ABSTRACT. Accumulation of the red carotene pigment, lycopene, in Citrus fruit is an unusual feature restricted to grapefruit, pummelo and few orange mutants. Recent studies indicate that differential mechanisms may be operating in the different lycopene-accumulating varieties, highlighting the importance to understand these processes. It is well characterized in Citrus fruit that light positively affects color development and consequently carotenoid content and composition. However, it is paradoxical that by shading degreening of the red grapefruit ?Star Ruby?

ABSTRACT. Five-year-old 'Spring' navel (Citrus sinensis (L.) Osbeck) orange trees were completely defruited, 50% defruited or left fully laden to study effects of fruit load on concentrations of nitrogen (N) and carbohydrate, net assimilation of CO2 (Ac) and stomatal conductance (g s) of mature leaves on clear winter days just before fruit harvest. Leaves on defruited trees were larger, had higher starch concentrations and greater leaf dry mass per area (LDMa) than leaves on fruited trees.