Comparative Assesement of Fruit Develpoment Behaviors and Sugar Acid Cumulant of Two Blackberry(Rubus spp.) Cultivars

The characters of fruit development of two cultivated blackberry cultivars Boysen and Kiowa were investigated.The results showed that blackberry fruit development was divided into the three stages of rapid growth stage,stationary growth stage and mature growth stage.Rapid growth stage occupied 15%—20% development duration,during which fruit average diameter increased quickly,sugar and acid accumulated slowly,sugar acid ratio stagnated or increased;Stationary growth stage occupied 50%—60% development duration,during which fruit weight and average diameter increased slowly,the accumulation rate of reducing and total sugar decreased,and that of titratable acid increased quickly,sugar acid ratio decreased,the titratable acid accumulation of Kiowa fruit was mainly in this stage.Mature growth stage occupied 20%—30% development duration,during which fruit weight and the accumulation rate of reducing and total sugar acid increased quickly and sugar acid ratio increased quickly.Mature growth stage is the main stage of sugar accumulation in fruit,and it is also the main titratable acid accumulation stage of Boysen fruit.