不同生育期水分胁迫对水稻根叶渗透调节物质变化的影响

EFFECTS OF WATER STRESS ON OSMOLYTES AT DIFFERENT GROWTH STAGES IN RICE LEAVES AND ROOTS

干旱是限制水稻(Oryza sativa)作物产量的主要生态因子之一,渗透调节是作物适应干旱逆境的生理机制之一。在人为控制水分的盆栽条件下,对水稻生长的分蘖期、幼穗分化期、抽穗期、结实期分别进行水分胁迫,研究水稻根系及叶片渗透调节物质的变化规律。结果表明,不同生育期干旱胁迫后叶片水势均显著下降,根系和叶片的有机渗透调节物质如可溶性糖、游离氨基酸、脯氨酸和无机渗透调节物质包括K+、Mg2+等含量均大幅度上升,而且幼穗分化期和抽穗期这两个对水分胁迫最敏感的时期上升幅度最大,其中又以有机渗透调节物质变化最显著。不同生育期渗透调节大小的顺序为:抽穗期>幼穗分化期>结实期>分蘖期,反映了不同生育时期渗透调节能力的差异。同时幼穗分化期和抽穗期水分胁迫结束后再复水后根系和叶片的有机渗透调节物质含量仍长期明显高于对照,而无机离子则变化规律比较复杂,有的升高有的则降低。叶片的渗透调节能力大于根系,无论是叶片或根系都是K+对渗透调节的贡献最大;其次是Ca2+,6种渗透调节物质含量大小排列顺序为K+>Ca2+>可溶性糖>Mg2+>游离氨基酸>脯氨酸。

Aims Water stress is one of the most important ecological factors affecting yield and quality of rice （ Oryza sativa）, and osmotic adjustment is the main mechanism for the crop to adjust to drought. Our objective was to elucidate the effects of water stress on osmolytes at different growth stages in leaves and roots of rice. Methods We used the rice variety Feng-Hua-Zhan grown in pots to study the effects of water stress on inorganic and organic osmolytes in leaves and roots. Water was withheld 15 d at the growth stages of tillering, panicle differentiation, heading and filling. Important findings Water stress significantly decreased leaf water potential. Organic osmolytes including soluble sugar, proline and free amino acid and inorganic osmolytes including K^＋ and Mg2^＋ in leaves and roots increased significantly after drought treatment at different growth stages. These osmolytes could be reduced to normal levels after re-watering at the tillering stage, but not at the panicle differentiation and heading stages. Osmolytes accumulated to higher levels after drought treatment at panicle differentiation and heading stages than at other growth stages, and organic osmolytes accumulated to higher levels than inorganic osmolytes in the different treatments. The order of osmotic adjustment （OA） ability at different growth stages was： heading, panicle differentiation, filling and tillering. The OA in roots was lower than but positively correlated to OA in leaves. Roots were more sensitive and had a more rapid response to water than did leaves. The order of contri- bution for osmotic adjustment in leaves and roots with different osmolytes was： K^＋ 〉 Ca^2＋ 〉 soluble sugar 〉 Mg^2＋〉 free amino acid 〉 praline.