Evaluation the Effects of Morphological and Physiological Factors of Different Date Palm Cultivars on Date Bunch Fading

Date bunch fading disorder is one of the most important problems threating fruit production in date plantations of south regions of Iran. Most of commercial date cultivars such as Mozafti, Mordasang, Kabkaab, Khassi and Kalooteh are susceptible to this disorder. In this research, the effects of some morphological and physiological factors probably play a role in plant resistance to environmental stresses, were studied on disorder severity in susceptible and unsusceptible cultivars in Khouzestan and Boushehr provinces. The factors were stomata densities in leaf and fruit surfaces, amounts of fruit pectin and fiber, amounts of reducing and non-reducing sugars and total sugar of fruit, fruit firmness and fruit total soluble solids, amounts of mineral elements of leaf and fruit including nitrogen, phosphorus, potassium, sodium, iron, manganese, zinc and copper, amount of leaf chlorophyll, palm trunk height, numbers of leaves and bunches per palm and leaf to bunch ratio. The cultivars studied in Khouzestan province included Khassi, Kabkaab, Haji Mohammadi, Gantar and Zahidi in Behbahaan and Bent el Sabae, Reem, Sayer, Gantar, Shekkar, Fersee, Khadhrawi, Deglet Nour and thoory in Ahwaz and those studied in Boushehr province were comprised of Kabkaab, Kabkaab Sorkh, Maktiv, Zahidi, Shahaabi, Kheneizi, Hallawi, Shahaani and Barhee. 4 palms (as replications) of each cultivar were selected, labeled and used for samplings and data collecting of factors and date bunch fading percentage. The most important factors related to disorder in each province and amount and kind of effect of each factor on the disorder severity was determined using multiple linear regression analysis and superior model selection. In Khouzestan region, palm trunk height and amounts of leaf chlorophyll, fruit total soluble solids and fruit potassium were negatively related to disorder severity and stomata density in fruit surface and amounts of fruit firmness and fruit nitrogen were positively related to that. In Boushehr region, palm trunk height and amount of fruit phosphorus showed negative relationships with disorder severity and number of bunches per palm, amount of fruit fiber and amounts of leaf nitrogen, zinc and copper had positive relationships with that.