水稻品种演进过程中根系形态生理的变化及其与产量形成的关系

Rice roots are an integral part of plant organs and play an important role in the acquisition of water and nutrients, and the growth and development of its aboveground parts. However, it remains much yet to be understood that the changes in morphology and physiology of roots and their relationship with yield formation during the evolution of rice cultivars. The main contents of the study including: (1) the changes in morphology (roots number, length, length density, diameter, weight, weight density, surface area, and volume) and physiology (roots oxidation activity, total absorbing surface area and active absorbing surface area, contents of hormones, and components and contents of hormones, organic acids, and amino acids in root bleeding) of roots and their relationships with yield evolution during the evolution of rice cultivars; (2) the changes in morphology and physiology of roots and their relationships with nutrient uptake, matter production, and yield formation at main growth stages of modern high-yielding rice cultivars; (3) the regulating effect of water and fertilizer on morphology and physiology of roots， and yield formation of rice. To clarify the changes in morphology and physiology of roots and their relationships with yield evolution during the evolution of rice cultivars, definite the main indexes of morphology and physiology of roots at main growth stages of modern high-yielding rice cultivars, propose the techniques of water and fertilizer management to improve yield through regulating the morphology and physiology of roots, and provide theoretical basis and practical guidance for high-yielding and good-quality cultivation and breeding of rice.

水稻根系对水分养分吸收及地上部生长发育起着十分重要的作用。水稻品种演进过程中根系形态生理的变化及其与产量形成的关系目前尚不清楚。本项目主要研究：(1)水稻品种演进过程中根系形态(根数、根长、根长密度、根直径、根重、根重密度、根表面积和根体积)和生理(根系氧化力、根系总吸收表面积和活跃吸收表面积、根系激素浓度、根系伤流液中激素、有机酸和氨基酸组分和浓度)的变化及其与产量演进的关系；(2)现代高产品种主要生育期根系形态生理的变化及其与养分吸收、物质生产和产量形成的关系；(3)水、肥对水稻根系形态生理和产量形成的调控作用。以期阐明水稻品种演进过程中根系形态生理的变化及其与产量演进的关系，明确现代高产品种主要生育期根系形态生理的主要指标，提出通过调控根系形态生理来提高产量的水、肥管理技术。为水稻高产优质栽培和育种提供理论依据和实践指导。

以各阶段在江苏具有代表性的12个中籼水稻品种和12个粳稻品种（含组合）为材料，研究了水稻品种演进过程中根系形态生理的变化及其与产量形成的关系。主要结果如下：.（1）明确了水稻品种的产量演进特征。产量随品种演进显著提高，产量的提高主要在于总颖花量的增加，以现代超级稻尤为明显。但是，较低的结实率限制了超级稻产量潜力的充分实现。.（2）揭示了水稻产量形成过程中籽粒灌浆的生理机制。花后适度土壤干旱条件下，籽粒中ABA含量的增加和乙烯释放速率的减少使得籽粒中抗氧化酶活性增强和自由基减少，进而促进了水稻的籽粒灌浆。.（3）明确了品种演进过程中的养分（氮）吸收特征。随品种演进，水稻品种的氮肥农学利用效率显著增加，而氮肥吸收利用效率在品种间无显著差异。现代超级稻品种低的结实率限制了氮肥农学利用效率的进一步增加。自抽穗至成熟，随品种演进氮素吸收量的减少导致了现代超级稻品种较低的氮肥吸收利用效率。现代超级稻品种灌浆期根系早衰可能是导致低的结实率和氮素吸收量的生理原因。.（4）阐明了根系形态生理的变化及其与产量形成的关系。根干重、根长、根数、根直径、根系氧化力、根系总吸收表面积和根系活跃吸收表面积与产量呈极显著线性正相关关系；颖花数、粒重和产量与根系分泌物/伤流液中有机酸和氨基酸组分和浓度显著相关。分蘖期根尖细胞中线粒体和高尔基体数目与根干重、根系氧化力、苗干重和分蘖数呈显著或极显著正相关关系。根系和地上部农艺和生理性状的改善，共同促进了现代品种尤其是超级稻品种产量的提高。.（5）实地氮肥管理技术、饼肥与无机氮肥配施技术和全生育期干湿交替灌溉技术有助于改善水稻根系形态生理，进而提高产量。.上述研究内容对水稻高产优质栽培和育种有指导意义。