Effects of different cultural practice on the occurrence of reddish-pulp fruit and fruit development in 'Beni Shimizu' peach [Prunus persica]

Using 'Beni Shimizu' peach (Prunus persica (L.) Batsch) trees maintained by light pruning with heavy disbudding (LP) or conventional method (CM) as heavy pruning with no disbudding fruit development was investigated in relation to the occurrence of reddish-pulp for four years. Fruits harvested from LP trees had a higher rate of reddish-pulp development, whereas in fruits harvested from CM trees the percentage was low, irrespective of the year surveyed. LP trees resulted in greater yield compared to CM trees. Nitrogen content in the flesh of fruits was significantly higher in LP trees than in those of CM trees during stage 1 of fruit development. When carbohydrate concentrations in the cane and root of LP and CM trees were compared between before and after full bloom, the former trees showed a greater decrease than the latter. Throughout fruit development, the diameter of cells in the flesh of fruits from LP trees was significantly larger than those from CM trees. Besides, the fruit growth rate was greater in the former than in the latter at stage 3 of fruit development. Fruits harvested from LP trees attained higher weight than those from CM trees. Total soluble solid contents of the juice in fruit harvested were significantly higher in LP trees than in CM trees. In LP trees, shoot growth ceased by the beginning of stage 2 of fruit development, while in CM trees, shoot growth continued until stage 3. In LP trees, anthocyanin concentration in the flesh of fruit increased rapidly just before harvest. Total phenolic concentration in the flesh was higher in fruits from LP trees than in those from CM trees throughout fruit development. Further, there was a higher L-phenylalanine ammonia-lyase (PAL) activity in fruit from LP trees than in those from CM trees. Based on these results, the relationship between pruning levels and the occurrence of reddish-pulp in peach fruit is discussed.