干旱胁迫与复水对苗期玉米光合特性的影响

Effects of Drought Stress and Re-watering on Photosynthetic Characteristics of Maize Seedlings

研究不同干旱胁迫与复水处理对玉米光合作用的影响,为优化玉米蹲苗提供技术措施。以郑单958玉米品种为研究材料,采用水培法,测定不同干旱胁迫与复水周期下玉米幼苗光合色素、光合参数和叶绿素荧光参数等光合生理指标。随着干旱胁迫周期的增加,叶绿素和类胡萝卜素含量分别呈现先减小后增加和先增加后减小的趋势;PSⅡ最大光化学效率(F_(v)/F_(m))、实际光化学效率(Φ_(PSⅡ))和光化学猝灭系数(qP)呈现先降低后增加的趋势,非光化学猝灭系数(qN)呈现先增加后降低的趋势;干旱胁迫下,玉米净光合速率(P_(n))、气孔导度(G_(s))、蒸腾速率(T_(r))和水分利用效率(WUE)显著下降,胞间CO_(2)浓度(C_(i))显著升高(P<0.05);最大净光合速率(P_(nmax))、表观量子效率(AQE)和暗呼吸速率(R_(d))显著降低,光补偿点(LCP)显著增加(P<0.05)。复水后,叶绿素含量、P_(nmax)、AQE、LCP、光饱和点(LSP)总体表现为增加的趋势,R_(d)总体表现为降低的趋势;P_(n)、G_(s)、T_(r)、C_(i)、WUE、F_(v)F_(m)、Φ_(PSⅡ)、qP和qN总体上随着复水时间的延长逐渐增加,表现为一定的补偿效应,但3次干旱胁迫下的P_(n)和WUE复水后仍然很低,甚至在复水后3 d降低到负值。玉米幼苗经2次干旱复水后补偿性吸水显著,3次干旱对玉米幼苗可能造成一定伤害,复水后补救作用有限。因此,玉米在蹲苗时应严格控制干旱锻炼的次数,避免因干旱太过对植株造成损伤,影响幼苗生长。

Effects of different treatments of drought stress and re-watering on photosynthesis of maize were studied to optimize measures of restraining growth of maize seedlings.The maize variety,Zhengdan 958 was used as material.Hydroponics was used to study photosynthetic physiological indexes of maize seedlings under different treatments of drought stress and re-watering,such as content of photosynthetic pigments,photosynthetic parameters,chlorophyll fluorescence parameters etc.With increasing of drought stress cycles,contents of chlorophyll and carotenoid decreased first and then increased,and increased first and then decreased,respectively.The maximum photochemical efficiency(F_(v)F_(m)),actual photochemical efficiency(Φ_(PSⅡ))and photochemical quenching coefficient(qP)of PSⅡdecreased first and then increased,while non photochemical quenching coefficient(qN)increased first and then decreased.Under drought stress,net photosynthetic rate(P_(n)),stomatal conductance(G_(s)),transpiration rate(T_(r))and water use efficiency(WUE)of maize decreased significantly,while intercellular CO_(2)concentration(C_(i))increased significantly(P<0.05).The maximum net photosynthetic rate(P_(nmax)),apparent quantum efficiency(AQE)and dark respiration rate(R_(d))decreased significantly,while light compensation point(LCP)increased significantly(P<0.05).After re-watering,the chlorophyll content,P_(nmax),AQE,LCP and light saturation point(LSP)showed increasing trends,while R_(d)showed a decreasing trend.P_(n),G_(s),T_(r),C_(i),WUE,F_(v)F_(m),Φ_(PSⅡ),qP and qN increased with the extension of re-watering gradually,showing a certain compensation effect.However,P_(n)and WUE were still very low after treatments of 3 times of drought stress and re-watering,and even decreased to a negative value when 3 days after re-watering.The compensatory water absorption was significant under treatments of 2 times of drought stress and re-watering,while the treatments of 3 times of drought stress and re-watering might cause some damage to maize seedlings,compensation effect was limited after re-watering.In conclusion,times of drought stress should be strictly controlled in restraining growth of maize seedlings,in order to avoid damage to plants and affect growth of seedlings.