RICE RATOONING - IRRI books - International Rice Research Institute

Ratooning in ChinaXu Xue-BinSouth China Agricultural University, Guangzhou, ChinaZhang Jong-GuoCrop Breeding and Cultivation InstituteSichuan Academy of Agricultural Sciences, Chengdu,Sichuan Province, ChinaandJiang Xian-XiangSouth China Agricultural UniversityGuangzhou, ChinaABSTRACTRice ratooning in China is concentrated mainly in the middle and lower reaches of theYangtze River. Semidwarf and hybrid ratoon rices were developed in the 1970s with arecord yield of 8.7 t/ha obtained in Guangdong Province. A total yield equal to that ofdouble-cropped rice is possible with the variety 40-1, a medium-duration rice withgood ratooning ability. This may expand ratoon culture in Hubei Province. In southeastSichuan, the medium-duration hybrid Zai Sheng You produced a total yield (main cropplus ratoon crop) on winter flooded fields 26% higher than that of single-croppedmedium-duration rice.Rice is grown on 33 million hectares in China. The area extends from 18°9’N in thesouth to 53°20’N in the north and from as far east as Taiwan to as far west asXinjiang, Uygur Autonomous Region. Rice is grown as low as in the tidal-swamplowlands along the southeast coast and as high as 2,400 m or higher in thesouthwestern highlands (4).In such a wide rice area, the climatic and physical conditions for rice culture,varieties, and cropping systems are very complex. Hence, the rice-growing area inChina is divided into six regions (Fig. 1).Among the six zones, the central China single-double cropping rice zone is thelargest. Ratoon rice is also concentrated in that area, particularly near the margin ofthe double-cropped rice zone (i.e. double cropping early rice and late rice). Mediumdurationand long-duration rice prevail in the single-cropping area of this zone.Generally, after the harvest of medium-duration rice, the temperature is high enoughfor a ratoon crop. Rape, barley, wheat, or green manure is grown as a winter crop.However, changes in cropping systems or improvement of cultivars may affect thecultivation of ratoon rice. For example, sometimes late-season rice or doublecropped rice takes the place of the medium-duration rice. After their harvest, thetemperature is too low for a ratoon crop.