Abstract
Physical and biochemical changes in 'Helali' date palm fruit were studied during development and ripening. In two successive seasons, the results showed that fruit and flesh weight, diameter and length were gradually increased during development until week 17 (Bisir stage), slightly decreased during ripening at week 23 (Rutab stage), but sharply decreased during the Tamer stage at week 27 from pollination. The changes in these parameters showed a clear sigmoidal pattern for fruit growth. Seed weight gradually increased during development until week 17, but decreased during the Tamer stages at week 23 and 27 from pollination, respectively. Flesh/seed ratio sharply decreased from week 6 to week 10, fluctuated until week 14, gradually increased until week 23 from pollination and then decreased during the Tamer stage. TSS and flesh dry weight percentage remained constant or slightly fluctuated from week 6 to week 14 from pollination and then rapidly increased during maturation and ripening. Acidity percentage gradually decreased from week 6 to week 17 from pollination, and then increased during ripening (Rutab and Tamer stages). Vitamin C concentration sharply decreased from week 6 to week 10 from pollination, slightly decreased during maturation, but decreased at a faster rate during ripening. Total phenols concentration gradually increased during development until week 14 from pollination, but sharply decreased during maturation and ripening to a low level. The concentration of soluble tannins gradually increased from week 6 to week 17 from pollination, and then sharply decreased at a faster rate during ripening. However, on a fruit basis (mg/fruit), the soluble tannins content gradually increased during development until week 17 from pollination and then sharply decreased during ripening to a low level. The concentration of nutrient elements (nitrogen, potassium, phosphorus, magnesium, calcium, sodium, zinc, iron, copper and manganese) gradually decreased during development and more progressively during ripening.