3种植物生长调节剂对不同干旱胁迫下巨菌草光合指标的影响

Effects of three plant growth regulators on the photosynthetic indicesindexes of giant juncao under different drought stress conditions

本研究以巨菌草(Pennisetum giganteum)幼苗为试验材料,通过叶面喷施生长调节剂法,利用CIRAS-3光合仪测定巨菌草叶片的净光合速率(P_(n))、蒸腾速率(T_(r))、气孔导度(G_(s))和水分利用效率(WUE),分析不同浓度茉莉酸甲酯(MeJA)、3-吲哚乙酸(IAA)和玉米素(ZT)对干旱胁迫下巨菌草光合指标的影响。结果表明,15%PEG模拟干旱胁迫下,未喷施植物生长调节剂的巨菌草生长受到了明显抑制,P_(n)、T_(r)、G_(s)和WUE显著降低;通过喷施不同浓度的MeJA、IAA、ZT发现,25μmol·L^(−1)MeJA、510μmol·L^(−1)IAA、6μmol·L^(−1)ZT浓度下的P_(n)、T_(r)、G_(s)和WUE显著高于对照(P<0.05);MeJA、IAA、ZT影响巨菌草光合特性的最佳浓度依次为25、510、6μmol·L^(−1);通过对不同干旱胁迫程度不同时段下巨菌草喷施25μmol·L^(−1)MeJA、510μmol·L^(−1)IAA、6μmol·L^(−1)ZT,发现MeJA最佳影响时段为胁迫的后半段时间(8~24 h),而IAA和ZT为胁迫的前半段时间(1~8 h)。本研究揭示了MeJA、IAA、ZT对干旱胁迫下巨菌草光合指标的影响机制,为研究其对巨菌草响应干旱胁迫的机理提供了参考。

Using giant juncao seedlings as an experimental material,we measured the rates of net photosynthesis(P_(n)),transpiration(T_(r)),stomatal conductance(G_(s)),and water-use efficiency(WUE)using CIRAS-3.We analyzed the effects of different concentrations of the growth regulators methyl jasmonate(MeJA),3-indoleacetic acid(IAA),and zeatin(ZT),applied via foliar spraying,on the photosynthetic indices of giant juncao subjected to drought stress induced by 15%PEG.The results revealed that under drought stress alone,plant growth was significantly reduced,and there were significant reductions in P_(n),T_(r),G_(s),and WUE compared with control plants.However,spraying stressed plants with different concentrations of MeJA,IAA,and ZT resulted in significant increases in P_(n),T_(r),G_(s),and WUE after spraying with 25μmol·L^(−1 )MeJA,510μmol·L^(−1 )IAA,and 6μmol·L^(−1 )ZT compared with stressed control,and these were established to be the optimal concentration of the respective growth promoters Furthermore,by spraying plants with 25μmol·L^(−1 )MeJA,510μmol·L^(−1 )IAA,and 6μmol·L^(−1 )ZT under different levels of drought stress and at different periods of time,we found that the optimal time for applying MeJA was during the second half of the stress period,between 8 and 24 h after stress onset.In contrast,application of IAA and ZT during the first half of the stress period,between 1 and 8 h,was found to be the most effective.In conclusion,this study revealed the effect mechanism of MeJA,IAA and ZT on photosynthetic indexes of giant juncao under drought stress,which provided a reference for studying its response mechanism to giant juncao under drought stress.