重逆境对辣椒幼苗叶片光合参数、需光特性及CO2需求特性等指标的影响。低温、弱光、盐胁迫单一及复合逆境均导致辣椒叶片净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)下降,低温盐胁迫处理的上述各指标降低幅度较大,处理后15d净光合速率比对照降低71.28%。各逆境导致净光合速率下降的限制因子不同。弱光处理提高了辣椒叶片表观量子效率(AQY),其他逆境处理均导致辣椒叶片光补偿点(LCP)、光饱和点(LSP)、AQY及光饱和时的光合速率降低;低温弱光处理辣椒幼苗的CO2补偿点(CCP)高于对照,其他逆境处理辣椒幼苗的CCP、CO2饱和点(CSP)、羧化效率(CE)及RuBP最大再生速率均有所降低;低温盐胁迫处理辣椒叶片上述各指标降低幅度最大,其次为低温弱光及盐胁迫处理。说明低温、弱光及盐胁迫3重逆境下辣椒叶片光合特性的响应机制与单一或双重逆境下有所差异,弱光在一定程度上可缓解低温盐胁迫复合逆境处理引起的辣椒叶片光合能力的降低。

Effect of combined low temperature, poor light and salt stress on photosynthetic characteristics of pepper seedling leaf

Photosynthetic parameters, and light and CO_2 requirement characteristics were analyzed to determine effects of combined low temperature (18 ℃/10 ℃, day/night), poor light (80 mmol·m~(-2)·s~(-1)) and salt stress (70 mmol·L~(-1) NaCl) on photosynthetic characteristics in pepper leaf. Net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) decrease under single or combined low temperature, poor light and salt stress. Pn under low temperature and salt stress decreases by 71.28% after treatment for 15 days compared with the control. The limiting factor of different stresses regarding decreasing Pn is different for pepper leaves. Except for the increase in apparent quantum yield (AQY) for leaves under poor light, and CO_2 compensation point (CCP) for leaves under low temperature and poor light, all other stresses suppress light compensation point (LCP), light saturation point (LSP), AQY, photosynthetic rate at light saturation point, CCP, CO_2 saturation point (CSP), carboxylation efficiency (CE) and maximum reproductive rate of RuBP. The degree of suppression is higher in leaves under combined low temperature and salt stress, followed by those under combined low temperature, poor light and salt stress. It implies that the response mechanism of photosyn-thetic characteristics of pepper leaves under combined low temperature, poor light and salt stress is different from that of single or double stress. Poor light could, to some extent, relieve the drop in photosynthetic capacity of pepper leaf under low temperature and salt stress.