土壤含水量對菊花生長、開花與切花品質之影響

Effects of Soil Water Content on Growth, Flowering, and Cut flower Quality of Chrysanthemum Cultiva

本研究探討土壤含水量對四品種菊花[Dendranthema×grandiflorum（Ramat.）Kitam.]不同生長時期生長和切花品質之影響。在土壤含水量測定方法上，分析土壤體積含水量測定儀WaterScout SM100測定結果與重量法之相關性，結果兩者數值呈直線正相關。‘F15’、‘雙色紅’（‘Remix’）、‘花御殿’（‘Hua-Yu-Dieng’）和‘青心黃’（‘Regatta’）菊花於可見花苞前，以低土壤含水量（14%）處理使株高與葉片數大幅下降，但使葉綠素計讀值增加。在過高含水量（48%）處理之‘青心黃’株高、葉片數和葉綠素計讀值皆下降。土壤含水量30%處理之四品種菊花皆生長良好。四品種菊花於可見花苞後進行不同土壤含水量處理對開花期皆無影響；但低含水量（14%-22%）會使採收時花徑、主花序梗長下降，對‘雙色紅’與‘青心黃’多花菊則會減少採收時顯色之花數。‘雙色紅’及‘青心黃’栽培於高含水量（40%-55%）下，採收時花徑較大，但瓶插時花朵開放數無顯著差異。可見花苞後限水至土壤含水量14%和22%會使四個品種於切花瓶插時氣孔導度和蒸散速率降低，導致切花鮮重下降幅度較緩。然而，不同土壤含水量處理對四品種菊花瓶插壽命影響不大。綜合本研究結果顯示，參試之四品種菊花於可見花苞前宜栽培於含水量30%之土壤；於可見花苞後降低土壤含水量至14%-22%，可減少瓶插時鮮重降低。 This study investigated the effects of soil water content on growth and cut flower performance of four chrysanthemum [Dendranthema ×grandiflorum (Ramat.) Kitam.] cultivars. The volumetric water content (VWC) was compared with two methods. Results showed a linear relationship exists between VWCs, as measured with WaterScout SM100 soil moisture sensors (SM100) and gravimetric method. Four VWC treatments were given during the period from planting to visible floral bud stage. Results showed that chrysanthemum 'F15', 'Remix', 'Hua-Yu-Dieng', and 'Regatta' grown at 14% VWC as measured with SM100 exhibited reduced plant height and leaf number, but increased SPAD-502 value. 'Regatta' grown at 48% VWC exhibited reduced plant height, leaf number, and SPAD-502 value. All chrysanthemum cultivars grew well at 30% VWC. Time to anthesis was not altered in four chrysanthemum cultivars under 14%-55% VWC after visible floral bud stage. Deficit-irrigation (14%-22% VWC) resulted in smaller inflorescence diameter, shorter main peduncle length, and fewer show-colored flower buds of 'Remix' and 'Regatta' at harvest. High-irrigated (40%-55% VWC) 'Remix' and 'Regatta' plants had higher inflorescence diameter than deficit-irrigated plants. After visible floral bud stage, the deficit-irrigated plants of four cultivars had lower stomatal conductance and transpiration rates during vase, which led to better water balance and slower water loss. However, all four irrigation regimes resulted in similar number of opened inflorescences during vase life. We concluded that prior to floral bud stage, the four chrysanthemum cultivars should be well-irrigated to 30% VWC, as measured with SM100. After visible floral bud stage, plants of four cultivars at 14%-22% VWC produced cut flowers with delayed water loss.