Improving fruit quality, nutritional value and yield of Zaghloul dates by the application of organic and/or mineral fertilizers

A field study was carried out during the years 2007 and 2008 on 30-year old Zaghloul cultivar growing in clay soil. Mineral fertilization sources: N, ammonium nitrate or NPK, ammonium nitrate + calcium superphosphate + potassium sulphate, and organic sources: chicken manure (CM), cow dung (CD) and composted domestic refuse (CDR) were applied either alone or in combinations in order to study their influence on the yield and fruit physical and chemical quality characteristics. The results revealed that applying organic manure alone or in combination with mineral NPK increased palm yield as compared to mineral fertilization alone (NPK or N). In general, fruit weight, flesh weight, length, diameter and dry weight were increased, while fruit moisture content decreased by the application of organic manures either alone or in combination with mineral NPK as compared to the mineral N. Higher fruit TSS and total sugars content were obtained by the application of organic manures alone or in combination with mineral NPK as compared with mineral fertilization alone (NPK or N). Overall values of fruit minerals content did not differ among the different treatments. Organic manures fertilization (especially CM and CD) resulted in decreasing fruit lead, cadmium, nitrate and nitrite contents more than mineral fertilization. In general, the application of organic manures either alone or in combinations with mineral NPK did not differ from each other in their effect on yield and fruit quality.

Research highlights▶ The present study was undertaken to investigate the effect of different nutrient supply sources namely, chicken manure, cow dung, composted domestic refuse and mineral fertilizers on the yield, fruit quality and nutritional value of Zaghloul date palm. ▶ From this study, in general, the application of organic manures either alone or in combinations with mineral NPK did not differ from each other in their effect on fruit yield and quality. ▶ In conclusion, Zaghloul date palm production in Egypt can rely on organic manure as an alternative to mineral fertilization, or at least rationalize its use in the production of organic palm dates as well as increasing in yield and fruit quality. Organic manures fertilization (especially CM and CD) resulted in decreasing fruit lead, cadmium, nitrate and nitrite contents more than mineral fertilization.