中文摘要：

【目的】研究不同吸氮量类型粳稻品种根系性状的演变趋势与差异,明确吸氮量大的粳稻品种根系性状的特征,为粳稻品种根系性状的遗传改良提供参考依据。【方法】2008—2009年,在群体水培条件下,以国内、外不同年代育成的94个常规粳稻品种为供试材料,测定根系形态、根系活性、植株各器官干物重和含氮量、产量构成因素等,采用组内最小平方和的动态聚类方法将供试品种按吸氮量的大小从低到高依次分为A、B、C、D、E、F等6类,研究各类品种根系等性状的差异,分析影响氮素高效吸收的主要根系性状。【结果】供试品种间吸氮量的差异很大,吸氮量最大品种为最小品种的2.94倍（2008年）和2.59倍（2009年）;吸氮量大的品种平均产量极显著高于吸氮量小的品种;生育期、吸氮强度均是影响吸氮量的重要因素,吸氮强度对吸氮量的影响大于生育期对吸氮量的影响;不同吸氮量类型粳稻品种间单株根干重、单株不定根总长、单株总吸收面积、单株活跃吸收面积差异显著,单株根数、单株根系活力的差异因年而异。吸氮量大的品种单株不定根数、单株根干重、单株不定根总长、单株根系总吸收面积、单株根系活跃吸收面积优于吸氮量小的品种;改良根干重、冠根比、单株不定根总长、单条不定根重等性状能显著提高水稻的吸氮量。【结论】供试粳稻品种间吸氮量的差异很大。吸氮强度大是粳稻品种吸氮量大的重要因素。吸氮量大的品种单株根数、单株根干重、单株不定根总长、单株总吸收面积、单株活跃吸收面积、单株根系活力优于吸氮量小的品种,根干重、冠根比、单株不定根总长、单条不定根重是影响粳稻品种吸氮能力的主要根系性状。

英文摘要：

【Objective】 The objectives of the study were to investigate the evolution trends and diversities of root traits in conventional japonica rice cultivars of different N accumulation types,define the root traits of japonica rice cultivars with high N accumulation,and to provide experimental evidence for genetic improvements of root traits in conventional japonica rice cultivars.【Method】A total of 94 conventional japonica rice cultivars were solution-cultured in 2008 and 2009.Morphological and physiological traits of root,dry weight and N concentration of rice plant,grain yield and its components were measured.Then,the tested rice cultivars were clustered into 6 types based on their N accumulation at maturity by MinSSw method,and the differences in root and other traits between the types were analyzed.【Result】There was a significant difference among all tested cultivars in N accumulation.The highest N accumulation was 2.94 and 2.59 times as the lowest in 2008 and 2009,respectively.The average yields of japonica rice cultivars with high N accumulation were significantly higher than those with low N accumulation.Both growth duration and nitrogen uptake intensity were the main factors influencing N accumulation,but the influence of nitrogen uptake intensity to N accumulation was bigger.There were significant differences in root dry weight per plant,total length of adventitious roots per plant,total root absorption area per plant and root activity absorptions per plant of different types of japonica rice cultivars.The number of adventitious roots per plant and root activity per plant varied in different years.The root traits of cultivars with high N accumulation,including the number of adventitious roots per plant,root dry weight per plant,total length of adventitious roots per plant,total root absorption area per plant,root activity absorptions per plant and root activity per plant,were superior to those with low N accumulation.High accumulation could be reached by improving root dry weight per plant,ratio o