The improvement of antioxidant contents and fruit quality of Sukkary date cultivar using various Potassium levels and Irrigation interval

Sukkary date palms (Phoenix dactylifera L.) were treated with three levels of potassium fertilizer combined with three irrigation intervals regime, five replicates were allocated per treatment, to enhance better date peel color; decrease loose crust, and subsequently, improve high market ability. Potassium sulfate (49% K2O) was applied annually at a rate of 490 g (as common fertilization applied in the farm in which this experiment was carried out, therefore, it was considered as a control treatment), 735 g, or 980 g K2O per palm tree, each level was divided into three equal doses. The first dose was added one month after pollination; the other two doses were added at two month interval, whereas the irrigation treatments were as follows: 24 hrs (as common irrigation application in the farm used for this study, and it was considered as a control treatment), 48 hrs, or 72 hrs. The results showed a great decrease in the loose crust dates at harvesting time. An inverse proportional relationship between irrigation intervals and loose crust of dates was observed. The High potassium fertilizer treatment accompanied with 72 hrs irrigation interval treatment produced a significantly higher date quality regarding with bright yellow color, less darkening, and loose crust. High potassium fertilizer treatments (735, or 980 g K2O per palm) increased total yield, improved date weight, size, and color. Moreover, increasing potassium level affected significantly the date total antioxidant. This study showed that, a potential means to control peel darkening and loose date crust and improve quality of cv. Sukkary dates, which ultimately improves its market ability, through implementing appropriate potassium and irrigation regimes.