Improvement of Lodging Resistance in Submerged Direct Seeding Rice (Oryza sativa L.) Cultivation Using a Newly Developed 'Shooting hill-seeder' : Method of hill-seeding for the improvement and stabilization of lodging resistance (<Regular Paper>Agronomy)

Abstract

By using a newly developed 'Shooting hill-seeder', it is easy to adjust the hill space within a row or the seeding depth, and change the hill-seeding form in the submerged direct seeding rice cultivation. In this study, the effects of these seeding conditions on the lodging resistance of hill-seeded rice were examined. It was suggested that the increased hill space within a row resulted in lower lodging resistance because of the elongation of culm and decrease in pushing resistance of the hill. These results show the importance to adopt a variety with high lodging resistance, or to control the nitrogen uptake by improvement of fertilizer application or water management, when a large hill space is necessary. On the other hand, the hill-seeding form did not seem to affect the lodging resistance. Furthermore, in hill-seeded rice, the chance of shallow seeding is rare, and the degree of lodging due to shallow seeding is extremely small as compared with broadcast-seeded rice. These characteristics are very important for the stabilization of the submerged direct seeding cultivation, in which unification of the seeding depth is difficult, and the stabilization of seedling emergence is important.