Abstract
Using biofertilizers has been a good method in this respect. Field experiments were conducted in 2014 and 2015 on 6-year-old grapevine cv. "Flame Seedless" grown under arid conditions (Riyadh, Saudi Arabia) to evaluated the effects of foliar application with natural sources and chemical of fertilizer on yield and fruit quality. Eight different foliar spray treatments were applied at 4 weeks after fruit set and repeated after another 4 weeks. These treatments were yeast at 4, 6 or 8%; seaweed extract at 1 or 2%; potassium nitrate at 2%; potassium hydrogen phosphate at 2%, and the control (water only). Results indicated that the application of 8% yeast had improved fruit chemical characteristics (soluble solid content, reducing sugars and total sugars) and some physical characteristics (cluster width and weight of 100 berries). Application of 2% potassium nitrate had a significant effect on yield, cluster weight, cluster length, and volume of 100 berries.