【作者】 常二华；

【导师】 杨建昌；

【作者基本信息】 扬州大学 ， 作物栽培学与耕作学， 2008， 博士

【摘要】 本研究旨在阐明水稻根系化学讯号(激素、有机酸、氨基酸、多胺和离子等)与稻米品质形成的关系及其调控途径。试验以不同基因型水稻品种为材料,分别种植于水培池、盆钵和大田,观察了结实期根系化学讯号的变化,分析了根系化学讯号与稻米品质的关系,并对根系化学讯号对稻米品质的影响机理做了探讨,提出了调节根系讯号产生和改善稻米品质的技术途径。主要结果如下:1.水稻花后根和籽粒细胞分裂素与籽粒灌浆及蒸煮品质的关系1)灌浆早期根和籽粒玉米素+玉米素核苷(Z+ZR)浓度与籽粒起始生长势、平均灌浆速率、最大灌浆速率、糙米重呈显著或极显著正相关,与活跃灌浆期呈显著或极显著负相关;灌浆中、后期根和籽粒Z+ZR浓度与活跃灌浆期呈显著或极显著正相关;灌浆后期Z+ZR浓度与灌浆速率呈极显著负相关。2)灌浆中、后期根和籽粒Z+ZR浓度与胶稠度及碱化值呈显著或极显著正相关,与直链淀粉含量呈显著或极显著负相关。表明根和籽粒细胞分裂素对籽粒灌浆和稻米蒸煮品质起调控作用,其调控的正、负效应取决于灌浆的时期。2.水稻花后根和籽粒脱落酸浓度与籽粒灌浆及蒸煮品质的关系1)灌浆中期根和籽粒脱落酸(ABA)浓度与籽粒起始生长势、平均灌浆速率、最大灌浆速率、糙米重呈显著或极显著正相关,与活跃灌浆期呈显著或极显著负相关;灌浆早期和后期根和籽粒ABA浓度与各灌浆特征参数的相关不显著。2)灌浆中期根和籽粒ABA浓度与胶稠度及碱化值呈极显著负相关,与直链淀粉含量呈极显著正相关。3.根系伤流液1-氨基环丙烷1-羧酸浓度与稻米外观品质的关系结实期根系伤流液中1-氨基环丙烷1-羧酸(ACC)浓度在灌浆前期最高,但在品种间差异较小。随灌浆进程,根系ACC浓度减小,品种间差异增大。相关分析表明,灌浆中期根系ACC浓度与垩白粒率和垩白度呈极显著正相关,灌浆后期根系ACC浓度与米粒的垩白度和垩白大小呈极显著正相关。灌浆前期根系ACC浓度与垩白粒率、垩白度和米粒的垩白大小的相关均不显著。结实期根系ACC浓度低的品种,扫描电镜下稻米淀粉体排列紧密,相互间间隙较小。结实期根系ACC浓度高的品种稻米淀粉体排列疏松,相互间间隙大,淀粉体大小差异悬殊。在花后10～15 d和花后25～30 d分别用10-6 mol L-1 ACC处理根系,稻米的淀粉排列变疏松,垩白粒率、垩白大小和垩白度均显著增加。用10-6 mol L-1氨基-乙氧基乙烯基甘氨酸(AVG,ACC合成酶抑制剂)处理根系,结果则相反。4.根系分泌有机酸与稻米品质的关系结实期根系分泌的苹果酸和琥珀酸越多的品种,其稻米淀粉谱的崩解值就越大,消减值就越小;而根系分泌的酒石酸和柠檬酸越多的品种,崩解值就越小,消减值就越大;根系分泌的乳酸较多,其稻米的胶稠度和碱化值就较小,直链淀粉含量就较高。相关分析表明,根系分泌的苹果酸及琥珀酸浓度与淀粉谱的崩解值呈极显著的正相关,与淀粉谱的消减值呈极显著的负相关;根系分泌的酒石酸和柠檬酸浓度与淀粉谱的崩解值呈极显著的负相关,与淀粉谱的消减值呈极显著的正相关;根系分泌的乳酸浓度与稻米胶稠度和碱化值呈显著负相关,与直链淀粉含量呈显著正相关。5.根系分泌有机酸与水稻重金属吸收的关系根系分泌物中乳酸浓度较高的品种,根系和稻株吸收Cd的重量较低;而根系分泌苹果酸和琥珀酸浓度较高的品种,根系和稻株对Pb的吸收重量较低。根系分泌的乳酸浓度与根和稻株对Cd的吸收重量呈极显著负相关。根和稻株中Pb的累积量与根系分泌的苹果酸浓度和琥珀酸浓度呈极显著负相关,与酒石酸和柠檬酸浓度呈极显著正相关6.根系分泌的氨基酸和离子与稻米品质的关系结实期水稻根系分泌的氨基酸含量随灌浆进程逐渐降低。结实前中期(抽穗后10 d和20 d)根系分泌的氨基酸与籽粒中氨基酸的相对含量、根系分泌的碱性氨基酸与籽粒的千粒重呈显著或极显著的负相关。根系分泌的[Ca2+]、[K+]与稻米的垩白度和直链淀粉含量呈极显著负相关,根系分泌的[NO3-]与直链淀粉含量呈显著负相关。[Na+]、[NH4+]和[PO43-]与蛋白质组分关系密切。7.根系多胺浓度与稻米蛋白质组分的关系结实期根系多胺浓度在品种间存在差异,一般稻米醇溶蛋白较高的品种,根系腐胺浓度较高,精胺浓度较低,反之,球蛋白含量较高的品种,根系腐胺浓度较低,精胺含量较高。相关分析表明,根系精胺浓度与稻米醇溶蛋白呈极显著负相关,与球蛋白呈显著正相关;根系腐胺浓度与稻米醇溶蛋白呈极显著正相关,与球蛋白呈显著负相关;根系精胺/腐胺浓度比值与醇溶蛋白呈极显著负相关,与球蛋白呈极显著正相关。8.根系细胞分裂素和ABA对籽粒淀粉合成关键酶活性的调节籽粒中的ADPG焦磷酸化酶(ADPGase)、可溶性淀粉合成酶(SSSase)和淀粉分支酶(Q-酶)在灌浆前期的活性、灌浆期的最大活性和平均活性与平均灌浆速率、最大灌浆速率和籽粒中淀粉的含量(mg/粒)均呈显著或极显著的正相关。灌浆各期籽粒中ADPGase活性以及灌浆前、中期的Q-酶活性与蒸煮品质(胶稠度,碱化值和直链淀粉)的相关均不显著;灌浆前期SSSase活性与胶稠度和碱化值呈显著负相关,与直链淀粉呈显著正相关,灌浆中期和后期的SSSase活性以及灌浆后期的Q-酶活性与胶稠度和碱化值呈显著正相关,与直链淀粉呈显著负相关。于花后7~10 d分别喷施10-6 mol L-1的玉米素(Z)后,灌浆前中期(花后12~24 d)上述各酶活性与对照(仅喷清水)无显著差异,但灌浆后期(花后27~39 d)各酶活性较对照显著增加。于花后7~10 d喷施10-6 mol L-1的ABA后,灌浆前中期籽粒中各酶活性较对照显著增加,灌浆后期则各酶活性显著降低。9.调控根系化学讯号的途径与技术1)化学物质化学物质对稻米品质的调控的正负效应,取决于取决于化学物质的种类。花后14～20 d外源ABA处理,使直链淀粉含量增加,碱化值减小,米胶长度缩短;花后24～30 d外源ZR处理则显著降低了直链淀粉含量,增加了碱化值和米胶长度。结实期ACC处理能够增加稻米的垩白粒率、垩白大小和垩白度,而结实期AVG处理可以降低稻米的垩白度,改善稻米的外观品质。2)结实期干湿交替灌溉结实期轻干-湿交替灌溉能减少根系ACC的产生,降低籽粒中ACC浓度和乙烯释放速率,增加米粒的透明度和崩解值,明显降低垩白粒率、垩白度和消减值,改善稻米的外观和食味品质。此外,结实期轻干-湿交替灌溉还增加了籽粒中蔗糖合成酶(SuSase)、ADPGase、SSSase和Q-酶活性。SuSase、ADPGase、SSSase和Q-酶活性与崩解值呈显著正相关,与垩白度和消减值呈显著负相关。说明结实期轻干-湿交替灌溉可以改善稻米品质,SuSase、ADPGase、SSSase和Q-酶在籽粒形成中起重要作用。3)养分管理结实期氮、磷、钾、钙的供应水平对根系化学讯号及稻米品质能产生调控作用。总体表现在缺氮、缺钾及缺钙条件下,加快了根系的衰老,根系分泌的有机酸、氨基酸、离子均有所降低,稻米的外观品质、蒸煮食味品质变劣。而在缺磷条件下,则显著促进根系有机酸、酸性氨基酸、离子的分泌,籽粒的蛋白质含量及氨基酸含量显著降低。表明在结实期适当的增加氮、磷、钾、钙的供应,能够调控根系分泌物的产生,从而使米质变优。在基肥中用菜籽饼作有机肥,根系分泌的苹果酸和琥珀酸浓度增加,酒石酸和柠檬酸浓度降低,乳酸的浓度无显著变化,稻米淀粉谱的崩解值增大,消减值减小。在施等氮量(225kg N ha-1)条件下,随着基肥施用的增多或穗肥施用的减少,结实期根系分泌的苹果酸和琥珀酸含量显著增加,米粒的出糙率、精米率、整精米率增加,蛋白质含量降低,稻米品质变优。表明合理的氮肥运筹能够调控水稻根系有机酸的含量和组分,影响稻米品质。优质高产的氮肥运筹为基肥:分蘖肥:穗肥= 6:1:3。更多还原

【Abstract】 This study was designed to elucidate the relationship between root chemical signals (hormones, organic acids, amino acids, polyamines and ions) and the grain quality of rice and its regulation techniques. Various rice genotypes were used and experiments were conducted in the water-culture pools, pots and paddy field. The relationship between root chemical signals and grain quality and its mechanisms were studied. The techniques to regulate root chemical signals and improve grain quality were investigated. The main results are as follows:1.Relationships of cytokinins in roots and grains with grain filling and cooking quality of rice1)Concentrations of zeatin + zeatin riboside (Z+ZR) in roots and grains at the early grain filling stage were significantly or very significantly correlated with the initial grain growth potential, mean grain filing rate, maximum grain filing rate and brown rice weight, whereas significantly and negatively correlated with active grain filling period. Z+ZR concentrations at the mid or late grain filling stage significantly or very significantly correlated with active grain filling period but those at the late stage negatively correlated with grain filling rate.2)Z+ZR concentrations in roots and grains at mid and late grain filling stages were significantly or very significantly correlated with the gel consistency and alkali spreading value of rice, whereas significantly and negatively correlated with amylase content. The results suggest that cytokinins play an important role in the regulation of grain filling and quality of rice, and the effects that are positive or negative may depend on grain filling stages.2.Relationships of abscisic acid (ABA) in roots and grains with grain filling and cooking quality of rice1)Concentration of ABA in roots and grains at mid grain filling stage were significantly or very significantly correlated with the initial grain growth potential, mean grain filing rate, maximum grain filing rate and brown rice weight, whereas significantly and negatively correlated with active grain filling period. The correlations were not significant between ABA concentrations in roots and grains at early and late grain filling stages and grain filling characteristics.2)Concentrations of ABA in roots and grains at mid grain filling stages were significantly and negatively correlated with gel consistency and alkali spreading values, whereas significantly correlated with amylose content.3.Relationships of 1-aminocylopropane-1-carboxylic acid (ACC) in root bleedings with appearance quality of riceACC concentrations in root bleedings were higher at the early grain filling stage, and showed a small difference among the cultivars. It was reduced rapidly and differed markedly among the cultivars with the progression of grain filling. Regression analysis demonstrated that ACC concentrations in roots at the mid grain filling stage were very significantly correlated with chalky kernel percentage and chalkiness, and the concentration at the late grain filling stage was very significantly correlated with chalkiness and chalky size. ACC concentrations in roots at the early grain filling stage were significantly correlated with chalky kernel percentage, chalkiness and chalky size.Observation form scan electron microscope showed that the cultivars with the lower ACC concentration in grains during the grain filling period had close arrangement and small space in/ between starch granules of endosperm, whereas those with higher ACC concentration in the grains exhibited a loose arrangement, larger spaces and disparity in /between starch granules.The starch granules were loosely arranged and chalky kernel percentage, chalky size and chalkiness increased significantly when 10-6 mol L-1 ACC was applied, whereas the results were reversed when 10-6 mol L-1 amino-ethoxyvinylglycine (AVG inhibitor of ACC synthase) was applied to panicles during 10-15 and 25-30 DAA.4.Relationships of organic acid exuded from roots with grain qualityThe more malic acid and succinic acid exuded from roots for a cultivar, the greater the breakdown values and smaller the setback values in the starch profile, and the results were reversed for a cultivar with more tartaric acid and citric acid exuded from roots during the grain filling period. The cultivar with more lactic acid in exudates had smaller gel consistency and alkali spreading values, but had greater amlyose content. Regression analysis demonstrated that malic acid and succinic acid exuded from roots were significantly correlated with breakdown values, and significantly and negatively correlated with setback values in starch profile. Relationships of tartaric acid and citric acid exuded from roots with breakdown values and setback values in starch profile were reversed. Lactic acid in exudates was significantly and negatively correlated with gel consistency and alkali spreading values, whereas significantly correlated with amylose conent.5.Relationships between organic acid exuded from roots and metal absorbed in rice The root and plant absorbed less amount of cadmium (Cd) for a cultivar with more lactic acid in root exudates, whereas absorbed more amount of lead (Pb) for a cultivar with more the malic acid and succinic acid exuded from the roots. Lactic acid in exudates was significantly and negatively correlated with the amount of cadmium (Cd) absorbed by the root and plant. Pb accumulations in roots and plants were significantly and negatively correlated with contents of malic acid and succinic acid exuded from roots, and significantly correlated with contents of tartaric acid and citric acid.6.Relationships of amino acid and ions in root exuded with grain qualityThe concentration of each amino acid in root exudates decreased gradually with the process in grain-filling. The concentrations of amino acids in root exudates were significantly and negatively correlated with the relative content of amino acids in grains, and the concentration of alkali amino acids in root exudates was significantly and negatively correlated with 1000-grain weight. Concentrations of [Ca2+] and [K+] exuded from roots were significantly and negatively correlated with chalkiness and amylose content. The concentration of [NO3-] exuded from root was significantly and negatively correlated with amylose content. Concentrations of [Na+], [NH4+], and [PO43-] exuded from root were significantly correlated with protein composition.7. Relationships between polyamine concentration in roots and protein composition of riceThe more prolamin content in grains for a cultivar, the higher putrescine concentration and smaller spermine concentration in root. The results were reversed for a cultivar with higher globulin content in grains. Concentrations of spermine in rice roots were very significantly and negatively correlated with prolamine content in the grain, whereas significantly and positively correlated with the content of the globulin. The concentrations of putrescine secreted by roots were very significantly and positively correlated with prolamine content in grains,but significantly and negatively correlated with the globulin content. The ratio of spermine to putrescine (spermine/ putrescine) in roots was very significantly and negatively correlated with the content of the prolamine and significantly and positively correlated with globulin.8. Regulation of cytokinins and ABA in roots with activities of key enzymes in starch synthesisActivities of adenosine diphosphate glucose pyrophosphorylase (ADPGase), soluble starch synthase (SSSase) and Q-enzyme at the early grain filling stage, and the mean and maximum activities of each enzyme during the grain filling period were positively and significantly or very significantly correlated with the mean and maximum grain filling rate and starch content (mg grain-1) in grains. Activities of ADPGase at all grain filling stages and those of Q-enzyme at the early and mid filling stages were not significantly correlated with the cooking quality (gel consistency, alkali spreading value, and amylose content). SSSase activities at the early filling stage were significantly and negatively correlated with gel consistency and alkali spreading value, and positively correlated with amylose content. Activities of SSSase at mid and the late grain filling stages and Q-enzyme at the late filling stage were significantly and positively correlated with gel consistency and alkali spreading value, and negatively correlated with amylose content.Application of zeatin (Z) of 10-6 mol L-1 at 7-10 d after anthesis (DAA) showed no significant effect on activities of the three enzymes at early and mid grain-filling stages (12-24 d after anthesis), whereas significantly increased activities of the enzymes at the late grain-filling stage (27-39 d after anthesis). Spraying ABA of 10-6 mol L-1 at 7-10 d after anthesis significantly increased enzyme activities at early and mid grain-filling stages, but significantly reduced enzyme activities at the late grain-filling stage.9. Techniques of regulating the root chemical signals1) Chemical regulation: The positive or negative effects of chemical regulators on root chemical signals and grains quality depend on categories of the regulators. Spraying ABA at 14-20 DAA increased amylose content, reduced alkali values and gel consistency. The results were reversed when exogenous ZR was applied at 24-30 DAA. Application of ACC increased chalky kernel percentage, chalky size and chalkiness, while spraying AVG reduced chalkiness and improve grain appearance quality.2) Dry-wet alternate irrigation during grain-filling: moderate dry-wet alternate irrigation during grain-filling reduced ACC concentration in roots, increased transparency, peak viscosity and breakdown value, significantly reduced chalky kernel percentage, chalkiness, hot viscosity, peak viscosity and setback value, and improved rice appearance and cooking quality. Moreover, moderate dry-wet alternate irrigation during grain-filling increased activities of SuSase、ADPGase、SSSase and Q-enzyme. The activities of SuSase, ADPGase, SSSase and Q-enzyme were positive and significantly correlated with grain-weight, peak viscosity and breakdown value, negatively and significantly correlated with chalkiness and setback value. The results suggest that moderate dry-wet alternate irrigation during grain-filling could improve rice quality. Enhanced activities of SuSase, ADPGase, SSSase, Q-enzyme play an important role in the improvement of grain quality under such a condition.3) Nutrient management: application of nitrogen (N), phosphorus (P), potassium (K) and calcium (Ca) during grain-filling regulated the root chemical signals and rice quality. Deficiency of N, K and Ca accelerated root senescence, reduced organic acids, amino acids and ions exuded from roots, worsened appearance and cooking quality of rice. Deficiency of P significantly increased organic acid, amino acid and ion concentrations in root exudation, reduced protein and amino acid contents in grains. The results suggest that an appropriate application of N, P, K and Ca can regulate root chemical signals and improve rice quality.When rape cake was used as organic fertilizer in the basic fertilizer, the concentrations of malic acid and succinic acid in root exudates were increased, while the concentrations of tartaric acid and citric acid were decreased, and no significant changes in lactic acid were observed. Application of rape cake increased the breakdown value, whereas reduced the setback value, in starch-profile. Moreover, with basic fertilizer increased or panicle fertilizer decreased under the same amount of nitrogen application (225 kg N ha-1), the concentrations of malic acid and succinic acid in root exudates, brown rice, milled rice, and head milled rice were increased, and protein content reduced, and rice quality improved. The results suggest that rational nitrogen strategies can regulate the concentration and component of organic acids in root exudates and then influence rice quality. The nitrogen management for high-yielding and good quality would be 6:1:3 for basic fertilizer: tiller fertilizer: panicle fertilizer.更多还原