外源多效唑对干旱胁迫下闽楠幼苗抗旱性的影响

Effect of exogenous paclobutrazol on the drought resistance of Phoebe bournei seedlings under drought stress

为明确外源多效唑对闽楠幼苗抗旱性的响应机制,以2年生闽楠幼苗为试材,采用自然干旱法,研究不同浓度多效唑(25、50、100mg·L^(-1))喷施对干旱胁迫下闽楠幼苗光合系统和抗氧化系统的影响。结果表明:干旱胁迫显著减弱闽楠幼苗的光合作用,打破抗氧化系统的动态平衡,不同浓度多效唑喷施均能有效缓解干旱胁迫下闽楠幼苗受到的胁迫损伤,提升光合系统和抗氧化系统的防御能力,其中100mg·L^(-1)多效唑处理最为有效。100mg·L^(-1)多效唑处理下,与干旱处理相比,闽楠幼苗叶片中叶绿素总量显著增加,最高增幅为51.9%,表观光合电子传递速率、光化学淬灭系数、实际光化学量子产量显著提高,最高增幅分别为67.8%、58.4%、59.7%,净光合速率、气孔导度、蒸腾速率显著增长,最高增幅分别为65.5%、65.4%、68.6%。外源100mg·L^(-1)多效唑通过调控闽楠幼苗光合系统和抗氧化系统提升闽楠幼苗抗旱性的能力最强。

To clarify the response mechanism of exogenous paclobutrazol on drought resistance in Phoebe bournei seedlings,we investigated the effects of spraying different concentrations of paclobutrazol(25,50,100 mg·L^(-1))on the photosynthetic and antioxidant systems of 2-year-old P.bournei seedlings under drought stress using natural drought method.The results showed that drought stress significantly reduced the photosynthesis and broke the dynamic balance of antioxidant system in P.bournei seedlings.Spraying with dfferent concentrations of paclobutrazol effectively alleviated the negative impacts of drought stress,and enhanced the defense capability of photosynthetic and antioxidant systems,with the 100 mg·L^(-1) paclobutrazol treatment being the most effective.Under exogenous 100 mg·L^(-1) paclobutrazol treatment,the total chlorophyll in leaves increased significantly,with a maximum increase of 51.9%.The apparent photosynthetic electron transfer rate,photochemical quenching coefficient and actual photochemical quantum yield were significantly increased,with maximum increase of 67.8%,58.4%,and 59.7%,respectively.The net photosynthetic rate,stomatal conductance and transpiration rate,were enhanced,reaching maximum increase of 65.5%,65.4%,and 68.6%,respectively.In summary,exogenous 100 mg·L^(-1) paclobutrazol has the strongest ability to enhance drought resistance of P.bournei seedlings by regulating photosynthetic and antioxidant systems.