為瞭解土壤水份變化對柑桔果實水份與糖份轉變之影響，本試驗採用六年生四季桔盆栽植株，土壤水份控制為連續乾旱、間歇性乾旱及正常灌溉等三種情形，分別測定土壤水份變化前之果實大小、水份潛勢、滲透潛勢、壓力潛勢、蔗糖、還原糖、全糖濃度以及含量等。結果顯示：乾旱處理使果實水份潛勢、滲透潛勢均降低，蔗糖轉變為還原糖，乾旱後9天漸趨平穩，上述變化顯著減緩。恢復灌水後5天，果實水份、糖份可恢復至接近乾旱處理前之情況。再度乾旱處理3天，果實水份、糖份及轉變至乾旱處理9天之狀態。乾旱處理下果實滲透壓調節作用極為明顯，蔗糖大量轉變為還原糖，以維持壓力潛勢。乾旱處理10 天每個果實內蔗糖含量減少0.52g，還原糖增加0.57g，換算蔗糖濃度降低40％，還原糖濃度提高75％，糖份總莫耳濃度提高15％。恢復灌水後5 天，每個果實蔗糖含量增加約0.45g，還原糖則減少0.3g。間歇乾旱處理下，影響果實糖份草耳濃度變化之主要因素係果實體積之縮小或膨脹，次要因素才是蔗糖轉變為還原糖。連續乾旱處理使果實甜度提高主要係果實體積縮小，糖份相對濃度提高所致，事實上糖份總含量並未增加，反而略為減少。
Calamondin trees (citrus madurensis Lour.)were used in this research to clarify the relationship between altered water availability and fruit sugar, and to determine the extent to which changes in the latter are mediated by reduced sugar import, osmotic adjustment, or sugar exit via xylem back-flow. Responses to a soil moisture cycle of ”stress:regular irrigation:stress” was compared to ”continuous stress” and ”continuous irrigation” to contrast changes in carbohydrate translocation and/or metabolism resulting from alterations in soil water availability.The results showed that water and sugar parameters appeared to stabilize in fruit after approximately 9 days of water stress. Pre-stress osmotic status was regained 5 days after reirrigation, but lost after only 3 days of additional stress. ”Sweeter” fruits produced under mild stress appeared to result from a decrease in fruit size, but sugar conversion occurred.The most striking observations in alternating stress experiments were dramatic sucrosehexose conversions in fruit apparently associated with osmotic adjustment. Under drought stress, sucrose content decreased 0.52g and reducing sugar content increased 0.57g per fruit. Calculated sucrose concentration in fruit decreased by 40％, reducing sugar concentration increased by 75％whereas total reducing sugar content per fruit increased 41％. This sugar conversion increased osmolality of the juice by 15％. The process was partially but rapidly reversed by reirrigation. Fruit volume change was the major factor contributing to alteration of osmolarity under cyclic water stress.
