PRUNING AND FERTILIZATION AFFECT FRUIT PRODUCTION OF A Malus doumeri PLANTATION

Malus doumeri, an apple species, naturally distributes in South China, North Vietnam, and Laos. It has been widely planted in North Vietnam by ethnic communities and contributed significantly to poverty reduction. In this study, the effect of fertilization and pruning on fruit production of a M. doumeri plantation was studied. There were two treatments of pruning as (C1) removing small, unproductive and dense branches which were applied in August 2018, and (C0) control/no pruning. There were four treatments of fertilization as (P1) 0.5 kg compost + 0.5 kg NPK (12:5:10)/tree, (P2) 1 kg compost + 1 kg NPK/tree, (P3) 1.5 kg compost + 1.5 kg NPK/tree which were applied in September 2018 and February 2019 and (P0) control/no fertilization. The experiment was designed by two-factor with three replicates in a randomly completed block. The results indicated that P1C0 treatment had the highest fruit production as 2.61 kg/tree/year, while the lowest fruit production belonged to P0C1 (0.78 kg/tree/year). However, the smallest fruit size was also found in P1C0 with 59 fruits/kg and a fruit diameter of 3.1 cm. It is concluded that treatment of no pruning and fertilization of 0.5 kg compost + 0.5 kg NPK/tree should be applied to M. doumeri plantation in North Vietnam, which resulted in highest fruit production. However, a cost-benefit analysis should be conducted to the present study plantation for a better recommendation in practical application.