Studies on Methods of Lowland Rice Culture on Upland Fields under irrigation : I. Adaptability of lowland rice varieties to the cultivation on upland fields under irrigation. : II. Differences in the growth and physiological characteristics between lowland rice and upland rice cultivated on upland field under irrigation

Abstract

1) From 1955 to 1957, a large number of lowland rice varieties (early and medium ripening varieties prevailing in Tohoku, Hokuriku and Kanto region of Japan) were cultivated on upland fields under irrigation. The result showed that the early varieties of lowland rice having the same heading date as that of "Rikuto Norin No. 12 or No. 24" of upland rice were the most productive. Then we found out that there is the group of lowand rice varieties which is highly adaptable to the cultivation on upland fields under irrigation, and selected "Obanazawa No. 6" of lowland rice as a hopeful variety. 2) On irrigated upland fields, we cultured lowland rice (var, Obanazawa No. 6) and upland rice (var. Norin No. 12) under conditions of different seed rate and amount of fertilizers in 1957, and investigated the differences in the growth and physiological characteristics between them. By this investigation, it was found that lowland rice is superior in the number of spikelets per panicle, percent of ripened grains and percent of ear weight/straw than the upland rice, and the former is characterized by containing large amount of starch under higher level of nitrogen after heading. Moreover, we have proved that the method of drill planting and heavy application of fertilizers were very effective in increasing yield of lowland rice grown on irrigated upland field.