@article{oai:repository.naro.go.jp:00002004,
 author = {吉永, 悟志 and YOSHINAGA, Satoshi},
 journal = {九州沖縄農業研究センター報告, Bulletin of the NARO Kyushu Okinawa Agricultural Research Center},
 month = {Dec},
 note = {Practical methods for stabilizing the direct-seeding cultivation of rice (Oryza sativa L.) have been desired in Japan because of their lower labor-intensiveness compared to mechanical transplanting cultivation. However, the yield of direct-seeded rice is frequently reduced by the fluctuation of seedling emergence, lower lodging resistance, and luxuriant growth. In recent years, a hill-seeding system using a "Shooting hill-seeder" has been developed to improve the productivity of direct-seeding rice cultivation. Therefore, we examined the emergence and establishment of seedlings, lodging resistance and growth-yield performance in hill-seeded rice cultivation using the newly developed hill-seeder in this study as the most important factors to promote use of this system in southern Japan. 1. The shooting hill-seeder can shoot seeds coated with an oxygen supplier 1 to 2cm into the puddling soil. Under this seeding condition, it is important to obtain a uniform emergence and a higher emergence rate in order to stabilize and to improve productivity in submerged direct-seeding cultivation. This report demonstrates that drainage after seeding, and using seeds stored at 20 to 25℃ for three days after being coated with an oxygen supplier and proper desiccation were effective for achieving a uniform emergence and higher emergence rate in this hill-seeded rice cultivation. 2. Improvement of the lodging resistance in direct-seeded rice is important to stabilize the direct-seeding rice cultivation. The hill-seeded rice as well as the transplanted rice exhibited higher lodging resistance than that of the broadcast-seeded rice. This was because the number of panicles per hill was greater and relatively stable, even though the seedling density fluctuated as compared with the broadcast-seeded rice. Furthermore, this higher lodging resistance of the hill-seeded rice was apparent in different seedling densities, seeding depths, and types of fertilization. 3. Luxuriant growth may reduce yield through a deficiency of nitrogen uptake at the intermediate growth stage of rice in the southern part of Japan. For direct-seeded rice with a higher tillering rate, luxuriant growth is an especially significant factor in decreased yield. The hill-seeded rice could avoid this luxuriant growth through proper growth competition among individuals in each hill in the early growth stage. Increased nitrogen uptake at the panicle-initiation stage was also recognized as due to suppression of tillering, as compared with that of the broadcast-seeded rice. Furthermore, application of a release-controlled fertilizer, especially effective at the later growth stages, was effective in increasing the number of spikelets in the hill-seeded rice, due to higher nitrogen uptake at panicle-initiation stage compared to conventional fertilizer application. The increase in number of spikelets of the hill-seeded rice resulted in an increase in the yield because the hillseeded rice exhibited a higher ripening ability due to a higher photosynthetic rate as compared to broadcastseeded rice. 4. In conclusion, hill-seeded rice cultivation using the shooting hill-seeder enabled us to improve and to stabilize the productivity of the submerged direct-seeded rice, through the higher lodging resistance and higher ripening ability, based on the stabilized seedling emergence, and the increase in the number of spikelets by the improved fertilizer application., 本報告では, 近年開発された「打込み式代かき同時土中点播機」を用いた水稲の湛水直播栽培 (打込み点播栽培) における出芽・苗立ち, 耐倒伏性, 生育・収量に関する特性の解明を行い, 生産性の向上および安定化方策について検討した。出芽・苗立ちの安定化については, 播種後の落水管理や酸素発生剤被覆種子を適度な乾燥を行った後20 ～ 25℃で3日間貯蔵する短期間貯蔵処理が, 播種深度のばらつきによる出芽の不斉一化や播種深度確保による出芽率の低下の回避に有効であった。次に, 打込み点播栽培による点播水稲の耐倒伏性を検討した結果, 散播水稲に比較して1株穂数が安定して多いために移植水稲と同等の高い耐倒伏性を示すことや, 苗立ち密度, 播種深度および施肥条件が変動しても安定して高い耐倒伏性を示すことが明らかとなった。さらに, 点播水稲は登熟期間の光合成が旺盛なために登熟能力が高いことが示され, 緩効性肥料を用いた後期重点施肥を行うことにより籾数の増加にともなう収量性の向上が達成された。以上のように, 耐倒伏性や登熟能力の高い点播水稲は, 出芽・苗立ちの安定化を図るとともに施肥法の改善により籾数を増加させることにより生産性の向上および安定化が達成され, 湛水直播栽培の安定化に有効な栽培法となることが明らかとなった。},
 pages = {53--116},
 title = {打込み式代かき同時土中点播機を用いた水稲の湛水直播栽培における生産性の向上および安定化に関する研究},
 volume = {41},
 year = {2002},
 yomi = {ヨシナガ, サトシ}
}