弱光下长期亚适温和短期低温对黄瓜生长及光合作用的影响

Effect of long-term suboptimal temperature and short-term low temperature under low light density on cucumber growth and its photosynthesis.

弱光下长期亚适温 (T1)和短期低温 (T2 )对黄瓜幼苗的生长及光合作用有重要影响 ,表现为生长速度、Pn、CE、AQY、ФPSⅡ 等均显著降低 ,最大光化学效率PSⅡ (Fv/Fm)也有所下降 .两个处理相比 ,T1的Pn、CE、AQY降低幅度较小 ,但恢复速度慢 ;而T2 降低幅度大 ,但短期内即可恢复正常 .Fv/Fm 和ФPSⅡ 则是T1降低幅度小且恢复快 ;而T2 降低幅度大 ,恢复速度也较慢 .处理后T1的Chla、Chlb和Car含量均显著增加 ,而T2 的含量则明显降低 ,T1、T2 的Chla/b均显著下降 .随着恢复时间的延长 ,T1的色素含量多有下降趋势 ,T2 逐渐增加 ,恢复 3d时 ,含量均高于CK ,而Chla/b在恢复期间没有显著变化 ,仍明显低于CK .

The study on the effects of long-term suboptimal temperature (T 1) and short-term low temperature (T 2) under low light density on cucumber seedling's growth and its photosynthesis showed that the growth speed,photosynthetic rate (Pn),carboxylation efficiency (CE),apparent quantum yield (AQY) and actual quantum yield of P SⅡ electron transport (Ф PSⅡ ) all declined remarkably,and the photochemical efficiency of PSⅡ (F v/F m) also decreased to some extent.The decreasing extents of Pn,CE and AQY of T 1 were less than those of T 2,while the recovery rate of T 1 was slower than that of T 2.The F v/F m and Ф PSⅡ of T 1 declined to less extent and resiled quickly,while those of T 2 decreased to larger extent and recovered slowly.The contents of chlorophyll a,chlorophyll b and carotenoid of T 1 increased remarkably after being treated,while those of T 2 decreased evidently.The Chl a/b of both T 1 and T 2 declined remarkably.With recovery time going,the pigment of T 1 declined under most conditions,while that of T 2 increased gradually.Three days later,the pigment content of T 1 and T 2 were both higher than control.The Chl a/b had no significant change during the recovery period,and was still obviously lower than control.