Studies on direct sowing culture of rice in northern Kyushu. Effects of seedling establishment density and sowing styles on the growth and palatability of milled rice

摘要

The purpose of this study was to clarify the effects of seedling establishment density and sowing methods on the growth, palatability, and physicochemical properties of milled rice direct sowing in flooded paddy fields in northern Kyushu. The density of 80 seedlings/m2 under direct sowing culture was stable and superior in lodging tolerance, yielding ability, palatability, and physicochemical properties of milled rice than other densities (i.e., 20, 40, 100, 150, and 200 seedlings/m2). Furthermore,the palatability (i.e., overall eating quality) of cooked rice showed a significant negative correlation with the protein content of milled rice. The protein content of milled rice from 80 seedlings/m2 was lower than that of milled rice from other densities under different conditions such as production year and cultivars. A comparative study with three sowing methods (in hills, rows, and broadcast under direct sowing) was made on the lodging tolerance, yielding ability and palatability of milled rice.The lodging tolerance of hill sowing was superior to row and broadcast sowings. The yielding ability of hill and row sowings was superior to broadcast sowing. On the other hand, no significant difference was noted among these three sowing styles in relation to the palatability and physicochemical properties of milled rice. Judging from the deterioration of palatability caused by lodging, it is concluded that hill sowing was the most suitable and broadcast sowing the least suitable for direct sowing culture in flooded paddy fields.