EFFECTS OF SOME CONCENTRATIONS OF GIBBERELLIC ACID, AND CYCOCEL AND DATE OF SPRAY ON THE GROWTH AND YIELD OF SPRING POTATOES

Abstract

This study was carried out to study the effects of 3 concentrations of each of gibberellic acid (50,100 and 200ppm)and cycocel(500,1000and 2000ppm).Both growth regulators were sprayed at 3 different times(befor, during and after tuber formation). Generally, gibberellic acid has increased the vegetative growth in terms of plant height, stem number and dry matter accumulation. However, the opposite effects of cycocel were observed. No significant effect of the concentration of the growth regulators was observed on total yield, and tuber number per plant. Time of application showed a significant effect on the unmarketable yield. The lowest unmarketable yield was obtained from the first application time as compared with other application times. Different concentrations of the growth regulators showed a significant effect on the mean tuber weight and dry matter percentage and the best treatment was 200ppm.