春小麦对生殖生长期阶段性干旱与复水的光合生理响应

Photosynthetic response to stage drought and rehydration in spring wheat at flowering stage

【目的】探究不同抗旱能力小麦品种对阶段性干旱及复水的光合及荧光生理响应.【方法】以春小麦品种‘西旱2号’和‘永良4号’为材料,采用盆栽法,花期控水,灌浆期复水,测定光合与荧光特性参数.【结果】干旱胁迫造成小麦叶片叶绿素含量、净光合速率(P_n)下降,气孔导度(G_s)、胞间CO_2浓度(C_i)减小.轻度干旱胁迫(田间持水量的55%～60%)复水后,2个品种光补偿点变低,饱和点增高;当中度干旱胁迫(田间持水量的45%～50%)复水后,‘西旱2号’光强利用范围较充分供水(田间持水量的70%～75%)CK增宽,‘永良4号’则变窄.PSⅡ实际光合效率(ΦPSⅡ)、表观光合电子传递速率(ETR)、光化学淬灭系数(qP)、最大荧光(F_m)、PSⅡ原初光能转化效率(F_v/F_m)下降,初始荧光(F_0)升高,且随胁迫程度的加深变化幅度增大,‘永良4号’较‘西旱2号’变化幅度更大,表现出‘西旱2号’的抗旱性优势.轻度干旱复水各指标均可恢复,部分表现出补偿效应,中度干旱胁迫复水后,‘西旱2号’的ΦPSⅡ、ETR、qP和F_m恢复至CK水平,而F_0和F_v/F_m未能恢复.‘永良4号’仅ETR和qP恢复至CK水平,而ΦPSⅡ、ETR、F_0和F_v/F_m均未能恢复.【结论】轻度干旱胁迫,复水后小麦品种荧光特性表现一定的补偿效应;中度干旱胁迫复水后,抗旱性强的品种基本可恢复正常水平,而抗旱性弱的品种由于缺水对光系统的严重损伤,使其难以恢复正常水平.

【Objective】To explore the photosynthetic and fluorescence physiological responses of different drought resistant wheat varieties to stage drought and rehydration.【Method】Two spring wheat varieties‘Xihan 2’and‘Yongliang 4’was used as a material,using pot culture,water control at flowering stage,rehydration at grain filling stage,and determination of photosynthetic and fluorescence characteristics.【Result】Wheat leaves Chlorophyll content,net photosynthetic rate(P n),stomatal conductance(G s)and intercellular CO 2 concentration(C i)were decreased caused by drought stress.After mild drought stress(55%to 60%of the field water holding)and re-watering,the light compensation point of two varieties became lower,but light saturation point became higher.After middle drought stress(45%to 50%of the field water holding)and re-watering,the light intensity utilization range of"Xihan 2"was wider than that of CK(70%to 75%of the field water holding),while that of‘Yongliang 4’was narrowed.PSⅡactual photosynthetic efficiency(ETR),apparent photosynthetic electron transfer rate(ETR),photochemical quenching coefficient(qP),maximum fluorescence(F m),PSⅡinitial light energy conversion efficiency(F v/F m)decreased,initial fluorescence(F 0)increased,and the degree of change increased with the degree of stress,and the change range of"Yongliang 4"was more than that of‘Xihan 2’.It showed the drought resistance advantage of‘Xihan 2’.All indexes of mild drought stress and re-watering could be recovered and partly compensated.After After middle drought stress and re-watering,PSⅡ,ETR,qP and F m of‘Xihan 2’were restored to CK level,but F 0 and F v/F m failed to recover.‘YongLiang 4’returned to CK level only ETR and qP,while PSⅡ,ETR,F 0 and F v/F m failed to recover.【Conclusion】The fluorescence characteristics of wheat varieties after rehydration are compensated by mild drought stress,and the varieties with strong drought resistance can basically restore normal level after middle drought stress,and the varieties with weak drought resistance make it difficult to restore the normal level because of the severe damage to the light system.