effect of polyamines, 2, 4-d, isopropyl ester and naphthalene acetamide on improving fruit yield and quality of date (phoenix dactylifera l.)

this study was conducted to evaluate the effects of exogenous polyamines, isopropyl ester, 2, 4-d and naphthalene acetamide application on yield and quality of date palm of ‘kabkab’ cultivar. the inflorescences sprayed with 2, 4-d isopropylester (0, 10, and 20 mg l-1), naphthalene acetamide (0, 80, and 120 mg l-1), putrescence and spermidine (0, 0.1, and 1.0 mm), three or six weeks after pollination. the highest rate of initial fruit drop (42.2%) was obtained when fruits were treated with naphthalene acetamide at a concentration of 120 mg l-1, which was significantly higher than the control (32.0%). fruit treated with polyamines had a higher yield than the control. the lowest total soluble solids (tss) (21.5%) were found in spermidine 0.1 mm and the highest tss (46%) was found in the control. polyamines decreased fruit total soluble solids content (tss) compared with untreated fruits, and also delayed fruit maturity for at least 17 days. in conclusion, polyamine application significantly affected yield, physical and chemical characteristics of date cultivar under the study and it may be recommended to be applied in cultural practices to enhance production and improve the fruit quality of date trees orchards.