洋桔梗生長發育階段之營養元素含量與濃度

Abstract

取洋桔梗'Engage White'具3－4對葉的穴盤苗，在11－12h日長、平均最大光強度為682 μmol．m^(-2)．s^(-1)，平均日／夜溫為21/18℃的溫室內以強生氏養液（Johnson's solution,半量巨量元素、全量微量元素）水耕方式栽培，調查植株生長及植體元素分析。在水耕133天的四個生長階段中，第一階段為開始水耕定植至小苗具4－6對肉眼可見之葉片時開始抽苔，此階段生長與營養元素含量不高。第二階段為抽苔至花芽創始階段，生長與營養元素含量緩幅增加。第三階段為花芽創始至可見花苞，此時生長與營養元素含量皆穩定增加。第四階段為可見花苞至開花，期間之乾重與巨量元素含量急遽增加。植株巨量元素的累積含量依序為氮＞鉀＞鈣＞鎂＞磷，而微量元素的含量依序為鐵＞錳＞鋅＞銅。第二、三階段之植體氮濃度維持在48－65g．kg^(-1)，於可見花苞後氮濃度遞減降至38－41g．kg^(-1)。自抽苔後至可見花苞期間之植體鉀濃度維持於30－32g．kg^(-1)，於可見花苞後植體鉀濃度遞減降至16－18g．kg^(-1)，而鈣、鎂及磷濃度在第二、三、四階段變動不大，鈣濃度維持於3.2－7.0g．kg^(-1)、鎂濃度維持於3.2－5.8g．kg^(-1)、磷濃度維持於3.9－7.3g．kg^(-1)。 Seedlings of Eustoma 'Engage White', with 3-4 leaf-pairs, were grown hydroponically with half-strength macronutrients and full-strength micronutrients of Johnson's solution in a greenhouse at day and night temperature 21/18°C under 11-12 h natural daylengths with an average maximum photosynthetic photon flux of 682 μmol．m^(-2)．s^(-1) throughout the experiment. Plant growth and nutrient analysis in shoot or leaves were measured. During the 133-days experiment, four growth stages could be divided. Stage 1 started from transplanting to bolting with 4-6 leaf-pairs, and during this period the growth and nutrient content were at its lowest. Plant growth and nutrient content were relatively low in stage 2 from stem bolting to flower initiation. Dry weight and macronutrient and micronutrient contents increased steadily from flower initiation to flower bud visibility during stage 3. Plants accumulated dry weight and nutrient contents most rapidly during stage 4 from flower bud visibility to anthesis. The order of macronutrients content of Eustoma was N ＞ K ＞ Ca ＞ Mg ＞ P, and the order of micronutrients was Fe ＞ Mn ＞ Zn ＞ Cu. Shoot N concentration remained at 48-65 g．kg^(-1) in plants during stage 2 and 3, and decreased gradually to 38-41 g．kg^(-1) after flower bud visibility. Shoot K concentration remained at 30- 32 g．kg^(-1) in plants during stage 2 and 3, and decreased gradually to 16-18 g．kg^(-1) after flower bud visibility. The concentrations of shoot Ca, Mg and P in plants changed little during stages 2, 3 and 4. Shoot Ca concentration remained at 3.2-7.0 g．kg^(-1). Shoot Mg concentration remained at 3.2-5.8 g．kg^(-1). Shoot P concentration remained at 3.9-7.3 g．kg^(-1).