REPRODUCTIVE-VEGETATIVE SHOOT GROWTH INTERACTIONS AND RELATIONSHIP TONONSTRUCTURAL CARBOHYDRATES IN IMMATURE PONKAN MANDARIN (CITRUS-RETICULATA BLANCO)

The relationship of leaf carbohydrates to vegetative and reproductive growth during an annual growth cycle in young trees of ponkan (Citrus reticulata Blanco) was monitored over two consecutive seasons. Fruitin g, return bloom and fruit set was greater and more uniform in high fru it-load trees. These trees developed less vegetative growth and produc ed fruit with higher total soluble solids and skin colour than in tree s with lower fruit loads. At anthesis, high fruit-set trees (20%) had higher starch and/or sucrose content in the leaves. Conversely, low fr uit-load trees set less fruit (8%) despite having heavy return bloom a nd showed greater variation in fruit numbers per tree. They developed more vegetative shoot growth and had lower sucrose and/or starch conte nt in the leaves at anthesis despite bearing fewer fruits per tree. Fr uiting efficiency (fruits per cubic meter of canopy) was highest in th e high fruit-load trees and lowest in the low-load and defruited trees .