Comparison of biochemical compounds and antioxidant activities in date palm bunch fading disorder

Abstract

Date palm bunch fading disorder, the cause of which remains unknown, is among the most harmful disorders affecting date production. In this study the contents of several biochemical compounds and antioxidant enzyme activity were measured in both faded and non-faded bunches. The experiment was conducted in a completely randomised block design with five replications on 10 uniform date palm trees. Five trees showing symptoms of fading disorder on some bunches and five trees showing no symptoms of the disorder were selected. The contents of starch, total protein, proline and hydrogen peroxide (H₂O₂), and activities of catalase, superoxide dismutase and polyphenol oxidase were significantly different (p < 0.05), whereas the contents of soluble sugars and total phenols, and of peroxidase and ascorbate peroxidase did not show significant differences (p > 0.05), between faded and non-faded fruit. Strands and stalks of non-faded bunches contained higher contents of organic compounds and showed higher antioxidant enzyme activity compared with those of faded bunches. Furthermore, the H₂O₂ content in faded fruit was higher compared with that of non-faded fruit. The highest H₂O₂ content was observed in strands and stalks of non-faded bunches. The results indicate that the disordered trees were under stress.

Keywords: bunch fading disorder, date palm, organic compounds, phenol, superoxide dismutase