Research and prospect on physio-ecological properties of ratoon rice yield formation and its key cultivation technology

This article reviewed the current situations of ratoon rice in China and summarized the research progresses on the ratoon rice yield formation from the perspectives of the developmental genetics and physiological ecology. The key cultivation technology and eco-physiological mechanisms of the ratooning plants from low and high rice stubbles were comprehensively reviewed also. The ratoon rice technique gives two yields from one seeding, with significant yield advantages over single cropping rice and double cropping rice. Appropriate rice cultivars and cultivation methods are decisive factors of high yield of ratoon rice. For the ratoon rice from the high stubble of the hand-harvested first-season rice, to get high yield, the hybrid indica rice cultivars with heavy panicles were the best choices, which were relative weak in tillering ability for the first-season, and high regeneration capacity from lower nodes for the ratoon season. For the ratoon rice from the lower stubble of the mechanically harvested first-season rice, to get high yield, the hybrid indica rice with high regeneration capacity from lower nodes, or hybrid indica and japonica/indica rice crosses with the heavy panicle but weak photosensitivity were the best choices. Previous studies also suggested that roots adjustment was crucial to realize yield potential of ratoon rice. The ratoon rice root system was composed of the roots of the first-season rice and new roots of the ratoon season rice. The higher root activity from the mature stage of the first-season rice to the heading stage of the ratoon rice improved germination of axillary bud in rice stubbles and increased the panicles number of ratoon rice, which was favorable for high yield of ratoon rice. According to our study results and previous reports, we summarize the high-yielding cultural techniques of ratoon rice from hand-harvested first-season rice, such as early sowing in optimal time, ridge transplanting and furrow irrigation, two-time soil drying (heavy drought at tillering stage and moderate drought at 25 days after full heading stage in the first season), increased N application for bud development, and higher stubbles of 40 50 cm. In addition, the key cultivation technology and eco-physiological mechanisms of the ratoon rice from the low stubbles of machine-harvested first-season rice were comprehensively discussed from variety selection, fertilizer application, and the height of the remained stubbles. At last, the problems and future trends of ratoon rice were discussed. It was suggested that ratoon rice from low stubbles of mechanically harvested rice were the direction of ratoon rice development. The corresponding researches were therefore prospected.