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.

Abstract

The purpose of this study was to clarify the effects of seedling establishment density and sowing styles on the growth, palatability, and physicochemical properties of milled rice under direct sowing culture in flooded paddy fields in northern Kyushu. The density of 80 seedlings/m2 under direct sowing culture was stable and more 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(p<0.01)negative correlation with the protein content of milled rice. Especially, 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 varieties. A comparative study with three sowing styles in hills, rows, and broadcast under direct sowing culture was made on the lodging tolerance, yielding ability and palatability of milled rice. The lodging tolerance of hill sowing was superior to the row and broadcast sowings. The yielding ability of hill and row sowings was superior to the 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 by lodging, we concluded that hill sowing was the most suitable and broadcast sowing the least suitable for direct sowing culture in flooded paddy fields.