不同耐镉基因型水稻农艺和生理性状的比较研究

于2004和2005年在扬州大学试验农场进行了不同耐镉基因型水稻农艺和生理性状的比较研究。2个耐镉(Cd)基因型汕优63(杂交籼稻)和扬粳9538(粳稻)及2个Cd敏感基因型扬稻6号(籼稻)和武运粳7号(粳稻)种植于盆钵。于移栽前盆钵土中加入Cd, 浓度为150 mg kg^-1(Cd处理), 以未加Cd为对照(CK)。Cd处理后, 耐Cd基因型籽粒产量较CK降低6.2%~8.9%, Cd敏感基因型产量较对照降低38.3%~47.1%。每盆穗数和每穗颖花数显著减少是减产的主要原因, 结实率和千粒重在Cd处理和CK间无显著差异。Cd处理显著抑制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, 但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。

Comparisons in Agronomic and Physiological Traits of Rice Genotypes Differing in Cadmium-Tolerance

Cadmium (Cd) is one of major contaminants in agricultural soil, threatening agricultural production and human health. To understand agronomic and physiological characteristics of rice genotypes differing in Cd-tolerance would have great significance in selecting or breeding a Cd-tolerant cultivar. In this study, two Cd-tolerant rice genotypes of Shanyou 63 (indica hybrid) and Yangjing 9538 (japonica) and two Cd-susceptible genotypes of Yangdao 6 (indica) and Wuyunjing 7 (japonica) were pot-grown at a farm of Yangzhou University, Yangzhou, Jiangsu Province in 2004 and 2005. 150 mg kg^-1 Cd was added into pot soil before seedling transplanting (Cd treatment), and no Cd addition was taken as control (CK). Under the Cd treatment, the grain yield was reduced by 6.2–8.9% for the Cd-tolerant genotypes and by 38.3–47.1% for the Cd-susceptible ones when compared with their respective CKs. The reduction in grain yield was mainly attributed to the reductions of panicles per pot and spikelets per panicle. The differences in seed-setting rate and 1 000-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 superoxide dismutase and catalase of leaves, and obviously increased contents of superoxidate radical and hydrogen peroxide and ethylene evolution rate of leaves, and 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.