Innovative production systems for non-astringent persimmon

Abstract

Traditional production systems for growing non-astringent persimmon throughout the world have changed rapidly in the last 10 years. New systems have been developed to grow persimmon in subtropical regions of the world. In Australia most orchards are now trained to a palmette system rather than the conventional vase shape system, allowing for easier management and growth control. In contrast, in New Zealand trees are trained to a Y trellis system to improve light interception under cloudy growing conditions. Reflective mulch is also used to further maximise light use and increase fruit heat units necessary to fully mature the fruit. Tree planting densities have increased from 400 to 800 trees per hectare. In Japan high density plantings using micro-propagated trees are being evaluated. In Australia many orchards are netted to exclude birds and fruit eating bats. Multi-purpose fruit fly exclusion netting is also being evaluated as an environmentally friendly alternative to insecticidal cover sprays. New formulations of fruit fly bait sprays with greater efficacy and longer field life have also been developed. Sporadic and erratic budbreak can be a major problem in subtropical regions where trees do receive sufficient chilling. A new range of rest-breaking chemicals such as Armobreak (akolated amine) and Waiken (fatty acid esters) can increase the percentage budbreak, flowering and yield. Excessive vegetative growth during the flowering period leads to competing sinks, reducing fruit set and fruit size. The growth retardant paclobutrazol has been shown to effectively control growth reducing tree size by about 20%. Paclobutrazol also advanced the harvest period by about 2 weeks without loss of fruit quality or storage life. Attempts at improving fruit firmness and post-harvest shelf life through foliar application of Ca have been partially successful but multiple sequential applications are necessary to be effective. Preliminary studies have shown that a new group of growth regulators, ethylene biosynthesis inhibitors, when applied 2 to 3 weeks prior to harvest, delayed fruit maturity and improved fruit size, firmness and storage life.