@article{oai:miyazaki-u.repo.nii.ac.jp:00003374,
 author = {西口, 友広 and 清水, 友 and 大田, 守也 and 佐伯, 雄一 and SAEKI, Yuichi and 赤尾, 勝一郎 and Akao, Shoichiro and NISHIGUCHI, Tomohiro and SHIMIZU, Tasuku and NJOLOMA, Joyce and OOTA, Moriya and 赤尾, 勝一郎 and Akao, Shoichiro},
 journal = {宮崎大学農学部研究報告, Bulletin of the Faculty of Agriculture University of Miyazaki},
 month = {Mar},
 note = {沖縄県やその周辺諸島では地下水の硝酸態窒素汚染が深刻な問題となっており,沖縄での基幹作物であるサトウキビ畑からの流出窒素の低減が求められている.そこでサトウキビに内生する窒素固定細菌を活用した施肥窒素の低減が期待されでおり,本試験では硝酸態窒素濃度が与える植物体の生育や窒素固定活性への影響を調査した.試験には特性の異なる三品種(Ni15,F172,NiF8)を供し,茎内の窒素固定細菌数を計測すると共に,幼植物を重窒素標識したKNO_30.5mMを加えたMS無窒素培養液を用い,窒素供給の継続・停止区に分け水耕栽培を行った.その結果として,窒素固定寄与率は窒素供給停止により全ての品種で向上が認められたが,乾物重では窒素継続区に比較して減少しており植物本来の窒素要求量には満たなかったと考えられた.しかし,窒素停止処理区のNi15は窒素継続区のNiF8と乾物重において同等の生育を示した.Ni15は早期高糖性品種であり窒素固定細菌の増殖に有利な特性を有し,また本試験では全体に占める根の乾物割合が他品種と比較して高いという特徴が認められ,土壌窒素の高い吸収量が示唆された.これらのことから低窒素の同一環:境下においてNi15は窒素固定寄与率が高く,同時に土壌窒素の吸収量も高いと考えられ,緩効性肥料を用いた施肥形態との適合性が高く,硝酸態窒素汚染問題の解決のための有用な品種である可能性が示唆された., Recently, the pollution of underground water by nitrate nitrogen which flows from sugarcane fields has been a major problem in Okinawa. Therefore, it is expected that the use of biologically fixed nitrogen will reduce the amount of fertilizer nitrogen. In this study, we estimated the contribution of N_2-fixation by bacteria existing inside sugarcane plant tissues to total nitrogen in sugarcane by using ^15N dilution technique. Cultivars (Ni 15, F 172 and NiF 8) of different characteristics were used in the determination of the number of N_2-fixing bacteria inside the stem of parent sugarcane plants before sprouting new shoots, new-grown shoots were cultivated in 100 ml MS nitrogen free liquid medium with and without K^<15>NO_3 (^15N : 10.3 atom% ). It was expected that by terminating K^<15>NO_3 supply the activity of the endophyte will be enhanced. However, considering the amount of dry weight in K^<15>NO_3 terminated treatments, it is not enough to supply the nitrogen which host plant demand. But, cultivar Ni 15 in K^<15>NO_3 terminated treatments showed equal growth to cultivar NiF 8 in K^<15>NO_3 continuation treatments. Cultivar Ni 15 is an early high-sugar cultivar, and it's conceivable that this characteristic enhances growth of N_2-fixing bacteria. Ni 15 showed higher rate of root dry weight than the other cultivars thus, with the high root biomass it can be suggested that the amount of absorbed soil nitrogen could also be high. Therefore, it's considered that cultivar Ni 15 has high contribution of N_2-fixation by bacteria and high absorption of soil nitrogen. These characteristics fit in well with the fertilizer placement method used for delayed release fertilizer, it can be suggested that cultivar Ni 15 could be utilized to reduce 'pollution of underground water by nitrate nitrogen.},
 pages = {53--62},
 title = {15N同位体希釈法によるサトウキビの固定窒素量の推定},
 volume = {51},
 year = {2005},
 yomi = {ニシグチ, トモヒロ and シミズ, タスク and オオタ, モリヤ and サエキ, ユウイチ and アカオ, ショウイチロウ and アカオ, ショウイチロウ}
}