Fruit growth and abscission, as well as gibberellins (GA, mainly 1 and 3) and free and bound abscisic acid (ABA) in the fruitlets and subtending leaves, were monitored in 'Valencia' orange (Citrus sinensis) from full bloom (FB), with the aim of identifying the physiological factors influencing fruit growth. Particularly from 30 days after FB, the mass of fruitlets adjacent to young leaves ("leafy" fruitlets) were greater than fruitlets adjacent to mature leaves ("leafless" fruitlets). In addition, leafy fruitlets showed considerably greater tree retention after 10 weeks (12.7%) than leafless fruitlets (1.2%). There was little difference in ABA and GA concentrations between the leafy and leafless fruitlets, and concentrations were fairly consistent throughout the 10-week analysis period. However, the masses of ABA and GA per fruit increased during growth. Leaf ABA and GA concentrations remained fairly constant except during the very early stages of leaf development, and the mature leaves contained greater concentrations than the immature leaves. These results are discussed in relation to the role of plant growth substances in citrus fruit growth. © 1990.
Hofman, P. J. (1990). Abscisic acid and gibberellins in the fruitlets and leaves of “Valencia” orange in relation to fruit growth and retention. Scientia Horticulturae, 42(3), 257–267. https://doi.org/10.1016/0304-4238(90)90088-V