地表覆蓋資料對兔眼藍莓生長及雜草防治之影響

Effects of Mulching Materials on Growth and Weed Control in Rabbiteye Blueberries

以樹皮或木屑行地表覆蓋為商業藍苺栽培的重要田間管理作業，但兩者在臺灣因成本及來源考量，不符合經濟效益。本研究以易取得且成本低的稻殼及銀黑色塑膠布，與進口樹皮進行比較，探討不同覆蓋資材對藍苺果園土壤理化性質、植株生育及雜草防治的效果，以期找出可替代樹皮之材料。2015 年春於田間定植'Blueshower'兔眼藍苺（Vaccinium virgatum Ait.）後，以松樹皮、稻殼或塑膠布行土表覆蓋處理，並以無覆蓋作為對照組。處理6 個月後，經稻殼及松樹皮覆蓋之土壤酸鹼值（pH）及電導度（EC）與對照組無顯著差異，但塑膠布覆蓋下之土壤pH 值下降，EC 值上升。松樹皮及稻殼覆蓋下之土壤溫度於夏季高溫期低於其它兩組，但於冬季低溫期則較高；三種覆蓋處理之土壤含水率皆顯著高於對照組。樹皮及稻殼覆蓋顯著提高枝條生長量與花芽數量，塑膠布覆蓋處理則顯著提高冬季落葉率。覆蓋處理一年後，距植株基部25cm，地表15cm 內，松樹皮覆蓋處理之根系總面積及根徑1 mm 以下根系面積最高，而稻殼覆蓋處理根徑1 mm 以上根系面積最高。樹皮及稻殼覆蓋之植株根系發展至表土上與覆蓋物間。雜草防治效果以塑膠布覆蓋最佳，稻殼與樹皮覆蓋相似，對照組雜草最多。稻殼分解速度較松樹皮快，須每年補充覆蓋物。總體而言，稻殼與松樹皮覆蓋處理表現良好且相似，而稻殼兼具環保、實用及經濟性，可以替代松樹皮作為臺灣藍苺栽培的良好覆蓋資材。

Mulching with pine bark or sawdust is an important orchard practice in commercial blueberry production. However, both materials are economically impractical in Taiwan. Regarding the economical availability and feasible chemical and physical properties, rice hull and silver on black plastic film were compared with pine bark to evaluate their potential as mulching materials for blueberry cultivation. Field grown 'Blueshower' rabbiteye blueberries (Vaccinium virgatum Aiton) were mulched with pine bark, rice hull, or silver on black plastic film, or not mulched as the control. Plastic film mulch resulted in lower soil pH but higher EC while other treatments maintained more consistent soil pH and EC. Mid-day soil temperature under pine bark and rice hull were lower in the summer but higher in winter than the plastic film treatment and the control. Soil moisture content was higher with all mulching treatments than the control. Pine bark and rice hull mulching increased shoot length and number of flower buds per shoot. By the end of the first growth season, plastic film mulching had greatest percent defoliation. Within the soil 25 cm from the bush base and 0-15 cm in depth, plants mulched with pine bark produced the greatest total root area and area of root < 1 mm in diameter, while plant mulched with rice hull produced the greatest area of root > 1 mm in diameter. Fine roots extended to the mulch layers were observed on plants mulched with pine bark or rice hull. Plastic film mulching had the best weed control than the other treatments. Rice hull decomposed faster than pine bark, thus requiring annual supplement. Overall, rice hull was an environmentally friendly and an economical practical substitute of pine bark for mulching blueberry orchards in Taiwan.