采用池栽和干旱棚模拟花期干旱胁迫,试验研究植物生长调节剂对玉米旱害和正常植株不同时期茎流和光合性能的影响.结果表明:在干旱胁迫条件下,外源CaCl_2、ABA、6-BA、KT-30处理10 d显著抑制植株茎流强度,减少植株失水.还促进干旱影响植株的叶绿素含量(SAPD)、光化学效率(Fv/Fm)、光系统潜在活性(Fv/Fo)显著提高或者保持相对稳定,减缓干旱对植株光合作用的影响.在充分灌溉条件下,植物生长调节剂也使植株茎流强度下降,SAPD、Fv/Fm和Fv/Fo增加,但其作用强度弱于干旱胁迫处理.随着生育进程(处理20 d),植物生长调节剂还能增强玉米灌浆后期的植株茎流强度,使SPAD、Fv/Fm、Fv/Fo显著增加或者保持相对稳定,延缓干旱导致的植株衰老,但外源ABA具有双重作用,这与水分条件密切相关.研究还发现,Fv/Fm和Fv/Fo可作为植株衰老诊断指标.%The controllable trials were carried out to study effect of plant growth regulators (PGRs) on stem sap and photosynthesis of maize growth stage on drought injury and irrigation plant at flowering stage with pool planting and canopy experiment. The results showed that both exogenous CaCl_2 and abscisic acid(ABA) and 6-benzyl adenine(6-BA) and kinetin-30(KT-30) markedly reduced stem sap intensity and controlled transpiration of plant,markedly increased or maintained relative stabilization on chlorophyll content (SPAD),the photochemistry efficiency (Fv/Fm) and latency activity (Fv/Fo) of photosystem Ⅱ on five leaves up and under spike at 10 days after the treatment of PGRs under drought stress,that reduced injury on photosynthesis of plant (Fig.1,2,3,4). The PGRs markedly reduced stem sap intensity and increased SPAD,Fv/Fm and Fv/Fo at 10 days after the treatment of PGRs under full irrigation,but effect of PGRs was smaller and weaker under irrigation than that under drought stress. The PGRs incarnate to stay senescence of plant because of increasing stem sap intensity and SPAD and Fv/Fm and Fv/Fo at 20 days (milking later stage) after the treatment,but exogenous ABA had double effect,which was related to water intensity. Studies discovered that Fv/Fm and Fv/Fo could be used as a index to estimate senescence of plant.
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