An attempt to construct stable and high yielding cultivation methods through the approach from the system controlling the filling priority of grains within the panicle in rice

Research Project

Project/Area Number	16K07566
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Crop production science
Research Institution	Tohoku University
Principal Investigator	NAKAMURA Teiji 東北大学, 農学研究科, 助手 (70155844)
Project Period (FY)	2016-10-21 – 2021-03-31
Project Status	Completed (Fiscal Year 2020)
Budget Amount *help	¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000) Fiscal Year 2020: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000) Fiscal Year 2019: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000) Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000) Fiscal Year 2017: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000) Fiscal Year 2016: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Keywords	イネ / 穎果 / 登熟 / 登熟優先度 / 品質 / ABA / 水制限 / 栽培 / 水不足
Outline of Final Research Achievements	Abscisic acid (ABA) controls the filling priority of grains within the panicle of rice, and there is the genetic difference in the strength to control the filling priority (SCFP). In cultivars or lines with strong SCFP, low source/sink condition reduce the grain filling and quality of inferior grains through delaying early grain growth, and decreasing endosperm cell number and starch synthesizing ability. In this work, by using popular cultivar, an attempt was done to construct stable and high yielding cultivation methods which decrease SCFP. Higher planting density or lower nitrogen application decreased the panicle size, and increased the percentage of grain filling and quality through weakening SCFP. However high density often enhances lodging. To resolve this problem, water restriction which is known to increase endogenous ABA was applied. The results indicated water restriction during grain filling is effective to decrease SCFP and increase grain filling and quality.
Academic Significance and Societal Importance of the Research Achievements	世界人口の急増に対処するための重要作物であるイネでは、穂下部の穎果が弱勢で登熟優先度が低い。低日射下で、また多収を求め穎花数が多くなる栽培や育種を行うと、弱勢な穎果の登熟が悪化し収量は増加しない。この解決のために光合成つまりsource側の研究が多く行われたがsink側の研究は少ない。本研究ではsinkに本来備わった登熟優先度調節つまり生き残り戦略機構を栽培により制御した点、そして他の作物にも応用できる可能性が高い点に学術的意義がある。さらに、最近品質が重要視され、高品質栽培は必須となり、そのために収量を低く設定する場合もある。本研究は高収量と高品質の両方を目指すもので、社会的意義も大きい。