| Summary: | 碩士 === 國立臺灣大學 === 園藝暨景觀學系 === 104 === Mulching with pine bark is a standard operation for commercial blueberry production in the USA. However, it is not economically practical in Taiwan. Alternatives with benefit similar to pine bark should be identified. Regarding the availability, economic efficiency and feasible chemical and physical properties, rice hull and silver-black plastic film were considered as potential candidates of mulching materials for blueberry cultivation. In this study, field grown ‘Blueshower’ and ‘Powderblue’ rabbiteye blueberries (Vaccinium ashei) were mulched with pine bark, rice hull, or silver-black plastic film, or not mulched as the control in 2015. Soil pH and EC were not significantly different among rice hull, or pine bark mulching and the control, but lower soil pH and higher soil EC were discovered with plastic mulching. Mid-day soil temperature under pine bark and rice hull were lower in the summer but higher in winter than the control. Soil moisture content was higher with mulching treatments than the control. Pine bark and rice hull mulching increased shoot length within the second and third flushes and number of flower buds per plant. Plastic mulching significantly increased number of defoliation before winter dormancy. Total leaf area by the end of the second flushing cycle in ‘Blueshower’ mulched with rice hull (6858.2 cm2) was significantly higher than the control (5080.8 cm2), but not different from pine bark (5709.0 cm2) or plastic film (5559.2 cm2). Fruit yield per plant in 2016 was higher but total soluble solids content was lower in plants mulched with rice hull or pine bark, berry size was smallest in plants mulched with plastic film. More roots developed on soil surface in the rice hull and pine bark mulching treatments compared to plastic film and the control. Root dry weight and root surface area in the upper 15 cm of soil increased with pine bark and rice hull mulching; however, total root area was not affected by treatments. The number of roots with diameter >1 mm was highest in plants mulched with rice hull, while the number of roots with diameter <1 mm was highest in plants mulched with pine bark. Plastic mulching was most effective on weed control than rice hull and pine bark mulching. Rice hull decomposed faster than pine bark, thus requiring supplement more frequently. Overall, rice hull performed well and was an environmental friendly, economical, and practical substitute of pine bark mulching for blueberry cultivation in Taiwan.
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