Effect of Pollination Method on Changes in Physical and Chemical Characteristics of Date Fruit During Development

Abstract

Date palms were pollinated by hand, hand duster and motorized duster. Pollen for the hand and motorized dusters was diluted with wheat flour each at 1:5, 1:7, 1:9 and 1:14 ratios. Fruit samples were collected during ‘Hababook’, ‘Kimri’, ‘Bisir’, ‘Rutab’, and ‘Tamr’ stages. Chemical and physical characteristics were determined in the laboratory. The motorized duster produced lower fruit set than the hand duster. No significant effect of pollination method on yield was observed. None of the physical or chemical differences that appeared during the same stage of fi'uit development proved to be an indicator of maturity. During ‘Kimri’, more fiuits with higher pectin (late maturing) were produced by the motorized duster than those produced by hand pollination and hand duster. But the motorized duster produced fi'uits with larger volume (i.e. ‘Rutab’ and ‘Tarnr’) than those of hand pollination. However, the reduction in acidity between ‘Bisir’ and ‘Rutab’ and in volume between ‘Rutab’ and ‘Tamr’ clearly indicated early maturity of the hand-pollinated fruits. The reduction in acidity between ‘Rutab’ and ‘Tamr’ indicated that hand-pollinated fruits ripen at a slower rate than the fruits of mechanized pollination at any of the pollen to flour ratios. The latter case could be attributed to the conversion of the acids to the dark pigmentation of ‘Tamr’. The lowest pollen : flour ratio (1:14) produced the lowest yield, moderate Fruit set and highest dry matter, whereas the highest ratio (1:5) produced a lower sucrose and dry matter and higher yield.