旱后复水对玉米后继新生叶片生理特性的影响

利用盆栽试验研究了不同程度和历时的水分胁迫对玉米叶片光合指标和叶绿素浓度的影响规律.结果表明:胁迫期间新生的叶片,在复水后短期内,其光合速率、蒸腾速率在复水后一段时间内仍然低于对照,且随着胁迫历时和胁迫程度的增加而加强,叶片蒸腾效率亦降低.5 d和10 d轻度胁迫结束后新生叶片,复水后其光合速率高于对照而蒸腾速率略低于对照,叶片水分利用效率提高;10 d重度胁迫处理的光合速率、蒸腾速率均低于对照,但叶片水分利用效率高于对照.直接遭受水分胁迫的叶片,叶绿素质量浓度降低,胁迫程度越重,胁迫历时越长,叶绿素含量下降幅度越大;复水后,后继新生叶片的叶绿素含量均高于对照,且10 d胁迫处理显著高于对照和5 d胁迫处理.上述结果表明,遭受水分胁迫的叶片,其生理性状主要表现为抑制效应,而胁迫后新生叶片则表现为补偿效应.因此早期的水分胁迫对后期补偿生长较为有利.

Effect of water recovery on physiological characteristics of newly-growing leaves of maize during and after stress period

Net photosynthetic rate(Pn),transpiration rate(Tr),water use efficiency(WUE) and chlorophyll content(CC) of maize in pots were measured after water recovery to investigate the after-effect of water stress on physiological properties of leaves developed during and after water stress.The results showed that shortly after water recovery,Pn,Tr and WUE of the newly-growing leaves during stress time were lower than full irrigation treatment(CK) and the effects were enhanced with the duration and severity of water stress.For the leaves developed after stress,Pn of 5 days mild and severe water stress and 10 days mild stress treatment increased after water recovery while that of 10 days serious stress decreased.Tr was lower than CK for all treatments while for 5 days and 10 days mild stress no significant differences were observed.WUE increased after water recovery and decreased gradually.Mass chlorophyll content of stressed leaves,fully developed or developing during stress period, deceased at the end of stress and the tendency was enhanced with the severity and duration of water stress.While for the newly-growing leaves after water stress,mass chlorophyll content was higher and increased with stress duration.The results above showed that water stress resulted in suppression effects on the stressed leaves but compensatory effects on the newly-growing leaves after stress.The suggestion is that water stress in early growth stage is more benefit.