Effect of Pre-Harvest Application of Gibberellic Acid

In this study the effects of plant growth regulators including; ga3 (0 and50 mg/l) and ethephon (0 and 500 mg/l) were studied on the quality propertiesof two grape cultivars (perlette and yaghuti). at the harvest time, some physicochemicalcharacteristics such as fruit cluster weight, fruit diameter, length,volume and l/d ratio, flesh firmness, fresh weight, ta, ph, tss and fruit colorwere measured at the harvest time. results showed that fruits treats with ga3had the highest, cluster weight, fruit diameter, length, volume and l/d ratiocompared to ethephon, although ph and flesh firmness showed no differencesbetween the treatments. none of treatments affected negatively the quality ofthe fruit in term of tss. using of ga3+ ethephon treatment significantlyincreased cluster weight, length, volume, l/d ratio and fresh weight in bothcultivars. ethephon had no significant effect on the fruit size, but promotedberry softening and its effect was different for studied quality parameters.