Abstract
► Partial fruit set failure was not affected by pollinator type or pollination method. ► Fruit set was higher in 2011 than 2010 season only in ‘Nabbut-Ali’ cultivar. ► Fruit quality was significantly affected by pollinator type and pollination method. ► Date palms have chilling requirement upon cultivar for subsequent normal fruit set. ► Chilling requirements should be considered before cultivation in a certain region.
Partial fruit set failure phenomenon is one of the major problems that limit tree productivity of some date palm cultivars under hot arid regions. As an attempt to understand the nature of this problem, the effects of pollinator type and pollination method with bunch bagging following pollination on fruit set and bunch weight of ‘Nabbut-Ali’ and ‘Sabbaka’ date cultivars which are suffering partial fruit set failure were studied. The results showed that fruit set was not significantly affected either by pollinator type or pollination method in both cultivars during 2010 and 2011 seasons. Fruit set was higher in 2011 than 2010 season only in ‘Nabbut-Ali’ cultivar. In this respect, there were significant interaction effects between season and both of pollinator type and pollination method in ‘Nabbut-Ali’ cultivar. The pollinator ‘Hada-8’ produced lower bunch weight than all the other pollinators in ‘Nabbut-Ali’ cultivar. Also, the bunch weight was higher in the spray than in the traditional pollination. However, in ‘Sabbaka’ cultivar the bunch weight was not affected by pollinator type or pollination method. Bunch weight was higher in 2011 than 2010 season only in ‘Nabbut-Ali’ cultivar. The physical and biochemical quality characteristics of fruit were significantly affected by pollinator type and pollination method, upon cultivar, and were greatly lower in 2011 than 2010 season. Generally, under the conditions of Hada Al-Shame valley, neither of the used pollinators nor the pollination methods gave satisfactory level of fruit set in both ‘Nabbut-Ali’ and ‘Sabbaka’ date palm cultivars. Possibly, date palms have chilling requirements, upon cultivar, for subsequent normal flowering and fruit setting and this should be considered for each individual cultivar before cultivation in a certain region.