Effect of Gibberellic Acid on Germination Behaviour of Sugar Beet Cultivars under Salt Stress Conditions of Egypt

The response of six sugar beet genotypes (Raspoly, Nada, Strube, Almaz, Toro, Oskarpoly) under seven salinity levels (distilled water as control, 1500, 3000, 45000, 6000, 7500 and 9000 ppm NaCl) and soaking in gibberellic acid levels were studied on germination parameters. An experiment with factorial arrangement was conducted by using randomize complete block design with four replications. Seed soaking in GA(3) significantly affected final germination percentage (FGP), mean germination time (MGT), coefficient velocity (CV), seedling vigor index (SVI), energy of germination (EG), emergence rate (ER) and speed of germination (SG). Highest averages of FGP, CV, SVI, EG, ER and SG, were produced from soaking seed in 200 ppm of GA(3). Moreover, highest averages of MGT were recorded from soaking sugar beet seed in the control treatment. Sugar beet cultivars significantly differed in FGP, MGT, CV, SVI, EG, ER and SG. Highest averages of FGP, MGT, CV, SVI, EG, ER and SG were recorded with sown Raspoly cultivar. Increasing salinity concentrations from 0 to 9,000 ppm significantly decreased FGP, CV, SVI, EG, ER and SG. While, MGT increased with increasing salinity concentrations. Results of means comparison showed that in all genotypes, there was a decrease in germination percentage due to salinity stress increment and maximum germination percentage was delayed. The interaction between cultivars and seed soaking in GA(3) levels significantly affected FGP, MGT, CV and SVI. The interaction between seed soaking in GA(3) levels and salinity concentrations significantly affected FGP, MGT and SVI.