Relationship of leaf position and CO₂ assimilation with fruit growth in Litchi

An experiment was conducted on 22-years old ‘Bombai’ litchi (Litchi chinensis Sonn.) trees to study the retention and development of fruit in relation to assimilate supply. One week after fruit set, bearing panicles were manually adjusted to achieve leaf/fruit ratio of 0 to 6 by careful removal of leaf or fruit or both, on girdled as well as ungirdled branches. The results suggested that four leaves behind the panicle essentially supported retention and development of a litchi fruit. However, on ungirdled, defoliated (leaf:fruit=0) branches the developing fruits showed ability to draw resources from rest of the tree's carbon balance. The leaves just behind the fruit cluster were more effective for supplying assimilates to developing fruit than those which were old and away from fruits.