Characteristics of Leaf Water Retention Capacity in Flue-cured Tobacco at Different Growth Stages

In order to elucidate the characteristics of leaf water retention at different developmental stages of flue cured tobacco, excised leaves of three varieties Yuyan 6, ND202 and K326 with different drought resistance 10, 30, 50 and 70 d after transplanted were used as materials to analyze the change of leaf water retention, antioxidant enzyme activities, hormone and stress resistance gene expression.The results showed that variety, growth stage and their interaction all had significant effects on the water holding capacity, with the contribution rates being 63.09%, 24.65% and 12.25%, respectively.The water holding capacity of leaves of the three varieties was relatively higher at the late stage, with Yuyan6 being the highest and ND202 being the lowest at the same development stage.The activities of antioxidant enzymes (SOD, POD, CAT) were all increased after dehydration, and the increase of Yuyan 6 was the largest.The activities of SOD and POD increased greatly at the late stage.The increase of MDA content and relative conductivity of the three varieties were lower at later stage, and Yuyan6 had the lowest increase.After dehydration, the content of ABA increased, the content of IAA decreased slightly, and the contents of IAA, CTK and GA decreased obviously at the later stage.The expression levels of four stress responsive genes (AREB, CDPK2, LEA5, ERD10C) increased greatly after dehydration, and the largest increase was found in Yuyan 6, followed by K326 and ND202, which is consistent with the trend of water retention between varieties.The results suggested that the genetic factors of the varieties were the key factors affecting water holding capacity of tobacco, and leaf water retention could be used in drought resistance identification at different developmental stages in the field.