中文摘要：

以选育时期不同（两个选育时代）的12个水稻品种为材料,于施氮量为0,225,300 kg/hm2纯氮大田条件下,研究了不同氮肥水平下两选育时代的水稻品种产量、物质生产积累量及氮素吸收、利用效率的差异。结果表明,水稻产量随着选育时代的更替有所提高,并随施氮量的增加两时代产量表现不同,早期品种中有83.3%的水稻基因型的产量随施氮量增加呈增加趋势,当代品种产量则有一半基因型在225 kg/hm2氮肥水平下产量达最大,说明早期品种对氮肥反应较当代品种敏感。农艺性状中的株高和穗长随着育种时代的更替有矮化和减小的趋势,着粒密度有所增加。干物质和氮素平均积累量在生育时期各阶段均表现为当代品种大于早期品种,氮素利用效率亦表现相同的规律。相关分析表明,水稻产量与抽穗、成熟期物质积累量和氮素吸收量均呈显著或极显著正相关关系,与拔节期关系不密切。氮素利用效率与产量呈显著正相关,与株高和穗长呈显著负相关。说明随着选育时代的更替,水稻产量、吸氮量及氮素利用效率有所提高,株型趋于矮化,穗型由散穗向密穗型演变。

英文摘要：

A field experiment with 12 Japonica rices selected of different breeding（two breeding time）time was carried out on the farm of Yangzhou University,Jiangsu province,China.The effects of different N levels including 0,225,300 kg/ha N on rice grain yield,dry matter production,N accumulation and utilization efficiency were analyzed.Results showed that,rice yield increased with the selection time replacement and the performance of yield with two times was different with N application rate increasing.Yield of 83.3 % varieties selected early increased with N application rate increasing, while a half of contemporary varieties having higher yield level at 225 kg/ha N level. It indicated that varieties selected early responded more sensitive to N fertilizer than contemporary varieties. Among agronomic traits, plant height and .panicle length decreased, grain setting density increased with selection time replacement. Dry matter accumulation, N uptake and utilization efficiency of contemporary varieties were higher than those of varieties selected early. Correlation analysis showed that the relationship between rice yield and dry matter and N accumulation at heading, maturing but jointing stages were significant or highly significant positively. N utilization efficiency was positive significantly correlated with yield, negative with plant height and panicle length, It indicated that rice yield, N uptake and utilization efficiency increased, plant height tended to dwarf type and panicle type evolution from sparse dense to type with the selection breeding time changed