Identifications Of Cold Tolerant Germplasm Based On Physiological And Molecular Markers From Different Genotypes Watermelons

Watermelon (Citrullus lanatus) originates from Africa, liking warm and continental climate. Watermelon is sensitive to cold stress and is devoid of the germplasm that is tolerant to cold. Watermelon can be planted almost all over the world, but its growing largely limited seasonally . Furthermore, watermelon is in face of sensitivity to several kinds of diseases, and consumers desire the quality of watermelon is becoming better and better. Therefore, genetically improving watermelon, the important and cosmopolitan fruit, by biotechnology, is very urgent.The best climate for watermelon is upper temperature, enough sunlight and dry climate. The best vegetal temperature for watermelon is 18℃-32℃. Watermelon can . endure high temperature, but can not endure low temperature. Watermelon will growth slow when temperature droped to 15℃, stop growth at 10℃.In this study, we got cold tolerant germplasm and cold sensitive germplasm. And Identifications of cold tolerant germplasm based on physiological and molecular markers from different genotypes watermelon. This paper includes three parts mainly.The first part of this paper is the primary identification of the cold tolerance in watermelon. Primary filtrate cold tolerant germplasm and cold sensitive germplasm, and ensure the optimum temperature. We compare different genotypes watermelon at four different temperature, and observe the chilling circs. The result showed that different genotypes watermelon represent observable difference at 10℃. Primary filtrate cold tolerant germplasm 9# and cold sensitive germplasm 2#.The second part of this paper is the research of salicylic acid effect the cold tolerance of plant. Different salicylic acid sprays leaves before treatment at 10℃,choose the leaves at 0d, 1day, 2d, 4d, 6d, 8d treatment, compare the activity of antioxidant enzymes and content of MDA. The result showed that SA is 1.0mmol/L, which can increase the activity of antioxidant enzymes and reduce the content of MDA. At last, the result of cold tolerance identification through POD isoenzyme. The POD isoenzyme of Cold tolerant germplasm appear a new strap after treatment at 10℃. We clon the AOX gene.