Abstract
Pollination and thinning are critical processes in the date palm production chain that affect fruit development, yield and quality and regulates tree yearly bearing. Developing a pollination technique that results in an acceptable level of fruit set with a minimum amount of pollen grains and without a further need for thinning is critically required especially under harsh conditions. During 2009 and 2010 seasons, the effect of pollen grain-water suspension spray at different concentrations on fruit set, yield and quality were examined on 'Khenazy' date palm cultivar. Fruit setting was significantly higher in the spray pollination than in the traditional pollination. Spray pollination at the concentration of 1.5 or 2.0 g/l gave higher fruit setting than the application at 0.5 g/l. Both of bunch weight and total yield per tree were significantly higher in spray than in traditional pollination. The Rutab percentage was not affected by the method of pollination. At both the Bisir and the Rutab stages, fruit and flesh weight were significantly higher in the traditional pollination than all other treatments, except for the spray pollination at 0.5 g/l. However, seed weight was not affected by any of the pollination treatments. Fruit diameter was significantly higher in the traditional pollination than in spray pollination. Fruit length was significantly higher in the traditional pollination than in all other treatments, except for the spray pollination at 0.5 g/l at both stages. TSS, acidity, vitamin C, total phenols and soluble tannins concentrations of fruit were not significantly affected by any of the pollination treatments at both the Bisir and the Rutab stages. The concentrations of TSS and acidity were higher at the Rutab than at the Bisir stage. However, the concentrations of vitamin C, total phenols and soluble tannins were greatly lower at the Rutab than at the Bisir stage. The time needed for spray pollination was about half of the time needed for traditional pollination. In addition, the amount of the pollen grain required for the spray pollination was less than the half of that needed for the hand pollination. This study showed the possibility to pollinate 'Khenazy' date palms by pollen grain-water suspension spray with optimum amount of pollen grains and without a further need for thinning in attempt to reduce labor and costs especially under hot arid conditions. However, more research work is required to justify the optimum concentration of grain-water suspension and the response of each date palm cultivar to this pollination technique.