Crossing of Alphonse Lavallee and Regent Grape Cultivars for Downy Mildew Resistant Genotypes. 1. Seed Germination and Seedling Growth

Crossing for disease resistance of grape cultivars is one of the main interests of grape breeding. Downy mildew is one of the destructive diseases of grapevines. V. vinifera has superior characteristics for wine or fresh consumption but mildew sensitive. Vinifera grapevines are cross with American wild grapes to obtain resistant cultivars. But some hybrid grapes have low seed germination. The main goal of this study was to develop hybrid table grape F1 offsprings with resistance to downy mildew disease and to test seed characteristics of them. Alphonse Lavalle (susceptible) and Regent (resistant) grape cultivars were crossed to obtain resistant F1 progenies. Hybrid seeds were soaked in gibberellic acid (GA3, 1 000 ppm), Benzylaminopurine (BAP, 1 000 ppm) and hydrogen peroxide (H2O2, 1 M) solutions and water (control) for 24 hours after stratification (4 months at 5oC) and then sown in Perlite : Peat moss (1:1) potting soil. Germination was carried out in the plastic boxes with constant temperature (27oC) and relative humidity (99%). Total germination ranged from 60.39% to 78.32% in the control and GA3 treated seeds respectively. Also, GA3 significantly increased total germination when compared to the other treatments. Optimization of growth chamber, greenhouse and open field conditions for seed germination and seedling growth accelerated shoot growth up to 2 m in offsprings at the first year