Canopy architecture for high density litchi (Litchi chinensis Sonn.) plantings

Crown structure and canopy size play an important role in productivity and quality production of fruit crops. In litchi, once trees begin to bear, fruit production is simply a function of the effective canopy surface area. The crown structure of a tree solely depends on branching pattern and crotch angles. The strongest crotches are those in which branches grow up from the trunk at angles ranging from 40-90°. Scaffold branches should be evenly spaced around the tree, with each branch at least 90° from the next one. Hence, a hypothesis is made to estimate the effect of canopy architecture on vegetative growth of tree canopy size and crown structure, light interception, flowering and fruiting behaviour, microclimate, generation of effective canopy area, etc. In order to test the hypothesis, three types of first order branches (FOB) viz., 2, 3, 4 and second order branches (SOB) viz., 2, 3, 4 and a control (total of ten treatments) will be used for the proposed study. The FOB will have a crotch angle of 90° on the main trunk at a height of 70 cm, whereas SOB will have a crotch angle of 60°. Both types of branches will be maintained at a length of up to 60 cm. The plant to plant distance is 6×6 m. Final height of plants at full grown stage will be 4.5 m with a canopy spread of 2.25 m on each side. The main framework (FOB and SOB) will cover 1 m distance from trunk from each side. The remaining 1.25 m will be available for growth of third order branches and fruiting terminals from each side. The managerial aspect of this density of plantation will be topping and hedging to avoid overcrowding. The purpose of proposing this canopy architecture scheme under this density of planting is to go for precision farming for litchi. The paper discusses optimum canopy architecture for high density litchi plantings and the hypothesis and layout of the proposed study.