夏秋季旱涝胁迫对红叶石楠光合特性的影响

 分别于夏、秋两季, 以1年生红叶石楠扦插苗为试材, 采用盆栽调控水分的方法, 研究了干旱和淹水胁迫下叶片的丙二醛(MDA) 含量和细胞膜透性、色素含量以及光合生理参数等的变化。结果表明, 夏、秋季干旱和淹水胁迫均使叶片MDA含量和质膜透性显著上升, 叶绿素(Chl. ) 含量降低, 花色素苷(Ant. ) 含量增加; 净光合速率( Pn) 、水分利用效率(WUE) 、表观量子效率(AQY) 和羧化效率(CE) 等指标下降, 光饱和点(LSP) 降低; 光补偿点(LCP) 升高, 可利用的光强范围变小; 夏季水分胁迫对红叶石楠的膜伤害大于秋季, Chl. 降幅低于秋季, 类胡萝卜素(Car. ) 含量夏季上升而秋季下降,LSP对降及LCP上升的幅度小于秋季, 但Pn降幅却表现为干旱处理小于秋季, 淹水处理大于秋季; 其中夏季淹水胁迫对红叶石楠膜伤害和Pn、WUE、AQY、CE的影响较干旱胁迫大, 光合下降在胁迫初期为气孔限制, 到中、后期转化为非气孔限制; 与Pn密切相关的气候因子(关联度从高到低排列) 依次为大气温度( Ta) 、大气CO₂浓度(CO2 ) 和光照强度( PFD) 。而在秋季, 干旱胁迫对红叶石楠膜伤害和Pn、WUE、AQY和CE的影响较淹水胁迫大, 光合下降主要表现为非气孔限制; 与Pn密切相关的气候因子(关联度从高到低排列) 依次为大气水汽压(Vp) 、PFD和CO₂。

Effects of Drought and Flooding Stress on Photosynthetic Characteristics of Photinia frasery in Summer and Autumn

By controlling the soil water content,1-year-old potted cutting plants of Photinia frasery as the materials,the effects of drought and flooding stress on the changes of malondialdehyde(MDA)content,the membrane permeability,pigment content as well as photosynthetic and physiological characters in summer and autumn were studied.The results showed that MDA content,membrane permeability and anthocyanin(Ant)content were distinctly increased,while the content of chlorophyll,the index values of net photosynthesis rate(Pn),water use efficiency(WUE),apparent quantum yield(AQY)and carboxylation efficiency(CE)were decreased.Meanwhile the available light intensity range was shortened with the declining of light saturation point(LSP)and rising of light compensation point(LCP)under drought and flooding stress in summer and autumn.On the other hand,the chlorophyll(Chl.)content of control in summer was lower than that in autumn,but the values of Pn and CE in summer were higher than these in autumn.In addition,the membrane injury of Photinia frasery under drought and flooding stress in summer was worse than autumn,the degradation of Chl.in summer was lower than autumn,the carotinoid(Car.)content increased in summer and decreased in autumn,the decrease of LSP and increase of LCP in summer were lower than autumn,but the decrease of Pn under drought stress in summer was lower than autumn,and the decrease of Pn under flooding stress in summer was higher than autumn;moreover,flooding in summer had much more influence on membrane injury and Pn,WUE,AQY,CE than drought stress,the decrease of Pn in initial stage was due to stomatal limitation,and then nonstomatal limitation dominated.The gray relational grade analysis showed that the relationship among climate factors and Pn(from high to low)were temperature of atmosphere(Ta),CO2 concentration and photon fluxdensity(PFD).While drought in autumn had much more influence on membrane injury and Pn,WUE,AQY,CE than flooding stress,the decrease of Pn was mainly decided by nonstomatal limitation;The gray relational grade analysis showed that the retational factors to Pn(from high to low)were Vapor pressure(Vp),PFD,and then CO2 concentration.