effect of application time of copper sulfate, streptomycin and ga3 on parthenocarpy and quality of grapevine (vitis vinifera l. cv. ‘siyah-e-shiraz’)

abstract an investigation was performed in a commercial orchard in shiraz to study the effect of time of application of cuso4 and streptomycin on quality and seedlessness of grapevine (vitis vinifera l. cv. ‘siyah-e-shiraz’). the experiment was conducted as completely randomized block design with 3 replications. plants were treated with 25 mgl-1 cuso4. 5h2o and 200mgl-1 streptomycin 2,4 and 6 days before full blooming. 50 mgl-1 ga3 was applied 10 days after full blooming. results indicated that both cuso4 and streptomycin increased parthenocarpy compared with untreated control. streptomycin and cuso4 6 days before full blooming plus ga3 produced the highest rate of seedlessness (84%). both cuso4 and streptomycin reduced the number of seeds, cluster weight, berry weight, length and diameter of the berries compared with untreated controls. ga3 increased weight of seedless berries, vitamin c and total acid contents unsignificantly.