Anti-gibberellins' effect on grapefruit size and quality
Fucik, J.E.; Swietlik, D.
Proceedings of the Plant Growth Regulator Society of America 17th Annual Meeting, St Paul, Minnesota, USA, 5-9 August 1990: 107-113
Five year-old 'Rio Red' grapeCruit trees were treated with the anti-gibberellins, unlconazol(unlcon) and paclobutrazol(paclo). Treatments were: soil drenches at 10, 20, and 40 g. a.i. tree-l applied In May, 1985; trunk banding applied In an 80/20 vol-vol diesel/toluene mix of unicon at 7 rates(.062 to 2 g a.i. tree-l and paclo at .062 and 2 g. and 2 Collar sprays of 1000 ppm(Oct. 1985, Feb. 1986) and one oC 500 ppm (Feb. 1986) of both materials. Fruit size, external and juice quality were evaluated In 1987 and Crult size and juice quality In 1988. Both chemicals decreased average Crult size by Increasing the number of Crult In the smaller sb.e classes. Except Cor slightly Cewer Cruit with peel abrasions on Coliar sprayed trees the treatments did not affect the Crults' external quality. The soli drench and foliar sprays of both unlcon and paclo reduced juice quality by decreasing soluble solids, Increasing acid thus lowering sugar acid ratio and increasing the peel percentage. Trunk banding tended to Increase the percent juice and lower percent peel with the response Cor unlcon occurring the Orst and paclo the second season after treatment. Overall both antl-GA.'s appear to delay Cruit growth and maturity.