福岡県農業総合試験場研究報告

湛水直播用水稲品種の育成・選抜における押し倒し抵抗値の効率的な測定方法

[摘要］耐倒伏性の優れた湛水直播栽培用水稲良食味品種の育成・選定の効率化を図るため、移植栽培条件で湛水直播栽培での耐倒伏性の推定に利用する押し倒し抵抗値の調査の統計的検証を行うとともに、測定位置および測定に要する適正標本数について検討した。押し倒し抵抗値は、出穂後15日頃に稲株の地上10cmの部位で測定すると地上20cmや30cmの部位で測定するよりも変動係数が小さく、安定した値が得られる。この押し倒し抵抗値は極早生から晩生の耐倒伏性の異なった品種において正規分布を示し、適正な調査標本数は推定許容誤差率を15％とすると、耐倒伏性が弱い品種・系統を含む場合は1品種当たり8株程度である。また、耐倒伏性が「中」以上の品種・系統を対象とする場合は1品種当たり5株で十分である。多数の供試品種・系統の中から直播適性の高い品種・系統を選抜する場合には、測定の効率化に有効と判断される。

［キーワード：押し倒し抵抗、水稲、測定方法、耐倒伏性、湛水直播栽培］

　Measurement methods of pushing resistance for the selecting of rice cultivar well adapted to direct sowing culture. OGATA TAKEFUMI and YUJI MATSUE (Fukuoka Agricultural Research Center, Chikushino, Fukuoka 818-8549, Japan) Bull. Fukuoka Agric. Res. Cent. 18: 5 - 7 (1999)

　 This study was undertaken to find the effective measurement methods, which were the measurement position of rice plant and proper sample size, of pushing resistance for the selecting of rice cultivar well adapted to direct sowing culture in flooded paddy fields. Coefficient of variation for pushing resistance at 10 cm above the ground on rice plants was smaller than that at 20 cm or 30 cm. The pushing resistance of rice plants, which were transplanted by a seedling per hill, at fifteen days after heading was normally distributed by the Kolmogorov-Smirnov test. In the case of selecting rice cultivars with high lodging tolerance adapted for direct sowing culture under transplanting culture, varietal difference of pushing resistance could be showed by 5 - 8 hills per a variety for sample numbers. It was concluded that this small sample numbers for survey as 5 - 8 hills per a variety was efficient in selecting rice cultivars with high lodging tolerance.　