福岡県農業総合試験場研究報告23 (2004) pp 21 - 25
水稲品種‘つくしろまん’の安定栽培法
内川修＊・田中浩平・福島裕助・岩渕哲也・荒木雅登
水稲品種‘つくしろまん’の移植時期および施肥法が，生育，収量，品質に及ぼす影響を検討し，‘つくしろまん’の移植適期や土壌肥沃度に応じた窒素施用量および収穫適期を明らかにした。‘つくしろまん’は移植時期を早めると背白米が発生し外観品質が低下したことから，収量および品質からみた移植適期は６月５半旬であった。
土壌肥沃度が高いほ場では，穂肥の２回目を省略することにより外観品質および食味の向上が認められるものの，土壌肥沃度が低いほ場では８〜９％減収し低収となった。穂肥１回目の施用時期を基準の出穂20日前にすると，出穂15日前に比べて１穂籾数が多く，心白粒の発生が減少した。よって目標収量を550kg／10ａとした場合，窒素施用量は土壌肥沃度が高いほ場では10a当たり5+2+0kg，土壌肥沃度が低いほ場では5+2+1.5kgが適当であり、穂肥１回目は出穂前20日とする。外観品質が安定する‘つくしろまん’の収穫期の判定指標として，出穂後積算気温は900〜1050℃，籾水分は23〜28％，早限期の黄褐色籾比率は75％程度であった。
[キーワード：玄米品質，移植適期，窒素施用量，収穫適期，‘つくしろまん’]
Optimum Cultivation Method for the Rice Cultivar 'Tsukushiroman'. UCHIKAWA Osamu, Kohei TANAKA, Yusuke FUKUSHIMA, Tetsuya IWABUCHI and Masato ARAKI (Fukuoka Aguricultural Research Center, Chikushino, Fukuoka 818-8549, Japan) Bull. Fukuoka Agric. Res. Cent. 23: 21 - 25 (2004)
We examined the effect of transplantation time and fertilizer application method on the growth, yield point, and quality of the rice cultivar 'Tsukushiroman'. We also clarified optimal transplantation timing of 'Tsukushiroman' the level of nitrogen application in relation to differences in soil fertility and the optimal timing for harvesting. Yield and optimal transplantation timing from the viewpoint of quality were in the fifth pentad of June, based on the fast that the earlier transplantation timing for 'Tsukushiroman' resulted in an increase white back rice development and deteriorated appearance.
In the field for which soil fertility was high, there were improvements in appearance and eating quality when the second topdressing was omitted at the panicle formation stage. On the other hand, in the field with low soil fertility, that was a decrease in the yield by 8~9% when the second topdressing was omitted at the panicle formation stage. When the first topdressing at panicle formation was carried out 20 day prior to ear emergence, as is the standard, the number of unhulled rice spikes was larger and the generation of white core rice decreased compared to applying the first topdressing at panicle formation 15 days prior to ear emergence.
To sum up, when the goal yield was 550kg/10a, it was appropriate to administer 5+2+0 kg per 10 a for a field with a high soil fertility; 5+2+1.5 kg is adequate for a field with low soil fertility, 20 days prior to ear emergence.
Indices for determining optimal harvesting timing, which will result in stabilized appearance are post-ear emergence calculated temperature of 900~1050℃, unhulled rice moisture of 23~28% and about a 75% yellowish brown unhulled rice ratio in the primary harvesting stage.
[Key words: optimal harvesting timing, rice quality, optimal transplantation timing, amount of nitrogen fertilizer application, 'Tsukushiroman' ]
＊連絡責任者（農産部）