Effects of Nitrogen and Phosphate on the Growth of Ceratobium-Phalaenanthe Type Dendrobium (Department of Agriculture)

Ceratobium-Phalaenantheタイプデンドロビウムの開花株を対象に,栄養生長および開花に及ぼす窒素およびりん酸の組合わせ施用の影響を調査した。試験区として窒素50∿300,りん25∿150ppmを組合わせて区を設定し,各試験区13株を対象とした。実験は2年継続して行ない発育に関する諸調査の他に,乾燥葉における要素分析も行なった。実験の結果はおよそ次のとおりである。1.栄養生長に及ぼす窒素およびりん酸施用の影響については,窒素濃度の高い区で最終葉の形成が遅れ,茎長が増加することが認められたが,全体としてはほぼ同様の生長で差は見られなかった。2.開花の諸形質についても全般に処理間の差は見られずほぼ同様であったが,窒素濃度の高い区で開花が遅れ,低い区で早まる傾向が認められた。3.葉分析値についても施用濃度との関連性は明確ではなかった。窒素濃度の100ppmの分析結果をまとめて各要素の分析値をみると,N1.5%,P_2O_50.5%,K_2O3.2%,CaO1.7%,MgO0.9%,Fe120ppm,Mn150ppmであった。4.これら処理濃度と発育の調査結果に関連性が認められなかったことについては,根が鉢の外に伸び出して接地し,それらの気根が枯死する間に,かなりの養分吸収をすることが主要因のひとつとして考えられた。An experiment was carried out to clarify the effects of nutrients with combination and concentration of nitrogen and phosphate on the growth of Ceratobium-Phalaenanthe type Dendrobium. Thirteen groups of D. cv. Lim Hepa including 13 plants in each plot were set up along the range of 50-300 ppm nitrogen and 25-150ppm phosphate. Adding to the checking on various characteristics of vegetative growth and flowering during two years, analysis of minerals in the leaves on each plot was carried out. As a result of the investigation, the following matters were clarified. 1. Regarding the vegetative growth general tendency related with combination and concentration of both nitrogen and phosphate was not clear, except the duration for maturing of stem and longer stem were obtained with the plots with the high level of nitrogen. 2. There was not any paticular tendency on the flowering characteristics either, generally, though the flowering time was delayed with the plots with the high level of nitrogen. 3. Analized values of minerals in the dry leaves showed about the same ratio of composition in each plot. Analized values of each mineral in the 4 plots mixed with 100ppm of nitrogen were as follows, N 1.5%, P_2O_5 0.5%, K_2O 3.2%, CaO 1.7%, MgO 0.9%, Fe 120ppm and Mn 150ppm etc. 4. As one of the major reasons related to the lack of clarify in the resulting phenomena above was considered to be the over extension of the aerial roots which attached themselves to the surface of the ground beneath the pots and died soon