PERFORMANCE OF GRAPEFRUIT UNDER THE ECOLOGICAL CONDITIONS OF CENTRAL SUDAN .1. GROWTH, FLOWERING AND YIELD

Growth, flowering, production efficiency and fruit quality of 13 grape fruit (Citrus paradisi) cultivars on a sour orange rootstock were eval uated for over a 15-year-period in central Sudan. The newly introduced cultivars showed vigorous vegetative growth and were slow to come to bearing as they were nucellar line selections compared to the locally adapted cultivars. Two peaks of flowering were detected with a major p eak during winter (December-March),induced by temperature rhythm, and a minor one coinciding with tile rainy season (June-September). Both l eafy and bouquet types of bloom were observed, but the leafy type was dominant and resulted in maximum fruit set. During early cropping seas ons; the newly introduced cultivars trailed the locally adapted ones i n yield. However, by the 6th cropping season (11 years after planting) all trees apparently reached full cropping capacity and the newly int roduced cultivars started to excel tile locally adapted ones. The yiel d ranged from 22.4 to 40.8 t ha(-1) during this cropping season.