Chin J Plan Ecolo ›› 2005, Vol. 29 ›› Issue (5): 829-835.DOI: 10.17521/cjpe.2005.0110

• Research Articles • Previous Articles     Next Articles

THE EFFECTS OF CULTIVATION DENSITY ON THE PERCENT OF HEAD MILLED RICE AND SOURCE TO SINK RATIOS OF MID_SEASON HYBRID RICE IN EASTERN AND SOUTHERN SICHUAN PROVINCE

XU Fu_Xian, XIONG Hong, ZHU Yong_Chuan, XIE Rong, and WANG Gui_Xiong   

  1. Rice and Sorghum Institute, Sichuan Academy of Agricultural Sciences
  • Online:2005-08-30 Published:2005-08-30
  • Contact: XIONG Hong

Abstract:

Many studies on grain quality as affected by rice cultivation density have been conducted on one or two rice varieties, but there are few studies on varieties of hybrid midseason_rice. The hybrid midseason_rice grown in southern and eastern Sichuan Province has very low grain quality, especially the percentage of head milled rice, because of high temperatures and summer droughts. This paper explores the effects of low density cultivation on the percentage of head milled rice and source to sink ratios of varieties of hybrid midseason_rice, and it provides a theoretical and practical basis for improved cultivation. The experiment was conducted with eighteen mid_season rice hybrids grown at two densities, a low density cultivation and a traditional cultivation system, in a randomized block design with 4 replications using two hybrids (a big_panicle type hybrid `Gangyou 22' and a small_panicle type hybrid `II you 7') with 3 different treatments of grain or leaf cut. By using variance, correlation and regre ssion analysis, the results indicated that the percentage of head milled rice in creased in hybrids with small_medium panicles under low density cultivation but not for the hybrids with big_panicles. This was because of the significant decrease in the leaf to grain ratio and grain filling rate of hybrids for small_middle panicle under low density cultivation, as compared to the traditional cultivation system, resulting in an increase in the grain unit weight and percentage of head milled rice. The leaf to grain ratio and the grain filling rate of big panicle hybrids were low in traditional cultivation, and decreased significantly under low density cultivation, causing a decrease in the grain unit weight and percentage of head milled rice. These results were produced because of an imbalance in the leaf to grain ratios. Hybrids with less than 177 spikelets per panicle un der cultivation using traditional densities can adapt to the low density cultivation in the eastern and southern regions of Sichuan Province.