盐-旱复合胁迫下水稻产量和品质形成特征OA

This study is aimed to clarify the effects and physiological mechanisms of combined salinity-drought stress on rice grain yield and quality formation,with inbred japonica rice Yandao 12 as material,which is widely planted in coastal saline alkali land in Jiangsu province.The effects of combined salinity-drought stress on rice grain yield and quality formation were studied by setting no stress(control),single salinity stress(0.3％soil salt content),single drought stress(drought stress set from jointing to heading)and combined salinity-drought stress(drought stress set from jointing to heading under 0.3％soil salt content)treatments.The results showed that compared with the control,① the grain yield under single salinity stress,single drought stress and combined salinity-drought stress decreased by 61.6％,19.5％and 68.2％,respectively,across two years.The number of panicles,spikelets per panicle,filled-grain percentage and 1000-grain weight under combined salinity-drought stress were significantly lower than those under single salinity stress and single drought stress.② Under single salinity stress,single drought stress and combined salinity-drought stress,the milling quality(brown rice percentage,milled rice percentage and head rice percentage)and appearance quality(chalky rice percentage,chalky area and chalkiness degree)of rice deteriorated,and the degree of deterioration of rice milling quality and appearance quality was higher under combined salinity-drought stress.③ Single salinity stress,single drought stress and combined salinity-drought stress reduced amylose content,gel consistency and taste value,with a greater de-crease observed under combined salinity-drought stress.Single salinity stress,single drought stress and combined salini-ty-drought stress increased significantly the protein content of rice.④ Single salinity stress,single drought stress and combined salinity-drought stress reduced significantly the breakdown value and increased significantly the setback value.Compared with single salinity stress and single drought stress,the peak viscosity,hot viscosity,cool viscosity and break-down value under combined salinity-drought stress were lower,while higher for setback value.⑤ Single salinity stress,single drought stress and combined salinity-drought stress all reduced the activities of adenosine diphosphate-glucose pyro-phosphorylase(AGPase),granule-bound starch synthase(GBSS),starch synthase(SSS)and starch branching enzyme(SBE)enzymes in grains after heading.Under combined salinity-drought stress,the activities of AGPase,GBSS and SBE in grains after heading were lower than those under single salinity stress and single drought stress.⑥ This study indicates that under single salinity,single drought stress and combined salinity-drought stress,the sink size and sink-filling effi-ciency of rice populations significantly decrease,with a greater decrease and lower yield under combined salinity-drought stress.The degree of deterioration in rice milling quality,appearance quality and cooking taste quality under combined sa-linity-drought stress is higher than that under single salinity stress and single drought stress.Compared with single salini-ty and single drought stress,combined salinity-drought stress reduces the activity of key enzymes involved in starch syn-thesis,deteriorates grain starch enrichment traits,and has a stronger inhibitory effect on rice yield and quality,showing a significant cumulative effect.