干旱及复水对玉米叶片光合特性的影响

盆栽条件下,以玉米品种户单4号为材料,设正常供水(CK)、中度水分胁迫(MS)和重度水分胁迫(SS)三个水分处理,研究了拔节期和孕穗期水分胁迫及复水对玉米叶片光合、叶绿素荧光的影响,以期为玉米补偿机制的阐明提供理论依据。结果表明:(1)干旱胁迫使叶水势(ψleaf)降低,复水后拔节期重度胁迫叶水势迅速恢复并超过对照,而孕穗期则恢复缓慢;(2)拔节期和孕穗期重度胁迫降低了叶片净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)、PSII最大光化学效率(Fv/Fm)及光化学猝灭系数(qP),但复水5d后可基本恢复至对照;Ci最低,气孔限制值(Ls)较对照分别增加了6.85%,9.52%,Fv/Fm值分别降低了1.72%和0.61%,表明气孔限制是Pn降低的主要原因;(3)拔节期重度胁迫叶的水分利用效率(WUE)高于对照,表现出补偿效应;孕穗期干旱胁迫下WUE表现为:MS>CK>SS,在复水第一天达最大值,随后趋于降低。说明拔节期和孕穗期光合特性变化存在差异性。

Effects of Drought and Re-watering on Photosynthetic Characteristics of Maize Leaf

In this study,Maize(Zea mays L.) cross seeds(cv.Hudan4) were grown in pots.And three water treatments: normal water supply(CK),moderate water stress(MS) and severe water stress(SS) were designed to investigate the effects of water stress and re-watering on photosynthesis and chlorophyll fluorescence of maize leaf at elongation stage and booting stage,in order to provide theoretical basis for the explanation of compensation mechanism of maize.The results showed:(1) leaf water potential(ψleaf) reduced under drought stress,and leaf water potential of severe stress at elongation stage could recover rapidly and exceeded the control after re-watering,but the booting stage was slow;(2) severe stress at elongation stage and booting stage reduced the leaf net photosynthetic rate(Pn),stomatal conductance(Gs),the intercellular CO2 concentration(Ci),maximal efficiency of PSⅡ(Fv/Fm) and photochemical quenching coefficient(qP),but after five days of re-watering,these parameters can be recovered to control;the Ci was lowest,compared with control,stomatal limation value(Ls) increased by 6.85%,9.52%,Fv/Fm reduced 1.72% and 0.61%,which indicated stomatal limitation was the major factor to the reduction of Pn;(3) under the severe stress at elongation stage,the water use efficiency of leaf(WUE)was higher than the control,which showed the compensation effect;under drought stress at booting stage,the WUE showed that MS> CK>SS.After the first day of re-watering,the WUE were at peaks,then tended to decline.These results suggested that there would be different responses of photosynthetic characteristic between elongation stage and booting stage.