PRODUCTIVITY OF HIGH-YIELDING CROPS .1. COMPARISON OF GROWTH AND PRODUCTIVITY AMONG HIGH-YIELDING CROPS

By using high-yielding varieties (lines) and by applying coating urea which releases nitrogen slowly, it was possible to achieved a very high yield, which corresponded to the yield records reported in Hokkaido. The results obtained in the "high yield" compared with the "standard yield" treatments were as follows. 1) The economic yield (t/ha on a dry weight basis) for the "high yield" treatment was 6.4 in rice, 11.0 in winter wheat, 11.4 in maize, 5.3 in soybean, and 16.3 in potato. 2) The biological yield (t/ha on a dry weight basis) for the "high yield" treatment was 13.6 in rice, 18.6 in winter wheat, 22.4 in maize, 11.5 in soybean, and 17.7 in potato. 3) The LAI was improved in the "high yield" crops compared with the "standard yield" crops, whereas the NAR was not. 4) The grain (tuber) number was improved for the "high yield" crops compared with the "standard yield" crops, but 1,000 grains weight was not improved except for maize.