Root influence on shoot development in tea (Camellia sinensis(L.) O. Kuntze) following shoot pruning

Abstract
The physiological interaction between the factors controlling the development of new shoots in pruned tea plants was investigated in an experiment using a widely cultivated TRI clone growing at low elevation in Sri Lanka. The functional importance during new shoot growth of root reserves, feeder roots and leaves and buds on unpruned branches (lung-shoots) is critically evaluated. A scheme for their interaction is presented, which highlights the need to maintain feeder roots alive during new shoot development, for which a large proportion of both reserve and current assimilates seem to be utilized. Mature leaves on lung-shoots, besides supplementing carbohydrate supply by current photosynthesis, may also serve to maintain the flow of metabolites from feeder roots to developing shoots and also function as ‘sinks’ for excess, toxic levels of root metabolites. Removing all mature leaves, as is done during ‘clean pruning’, leads to the depletion of reserves below the critical level for feeder root survival, resulting in death of feeder roots and failure of new buds to form shoots.