Abstract
This study was conducted during 2010 and 2011 to investigate the effect of preharvest sprays on yield, harvest date, harvest period and fruit physico-chemical quality characteristics at commercial harvest date of Sokary date palm growing in Riyadh area, Saudi Arabia. These palms were sprayed at hababouk and khalal stages with naphthalene acetic acid (NAA), gibberellic acid (GA3), cytofex (CPPU), putrescine (Put), salicylic acid (SA) or ethyphon (Eth). The results showed that the yield components and fruit physical characteristics (except ground color) were improved by all sprayed bioregulators, especially NAA, GA3 and CPPU. The applications of bioregulators delayed harvest date in comparison with the control and Eth treatments. The latest harvest date was obtained with NAA followed by GA3 and CPPU treatments. On the other hand, Eth advanced fruit ripening date in comparison with the control. All the bioregulator treatments decreased the harvest period and the percentage of unmarketable fruits. It also delayed fruit carotenoids pigment formation, but increased fruit acidity and chlorophyll content as compared with control and Eth treatments. Fruit TSS and sugar content at rutab stage were higher compared to the control. However, at tamar stage, fruit acidity was decreased by all treatments. Key words: Date palm, bioregulators, preharvest, yield, ripening fruit quality.
Highlights
Date palm (Phoenix dactylifera L.) is one of the ancient domestic fruit trees in the Middle East countries
The latest harvest date was obtained with naphthalene acetic acid (NAA) followed by GA3 and CPPU treatments
NAA, GA3 and CPPU had similar and significantly higher fruit weight, volume and pulp weight than salicylic acid (SA) and Eth, with no significant difference between Put, SA and Eth obtained in both seasons
Summary
Date palm (Phoenix dactylifera L.) is one of the ancient domestic fruit trees in the Middle East countries. All dates are harvested and marketed at three stages of fruit development; mature firm (bisir or khalal), full ripe (rutab) and dry (tamar). The decision for harvesting at one or these stages depends on cultivar characteristics, especially soluble tannins levels, climatic conditions and market demand. Fruits of the Sokary cultivar are harvested and consumed at the tamar stage, because it contains high levels of soluble tannins, removal of tannins are necessary for the fruit to be edible. Sokary fruit is considered physiologically mature and firm with maximum weight and size and at this stage the colour has changed from green to yellow. Fruits start to ripen from the apex, change to brown or black in colour and become soft. Even fruits of the same bunch do not ripen evenly and they need several harvest dates are needed
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