Abstract: Studies were made on differences among types and varieties of rice in stomatal density and gas diffusion resistance, and on the relationship between these traits and photosynthetic rate. Significant differences among types and varieties were found in stomatal density and gas diffusion resistance.Generally, stomatal density was higher in indica varieties than in japonica varieties, gas diffusion resistance was lower in the former than in the later, in varieties developed through indica-japonica hybridization it was intermediate.The stomatal density was closely positively correlated with the gas conductivity and the net photosynthetic rate, had significant negative correlation with specific leaf weight, and was not correlated with single leaf area. Higher photosynthetic rate of indica varieties mainly results from its high stomatal density and low gas diffusion resistance.The result also suggested that high photosynthetic rate might be obtained if the characters of high stomatal densityonclick="SelectDisplayDiv('EnDivSummaryMoreSummary','EnDivSummaryMore');DisplaySpanDiv('EnDivSummaryHuanYuan')"> and low gas diffusion resistance in indica could be combined with the character of the larger specific leaf weight in japonica through crossing between two

Key words: Stomatal density, Gas diffusion resistance: Net photosynthetic rate, indica, japonica, indica-japonica variety

摘要： 气孔密度和气体扩散阻力存在着极显著的类型间和品种间差异，一般籼稻的气孔密度大于粳稻、气体扩散阻力则小于粳稻。通过籼粳稻杂交育成的品种表现为中间型，气孔密度与气体扩散导度和净光合速率之间呈极显著的正相关，与比叶重呈显著的负相关，与单叶面积的相关不显著。籼稻品种较高的光合速率主要来自其大的气孔密度和低的气体扩散阻力。如果通过籼粳稻杂交将籼稻气孔密度大、气体扩散阻力低的特性与粳稻比叶重大的特点适当结合在一起，将有可能获得较高的净光合速率。

关键词: 气孔密度, 气体扩散阻力, 净光合速率, 籼稻, 粳稻, 籼粳交品种