Physio-ecological characteristics of red rice (local name "Salebyeo", Oryza sativa L.) spontaneously occurring in Korea and its competition with cultivated rice (Oryza sativa L.)., 2; competitive ability of red rice with cultivated rice
1989
Kim, J.C. (Rural Development Administration, Sangju (Korea R.). Yeongnam Crops Experiment Station)
Red rice (local name "Salebyeo") has been a noxious weed plant to rice production in direct-seeded paddy field of Korean west sea-side. In this area, five varieties of red rice, "Monggeunsale", "Ssalsale", "Ginkkaragsale", "Galsaegssalsale" and "Galsaegkkaragsale" were collected in 1981. This experiment was conducted to find out the critical competitive period and competitive ability of cultivated rice against red rice. Plant height and number of tillers of cultivated rice decreased as red rice competed with cultivated rice during active tillering stage. The maximum tillering stage of cultivated rice competed with red rice became about 10 days earlier than those non-competed. The cmpetitive ability of red rice was predominant over cultivated rice, particularly, under the unfavorable fertilizing condition. The changes in panicle numbers and dry weights of red rice and cultivated rice by the replacement design were co-antagonistic, the relative yield total was considered lower than 1 and the competitive ability of panicle number in red rice was higher than cultivated rice. The culm length, the length of panicle, the grain weight and the ripening ratio of cultivated rice were not so much variable irrespective of inter-specific and additive competition with red rice. However the weight of dry matter and yield in cultivated rice were greatly influenced by the competition of panicle number. The longer was the competitive period by the red rice, the greater was the decrease in panicle number and yield of cultivated rice. Rice grain yield reduction was highly correlated with the number of panicles of red rice. And it was considered that 300 panicles of red rice per m** 2 caused rice yield reduction by 50 %, and the critical threshold level of red rice are 22 panicles per m** 2 in direct-seeded rice cultivation
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