RICE RATOONING - IRRI books - International Rice Research Institute

Inheritance of ratooning abilityin Chinese rice varieties[ O. sativa subsp. xian (or indica)]Li Shifen and Chen TingwenSichuan Agricultural University, Yaan SichuanABSTRACTTo study the inheritance of ratooning ability in rice varieties, short-duration Shu-FongNo. 1(11), a high ratooning variety, and Ai-Nan-Zao, a nonratooning variety, were usedas tester parents, mated reciprocally with Hon-Mei-Zao, short duration, and Tai-Guao-Dao-Xuan and Shong-Zao-Xian No. 26, medium duration. These varieties arecharacterized by different ratooning abilities. All F 1 , F 2 , BC 1 , BC 2 , and reciprocals wereraised. All F 1 crosses showed relatively large variation in hybrid vigor, ranging fromnegative to positive. The F 1 from crosses with Ai-Nan-Zao generally showed lowerheterosis than those from crosses with Shu-Fong No. 1(11). Cytoplasmic effects andnucleo-cytoplasmic interaction were observed in Shong-Zao-Xian No. 26. No suchsignificant effect or interaction was found in Hon-Mei-Zao. Estimates of narrow-senseheritability on ratooning ability varied greatly with the hereditary background of theparents. These results indicate the possibility of breeding new variety or hybrids withstrong ratooning ability, provided the right parents and mating scheme are selected.The first record of ratoon rice cultivation in China dates from more than 1,500 yr ago(1). In the 1950s, it was common practice for the peasants living in the lowlands bythe lakes, along the valley of the Yangtse River, and in the region of paddy fields toraise ratoon rice. This practice also has been adopted in the rice-based croppingsystem in Texas, USA.Ratooning offers many advantages: it makes better use of light and heat in thepaddy field in autumn and saves labor and seed to reduce production cost. However,in the past, ratoon yields were low and unstable and the practice disappearedgradually as rice production developed and yields increased in China. But ratoonrice again aroused the interest of some Chinese rice scientists when the EthiopianAcademy of Agricultural Science reported that when varieties IR8 and IR5 wereratooned, record yields were obtained — 8.7 t/ha and 8.3 t/ha, more than the maincrop yield.Studying ratoon rice, Kai Chiu Yang (5), professor in Sichuan AgriculturalUniversity, expected to enhance the yield level of ratoon rice by improvingcultivation techniques. He systematically studied its morphological and ecologicalcharacters in the early 1940s (5). Since the 1970s, reports on ratoon rice in the worldhave focused on rice morphology, ecology, and physiology, and it has beensuggested that strong ratooning ability is the most fundamental factor in enhancing