THE INFLUENCE OF FUNCTIONAL LEAF REMOVAL AT FLOWER EMERGENCE ON COMPONENTS OF YIELD AND PHOTOSYNTHETIC COMPENSATION IN BANANA

The probability was tested that by removing 'surplus' banana leaves (cv. Williams) at flower emergence, sucker growth of the following cycle could be accelerated without affecting bunch development of the current cycle. Treatments applied at flower emergence stage of three successive cycles were no leaf pruning (control, 14-16 leaves); removal of half or three quarters of the total leaves, or cutting each leaf back by 50%. In a subsequent experiment using vigorous tissue culture plants, from one to 12 leaves were retained at flower emergence. Photosynthesis was measured in relation to pruning and leaf age. With four leaves retained, ratoon cycles were shorter but bunch mass was reduced to a greater extent, decreasing annual yield per ha by 12.6 and 19.4% in the R1 and R2 cycles respectively. Harvested fruits also softened more quickly when fewer than six leaves were present after flower emergence. Net CO2 uptake increased by up to 35% on pruned plants. This compensation together with the greater photosynthetic efficiency of leaves 2 to 7, may have minimized any disadvantages of moderate leaf pruning (eight leaves retained), but there were no advantages. Green leaf pruning is therefore not recommended as a management technique. When leaf area is depleted by hail or frost before flowering, the emergence of four additional healthy leaves should be sufficient for the development of some marketable fruit.