effect of pre-harvest application of gibberellic acid and ethephon on the quality of table grape

in this study the effects of plant growth regulators including; ga3 (0 and 50 mg/l) and ethephon (0 and 500 mg/l) were studied on the quality properties of two grape cultivars (perlette and yaghuti). at the harvest time, some physicochemical characteristics such as fruit cluster weight, fruit diameter, length, volume and l/d ratio, flesh firmness, fresh weight, ta, ph, tss and fruit color were measured at the harvest time. results showed that fruits treats with ga3 had the highest, cluster weight, fruit diameter, length, volume and l/d ratio compared to ethephon, although ph and flesh firmness showed no differences between the treatments. none of treatments affected negatively the quality of the fruit in term of tss. using of ga3+ethephon treatment significantly increased cluster weight, length, volume, l/d ratio and fresh weight in both cultivars. ethephon had no significant effect on the fruit size, but promoted berry softening and its effect was different for studied quality parameters.