An analysis of the yield gap of hybrid rice in farmers’ fields

摘要

Planting area of hybrid rice in China has been increasing since the 1970s. Now,it covers more than 50% of the total national rice-planting area. Hybrid rice gives about 20% more yield than inbred rice in farmers’ fields to contribute to the continuous increase in the yield of rice in China. However, a yield gap of hybrid rice is common among farmers’ fields and demonstration fields guided by rice experts in hybrid rice-growing regions. This study describes the main factors that result in a yield gap of hybrid rice in farmers’ fields for the development of corresponding management practices. More than 100 farmers’ fields planted with hybrid rice with various yields in early rice, late rice, and single rice were targeted for a survey. Yield and its components and a series of management practices were investigated. Through comparison and analysis, results are as follows. (1) The yield gap mostly ranges from 10% to 50% between farmers’ fields in the same location, season, and hybrid combination. (2) For yield components, the yield gap mainly results from panicle size and spikelet fertility. However, in some transplanted hybrid rice,insufficient panicle number also results in lower yield due to insufficient basic seedlings, poor seedlings, and less growth in the early stage. And, in directseeded hybrid rice, too many panicles caused by a high seed rate is the main factor reducing yield. (3) For management practices, the main factors causing small panicles of hybrid rice are poor seedlings resulting from a high seed rate,incorrect water and fertilizer management, unsuitable pest control, and longer seedling duration in the seedbed. In the main field, hybrid rice overgrows in the early stage. That results in poor plant type, which causes low spikelet fertility and small panicles due to strong competition. In addition, optimum population and ideal plant type of hybrid rice areimportant for bridging the yield gap among farmers’ fields.