椪柑採收前斷水處理對土壤水分含量變化與果實品質之影響

Influence of Refraining Water Supply Before Harvest on Soil Water Content and Fruit Quality of 'Ponkan' Mandarin (Citrus reticulata Blanco)

為探討採收前斷水處理對土壤水分含量及‘椪柑’果實品質之影響，試驗果樹分別於採收前56日、28日、14日、7日及3日施行斷水處理，每處理4株，計20株。斷水後土壤含水量逐漸減少，較早斷水者土壤水分張力漸升至90cbar以上，並維持在較乾狀態。晚斷水者土壤含水量相對較高，土壤水分張力值相對維持較低，約在60cbar左右。斷水遲早與土壤含水量對果實轉色程度、果重及果汁率無顯著影響。但較晚斷水者果實分級過程損傷率、浮皮率及體積有增加之趨勢。早斷水者可溶性固形物含量三年中有二年呈增加之趨勢，而含酸量則三年皆呈增加之趨勢。 The influence of refraining water supply before harvest on soil water content and fruit quality of 'Ponkan' was investigated for 3 consecutive years. Irrigation was ceased for 56, 28, 14, 7, or 3 days prior to harvest. Early refraining water supply caused soil water tension to increase above 90 centi bar and the soil at drier condition. Irrigation regularly until 3 days before harvest resulted in higher soil water content and soil water tension at 60 centi bar. The starting time of refraining water supply did not significantly affect fruit coloration, weight per fruit, and fruit juice content. However, delayed refraining water supply resulted in increased fruit damage during grading, fruit puffing and fruit size. Early refraining water supply resulted in higher fruit soluble solids in 2 out of 3 years and higher titratable acidity in all 3 years of observations.