Influence of harvest date on fruit yield and return bloom in Marsh grapefruit trees (Citrus paradisi Macf.) grown under a tropical climate

Abstract

Grapefruit grown in tropical climates reach a suitable fruit size and juice content for fresh consumption during August – October in the northern hemisphere. However, some tropical plantations delay harvesting until November or December, with the fruit then being used for processing. In our experiments, delaying the harvest from October to December reduced the average mature fruit weight by 10% and increased abscission from 29 to 70 fruit per tree. Juice contents decreased slightly, from 44.5% (w/w) to 43.2% (w/w), while total soluble solids (TSS) contents barely changed, from 10.4 ºBrix to 10.2 ºBrix. Delaying the harvest date also reduced return flowering by 20% in the following Spring, and the number of fruit set by 20%. Mature fruit abscission and reduced flowering were not dependent on weather conditions.The former was spontaneous and due to senescence, while the latter was due to fruit remaining on the tree. Over a 4-year period, our results showed an average reduction of 30% in fruit yield per tree when harvest dates were delayed from October (153 kg tree–1) to December (105 kg tree–1). As juice content and TSS content values were suitable for processing in October, there was no reason to delay the harvest date.