【作者】 张振华；

【导师】 刘强； 荣湘民； Abdelbagi M.Ismail；

【作者基本信息】 湖南农业大学 ， 植物营养学， 2010， 博士

【摘要】 农业土壤盐碱化程度日趋严重,已经成为现代农业的最重要议题之一。据统计,全世界受到盐胁迫的耕作土壤已超过30%,严重影响了作物的正常生长,甚至导致死亡,这主要是由于土壤过量的Na+积累和植物体营养元素不平衡所致。因此,盐胁迫条件下相关营养元素与作物耐盐胁迫能力的关系成为众所关注的问题。本论文研究在2008-2010年间分三个大试验分别讨论了不同基因型水稻在大田和人工气候室(严格控制水、温、光和营养元素供应)条件下栽培条件、营养元素和植物激素对水稻耐盐胁迫性的调控机理。为进一步增强作物耐盐胁迫能力和提高产量提供理论依据。主要研究结果如下：1通过对水稻正常和盐胁迫条件下的对比研究,探讨了植株养分与耐盐性的关系。试验结果表明,幼苗移栽时期的植株干物质量和叶面积与幼苗的耐盐性有显著的正相关性。正常条件下耐盐基因型植株把更多的可溶性糖转化成淀粉储存在体内,有更高的淀粉和碳水化合物含量；以及在盐胁迫条件下抑制可溶性糖转化成淀粉,同时把更多的淀粉转化成可直接利用的可溶性糖,是盐胁迫条件下水稻幼苗提高耐盐性的重要途径,也是耐盐基因型耐盐胁迫能力较强的重要原因。盐胁迫条件下植株能够保持较高的叶绿素a含量和叶绿素a／b比是植株有更强耐盐性的另一重要原因；是区分耐盐胁迫能力的重要生理指标。植株体内的Na+、K+含量和Na+／K+比是影响植株盐胁迫程度的主要影响因子,也是造成耐盐基因型和敏感基因型耐盐性差异的最直接指标；盐胁迫和正常条件下植株Ca2+和Mg2+含量差异显著,并且有显著的基因型差异。早期盐胁迫延迟了植株整个生长时期,是造成产量下降的主要原因；不会因为早期盐胁迫的结束而影响也随之结束。2探讨了不同栽培条件对盐胁迫条件下水稻幼苗移栽成活率和生长情况以及水稻产量的影响及其基因型差异。结果表明,营养条件和栽培方式对不同基因型水稻耐盐胁迫性的影响机理各不相同。推迟幼苗移栽时间和施氮处理可以增强移栽幼苗的耐盐胁迫性都是由于植株干物质量和叶面积显著增加的结果。但不是造成耐盐基因型差异的原因；耐盐基因型特有的碳水化合物代谢机制,根生长相对良好,以及减少Na+向地上部分的转运,都有利于增强耐盐胁迫性。盐胁迫条件下耐盐基因型和施氮处理植株能够保持较高的叶绿素a含量和叶绿素a／b比,是其有更强耐盐性的另一重要原因。带土移栽对根的伤害最小,从而减少根系对盐分离子的被动吸收；在以后的营养生长期有更高的生物量和更好的营养吸收能力。早期盐胁迫对耐盐基因型生育期的影响较小；带土移栽可以显著减轻盐胁迫对于水稻生育期的影响。这些都是盐胁迫条件下耐盐基因型和带土移栽有更高产量的重要原因。3试验研究了营养液中的养分浓度及其养分在植株体的含量差异对苗期不同水稻基因型耐盐性的影响。结果表明,盐胁迫条件下耐盐基因型与盐敏感基因型相比,植株体内有较低的Na+含量和Na+／K+、Na+／Ca2+和Na+／Mg2+比,有较高的K+含量。盐胁迫条件下提高营养液中Ca2+和Mg2+的含量(60mM)可以显著降低植株体Na+的含量和Na+／K+Na+／Ca2+以及Na+／Mg2+比,且Ca2+处理的影响大于Mg2+处理；而K+处理对以上指标的影响远远小于Ca2+处理和Mg2+处理,这也是K+处理对水稻耐盐性影响相对不明显的内在原因。盐胁迫条件下耐盐基因型相对于盐敏感基因型植株地上部分有更高的K+含量,更低的Na+含量,Na+／K+、Na+／Ca2+和Na+／Mg2+也明显降低；而根部K+含量反而降低,Na+／K+、Na+／Ca2+和Na+／Mg2+比则明显升高；这些都是耐盐基因型相对于盐敏感基因型保持较高的生长速率和较低的耐盐胁迫评价值的内在原因。4试验研究了植株体营养元素在各器官的分配差异对苗期不同水稻基因型耐盐性的影响。结果表明,盐胁迫条件下耐盐基因型和盐敏感基因型植株新生器官中的Na+含量以及Na+／K+、Na+／Ca2+和Na+／Mg2+比明显低于衰老器官,而K+含量则明显高于衰老器官；与光合作用密切相关的Mg2+在叶片中的含量明显高于其它器官。植株体把更多的Na+转运到植株体衰老器官,而把更多的K+转运到新生器官,同时保持新生器官较低的Na+／K+、Na+／Ca2+和Na+／Mg2+比是植株体提高耐盐胁迫性能的有效手段。5研究了两水稻基因型短期和长期盐胁迫条件下植株激素含量、耐盐性和生理反应的差异。结果表明,盐胁迫条件下耐盐基因型相对于敏感基因型保持了较高的光合作用效率、蒸腾速率、气孔导度和叶片水势,从而保持了更高的生物量,稀释了植株体内盐分离子的浓度而减轻盐胁迫。两水稻基因型在盐胁迫条件下对盐分的总吸收量并无明显差异,耐盐基因型根部较强的耐盐性和较大的生物量可以储存更多的Na+,从而减少Na+向地上部的转运量。盐胁迫初期植株还没有时间形成更多的耐盐胁迫机制,盐分离子的大量吸收对植株造成的伤害不可恢复。而盐胁迫初期耐盐基因型根部激素ABA的大量合成是叶片气孔导度值迅速降低的主要原因,并且使蒸腾速率显著降低,从而抑制了盐分离子在盐胁迫初期的大量吸收,大大减轻了盐胁迫初期大量盐分离子吸收对植株造成的不可恢复性伤害。本文研究表明,盐胁迫条件下营养元素含量和代谢都可以显著影响植株的耐盐性；耐盐基因型特有的碳水化合物代谢,叶绿素含量以及营养元素含量和分配使其有较强的耐盐胁迫性。带土移栽、推迟幼苗的移栽时间和氮肥的合理施用是增强幼苗移栽成活率的有效手段；提高幼苗的耐盐胁迫性对于产量的提高有着至关重要的作用。适当提高水稻生长环境中可利用营养元素Ca2+和Mg2+的浓度可以明显增强植株耐盐胁迫能力,且营养元素Ca2+的效果比Mg2+元素明显。根据不同基因型植株地上部和根的营养元素分配特性对水稻各基因型进行合理的选育是提高水稻耐盐性能的重要手段。盐胁迫条件下耐盐基因型较大的生物量、根的生理特性以及盐胁迫初期植物激素ABA的特有调控都大大增强了其耐盐胁迫性能,是耐盐基因型相对敏感基因型有更强耐盐胁迫能力的重要原因。更多还原

【Abstract】 Increasing salinization of agricultural soils is one of the most challenging issues faced by modern agriculture. In excess of 30% of cultivated soils are affected by salinity. Much of this salinization is attributable to the infiltration and accumulation of Na+ and plant nutrients. So, it should pay more much attention to the relationship between plant nutrients and tolerance ability of crop under salinity in the future. This thesis included three experiments totally, study on the physiological mechanisms of salt tolerance of different rice genotypes regulated by the cultivation conditions, plant nutrients and hormone under the field and phytotron (controlled water supply, temperature, light and nutrients supply) conditions during 2008-2010 year. It has been supplied some further basic theory evidence for the salt tolerant improvement and the crop production increasing. The main results showed as below:1 There is significant positive correlation between plant biomass, leaf area and salt tolerant ability of seedling. The larger amount of sugar has been transformed into starch, accumulated in plant tissues and has higher contents of starch and carbohydrate under normal condition; and inhibition the sugar transformed into starch, the larger amount of starch has been transformed into sugar under saline condition are the effective methods to improve the tolerant ability of rice, and it is the important reasons for tolerant genotype to increase tolerant ability. Plant maintained higher contents of chlorophyll a and chlorophyll a/b ratio is the physiological characters of salt tolerant genotypes, and it is the important reasons of salt tolerant ability increased. The differences of salt tolerant ability between tolerant genotypes and sensitive genotypes as affected by the contents of Na+, K+ and Na+/K+ ratio in plant tissues, which will directly affect the level of salt stress. The differences of Ca2+ and Mg2+ contents in plant tissues between normal and saline conditions are significant, and the differences between genotypes are significant also. Growth stages can be delayed by early salt stress, and the affect of salt stress can not be eliminated with the salt stress finished, it is the main reasons for the production decreasing.2 The effect of plant nutrients and cultivations on salt tolerant ability of different rice genotypes and its mechanisms are different. The salt tolerant ability of seedling can be improved by delaying the transplanting time and N application is because of the higher plant biomass and leaf area. Because of the special metabolic mechanisms of carbohydrate and the physiological characters of root, the tolerant genotype has higher salt tolerant ability under saline condition. There are higher chlorophyll a content and chlorophyll a/b ratio in plant tissues of tolerant genotype and N treatments, these are important physiological characters for salt tolerant ability increased. Compared with the root washed transplanting, seedling transplanting with soil can protect the root, so the passive absorption amount of sodium is decreased significantly; it is help plant to maintain higher nutrients absorption ability and higher plant biomass during the later growth period. The effect of salt stress on growth stage of salt tolerant genotype is smaller, and the effect of salt stress on growth stage of transplanting with soil is smaller also. These are the reasons of tolerant genotype and transplanting with soil treatment have higher production under salt stress condition.3 The salt tolerant genotypes (FL478 and IR651), when compared with the sensitive genotypes (IR29 and Azucena), had lower content of Na+ and lower ratios of Na+/K+, Na+/Ca2+ and Na+/Mg2+, but had higher content of K+ in plant under salt stress (100 mmol·L-1 NaCl), that’s why tolerant genotypes have higher tolerant ability than sensitive genotypes. The content of Na+ and ratios of Na+/K+, Na+/Ca2+ and Na+/Mg2+ in plant can be declined significantly, the effect of salt stress on plant growth is alleviated significantly, the salinity tolerance of rice is improved significantly and the influence of Ca2+ treatment is higher than Mg2+ treatment, when the concentrations of Ca2+ and Mg2+ in culture solution were increased (60 mmol·L-1). However, the effect of K+ treatment on the above parameters is lower than Ca2+ and Mg2+ treatments respectively, that’s why the effect of K+ treatment on salinity tolerance of rice is not significant. In addition, the salinity tolerance genotypes, when compared with sensitive genotypes, had higher amount of K+ distributed into the shoot, and had higher amount of Na+ accumulated at root, the salinity tolerance of root is higher; the contents of K+ in shoot is higher, and had lower contents of Na+ in shoot, the ratios of Na+/K+, Na+/Ca2+ and Na+/Mg2+ in shoot are decreased significantly also; however, the content of K+ in root is lower, while the ratios of Na+/K+, Na+/Ca2+ and Na+/Mg2+ in root are increased significantly.4 The content of Na+ and the ratios of Na+/K+, Na+/Ca2+ and Na+/Mg2+ in new plant tissues are lower than old tissues significantly under saline condition, but the content of K+ in new tissues is higher than old tissues. The content of Mg2+ in leaves is higher than other plant tissues significantly. The larger amount of Na+ is distributed into old plant tissues, while larger amount of K+ is distributed into new plant tissues, and maintained lower ratios of Na+/K+、Na+/Ca2+ and Na+/Mg2+ in new plant tissues is a effective method to increase the salt tolerant ability.5 Compared with sensitive genotype, the photosynthesis effective, transpiration effective, stomatal conductance and leaf water potential of tolerant genotype are higher under saline condition; so the biomass of tolerant genotype is higher than sensitive genotype, and the sodium content of tolerant genotype is lower than sensitive genotype. There is no significant difference of total sodium absorption between sensitive and tolerant genotypes, root biomass of tolerant genotype is higher than sensitive genotype, and the amount of sodium in root of tolerant genotype is higher than sensitive genotype, so the amount of sodium in shoot of tolerant genotype is lower than sensitive genotype. There is not enough time to product more salt tolerant mechanisms during the early salt stress stage, and the injury of plant which caused by large amount of sodium absorption at early stage can not be alleviated in the future. However, because of the large amount of ABA in root of tolerant genotype has been produced during the early salt stress stage, the stomatal conductance in leaves of tolerant genotype is decreased significantly, and the transpiration effective is decreased significantly also. The sodium absorption has been inhibited by these physiological responses, and the salt stress of rice plant is alleviated at a large scale.It can be concluded that, the salt tolerant ability can be affected by plant nutrients contents and nutrients metabolic significantly under saline condition; because of some special physiological indexes:carbornhydrate metabolic, chlorophyll content, plant nutrients content and distribution, salt tolerant genotype has higher tolerant ability under saline condition. Transplanting with soil, delaying the transplanting time and N application are effective methods to increase the ratio of seedling transplanting survival; the salt tolerant ability of seedling increasing is very important for the production increasing. The concentrations of Ca2+ and Mg2+ in culture solution are increased properly can improve the salt tolerant ability of plant significantly under saline condition, and the effective of Ca2+ is higher than Mg2+. Compared with sensitive genotype, the tolerant genotype has special root physiology characters, higher biomass and the regulation of plant hormone (ABA), that’s why the tolerant ability of tolerant genotype is higher than sensitive genotype significantly under saline condition.更多还原