Can the productivity of mango orchards be increased by using high-density plantings?

Abstract

Mango (Mangifera indica) trees are traditionally established at about 100–200 trees per ha and eventually grow into large specimens 10m tall or more, making spraying and harvesting difficult. It also takes a long time to recover the initial costs of establishing and maintaining the orchard. There has been considerable interest in planting orchards up to 4000 trees per ha to take advantage of early production and to increase economic returns. However, trees planted at high density soon begin to crowd and shade each other and production falls. We reviewed the performance of high-density orchards in different growing areas, and the role of dwarfing cultivars and rootstocks, tree canopy management and the growth regulator, paclobutrazol to control tree growth. There has been no general agreement on the optimum planting density for commercial orchards which vary from 200–4000 trees per ha in different experiments. Some potential dwarfing material has been developed in India and elsewhere, but these cultivars and rootstocks have not been widely integrated into high-density orchards. Canopy management needs to take into account the effect of pruning on the regrowth of the shoots and branches, light distribution through the canopy and the loss of the leaves that support the developing crop. Pruning must also take into account the effect of vegetative growth on flower initiation. Annual light pruning usually provides better fruit production than more severe pruning conducted less regularly. There have only been a few cases where it has been demonstrated that paclobutrazol can counteract the negative effect of pruning on flowering and fruit production. There are also concerns with residues of this chemical in export markets and contamination of ground waters. The future development of high-density plantings in this crop is dependent on the use of dwarfing cultivars and/or rootstocks and better canopy management strategies. Dwarfing cultivars and rootstocks should provide small- to medium-sized trees with medium to large yields. This can readily be identified in experiments by examining the relationship between yield and tree growth. Research on canopy management should assess the impact of pruning on flowering, light distribution within the canopy and the leaf area supporting the developing crop. The productivity of mango is not likely to be increased by the use of high-density plantings without extensive efforts in plant breeding and canopy management.