High density orcharding and canopy management of some tropical and subtropical fruits

Abstract

High density planting (HDP) is a highly efficient and advanced production system of fruit cultivation. In most of the temperate tree and nut crops it is now commercially followed all over the world because of availability of suitable dwarfing rootstock to control tree vigor. Major tropical fruit crops are either propagated by suckers (banana, pineapple), seed (papaya) or by layering (guava) and grafting (mango). The use of dwarfing rootstocks, as in many temperate tree fruits, is not possible/available in most of the commercial tropical fruits for high density planting. High density planting is one of the novel methods to achieve high productivity per unit area both in short duration and perennial horticultural crops. High yield and high fruit quality can be achieved with a high-density orchard when the orchard has good light distribution throughout the tree canopy and there is a balance between vegetative growth and cropping. Many variables must be included in making a decision about spacing. Tree vigor and growth habit as influenced by cultivar and rootstock (where it could be utilized) are important. The ultimate limit on productivity of any crop is the amount of photosynthetically-active radiation (PAR) intercepted. Much of the planning that goes into the design of HDP orchards is actually based on average light interception over the life of the planting. This involves both minimizing the amount of light which strikes the ground and providing canopy structures in which the largest amount of canopy receives optimum light intensity. A tree with a large portion of its volume devoted to bearing has a greater potential for productivity than one with most of its volume devoted to tree support, middles or other functions. In India, HDP has been proved useful in many tropical and subtropical fruit crops e.g., mango, citrus, pineapple, banana, guava litchi, and papaya. The productivity of fruit crops depends on several factors, poor management of canopy architecture being the most important one. The fruiting potential of the trees is largely governed by their architecture, canopy density and photosynthetic efficiency. Canopy in a fruit tree refers to its physical composition comprising of the stem, branches, shoots and leaves. While, the canopy density is determined by the number, length and orientation of stem, branches and shoots. Tree canopy management, especially size control has become a priority for reducing production cost and increasing fruit yield and quality. The objective of canopy management is to optimize the plant model in such a way so that it may intercept maximum light by tree training, pruning, branch and tree orientation. Some of the basic principles in canopy management are: maximum utilization of the light, avoidance of the buildup of micro-climate congenial for the diseases and pests, convenience in carrying out the cultural operations, maximizing the productivity and quality and economy in obtaining the required canopy architecture.