CROP LOAD EFFECTS ON FLORAL QUALITY IN OLIVE

Alternate bearing in olive is largely determined by flowering load. In order to know if there are differences in floral quality related to flower load, and if these differences reinforce or alleviate the alternate-bearing tendency, we compared pistil abortion, floral sink strength and fruit set between ''on'' and ''off'' 'Manzanillo' olive trees. 'Manzanillo' trees with light flowering showed a higher percentage of pistillate inflorescences, higher dry weight and nitrogen content of the flower, and a higher percentage of fruit set. The tree with the lightest flower load had greater ovule longevity than the tree with the heaviest flower load, although differences were not found in the incidence of undeveloped embryo sacs. The results suggest partial compensation of the alternate habit by enhancement of female floral quality and an increase in fruit set when low levels of flowering occur.