Enhancing the Bearing Capacity and Quality of Superior Grapes Via Root Pruning, Ethephon and Mepiquat Chloride

 SUPERIOR IS one of the grapevine cultivars already cultivated in the Egypt vineyards to export and/or local market, which is spreading in new areas. The present study investigates additional treatments that may improve productivity and fruit quality of Superior grapevine. In this respect, the vines were subjected to: root pruning (RP), foliar application with either ethephon (ET) or mepequat chloride (MC). The vines were root-pruned along both sides of vine to a depth of 50 cm and 30, 45 or 60 cm from the trunk. Whereas ET and MC were sprayed at the concentration of 100, 200 or 300 ppm and at 100, 150 or 200 ppm, respectively. All treatments were carried out at two weeks before bloom.
The obtained results clearly showed that RP at 30 or 45 cm as well as all MC and ET treatments reduced shoot length, which in turn increased the intensity of light reaching the center of the vine. RP at 30 cm was significantly the highest in this respect followed by MC at 150 and 200 ppm. As a general trend all mepiquat treatments induced increment in the total carbohydrates stored in shoot tissues of treated vines compared with untreated ones. In addition, plant content of N, P and K showed different fluctuations. However, MC treatment seemed to enhance shoot content of N and K. In general, these effects were associated with an enhanced in vine productivity during following treatments season. RP mainly at 30 cm as well as MC application at 150 and 200 ppm resulted in significantly increased fruitfulness, whereas both ET applications (200 and 300 ppm) significantly decreased it. However, all MC treatments produced the heaviest bunch. Therefore MC gave the highest yield / vine while the lowest yield was recorded for ET followed by control treatment.
In conclusion, treating Superior vines with MC at medium (150 ppm) or high (200 ppm) concentrations could be recommended to an increase light density inside vine canopy as well increasing fruitfulness, number of cluster / vine, average berry or brunch weight and in turn vine yield.