关键词: 水稻, 粒位, 碾米品质, 氮素

Abstract: Milling quality of the grain is one of the most important quality indexes of rice. However, little is known what difference in the milling characters among the grains at different positions within a rice panicle. This study has investigated the distribution of the percentages of brown rice (BR), milled rice (MR) and head rice (HR) for different grains on a panicle. Two rice cultivars, Yangdao 6 (indica rice) and Wuyujing 3 (japonica rice), were field-grown. Three levels of nitrogen, 0, 120 kg·ha-1, and 240 kg·ha-1, were applied at pre-planting and topdressing. All primary branches on a panicle were evenly divided into three parts of the upper, middle and basal. The grains were numbered as 1 to 6 on a primary branch and 1 to 3 or 4 on a secondary branch from the top to base. Generally, BR, MR and HR for the grains on a primary branch were greater than those on a secondary branch at the same part of a panicle. On a secondary branch, the grain 1 had the least BR, MR and HR, and the grain 3 or 4 had the greatest. On a primary branch, the grain 2 had the greatest BR and HR, and the grain 1 had the least; the distribution of MR at different positions within a rice panicle or on a secondary branch varied with the amount of nitrogen applied. The milling quality of the grains at different parts in a panicle of Wuyujing 3 was better than those of Yangdao 6, especially the grains on a secondary at the same part of a panicle. Application of nitrogen fertilizer could improve the milling quality of rice when the amount of nitrogen was between 0 and 240 kg·ha-1.

Key words: rice, grain position, milling quality, nitrogen