【作者】 黄冬芬；

【导师】 杨建昌； 张建华；

【作者基本信息】 扬州大学 ， 植物学， 2008， 博士

【摘要】 镉（Cd）是农田土壤中主要的污染物质。随着工业的发展,Cd污染日趋严重,对农业生产和人类健康构成严重的威胁。本研究以水稻不同品种为材料,研究Cd对水稻产量和品质的影响及其生理机制,探讨通过灌溉和施肥等农艺措施减轻Cd对水稻危害的技术途径,为水稻优质安全生产提供理论依据和实践指导。主要结果如下:1、Cd对水稻产量和品质的影响当土壤Cd浓度为60或90 mg kg^-1时,扬稻6号和扬粳9538的产量与对照（土壤未加Cd处理）无显著差异。这两品种在Cd浓度为120或180 mg kg^-1以及武运粳7号在Cd浓度为60或120 mg kg^-1条件下产量均较对照显著降低。在Cd胁迫下产量降低的原因主要在于穗数或每穗颖花数的减少,Cd对结实率和千粒重无显著影响。Cd对稻米加工品质、外观品质、蒸煮品质以及蛋白质含量无显著影响。随土壤Cd浓度的增加,稻米醇溶蛋白含量增加,清蛋白和球蛋白含量则降低。当土壤Cd浓度为60和90 mg kg^-1时,稻米淀粉谱的最高粘度、热浆粘度、最终粘度、崩解值和消减值与对照无显著差异;当土壤Cd浓度为120和180 mg kg^-1时,稻米淀粉谱的最高粘度和崩解值显著降低,热浆粘度、最终粘度和消减值显著增加。在相同土壤Cd浓度下,同一器官的Cd浓度在品种间无显著差异,但扬稻6号Cd累积量高于扬粳9538。表明Cd对水稻产量的影响以及Cd在稻株的累积量在品种间存在差异,高浓度Cd可降低稻米的营养品质和食味性。2、水稻对Cd胁迫的生理响应Cd胁迫增加了根系和叶片自由基含量;诱导超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）同工酶小分子量的特异表达;增加了水稻根系分泌物含量;降低了水稻DNA和蛋白质含量;水稻可溶性蛋白质一维电泳和二维电泳分析结果表明,Cd胁迫后水稻可溶性蛋白质表达发生改变。Cd诱导了水稻幼苗根系10个蛋白质点和叶片8个蛋白质点的表达,抑制了根系4个蛋白质点和叶片8个蛋白质点的表达。3、水稻耐Cd性不同品种一些农艺与生理性状Cd处理后,耐Cd基因型（汕优63和扬粳9538）籽粒产量较CK（土壤中未加Cd）降低了6.2%⁸.9%,Cd敏感基因型（扬稻6号和武运粳7号）产量较对照降低38.3%⁴7.1%。Cd处理后每盆穗数和每穗颖花数减少是减产的主要原因,结实率和千粒重在Cd处理与CK间无显著差异。Cd处理显著抑制了Cd敏感基因型的分蘖发生,导致整个生育期干物质积累的显著下降。Cd处理对物质运转率和收获指数无显著影响。在Cd胁迫下,分蘖至拔节期Cd敏感基因型的根系活力、叶片光合速率、超氧化物歧化酶和过氧化氢酶活性明显低于耐Cd基因型,叶片超氧自由基和过氧化氢含量、乙烯释放速率及根系伤流液中1-氨基环丙烷1-羧酸浓度则显著高于耐Cd基因型。抽穗以后Cd对上述生理指标以及整个生育时期叶片脱落酸含量无显著影响。说明Cd对水稻生长发育的影响主要在生育前期（分蘖至拔节期）,此期分蘖发生多、根系活力和叶片抗氧化保护系统能力强及乙烯合成少是耐Cd基因型水稻的主要农艺和生理特征。4、结实期灌溉方式对水稻品质和不同器官Cd浓度与分配的影响在土壤Cd污染条件下,与水层灌溉（WW）相比,结实期轻干-湿交替灌溉（MD）可以增加产量和改善稻米的加工与外观品质,结实期重干-湿交替灌溉（SD）则降低产量和品质。MD和SD均可增加Cd在根的浓度和分配比例,降低Cd在茎叶的浓度和分配比例;MD对籽粒和精米中的Cd浓度无明显影响,但可显著降低Cd在籽粒中的分配比例,SD则增加了籽粒和精米的Cd浓度。在MD条件下,根系活力增强和叶片气孔导度降低（即蒸腾强度小）是根系Cd浓度大、茎叶Cd浓度小以及籽粒Cd分配比例低的重要原因;而在SD条件下,根系和籽粒Cd浓度大、茎叶Cd浓度小与气孔导度显著降低和茎叶Cd表观输出率大幅度增加有密切关系。5、全生育期干湿交替灌溉对水稻产量和品质及Cd积累的影响与保持水层（WW）相比,全生育期轻干湿交替灌溉（MD）提高了根系氧化力和光合速率,使产量增加了8.6-10%,改善了加工品质和外观品质,全生育期重干湿交替灌溉（SD）的结果则相反。MD和SD均降低了叶片蒸腾速率,SD尤为明显。MD和SD显著增加了根系中Cd的浓度,降低了稻草中Cd的浓度。MD使籽粒中Cd浓度降低了8.6-9.7%,精米中Cd浓度降低了27-31%。SD则显著增加了籽粒中Cd浓度,但降低了Cd在精米中浓度。说明全生育期轻干湿交替灌溉可以增加产量和减少Cd在水稻可食部分的含量。6、氮肥对水稻品质和不同器官Cd浓度与分配的影响在相同施氮量情况下,Cd处理显著降低了产量。在相同土壤Cd浓度下,产量随施氮量(0～600 kg ha^-1)的增加而提高。施氮量和Cd处理对稻米的出糙率、精米率和整精米率无显著影响。在相同施氮量情况下,Cd处理使胶稠度增加,直链淀粉含量降低。Cd对稻米垩白率、垩白度和蛋白质含量无显著影响。随施氮量的增加,颖壳、糠层和精米中Cd浓度均随之增加,但精米Cd浓度在0N（不施氮）与MN(300 kg ha^-1)之间无显著差异。Cd在颖壳和糠层中的分配比例也随施氮量的增加而显著提高,但Cd在精米中的分配比例则随施氮量的增加而显著降低。表明在Cd污染的稻田适当施用氮肥并不会明显增加Cd在精米中的浓度,并可降低Cd在精米中的分配比例。更多还原

【Abstract】 Cadmium （Cd） is a major contaminating heavy metal in the agricultural field. With the development of industry, Cd pollution becomes more and more serious, and has threatened the agricultural production and human health seriously. In this study, several rice （Oryza sativa L.） cultivars were used as materials, and effects of Cd on the growth, yield, quality, and their physiological mechanisms were investigated. The ways to reduce Cd toxicity through irrigation patterns and nitrogen （N） management were studied, so as to provide a theoretical basis and practical guidance to high yield, good quality, and safe production of rice. The main results are as follows:1. Effect of Cd on rice yield and qualityThere were no significant differences between Cd treatment and control （no Cd addition to soil） in grain yield of Yangdao 6 and Yangjing 9538 when Cd concentration in soil was 60 mg kg^-1 or 90 mg kg^-1. Compared with control, Cd significantly reduced the yield of the two cultivars at Cd concentration of 120 mg kg^-1 or 180 mg kg^-1 and that of Wuyunjing 7 at Cd concentration of 60 mg kg^-1 or 120 mg kg^-1 in soil. The decrease in grain yield under Cd stress was mainly attributed to the reduction in the number of panicles or/and number of spikelets per panicle. There were no significant differences in seed-setting rate, 1000-grain weight, milling quality, appearance quality, cooking quality, and content of protein between Cd treatment and control. The content of prolamine was increased, while the contents of albumin and glutelin were reduced with the increase in Cd concentrations in soil. There were no significant differences in the maximum viscosity, hot viscosity, final viscosity, break down values, and setback values of the starch profile in grains between Cd treatment and control when Cd concentrations in soil were 60 mg kg-1 and 90 mg kg-1. Cd significantly reduced maximum viscosity and break-down values, and increased hot viscosity, final viscosity and setback values when Cd concentrations in soil were 120 mg kg-1 and 180 mg kg-1. The Cd concentration in the same organ showed no significant difference among cultivars when Cd concentration in soil was the same. However, the cultivar Yangdao 6 accumulated more Cd in plants than the cultivar Yangjing 9538. The results indicate that the effect of Cd on rice yield and the accumulation of Cd in plants varies with cultivars, and high concentration of Cd could reduce the quality of nutrition and taste of rice.2. The physiological responses of rice to Cd stressCd stress increased the content of free radical in the root and leaf of rice, induced the special expression of low molecular weight isoenzyme of the superoxide dismutase （SOD）, catalase （CAT）, peroxidase （POD）, reduced the content of protein in roots and leaves, increased the content of organic acid in root exudates and decreased the contents of deoxyribonucleic acid （DNA） and protein in rice. The analysis of the SDS-PAGE and two-dimensional electrophoresis of proteome demonstrated that Cd stress could modify the expression of rice proteome. Cd induced ten new protein spots in roots and eight protein spots in leaves of a rice seedling, and inhibited four protein spots in the root and eight protein spots in the leaf.3. Agronomic and physiological traits of rice genotypes differing in Cd-toleranceUnder the Cd treatment, the grain yield was reduced by 6.2%-8.9% for the Cd-tolerant genotypes （Shanyou 63 and Yangjing 9538） and by 38.3%-47.1% for the Cd-susceptible ones （Yangdao 6 and Wujunjing 7） when compared with their respective CKs （no Cd addition to soil）. The reduction in grain yield was mainly attributed to the reduction in panicles per pot and spikelets per panicle. The differences in seed-setting rate and 1000-grain weight were not significant between the Cd treatment and CK. The Cd treatment markedly inhibited the tillering of the Cd-susceptible genotypes, resulting in the reduction in dry matter accumulation during the whole growth period. Cd little affected the translocation of non-structural carbohydrate from culms and sheaths and harvest index. For Cd-susceptible genotypes, the Cd treatment significantly reduced root oxidation activity and photosynthetic rate, activities of SOD and CAT in leaves, and obviously increased contents of superoxidate radical and hydrogen peroxide and ethylene evolution rate of leaves, and increased the concentration of 1-aminocylopropane-1- carboxylic acid in root bleedings from the tillering to jointing stages, while the Cd treatment much less affected the above physiological traits for the Cd-tolerant genotypes. The differences in the above traits at heading and afterwards and abscisic acid content in leaves during the whole growth period were not significant between the Cd treatment and CK. The results indicate that the effects of Cd on rice growth and development are mainly during the early growth period （from tillering to jointing）, and more tillers, stronger root activity and antioxidative defense system, and less ethylene synthesis in the plants during this period would be considered as agronomic and physiological traits of Cd-tolerant genotypes of rice.4. Effect of irrigation regimes during grain filling on grain quality and Cd concentrations and distributions in rice organsCompared with the well-watered （WW） irrigation, alternate wetting and moderate soil-drying （MD） increased grain yield and improve milling quality and appearance quality, and alternate wetting and severe soil-drying （SD） decreased the yield and quality when rice plants were grown in Cd contaminated soil. Both MD and SD increased the concentration and distribution proportion of Cd in the root, and decreased the concentration and distribution proportion of Cd in the stem and leaf. The MD had no significant effect on Cd concentration in the grain and milled rice, but significantly reduced Cd distribution proportion in the grain, whereas SD increased Cd concentration in the grain and milled rice. Under MD, the strong root activity and the low leaf stomatal conductance （namely the low transpiration） were the main reason for the higher concentration of root, lower concentration of Cd in the stem and leaf and lower proportion of Cd in the grain. Under SD, higher Cd concentration in the root and grain, lower concentration of Cd in the stem and leaf were closely associated with the decrease in the stomatal conductance and the increase apparent transportation rate of Cd in the straw.5. Effect of alternate wetting and soil-drying during the whole growth period on the rice yield, quality and Cd accumulationCompared with the well-watered （WW） irrigation, alternate wetting and moderate soil-drying （MD） during the whole growth period of rice increased the root activity and photosynthetic rate, and increased grain yield by 8.6^-10%, and improved milling quality and appearance quality, while alternate wetting and severe soil-drying （SD） during the whole growth period of rice showed an opposite effect. Both MD and SD reduced transpiration rates of leaves, with more reduction in SD. Both MD and SD increased Cd concentration in the root, and reduced Cd concentration in the straw. MD reduced the concentration of Cd in the grain by 8.6-9.7% and in the milled rice by 27-31%. SD increased Cd concentration in the grain, whereas reduced Cd concentration in milled rice. The results indicate that a moderate wetting and drying during the whole growth period could increase the grain yield and reduce the content of Cd in the diet of rice.6. Effect of nitrogen application on the yield, quality, and the Cd concentration and distribution in rice organsUnder the same rate of N application, Cd treatments significantly reduced grain yield. Under the same concentration of Cd in soil, grain yield was increased with the increase in N rates (0-600 kg ha^-1). There were no significant effects of N rates and Cd treatments on brown rice, milled rice and head rice. The Cd treatment increased gel consistency, reduced amylose content, and had no significant effect on the chalkness and protein content under the same rate of N. The concentrations of Cd in the hull, bran, and milled rice were increased with the increase of N rates. However, there was no significant difference in the concentration of Cd in the milled rice between 0N （no nitrogen application） and MN (300 kg ha^-1). The distribution proportion of Cd in the hull and bran was significantly increased, whereas the distribution proportion of Cd in the milled rice was significantly decreased, with the increase of N rates. The results suggest that rational nitrogen application would not obviously increase the concentration of Cd in the milled rice and even reduced the proportion of Cd in milled rice.更多还原