水苔介質栽培蝴蝶蘭後物化性質之變化

Abstract

蝴蝶蘭 (Phalaenopsis spp.) 為臺灣重要之盆花與切花作物，主要以具有良好通氣性與保水性的水苔 (sphagnum moss) 為栽培介質。然而，水苔有在使用後容易分解、腐敗及酸化的疑慮，以及水苔的物化性質改變，對植株生長可能造成之影響。另外目前無法確定使用前進行消毒是否會加速水苔的劣化。本研究欲探討介質乾濕循環、種植蝴蝶蘭及肥料對水苔物化性質的影響，蝴蝶蘭在全新與種植過植株的水苔中生長之差異，以及水苔消毒方式對水苔及植株的影響。 本研究在十個月間以蒸餾水澆灌水苔作為對照組，以種植蝴蝶蘭及澆灌肥料作為處理組，探討植株以及肥料對水苔物化性質之影響。無種植蝴蝶蘭並澆灌蒸餾水的水苔，總孔隙度因被壓實而下降，使充氣孔隙度及容器容水量分別下降2.2%及8.8%；澆灌液肥則導致pH下降，不影響物理性質；種植蝴蝶蘭十個月後，水苔的葉狀體變形脫落較嚴重，但葉狀體細胞維持完整。將植株移出水苔後調查水苔的物理性質，與開始時無明顯差異，表示水苔於種植十個月後僅輕微分解；但根部留存在水苔中調查物理性質，根部生長導致盆器內總孔隙度與容器容水量分別下降21.1%-26.6%及19.7%-27.4%，澆灌肥料使根部生長量提升，總孔隙度與容器容水量下降的幅度較大，而充氣孔隙度並無改變。 另一試驗中使用全新以及栽種過蝴蝶蘭四個月的水苔種植蝴蝶蘭，觀察新舊水苔對植株生長的影響，並調查乾濕循環中介質氣液相比例的變化。隨根部生長，介質固相比例增加，使總孔隙度下降，導致氣相和液相比例下降。舊水苔的物理性質與新水苔無差異，但蝴蝶蘭在新水苔中具較好的生長勢。雖然新水苔與舊水苔的CEC值相似，但新水苔介質溶液的EC值較高，顯示新水苔具較好的保肥能力，使蝴蝶蘭有較佳的生長勢。取換盆至2.5寸盆內0、10、18個月的蝴蝶蘭植株，以水滴滲透時間測定判斷水苔之疏水性，疏水性隨著栽培時間逐漸降低，但盆器內容水量因根部生長逐漸下降，最終使總體吸水量下降。 探討消毒方式對水苔物化性質的影響，分別以次氯酸水、80℃熱水和滅菌釜消毒水苔。結果顯示各消毒處理並未影響水苔的物理性質，且栽培蝴蝶蘭十個月間各處理的水苔僅輕微分解，其中蝴蝶蘭於次氯酸水處理與熱水消毒處理中生長勢較好，而熱水消毒能更有效地抑制雜草種子的萌發。 綜合以上，水苔於栽培蝴蝶蘭後葉狀體外形略有改變，但不影響其本身物理性質，而新的水苔保肥能力較佳，使植株具較好的生長勢。隨著蝴蝶蘭根部生長，壓縮盆器內的空間，孔隙度、通氣性與保水力大幅度下降，不容易保留澆灌之液體，雖水苔本身物理性質未改變，但仍需定期加大盆器尺寸避免蝴蝶蘭根部生長造成的介質通氣性及保水力下降問題。熱水消毒並不會破壞水苔結構或加速水苔分解，且可有效去除水苔內的雜草種子活性，相對其餘消毒方式植株生長勢較佳，故較適合應用於蝴蝶蘭產業。

Phalaenopsis spp. is an important potted plant and cut flower crop in Taiwan. The main substrate for Phalaenopsis cultivation is sphagnum moss due to its good aeration and water retention capacity. However, there are concerns about the decomposition and acidification of sphagnum moss. These changes in physicochemical properties might affect plant growth. Furthermore, the effects of various disinfection methods on the physicochemical properties of sphagnum moss are unclear. This study aimed to investigate the effects of medium dry-wet cycles, Phalaenopsis planting, and fertilizer on the physicochemical properties of sphagnum moss, the growth of Phalaenopsis grew with new or used sphagnum moss, and the effects of disinfection methods of sphagnum moss on Phalaenopsis. In this study, we irrigated sphagnum moss with distilled water for ten months as a control, Phalaenopsis planting and fertilizing as treatments to investigate the effects of plant and fertilizer on the physicochemical properties of sphagnum moss. Sphagnum moss without planting Phalaenopsis and irrigated with distilled water was compacted by water which caused a decrease in total porosity, air-filled porosity by 2.2%, and container capacity by 8.8%. Fertilization decreased the pH value of sphagnum moss, but it did not change the physical properties. Ten months after planting Phalaenopsis, the thallus of sphagnum moss dropped and distorted, but the cell structure of sphagnum did not change. We investigated the physical properties after removing the plant from sphagnum moss. The physical properties were with no difference from the start of the experiment, indicating that sphagnum moss only decomposed slightly after cultivation. However, we investigated the properties of sphagnum moss with roots remained, the total porosity and container capacity decreased by 21.1%-26.6% and 19.7%-27.4%, respectively, but the air-filled porosity did not change. The root growth of Phalaenopsis increased by fertilization, and it caused the magnitude of the decrease in total porosity and container capacity. In another experiment, new and old sphagnum moss, which had been used to plant Phalaenopsis for four months before the experiment, were used to observe the effects of old sphagnum moss on plant growth. We also investigated the changes in the percentage of air and liquid phases of the medium in several dry-wet cycles. As the roots grew, the percentage of solid phase increases, resulting in a decrease in total porosity, liquid, and air space. The physical properties of the old sphagnum moss were not different from those of the new sphagnum moss. Still, the Phalaenopsis had better growth in the new sphagnum moss. Although the CEC values of the new and old sphagnum moss were similar, the pore-water EC value of the new sphagnum moss was higher. Hence, the new sphagnum moss had better nutrient holding capacity, which may be the reason for the better growth of Phalaenopsis. We used Phalaenopsis plants which have been transferred to 7.5-cm pots for 0, 10, or 18 months to evaluate the hydrophobicity of sphagnum moss by water drop penetration time test (WDPT). The hydrophobicity of sphagnum moss gradually decreased with the cultivation time. Still, the water holding capacity decreased owning to the root growth, resulting in a decrease in the total amount of water absorbed by the sphagnum moss. To realize the effect of disinfection methods on the physicochemical properties of sphagnum moss, Hypochlorous acid, 80℃ hot water, and autoclave were used to disinfect the sphagnum water moss. Sphagnum moss in each treatment was only slightly decomposed in ten months. Phalaenopsis grew better in the sphagnum moss disinfected with hypochlorous acid and hot water, and hot water disinfection could effectively prevent the weed germination. In conclusion, the appearance of sphagnum moss changed slightly after cultivating Phalaenopsis, but the physical properties of sphagnum moss did not change. However, the new sphagnum moss had better nutrient holding capacity, which resulted in better growth in Phalaenopsis. As the roots of Phalaenopsis grew and compressed the space in the container, the porosity, aeration, and water holding capacity of sphagnum moss were significantly reduced, and it is thus harder to retain water in a container. In essence, the physical properties of the sphagnum moss itself did not change, but it is still necessary to regularly transfer the plants to a larger pot size to avoid the problem of the decrease in aeration and water retention. Hot water disinfection did not damage the cell structure of sphagnum moss nor accelerate the decomposition of sphagnum moss. Thurthemore, it can effectively inhibit seed gerimination of weed in the sphagnum moss. Compared with other disinfection methods, the plant growth vigour was betterin hot-water treated sphagnum moss, indicating hot water disinfection is more suitable for Phalaenopsis cultivation.