盐-旱复合胁迫下水稻根系的形态和生理特征及其与产量形成的关系

Morphological and Physiological Characteristics of Rice Roots Under Combined Salinity-Drought Stress and Their Relationships with Yield Formation

【目的】明确盐-旱复合胁迫影响水稻根系形态生理及产量形成的作用机制。【方法】以江苏沿海滩涂大面积种植的常规粳稻南粳9108为试材,设置对照(无胁迫,CK)、单一盐胁迫(0.15s,盐浓度0.15%;0.3s,盐浓度0.3%)、单一干旱胁迫(DJ,拔节期干旱;DH,抽穗期干旱)和盐-旱复合胁迫(0.15s+DJ、0.15s+DH、0.3s+DJ、0.3s+DH),比较研究盐-旱复合胁迫下水稻根系形态生理的变化特征及其与物质生产和产量形成的内在关联。【结果】与对照相比,单一盐胁迫(0.15s、0.3s)下水稻产量降幅为25.8%和65.0%;单一干旱胁迫(DJ、DH)下产量降幅为4.3%和22.3%;盐-旱复合胁迫(0.15s+DJ、0.3s+DJ、0.15s+DH和0.3s+DH)下产量降幅分别为33.3%、67.3%、48.3%和72.6%。单一盐胁迫和盐-旱复合胁迫处理的每盆穗数、每穗粒数、结实率和千粒重均显著低于对照,且盐-旱复合胁迫下水稻各产量构成因素均显著低于单一盐胁迫和干旱胁迫。单一盐胁迫、干旱胁迫和盐-旱复合胁迫下水稻成熟期地上部干物质量和收获指数均低于对照,且盐-旱复合胁迫下植株地上部和根系干物质量、根冠比和收获指数均低于单一盐胁迫和干旱胁迫。与对照相比,单一盐胁迫和盐-旱复合胁迫处理下根长、根表面积、根直径、根系氧化力和伤流强度均受到显著抑制,且在盐-旱复合胁迫下的抑制效应大于单一盐胁迫和干旱胁迫。单一盐胁迫、干旱胁迫和盐-旱复合胁迫处理降低了水稻叶片净光合速率和叶绿素含量,尤其在盐-旱复合胁迫下降幅更大。【结论】盐-旱复合胁迫显著抑制水稻根系形态生理,进而影响叶片光合生理、同化物积累以及产量形成,且其抑制效应高于单一盐胁迫和干旱胁迫,具有叠加效应。

【Objective】This study aims to elucidate the mechanisms by which combined salinity-drought stress affects rice root morphology,physiology,and yield formation.【Method】We used Nanjing 9108,a conventional japonica rice variety widely grown in the mudflats along the coast of Jiangsu Province,as the test material.The following treatments were applied:control(no stress,CK),single salinity stress(0.15s,salinity concentration 0.15%;0.3s,salinity concentration 0.3%),single drought stress(DJ,drought at jointing stage;DH,drought at heading stage),and combined salinity-drought stress(0.15s+DJ,0.15s+DH,0.3s+DJ,0.3s+DH).We conducted a comparative study to investigate changes in root morphology and physiology of rice under combined salinity-drought stress and their underlying relationships with crop production and yield formation.【Results】In comparison to the control,rice yield decreased by 25.8%and 65.0%under single salinity stress(0.15s and 0.3s,respectively).Under single drought stress(DJ and DH),the yield reduction was 4.3%and 22.3%,respectively.Under combined salinity-drought stress(0.15s+DJ,0.3s+DJ,0.15s+DH,and 0.3s+DH),the yield reduction was 33.3%,67.3%,48.3%,and 72.6%,respectively.The number of panicles,grain number per panicle,seed setting rate,and thousand grain weight were significantly lower under single salinity stress and combined salinity-drought stress treatments compared to the control.The yield components of rice under combined salinity-drought stress were also significantly lower than those under single salinity stress and drought stress.Aboveground dry matter weight and harvest index of rice during maturity were lower under single salinity stress,drought stress,and combined salinity-drought stress compared to the control.The aboveground and root dry matter weight,root to shoot ratio,and harvest index of plants under combined salinity-drought stress were lower than those under single salinity stress and drought stress.Root length,root surface area,root diameter,root oxidation activity,and bleeding intensity were significantly inhibited under single salinity stress and combined salinity-drought stress,with a stronger inhibitory effect under combined salinity-drought stress.Net photosynthetic rate and chlorophyll contents of rice leaves were reduced under single salinity stress,drought stress,and combined salinity-drought stress,with the greatest decrease observed under combined salinity-drought stress.【Conclusion】Combined salinity-drought stress significantly inhibits rice root morphology and physiology,consequently impacting leaf photosynthesis,assimilate accumulation,and yield formation.This inhibitory effect is more pronounced than that of single salinity stress and drought stress,with a synergistic impact.