the effects of drought stress on yield and quality of thompson seedless grape in takestan

partial rootzone drying (prd) is a new irrigation technique which improves water use efficiency without significant yield reduction in grape. to study the effects of partial rootzone drying and green pruning on yield and yield quality of thompson seedless grape a split plot experiment with randomized complete block design and three replications was conducted. the experiment was performed in takestan.the experimental treatments were irrigation and pruning and each treatment had three levels. during growing season, half of the root system was maintained in a dry state, while the rest was irrigated (prd). the irrigation levels were: full irrigation (irrigating both sides of root zone), drying left side of rootzone (irrigating from north direction) and drying right side of rootzone (irrigating from south direction). pruning levels included light, medium and heavy green pruning. the analysis of variance (anova) of data showed that the effects of irrigation were significant on ph and tss of grape juice at 5% level but there were no significant differences between irrigation treatments with respect to grapevine yield indicating that water requirement of grapevine can be reduced to half without significant yield reduction. the effects of pruning were also significant on grapevine yield, berry weight and diameter, cluster weight and length and sultana production. the interactive effects of pruning and prd were significant on weight and diameter of berry, weight and length of cluster and sultana production full irrigation with medium pruning, irrigation from north with medium pruning and irrigation from south with light pruning had higher grape yield than the other treatments. prd reduced shoot and lateral shoot growth about 8 and 30% respectively compared with full irrigation.