福岡県農業総合試験場24（2005） pp39−42

　

水稲の高温登熟条件下での食味変動の品種間差と評価指標形質

　

佐藤大和¹⁾・陣内暢明²⁾・尾形武文・内川修・田中浩平

（農産部）

　

　高温登熟でも品質が安定して優れる品種を育成するための基礎的知見を得る目的で，極早生品種から中晩生品種の20品種を用いて，食味変動の品種間差を明らかにするとともに，高温登熟条件下における食味評価指標形質を検討した。食味変動には品種間差が認められ，極早生品種では‘キヌヒカリ’が最も変動が小さかったのに対し，‘トヨニシキ’は最も大きく，早生品種では最小が‘日本晴’で，最大が‘南海137号’であった。また，‘夢つくし’，‘ちくし43号’および‘ちくし52号’は，‘コシヒカリ’に比べて食味変動が小さく，食味は同程度かそれ以上の値を示したことから，これらの品種を選定することによって高温登熟条件下においても食味の高位安定化が図れると考えられた。一方，食味 (総合評価) の向上に寄与する登熟期間中の最適温度 (出穂後35日間の日平均気温) は25〜26℃付近にあると推定された。さらに，本研究において登熟温度の基準値とした25.5℃以上の高温登熟条件下ではテクスチャー特性値 (H/-H) が食味を客観的に評価できる指標形質として認められ，アミロース含有率は利用できないことが判明した。

［キーワード：アミロース含有率，高温登熟，食味，水稲，テクスチャー特性］

　

 Varietal Differences and Indicator Characters of the Palatability of Rice under High Air Temperature Conditions during the Ripening Period. Hirokazu SATO, Nobuaki JINNOUCHI, Takefumi OGATA, Osamu UCHIKAWA and Kouhei TANAKA (Fukuoka Aguricultural Research Center, Chikushino, Fukuoka 818-8549, Japan)　Bull. Fukuoka Agric. Res. Cent. 24: 39−42 (2005)

 In this study, the varietal differences and the indicator characters of the palatability of rice were examined to obtain fundamental knowledge for establishing a breeding method useful under high air temperature conditions during the ripening period. The varietal differences in the variance of the palatability of rice were analyzed. Among the extremely early varieties, 'KINUHIKARI' showed the smallest variance, and 'TOYONISHIKI' the largest variance in the palatability of rice. Among the early varieties, 'NIPPONBARE' showed the smallest variance in the palatability of rice, and 'NANKAI 137' showed the largest. 'YUMETSUKUSHI', 'CHIKUSHI 43' and 'CHIKUSHI 52'　showed significantly smaller variance in the palatability of rice and overall eating-quality of cooked rice similar or higher than those of 'KOSHIHIKARI'. The present results suggested that it was possible to select varieties for the stable palatability of high-quality rice under the high air temperature conditions during the ripening period. The optimum air temperature conditions during the ripening period (mean air temperature for 35 days after the heading time) of overall eating-quality of cooked rice was estimated at approximately 25-26℃. Under the crucial conditions in which air temperature during the ripening period was over 25.5℃, the textural characteristic Hardness/Adhesion (H/-H) ratio was useful as an index of the overall eating-quality of cooked rice, but the amylose content was not.

［key words: amylose content, high air temperature conditions during the ripening period, paddy rice, palatability, textural characteristic］