花后喷施KH_(2)PO_(4)对灌浆期高温胁迫下小麦根系生理特性及产量的影响

Effect of Spraying KH_(2)PO_(4) After Anthesis on Root Physiological Characteristics and Yield of Wheat Under High Temperature Stress at Grain Filling Stage

为探究花后叶面喷施磷酸二氢钾(KH_(2)PO_(4))对灌浆期高温胁迫下小麦根系生理特性及产量的影响,本研究设置叶面喷施清水(NT)、清水+灌浆期高温胁迫(NHT)、KH_(2)PO_(4)溶液(PT)和KH_(2)PO_(4)溶液+灌浆期高温胁迫(PHT)共4个处理,考察了不同处理对小麦根系活力、抗氧化酶活性、丙二醛(MDA)含量、旗叶净光合速率(Pn)、成熟期干物质积累与分配和产量的影响。结果表明,花后喷施KH_(2)PO_(4)显著提高了高温前根系活力、超氧化物歧化酶(SOD)和过氧化物酶(POD)活性,显著降低MDA含量。高温胁迫处理显著降低了根系活力,但喷施KH_(2)PO_(4)的根系活力下降幅度较小,高温后根系内维持了较高的SOD、POD和过氧化氢酶(CAT)活性,且高温后NHT根系MDA含量显著高于NT,NT显著高于PHT,而PT显著低于PHT。花后喷施KH_(2)PO_(4)显著提高了灌浆期旗叶Pn,降低高温对叶片光合能力的危害程度。成熟期PT植株干物质积累量显著高于PHT和NT,后两者间无显著差异,NHT最低,且PT向籽粒分配的干物质量最高。与NHT相比,NT、PHT和PT产量分别提高了17.8%、18.9%和26.7%,喷施KH_(2)PO_(4)处理提高产量是由于千粒重的显著提高。综上,花后通过叶面喷施KH_(2)PO_(4)能显著延缓灌浆期小麦根系衰老,增强根系耐高温能力,提高成熟期植株干物质积累,降低灌浆中后期高温胁迫对小麦产量造成的损失。本研究为小麦花后喷施KH_(2)PO_(4)以减轻灌浆期高温对小麦生产造成的危害提供了一定的理论依据。

The purpose of this field experiment is to explore the effect of foliar spraying KH_(2)PO_(4) after anthesis on the physiological characteristics of wheat root and grain yield under high temperature stress during grain filling period.The experiment was designed with four different foliar spraying treatments,i.e.water(NT),water+high temperature stress during grain filling(NHT),KH_(2)PO_(4) solution(PT),KH_(2)PO_(4) solution+high temperature stress during grain filling(PHT),respectively.To investigate the effect of spraying KH_(2)PO_(4) on root vigor,antioxidant activity,malondialdehyde(MDA)content,net photosynthetic rate(Pn)of the flag leaf,dry matter accumulation and distribution at maturity,as well as grain yield in wheat under high temperature stress during the grain filling period.The results showed that the root vigor,superoxide dismutase(SOD)and peroxidase(POD)activity before high temperature stress treatment were significantly increased by foliar spraying of KH_(2)PO_(4),while the MDA content was significantly decreased.The root vigor was significantly decreased after being subjected to high temperature stress,however,the decline in spraying KH_(2)PO_(4) treatment was significantly reduced due to the higher SOD,POD and catalase(CAT)activity in the roots,and the MDA content in NHT was significantly higher than NT,NT was significantly higher than PHT,and PT was significantly lower than PHT.Spraying KH_(2)PO_(4) after anthesis significantly improved Pn of flag leaf during the grain-filling period,and alleviated the harm of high temperature stress on the photosynthetic capacity of leaf.At maturity,the dry matter accumulation amount in PT was significantly higher than that in PHT and NT,while no significant difference was found between PHT and NT.The amount was the lowest in NHT.The dry matter distribution amount to the grain for PT was the most.Owing to the significant increase in thousand-kernel weight,spraying KH_(2)PO_(4) after antheis significantly improved the grain yield,while compared with NHT,the grain yield of NT,PHT and PT was increased by 17.8%,18.9%and 26.7%,respectively.In conclusion,foliar spraying of KH_(2)PO_(4) after anthesis could delay senescence in wheat roots,enhanced the resistance of roots to high temperature stress during grain filling period,improve the accumulation of dry matter of plants at maturity,and reduce grain yields loss.This study provides a theoretical basis for spraying KH_(2)PO_(4) after anthesis in wheat to alleviate the harm of high temperature stress on wheat production.