选用8个杂交籼稻品种为试验材料,比较机直播不同品种间结实期物质转运、产量及穗部不同粒位（强、弱势粒,一次、二次枝梗,上、中、下部）米质的差异,并探讨结实期物质转运与不同粒位米质的关系,为机直播杂交籼稻品种筛选提供理论依据。结果表明,具有较高的颖花数和千粒重,且结实期具有较高的茎鞘和叶片物质输出与转换率,是机直播高产品种的主要特征。强势粒、一次枝梗籽粒垩白度和垩白粒率均低于弱势粒及二次枝梗籽粒,食味值均高于弱势粒及二次枝梗籽粒;穗上部籽粒米质特征均不同程度高于穗中部和下部籽粒,但穗中部和下部籽粒米质特征品种间存在差异;宜香优2115不同粒位食味值均不同程度高于其他品种。相关分析表明,结实期茎鞘物质输出率及转换率与不同粒位垩白均存在显著或极显著负相关（r=-0.66^*~-0.85^**）,与不同粒位食味值呈显著或极显著正相关（r=0.67^*~0.86^**）。提高机直播杂交籼稻结实期茎鞘物质转运率及转换率可改善不同粒位籽粒食味品质,宜香优2115作机直播在产量及米质上综合表现好,尤其在食味品质方面优势明显,适宜作为机直播水稻品种应用。

Eight hybrid indica rice varieties were selected as test materials to compare the differences in material transport at grain filling stage, grain yield, and rice quality in different grain positions （superior and inferior grains, primary and secondary branches, upper, middle, and lower）, and to explore the relationship between material transport at grain filling stage and quality of hybrid indica rice in different grain positions under mechanical direct seeding condition. The results showed that it has a high number of spikelets, 1000-grain weight, and export and translocation percentage of stem-sheaths and leaf during grain filling stage, which are the main characteristics of mechanical direct seeding varieties with high-yield. The chalky grain rate and chalkiness degree of the superior and the primary branch grains were lower than the inferior and the secondary branch grains, and the tasting value was higher than the corresponding inferior and the secondary branch grains. The rice quality characteristics of the upper part of the panicles were higher than those of the middle and lower parts of the panicle to different degrees, but there are differences between the varieties. The tasting value of Yixiangyou 2115 in different grain positions was higher than other varieties in different degrees. Correlation analysis showed that the export and translocation percentage of stem-sheaths during grain filling stage were significantly or extremely significantly negatively correlated with the chalkiness in different grain positions （r=-0.66^*~-0.85^**）and extremely significant positive correlation with tasting value （r=0.67^*~0.86^**）, which could improve the quality of different grain positions. Yixiangyou 2115 has a good performance in yield and rice quality in different grain positions, especially obvious advantages in eating quality, and suitable for application as a direct seeding rice variety.