穗分化期旱涝急转对超级杂交早稻产量和生理特性的影响

为了探明旱涝急转对水稻产量形成的影响及其成因,以超级杂交早稻组合淦鑫203为材料,采用桶栽方式,于穗分化初期设置不旱不涝(NDNF)、干旱不涝(DNF)、不旱淹涝(NDF)及旱涝急转(DFAA)4种处理,研究不同处理下超级杂交早稻组合的产量及其构成、叶片叶绿素含量、光合参数以及内源激素等的变化。结果表明,相对于NDNF,DNF、NDF及DFAA的单株产量均不同程度下降,降幅分别为33.60%、16.92%和37.31%,且DNF和DFAA与NDNF间差异显著,DNF较NDF更不利于淦鑫203产量的形成,因此,穗分化期干旱较淹涝对超级杂交早稻产量负面影响更大,而DFAA单株产量又较DNF低,表明旱后淹涝急转存在叠加减产效应。与NDNF相比,DFAA下淦鑫203倒2叶的蒸腾速率、气孔导度、胞间CO_2浓度和叶绿素含量均不同程度降低,稻叶光合速率显著下降,表明穗分化初期DFAA对淦鑫203光合作用具有一定的叠加损伤效应;此外,淦鑫203倒2叶内源生长促进类激素IAA和GA3含量上升,ZR含量下降,内源生长抑制类激素ABA含量在处理结束前期上升,后期下降。综上,超级杂交早稻幼穗分化期遭受严重干旱不仅影响其产量的形成,还会显著降低其耐淹能力,DFAA下光合性能的下降及内源激素平衡的改变可能是产量下降的主要原因。本研究结果为双季早稻应对"旱"、"涝",尤其是"旱涝急转"等气象灾害提供了参考依据。

Effects of Drought-floods Abrupt Alternation on Physiological and Yield Characteristics in Super Hybrid Early Rice During Panicle Differentiation Stage

To explore the effects of drought floods abrupt alternation (DFAA) on the rice yield and its cause of formation,super hybrid early rice Ganxin203 was selected as the material and grown by pot cultivation,and the rice plants were treated by four treatments such as no drought followed by no floods (NDNF),drought followed by no floods (DNF),no drought followed by floods (NDF) and drought floods abrupt alternation (DFAA) during panicle differentiation stage.Moreover,indexes of the yield and the components,leaf chlorophyll contents,photosynthetic parameters,endogenous hormones of the super hybrid early rice were determined as well.The results showed as follows:compared with NDNF,yield of rice plant of DNF,NDF and DFAA decreased by 33.60％,16.92％ and 37.31％,respectively.Significant differences were found between NDNF,DNF and DFAA for yield per plant and DNF was more disadvantageous to yield formation of super hybrid early rice Ganxin203 than NDF.Therefore,there was greater negative effect of DNF than NDF for yield on super hybrid early rice,while yield per plant of DFAA was lower than that of DNF,suggesting there was superimposing damage to rice plant of DFAA.Compared with NDNF,transpiration rate,stomatal conductance,intercellular CO2 concentration and leaf chlorophyll contents of DFAA decreased to a certain extent in the reciprocal second leaf,while leaf net photosynthetic rate dropped significantly,suggesting there was superimposing damage to photosynthesis of Ganxin203 during panicle differentiation stage.Besides,the endogenous growth promoted the rise of hormones indole-3-acetic acid (IAA) and gibberellin A3 (GA3) contents of DFAA in the reciprocal second leaf,while the contents of zeatin riboside (ZR) decreased,and its endogenous growth inhibited hormone abscisic acid (ABA) contents increased at earlier stage and decreased in later stage clearly after treatment.To sum up,it is highly obvious that relative-critically drought treatment would badly affect yield formation during panicle differentiation stage of super hybrid early rice,and the ability of flood-tolerant for rice plant would decrease markedly.The drop of photosynthetic ability and alteration of endogenous hormones balance may be the main reason of the dramatically fall in yield for DFAA.The results can supply reference for replying the meterological disaster such as drought,floods,especially drought-floods abrupt alternation in double-season early rice.