Screening of Sugar Beet Low Temperature Tolerance Germplasm and Identification on Seedling Cold Hardiness

Using artificial climate box,to take the resistance to low temperature germination screening methods,50 diploid sugar beet germplasm resources were tested.Chilling tolerance index in Bud stage of 12 low temperature resistant germplasm resources is more than 0.76.it was found that the performance of 12 diploid materials resistance to cold damage were similar to Bud stage through appraisal by seedling cold tolerance,but speed and persistent of individual response to low temperature were different.Six materials had a greater tolerance to seedling cold treatments.Experiment proved that seedling cold damage threshold temperature of sugar beet was 3-6 ℃,under this temperature range,strong cold-endurance germplasm was not sensitive,but weak cold-endurance was sensitive.Cold extreme temperature of diploid materials was 1-2 ℃,growth of strong cold-endurance germplasm was stagnant;Cotyledon became shrunk and curly;the leaves and hypocotyl seemed scalded,gradual to death.For weak cold-endurance materials,Chilling injury symptoms appeared earlier,and distortion and death appeared soon.