The effects of alternative training and planting systems on light relations in Mangifera indica (Mango) orchards in Far North Queensland

Part of a project to transform subtropical/tropical tree productivity in Queensland is a study of light relations in mango (Mangifera indica) orchards in Far North Queensland. A study of the baseline relationship between light interception, canopy volume and yield in ‘Kensington Pride’ trees found that as canopy volume increased, light interception reached a maximum between 61 and 68%. The relationship between light interception and tree yield (t ha-1) varied over two years highlighting the biennial bearing habit of mango. An associated ongoing study is looking at the effects on light interception, canopy volume and yield for three mango cultivars, resulting from various planting density and tree training systems. The planting systems being studied include three planting densities: low density (208 trees ha-1, 8×6 m), medium density (450 tree ha-1, 6×4 m) and high density (1250 trees ha-1, 4×2 m) and two training systems (conventional and single leader) in three commercial mango cultivars (‘Keitt, CalypsoTM’ and ‘NMBP 1243’). The first year’s results have indicated that density and cultivar had significant effects on light interception in 1.5-year-old trees. ‘Keitt’ canopies had higher light interception than ‘CalypsoTM’ or ‘NMBP1243’, while high density plantings intercepted significantly more light. Training system also increased light interception from 1.38% in the low-density conventional planting to 9.5% in the single leader, high-density planting although this increase was not significant. There were also significant positive relationships between light interception and canopy volume (m3 ha-1). When both experiments are considered the results suggest the total light interception in 1.5-year-old, high-density trees (9.2%) was similar to the total light interception of 4-year-old trees (11.0%) in the baseline study. These results highlight the benefits of high density plantings in increasing total orchard light interception earlier than in conventional low-density mango orchards. In the future, the relationships between yield, canopy volume, light interception and training systems will be further examined in the planting systems experiment. © 2018 International Society for Horticultural Science