Grapes are the biggest perennial fruit crop in Afghanistan and an increasingly important late season production area for table grapes for the Kabul market is the Shomali plain. Due to the absence of seeds, the Keshmeshi and Shondukhani grapes tend to produce small berries which are less acceptable on the fresh market, and can only achieve low prices.
The current problems include wrong timing of GA3 applications, and overdosing, which can promote tight berry clusters and introduction of fungal rots. GA3 is readily available in agricultural supply merchant stores, in tablet form in Afghanistan.
On other hand, White and Red Roucha are the very early maturing grape varieties that produced very compact clusters with fungal rots inside the clusters. The GA3 can use for the thinning of the berry before and during the flowering times on White and Red Roucha grape varieties for the purpose of looseness of clusters.
The present experiments follow the ones conducted last year which failed due to powdery mildew and shortage of water. These trails were conducted to evaluate the effect of the time and different concentration GA3 application on cluster compactness, quality improvement and production of White Roucha, Red Roucha and Shondukhani varieties of grapes in Kandahar, Herat and Shakardara district/Kabul provinces during April Oct. 2015.
The result of experiment has shown that treatment 7 (20 ppm at 40% flower opening +20 ppm at 80% flower opening on the treated bunch) for White Roucha and treatment number 3(10 ppm GA3 before flowering on the treated bunch) for Red Roucha are appropriate treatments for high yield.
The results of the experiments have shown that the application of GA3 10 ppm before flower opening + 60 ppm GA3 at 4 mm berry size (treatment # 8) and treatment 9 (20 ppm GA3 before flower opening + 60 ppm GA3 at 4 mm berry) were significant in both White and Red Roucha varieties for producing of loose cluster, good production and quality.
The result of experiment on Shondukhani grapes has shown that treatment # 9 (80 ppm GA3 at berry size 10 mm) is appropriate treatment for high yield, good quality and marketability.
