【作者】 张耗；

【导师】 杨建昌； 张建华；

【作者基本信息】 扬州大学 ， 作物栽培学与耕作学， 2011， 博士

【摘要】 植物根系既是水分和养分吸收的主要器官,又是多种激素、有机酸和氨基酸合成的重要场所,其形态和生理对地上部的生长发育、产量和品质形成均有重要作用。但根系作为植株“隐藏”的一半,与地上部分相比,对水稻根系形态生理及其与产量形成的关系了解较少。本研究以代表性水稻品种为材料,对水稻品种演进过程中根系形态生理的变化特点及其与产量形成的关系、超级稻品种在不同生育期根系形态生理变化特征、根系激素与强、弱势粒灌浆的调控作用、根系形态生理的关键栽培调控技术等进行了研究。主要结果如下：1.籼、粳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江苏省中籼水稻品种和粳稻品种在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表现基本一致。在各主要生育期,根干重、根重密度、根长、根长密度和根直径随品种演进增加。在生长早期和中期,根系氧化力、叶片光合速率、根系总吸收表面积和活跃吸收表面积以及根系伤流液中Z+ZR含量随品种演进增加或显著增加。随着品种演进产量逐步提高,其原因主要是每穗粒数的增多导致总颖花量的增加。回归分析表明,根干重、根长、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。随品种演进,分蘖期根尖细胞中线粒体、高尔基体、核糖体和淀粉体数目显著增多。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。说明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。2.超级稻品种主要生育期根系形态生理特征的变化及其与产量形成的关系整个生育期超级稻品种的根干重、地上部干物重和根长密度显著高于一般高产品种(对照)在抽穗前和抽穗期,超级稻品种单株根系氧化力(ROA)和根中玉米素(Z)+玉米素核苷(ZR)含量显著高于对照品种。在灌浆中后期则显著低于对照品种。超级稻品种两年的平均产量分别为10.2t hm-2和11.4t hm-2,分别比对照品种高13%和21%。产量的增加主要是由于库容量(总颖花量)的增大。超级稻两年的平均结实率分别为72.9%和79.0%,显著低于对照品种。相关分析表明,在灌浆期,ROA以及根中Z+ZR含量与结实率显著相关。表明超级稻具有较高的根干重、地上部干物重和根长密度以及生长早中期较高的单株ROA和根中Z+ZR含量,这些都促进了库容和产量的提高；通过提高灌浆期根系活性来提高结实率,有望进一步实现超级稻增产潜力。3.亚种间杂交稻根系和籽粒中激素与花后强、弱势粒灌浆的关系与强势粒及亚种内杂交稻的弱势粒相比,两个亚种间杂交稻组合弱势粒的胚乳细胞分裂速率低、籽粒灌浆慢。在灌浆前期,亚种间杂交稻组合弱势粒中赤霉素(GAs)含量较高,而细胞分裂素[玉米素(Z)+玉米素核苷(ZR)]、吲哚-3-乙酸(IAA)和脱落酸(ABA)含量较低。胚乳细胞的分裂速率和籽粒灌浆速率与根系和籽粒中Z+ZR和ABA含量及籽粒中IAA含量呈显著或极显著正相关关系,而与根系和籽粒中GAs含量及根系中IAA含量的相关性不显著。对颖花喷施激动素、IAA或ABA以及对根系施用激动素和ABA,促进了弱势粒胚乳细胞分裂速率和灌浆速率。说明根系和籽粒中较低的Z+ZR和ABA含量以及籽粒中较低的IAA含量可能是导致亚种间杂交稻弱势粒充实不良的重要原因。4.灌溉方式对水稻根系形态生理、产量和米质的影响4.1结实期干湿交替灌溉对水稻根系形态生理和产量的影响于抽穗后6天至成熟进行了轻干-湿交替灌溉(WMD)、重干-湿交替灌溉(WSD)和常规灌溉(CI,保持水层)3种灌溉方式处理。开花较早的强势粒的籽粒灌浆速率、粒重和Z+ZR含量在3种灌溉方式处理间无显著差异。与CI相比,WMD处理显著增加了弱势粒的籽粒灌浆速率和粒重,而WSD处理的结果则相反。WMD处理在土壤落干期,弱势粒和剑叶中Z+ZR含量与CI相比无显著差异,但复水后WMD处理的Z+ZR含量显著增加。在WSD处理下,弱势粒和剑叶中Z+ZR含量不论是土壤落干期还是复水期都显著下降。WMD与CI处理的根系中Z+ZR含量无显著差异。WSD处理显著增加了根系中Z+ZR含量,而显著降低了根系中异戊烯基腺嘌呤(iP)和异戊烯基腺苷(iPR)含量。弱势粒的籽粒灌浆速率和粒重与Z+ZR含量呈显著或极显著正相关关系。以上结果表明,抽穗后轻干-湿交替灌溉通过提高水稻弱势粒和剑叶中Z+ZR含量,进而促进了弱势粒的籽粒灌浆。4.2结实期干湿交替灌溉对稻米品质的影响在WMD处理下,籽粒灌浆后期的根系氧化力、剑叶光合速率和籽粒中蔗糖-淀粉代谢途径关键酶活性显著增加,而WSD处理的结果则相反。与CI相比,WMD处理的产量增加了9.3-9.5%,而WSD处理的产量降低了7.5～7.8%。WMD处理显著改善了稻米的加工品质、外观品质和食味品质,而WSD处理显著降低了稻米品质。说明结实期轻干-湿交替灌溉不仅可以提高水稻产量和改善稻米品质,而且还可以节约宝贵的水资源。4.3全生育期干湿交替灌溉对水稻根系形态生理和产量的影响在全生育期进行WMD.WSD和CI3种灌溉方式处理。与CI相比,WMD处理显著增加了根系氧化力、根叶穗中的细胞分裂素含量、叶片光合速率、籽粒中蔗糖-淀粉代谢途径关键酶活性和产量,而WSD处理的结果则相反。WMD和WSD处理均提高了水分利用效率。说明全生育期轻干-湿交替灌溉促进了根系生长,有利于其它生理过程,进而提高了产量和水分利用效率。5.养分管理和栽培模式对水稻根系形态生理和产量的影响5.1实地氮肥管理进行实地养分管理(SSNM,因地、因苗、因种施肥)和习惯施肥(FFP,对照)两种养分管理。抽穗前的根干重,FFP处理大于SSNM处理。在抽穗期及抽穗后,SSNM处理的根重大于FFP处理。SSNM处理提高了水稻整个生育过程的根-冠比。SSNM处理的水稻根系氧化力自幼穗分化期开始(尤其是单茎根系氧化力)均高于FFP处理。SSNM处理提高了抽穗后水稻剑叶光合速率。与FFP相比,SSNM处理的产量提高了7.2～9.4%,氮肥利用效率(氮肥偏生产力,产量/施氮量)增加了38～46%。表明SSNM促进生育后期根系生长是其提高产量和氮肥利用效率的一个重要原因。5.2饼肥和无机氮肥配施进行不施氮肥(T1)、施用无机氮(T2)、施用饼肥(T3)和饼肥与无机氮肥配施(T4)4种处理。各处理产量的高低表现为：T4>T2>T3>T1,4个处理间产量差异显著。T4处理显著增加了穗数、结实率、千粒重和收获指数,显著提高了抽穗期有效叶面积和高效叶面积、灌浆期叶片叶绿素含量和光合速率以及各主要生育时期的根干重、根长、根系氧化力、根系伤流量、根系总吸收表面积和活跃吸收表面积。表明饼肥与无机氮肥配施可以促进根部生长,进而促进地上部生长并提高产量。5.3高产高效栽培进行高产高效栽培(以实地养分管理和轻干-湿交替灌溉为核心技术的高产与水分养分高效利用的栽培技术体系)和当地高产栽培(对照)两种处理。与当地高产栽培相比,高产高效栽培增加了根系和地上部植株干物重、提高了根系细胞分裂素含量和根系氧化力。高产高效栽培的产量较对照增加了31%,并且显著提高了氮肥和水分利用效率。说明通过栽培技术的集成优化,可以促进根-冠生长,进而获得高产和水肥高效利用的效果。本研究在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、高产品种根系形态生理的诊断指标、超级稻品种主要生育期根系形态生理特征及其与地上部生长发育的关系、根系激素和籽粒激素水平的关系及其对强、弱势粒灌浆的调控作用以及根系形态生理的栽培调控技术等研究方面获得了新的认识,对水稻高产根系育种和高产、优质、高效栽培具有指导意义。更多还原

【Abstract】 Roots are an integral part of plant organs and involved in acquisition of nutrients and water, synthesis of plant hormones, organic acids and amino acids, and anchorage of plants. Root morphology and physiology play an important role in the growth and development of aboveground plants. As a "hidden half", however, it remains much yet to be understood the relationship between root morphological and physiological traits and the yield formation in rice, relative to the aboveground growth and its relation to grain yield. Using typical rice cultivars as materials, this study investigated changes in morphological and physiological traits of roots and their relationships with grain yield during the evolution of indica and japonica rice cultivars, changes in morphological and physiological traits of roots in super rice at different growth stages, roles of root-produced hormones in regulating grain filling of superior and inferior spikelets, and the cultivation techniques to increase yield by regulating morphology and physiology of rice roots. The main results are as follows:1. Changes in morphological and physiological traits of roots and their relationships with grain yield during the evolution of indica and japonica rice cultivarsMorphological and physiological traits of roots and their relationships with grain yield formation for the mid-season indica and japonica rice cultivars in Jiangsu Province showed a similar changing pattern during the evolution of rice cultivars. The root dry weight, root weight density, root length, root length density and root diameter at main growth stages were increased with the evolution of the cultivars. Compared with other cultivars, the root-shoot ratio of super rice cultivars was increased significantly at the panicle initiation stage, but showed no significant differences among the types of cultivars at latter growth stages. The root oxidation activity, leaf photosynthetic rate, total absorbing surface area and active absorbing surface area of root, and the content of cytokinins (zeatin+zeatin riboside) in root bleeding were increased or increased significantly with the evolution of the cultivars during the early and middle stages. Grain yield were increased gradually with the evolution of the cultivars. Increase in grain yield was attributed mainly to the increase in total number of spikelets, which resulted mainly from a large panicle. Regression analysis showed that the root dry weight, root length, root diameter, root oxidation activity, total absorbing surface area and active absorbing surface area of root very significantly correlated with grain yield. The numbers of spikelets, grain weight, and yield were associated with components and concentration of organic acids and amino acids in root exudates/bleeding. The number of mitochondrion, golgi body, ribosome and starch body in root-tip cells increased significantly with the evolution of the cultivars at the tillering stage. The number of mitochondrion and golgi body were significantly or very significantly and positively correlated with root dry weight, root oxidation power, seedling dry weight, and tiller number of rice at the tillering stage. The results suggest that the improved root and shoot growth increases grain yield of the modern cultivars, especially that of super rice cultivars.2. Changes in morphological and physiological traits of roots and their relationships with shoot growth in super riceRoot, shoot dry weight, and root length density was significantly greater in super rice varieties than in check ones throughout the growth season. Root oxidation activity (ROA) and root zeatin (Z) zeatin riboside (ZR) content, in per plant basis, were significantly greater in super rice than check varieties before and at heading time. However, both ROA and root Z+ZR content were significantly lower in super rice than in check varieties at the mid and late grain filling stages. Grain yield of the super rice varieties, on average, was10.2t ha-1and11.4t ha-1, and was13%and21%higher than that of check varieties, respectively. The high grain yield was mainly due to a larger sink size (total number of spikelets) as a result of a larger panicle. The percentage of filled grains of the super rice varieties, on average, was72.9%and79.0%, lower than that of the check varieties. The mean ROA and root Z+ZR content during the grain filling period significantly correlated with the percentage of filled grains. The results suggest that an improved root and shoot growth, as showing a larger root and shoot biomass and greater root length density during the whole growing season and higher ROA and root Z+ZR content per plant at early and mid growth stages, contributes to the large sink size and high grain yield in the super rice varieties. The results also suggest the yield of super rice varieties could be further increased by an increase in filled grains through enhancing root activity during grain filling.3. Hormones in the grains and roots in relation to post-anthesis development of superior and inferior spikelets in japonicalindica hybrid riceCompared with inferior spikelets of indicalindica hybrid rice and superior spikelets, the inferior spikelets of japonicalindica(J/I) hybrids exhibited low rate of endosperm cell division and slow grain filling. During the early grain filling period, the inferior spikelets of J/I hybrids had more gibberellins (GAs), but less Z+ZR, indole-3-acetic acid (IAA), and abscisic acid (ABA). Rates of endosperm cell division and grain filling were positively and significantly or very significantly correlated with Z+ZR and ABA concentrations in both grains and roots or IAA in grains, whereas not significantly correlated with GAs either in grains or roots or IAA in roots. Applications of kinetin, IAA, or ABA to panicles, or kinetin and ABA to roots, enhanced cell division and grain filling in the inferior spikelets. Results suggest that low concentrations of Z+ZR and ABA in both grains and roots, and IAA in grains may result in the poor filling of inferior spikelets in the J/I hybrid rice.4. Effects of irrigation regimes on morphology and physiology of roots, yield, and quality of rice4.1Effects of alternate wetting and drying during the grain filling stage on morphology and physiology of roots and yield of riceThree irrigation regimes, alternate wetting and moderate soil drying (WMD), alternate wetting and severe soil drying (WSD), and conventional irrigation (CI, continuous flooding), were imposed from6d after heading to maturity. No significant differences in grain filling rate, grain weight, and cytokinin contents were observed for the earlier-flowering superior spikelets among the three irrigation regimes. Compared with the inferior spikelets in the CI, grain filling rate and grain weight were significantly increased in the WMD, whereas significantly reduced in the WSD. Cytokinin contents in inferior spikelets and the flag leaves in the WMD at the soil drying time were comparable with those in the CI, but they were significantly increased when plants were re-watered. The WSD significantly reduced cytokinin contents in inferior spikelets and the flag leaves either during the soil drying or during the re-watering period. Cytokinin contents in roots showed no significant difference between WMD and CI regimes. The WSD significantly increased trans-zeatin-type cytokinins, whereas reduced isopentenyladenine-type cytokinins, in roots. Grain filling rate and grain weight of inferior spikelets were significantly or very significantly correlated with cytokinin contents in these spikelets. The results suggested that a post-anthesis WMD holds great promise to improve grain filling of inferior spikelets through elevating cytokinin levels in inferior spikelets and the flag leaves of rice.4.2Effects of alternate wetting and drying during the grain filling stage on rice qualityRoot oxidation activity, the photosynthetic rate of the flag leaf, and activities of key enzymes in sucrose-to-starch conversion in grains at the late grain filling stage were significantly increased under the WMD, whereas they were significantly reduced under the WSD. The grain yield was increased by9.3-9.5%under the WMD, while it was reduced by7.5-7.8%under the WSD, when compared with that under the CI. The WMD significantly improved milling, appearance, and eating qualities, while WSD decreased these qualities. The results suggested that alternate wetting and moderate soil drying regime during the grain filling period holds great promise to both increase yield quantity and quality and also could save precious fresh water resources.4.3Effects of alternate wetting and drying during the whole growing season on morphology and physiology of roots and yield of riceThree irrigation regimes, WMD, WSD, and CI, were conducted during the whole growing season of rice. Compared with the CI, the WMD significantly increased, whereas the WSD reduced, root oxidation activity, cytokinin concentrations in roots, leaves, and grains, leaf photosynthetic rate, activities of key enzymes involved in sucrose-to-starch conversion in grains, and grain yield of rice. Both WMD and WSD increased water use efficiency (WUE). The results suggested that a moderate wetting and drying regime can enhance root growth which benefits other physiological processes and result in higher grain yield and WUE.5. Effects of nutrient management and cultivation patterns on morphology and physiology of roots and yield of rice5.1Site-specific nitrogen managementTwo nitrogen (N) managements, site-specific N management (SSNM, N application according to soil fertility, leaf color and growth status, and cultivar types) and farmers’fertilizer practice (FFP), were designed. The root dry weight in the FFP was higher than that in the SSNM before heading, whereas it was lower at and after heading. SSNM significantly increased the root-shoot ratio during the whole growing season. Compared with that under FFP, SSNM increased ROA at and after panicle initiation (especially ROA per stem). SSNM increased the photosynthetic rate of the flag leaves after heading. Compared with FFP, SSNM increased grain yield by7.2-9.4%and N use efficiency expressed as N partial-factor productivity (grain yield/amount of N applied) by38-46%. The enhancement of root growth at the latter growing stage would account for the increase in grain yield and N use efficiency under SSNM.5.2Application of rapeseed cake combined with inorganic nitrogen fertilizerFour treatments, no N application (T1), application of inorganic N fertilizer (T2), application of rapeseed cake (T3) and application of rapeseed cake combined with inorganic nitrogen fertilizer (T4), were conducted. The order of grain yield was T4> T2>T3>T1, the differences among four treatments were significant. The T4treatment significantly increased panicles, percentage of filled grains,1000-grain weight, and harvest index. It also significantly increased effective leaf area index and high effective leaf area index at the heading time, SPAD (soil-plant analysis department) values and photosynthetic rate during the grain filling period. Root dry weight, root length, root oxidation activity, amount of root bleeding, the total absorbing surface area and active absorbing surface area at different growth stages were greater under the T4treatment than those under any other treatments. The results suggest that application of rapeseed cake combined with inorganic N fertilizer can improve root growth, and consequently enhance shoot growth and increase grain yield.5.3High-yielding and high efficiency cultivation (HYHE)Two cultivation patterns, the high-yielding and high efficiency cultivation (HYHE, a cultivation system with SSNM and WMD as key techniques) and the local high-yielding cultivation (LHY), were practiced. Compared with LHY, the HYHE increased the biomass of root and shoot, root cytokinin concentration and root oxidation activity, and increased grain yield by31%. The HYHE also significantly increased water use efficiency and N use efficiency. The results suggest that root and shoot growth could be improved, and high grain yield high efficiency of water and N utilization could be achieved through integrating and optimizing cultivation techniques in rice production.This study would provide novel insights to understand the changes in morphological and physiological traits of roots and their relationships with grain yield during the evolution of indica and japonica rice cultivars, morphological and physiological index of roots for high-yielding, morphological and physiological traits of roots and their relationships with shoot growth in super rice, hormonal levels in roots and grains and their regulatory roles in grain filling of superior and inferior spikelets, and cultivation techniques to regulate morphology and physiology of roots, and which would have great significance in the breeding of root system and the cultivation for high grain yield, good quality, and high efficiency.更多还原