Growth conditions, crop load and fruit size affect sheepnosing in grapefruit

James P. Syverstsen, L. Enea Albrigo, Jill M. Dunlop, Mark A. Ritenour, R. C. Vachon

Abstract


We evaluated crop load, fruit yield and size in several grapefruit blocks on the central Florida Ridge and in the Indian River areas over three growing seasons to determine potential causes of elongated, sheepnosed grapefruit. Previous studies showed that relatively higher rates of N fertilization and high early season (February-July) temperatures within tree canopies resulted in high percentages of sheepnosed fruit. Grapefruit trees on the Ridge generally had much lower percentages of sheepnosed fruit than in the Indian River area. Fruit shape became more sheepnosed between early and late harvests in all Indian River blocks evaluated, but not in most central Ridge blocks. Many factors including fruit variety, rootstock and crop removal that lowered yields or increased average fruit size, also increased the percentage of sheepnosed fruit. Doubling the potassium fertilizer rate in the spring time, tended to increase yield, decrease average fruit size, and decrease sheepnosing. Withholding all irrigation in a white grapefruit block in the Indian River area decreased fruit size and percentage of sheepnosed fruit. Overall, comparable trees with lower crop loads and larger fruit had more sheepnosed fruit than trees with higher crop loads and/or smaller fruit. These studies underscore the importance of crop load and fruit growth potential in determining sheepnosing in grapefruit.

Keywords


citrus paradisi; canopy position; fruit height/width ratio; irrigation frequency; potassium; rootstocks; yield

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283