Modern rice cultivars could only get higher yield than the classic ones under the application of chemical fertilizers
2001
Katano, M. (Kyushu Tokai Univ. (Japan). Dept. of Plant Science))
Forty one rice cultivars that were dominant during (1) 1860s' to 1890s', (2) 1900s' to 1910s', (3) 1910s' to 1920s', (4) 1920s' to 1940s', (5) 1950s' to 1960s', and (6) 1970s' to early 1980s' in Miyazaki Prefecture were cultivated in six paddy fields with the following different cultural practices in Kumamoto Prefecture neighboring to Miyazaki: (A) conventional farming with chemical fertilizers, (B) nature farming with only rice straw, (C) organic farming with cattle manure, (D) nature farming with decaying rice straw, (E) nature farming with rice straw; and (F) nature farming with no application of fertilizer and with no tillage. Yield per unit land area in Japan was conspicuously increased from 1900s' to 1910s' when fertilizers purchased like import soybean cake was heavily applied and from 1950s' to 1970s' when a vast amount of chemical fertilizers and pesticides came into wide use. Mean yield of modern cultivars that become popular since 1050s' was significantly higher than those of the classic cultivars only in the field with chemical fertilizers. These results showed the possibility of breeding for high yielding cultivars under the nature farming would still remain
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