福岡県農業総合試験場研究報告

福岡県における水稲品種の窒素吸収特性
第１報　良食味早生品種‘ほほえみ’，‘つくし早生’の収量および玄米窒素含有率からみた望ましい窒素吸収パターン

［摘要］福岡県における良食味早生品種‘ほほえみ’と‘つくし早生’の収量と玄米窒素含有率からみた合理的施肥法の確立を目的として，両品種の幼穂形成期，穂揃期および成熟期までの窒素吸収量と，生育・収量および玄米窒素含有率との関係について検討した。その結果，収量および玄米窒素含有率の両面から望ましい窒素吸収量の目標値とこれに対応する収量レベルは
１‘ほほえみ’で幼穂形成期に5.5gm^－２，穂揃期9.5gm^－２，成熟期11.5gm^－２で収量水準は550gm^－２，目標籾数は㎡当たり30,000粒，
２‘つくし早生’では幼穂形成期に7gm^－２，穂揃期10gm^－２，成熟期に10.5gm^－２で，収量水準は560gm^－２程度で㎡当たり籾数は26,000粒であった。
また，‘ほほえみ’よりも‘つくし早生’の方が，窒素の玄米生産効率が高く，成熟期窒素吸収量が同一の場合，収量が高かった。

［キーワード：玄米窒素含有率、水稲、窒素吸収、早生品種］

　Influence of Varietal Characteristics and Uptake of Nitrogen on the Growth, Yield and Quality of Rice in Fukuoka Prefecture (1). The Optimum Pattern of Nitrogen Uptake for Stable Yield and Nitrogen Content in Brown Rice of Early Varieties of　'HOHOEMI' and 'TSUKUSHIWASE'. ARAKI Masato, Tomizou YAMAMOTO and Kohei TANAKA (Fukuoka Agricultural Research Center, Chikushino, Fukuoka 818-8549, Japan) Bull. Fukuoka Agric. Res. Cent. 21: 6 10　(2002)

　To establish the optimum method of fertilization recommendation for improvement of yield and inhibition of increasing N content in brown rice, a study was conducted to know the relationship between the amounts of nitrogen(N) uptake at three major growth stages and yield and N content in two early brown rice varieties namely 'HOHOEMI' and 'TSUKUSHIWASE'. The results revealed that, at the same level of N uptake at harvest stage of both the varieties, the yield and N use efficiency of 'TSUKUSHIWASE' brown rice was higher than that of 'HOHOEMI'. The optimum pattern of N uptake for achieving high yield and low N content in brown rice was as follows: (1). The optimum amount of N uptake at panicle formation stage, full heading stage and at harvest stage was 5.5, 9.5 and 11.5gm^－２ respectively for 'HOHOEMI' variety. (2). In case of 'TSUKUSHIWASE' variety, the optimum amount of N uptake at panicle formation stage, full heading stage and at harvest stage was 7, 10 and 10.5gm^－２ respectively. Further, the total yield and number of spikelets per　m^２ for 'HOHOEMI' were 550gm^－２and 30,000 and that of 'TSUKUSHIWASE' were 560gm^－２and 26,000 respectively.