盐胁迫下4个不同耐盐基因型水稻Na^+、K^+积累效应

The Na^+ and K^+ Accumulative Effect of Four Different Salt Tolerance Genotypes in Rice under Salt Stress

选取耐盐性较强的水稻株系‘Fl478’、‘JX99’、‘Pokkali’和盐敏感型品种‘IR29’,设置6个NaCl浓度梯度处理,分别为0、0.1%、0.2%、0.3%、0.4%、0.5%,采用桶栽土培的方法培育至孕穗期,研究盐胁迫对孕穗期水稻植株不同器官Na^+、K^+分配规律与积累的影响。结果表明:(1)盐胁迫下水稻株系不同器官Na^+,K^+的积累效应存在差异,水稻株系耐盐性的差异主要表现在根系,而叶鞘对Na^+、K^+的吸收与分配的差异明显。(2)耐盐植株根系聚Na^+能力较强,叶片、叶鞘积累较多的K^+,而感盐品种根系积累K^+和Na^+以缓解根系渗透胁迫,调节根系Na^+/K^+平衡稳态,保持水稻正常的代谢活动。(3)叶鞘是水稻植株关键的Na^+-K^+调库,通过吸收和分配Na^+来调节根、叶、叶鞘Na^+/K^+平衡以提高水稻耐盐性。(4)耐盐株系叶鞘向叶片选择运输K^+的能力、限Na^+运输能力强于盐敏感品种,叶鞘对Na^+、K^+吸收与分配运输能力的大小,决定水稻株系的耐盐性,具体表现耐盐品种叶鞘向吸收与运输K^+能力较强、根系限Na^+能力显著高于感盐植株。(5)0.4%～0.5%盐浓度限制水稻叶鞘Na^+-K^+库吸收与分配能力,各组织中Na^+/K^+失衡,植株耐盐性降低,受盐害程度加深。(6)盐胁迫促进水稻株系叶鞘向根系吸收较多Na^+和向叶片、根系输出K^+,却限制Na^+对叶片的分配,保证根系保持较高的K^+/Na^+,耐盐幼嫩叶片积累较多的K^+以维持叶片组织保卫细胞渗透平衡,保证水稻植株获得生活必需的光合原料,而盐敏感植株积累的K^+主要用于缓解组织渗透胁迫,以维持正常生命活动。

The salt-tolerat rice varites ‘Fl478’, ‘JX99’, ‘Pokkali’,and salt-sensitive rice ‘IR29’ were cultured in barrels with soil until booting stage under six concentration grades of NaCl solution to study the absorption and distribution of Na＋ and K＋ in rice at booting stage under salt stress. There were differences in accumulative effect of Na＋ and K＋ in different organs of rice plants under salt stress. The difference in salinity resistance of rice lines was mainly reflected in the root system,however, the difference in the absorption and distribution of Na＋ and K＋ in leaf sheaths was significant. The roots of the salt-tolerant had strong ability to aggregate Na＋, and more K＋ was accumulated in the leaves and sheaths, but the roots of the salt-sensitive accumulated K＋ and Na＋ to alleviate the osmotic stress, adjust the Na＋/K＋ equilibrium, maintain normal metabolic activity. The leaf sheath is an important Na＋-K＋ buffer stock mainly used to absorb and par-tition Na＋ to regulate the Na＋/K＋ balance in the root, leaf and leaf sheaths to increase the salt resistance. The ability to transport K＋ to the leaves and to limit Na＋ transport of salt-tolerant leaf sheaths was stronger than the salt-sensitive va-rieties, and the ability of leaf sheaths to absorb and distribute Na＋ and K＋ would determine the salt tolerance of rice va-rieties. The specific performance was that salt-tolerant cultivars was stronger in the absorption and transport of K＋ and the root-limited Na＋ ability was much higher than that of the salt-sensitive varieties. The salt concentration of 0.4%–0.5% limited the absorption and distribution ability of Na＋-K＋ sinks in rice leaf sheaths, made the Na＋/K＋ imbal-anced in the tissues, decreased the salt tolerance of the plants and increased the degree of salt damage. Salt stress pro-moted the absorption of Na＋ from the leaf sheath to the root system and the output of K＋ to leaves and roots, but limited the distribution of Na＋ to the leaves to ensure that the root system maintained a high K＋/Na＋. The young leaves of the salt-tolerant accumulated more K＋ to maintain the osmotic balance of the guard cells of the leaf tissue to ensure that rice plants obtained the necessary photosynthetic raw materials for life. The accumulation of K＋ in salt-sensitive varieties was mainly used to relieve tissue osmotic stress to maintain normal life activities.