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Title :南西諸島におけるジャイアントスターグラス草地の低温期生産性に及ぼすイタリアンライグラス追播量の影響
Authors :波平, 知之
石垣, 圭一
井村, 信弥
堤, ひとみ
岡, 朋子
屋良, 朝宣
玉城, 政信
Issue Date :2018
Abstract :ジャイアントスターグラス(GS)草地に,低温期にイタリアンライグラス(IR)を4 水準(0.7,1.0,1.5,2.5 g/㎡)で追播し,播種量が混播草地の乾物収量ならびにGSとIRの競争関係に及ぼす影響を,南西諸島で検討した.IR 追播に伴う増収は刈取り回次で異なり,全ての処理区で増収効果があったのは平均気温が最も低かった2 回目刈取り時のみであった.低温期間内の3 回の刈取り合計乾物収量は,処理区間での有意差はなかったが,播種量の増加に伴い収量構成割合はIRで増加し,GSで減少した.IR追播区の相対収量(RY)も,GSとIRの両種ともに0.5 以上とはならず,どちらか一草種の優位性によってRYが0.5 以上となるのみであり,他草種の生長を抑制する競争関係にあると推察された.低温期間中,全ての刈取り時に合計相対収量(RYT)が1 以上となったのは,IR追播量が0.7 g/㎡の処理区のみであった.
A field experiment was conducted to determine the optimum over-seeding rate of Italian ryegrass (IR) among four levels 0.7, 1.0, 1.5 and 2.5 g/㎡) on cool-season production of giant stargrass (GS) stand in south-western Okinawa island, Japan. The effect of over-seeding IR was positive only at the second cutting among three defoliation, due to the lowest air temperature at 18.3℃ during the regrowth period. Cumulative dry matter yield among three cuttings tended to be higher at IR seeding rate of 0.7g/㎡ than GS pure stand. The yield of IR increased with the increasing over-seeding rates, while that of GS decreased. Relative yield (RY) of GS and IR, determined by yields of mixed grown GS and IR relative to those of pure GS and IR stands, respectively, was over 0.5 only in one species, however relative yield total (RYT), determined by sum of RY of both species, was over 1.0 only at IR over-seeding of 0. 7 g/㎡ in all three cutting times. The interspecific competition was causes of limiting growth of the species in mix culture. From these results, it is concluded that IR over-seeding at 0.7 g/㎡ to GS stand might be effective for getting higher yield in cool-season in south-western Okinawa island, Japan.
URL :https://doi.org/10.11461/jwaras.61.77
Type Local :雑誌掲載論文
ISSN :2185-1670
Publisher :日本暖地畜産学会
URI :http://hdl.handle.net/20.500.12000/44789
Citation :日本暖地畜産学会報 Vol.61 no.2 p.77 -82
Appears in Collections:Peer-reviewed Journal Articles (Faculty of Agriculture)

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