بررسی تنوع جوانهزنی بذر ارقام و ژنوتیپهای چغندرقند تحت تنش گرمائی

In order to evaluate sugar beet seed response to heat stress, a study comprising of three treatments was conducted under laboratory condition based on complete randomized design with four replications in 2015. In the first experiment, seeds of the four cultivars were subjected to different temperatures ranging from -20 to 44°C with 3°C intervals to determine the appropriate maximum temperature. In the second experiment, seed germination of 39 genotypes was evaluated under the optimum temperature of 20°C and also the maximum temperature. Based on existing variation, two sensitive and two tolerant genotypes to high temperature were selected and re-evaluated under optimum and maximum temperature together with their half-sib offspring. In all treatments, seven days after the start of the experiment, different traits such as germination percentage, root length, stem length, vigor index, and root to shoot ratio under both were measured. Based on linear regression between germination percentage and temperature, 30% of the seeds were unable to germinate at 30°C therefore, this temperature was selected as the maximum temperature. In the second experiment, variation was found among genotypes for the abovementioned traits. The results of the third experiment showed high heritability for seed germination under heat stress which confirms that the breeding of this trait can be successful.