Departmental Bulletin Paper Effects of Planting Bed Height and the Use of Plastic Mesh as Ground Cover on the Flowering of Citrus Trees

西川, 芙美恵  ,  ルサダ, エリッツァ  ,  メルガー, ワン カルロス  ,  バブ クンタ, マブラ  ,  セタモウ, マモデュ

(1)  , pp.1 - 8 , 2017-03-30 , 国立研究開発法人 農業・食品産業技術総合研究機構 , National Agriculture and Food Research Organization (NARO)
The effects of planting bed height and the use of a plastic mesh as ground cover on the flowering and fruit production of 3-year-old grapefruit trees (Citrus × paradisi Macfad) were investigated. Trees planted on a raised or flat bed with or without a black polypropylene mesh as ground cover were compared. From August 2014 to January 2015, the expression of one of the flowering-related genes, citrus FLOWERING LOCUS T (CiFT), was analyzed in stem tissues. The expression level of one of the CiFT homologs (i.e., CiFT2) started to increase in October, which corresponded to the beginning of the citrus flowering period in southern Texas, USA. CiFT2 expression levels were higher in trees planted in beds without ground cover than in trees grown in beds with ground cover, regardless of bed height. In the following spring, trees planted in beds without ground cover produced more inflorescences per node than trees grown in beds with ground cover. There was no significant difference in flowering intensity between trees planted in raised and flat beds. Trees planted in covered beds were larger than trees grown in non-covered beds, regardless of bed height. These results suggest that the use of ground cover affects CiFT2 expression, the balance between generative and vegetative growth, and tree canopy size, all of which may influence fruit yields.
本研究では,高畝の有無及びポリプロピレン製黒色マルチの有無がグレープフルーツ3年生樹の花成に及ぼす影響を調査した。2014 年8 月から2015 年1 月まで花成関連遺伝子の一つであるカンキツFLOWERING LOCUS T (CiFT) の発現を茎組織で定量した。南テキサスにおいてカンキツの花成は10 月に始まるが,CiFT ホモログの一つ,CiFT2 の発現がどの処理区においてもこの月に増大し始めた。実験期間中,CiFT2 の発現量は高畝・平坦にかかわらず,マルチ無しで植栽された樹で高かった。翌春に観察された花芽数はマルチ有りよりもマルチ無しで多かった。高畝と平坦の間で花芽数に有意差はなかった。樹の大きさは地面の高さに関係なくマルチ有りで大きかった。マルチ無しでは,高畝の方が平坦より樹が大きかった。これらの結果から,マルチ敷設はCiFT2 の発現,生殖・栄養生長のバランスおよび樹冠容積に影響を与えると思われる。

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