'帝王'番石榴果實品質之變化以冬季果(11-4月採收)、全可溶性固形物(10-11.3°Brix)及抗壞血酸(219-266mg/100g)均較高，7-9月採收夏季果則品質較差，且果實硬度明顯較低，全可溶性固形物、抗壞血酸及可滴定酸均較冬季果低。葉片微量元素之變化以4-7月急速下降，而果實微量元素之濃度較葉片低，但以3-9月有較高之濃度。大量元素之變化，葉片鉀濃度以4-8月份較低，而果實則較高，其關係互為消長，顯示葉片鉀可移動至果實，而鈣之變化以8月份果實鈣濃度最低，此與夏季果實硬度偏低有關，鎂濃度葉片與果實之變化呈同步之趨勢，果實氮濃度以4-8月較高，12-1月份較低，夏季果實高氮低鈣與可溶性固形物及硬度偏低有關。Seasonal fluctuations in mineral elements and fruit qualities of guava 'King' were investigated in this experiment. Results showed the winter crop, which was harvested from November to April, had total soluble solids of 10-11.3Brix and 219-266mg/100g ascorbic acid. These figures together with fruit firmness were relatively higher than those of summer crop (harvested from July to September) indicating a superior fruit quality. Moreover, leaf microelement concentrations decreased sharply from April to July, whereas fruits microelement increased from March to September. Leaf potassium concentration was found to be lower in April to August as compared with fruits. This indicated that potassium had been transported from leaves to fruits, as K is highly mobile element. Calcium concentration was lowest in August; this seemed to be responsible for the low firmness of fruits harvested during summer. Magnesium had the parallel pattern of changing in both leaves and fruits. Fruit nitrogen concentration increased from April to August, however, decreased from December to January. High nitrogen and low calcium seem to be related to the less firmness and total soluble solids of guava fruits harvested during summer months
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