Effects Of GA₃, 6-BA And 2,4-D Applied In Cucumber Seed Film Coating

Cucumber is an important economic crop which has been widely planted all over the world. Improving the cucumber seed quality is very helpful for the famers to increase productivity, income and plant quality. The effects of seed film coating with gibberellic acid(GA₃), 6-benzylaminopurine (6-BA) and 2,4-dichlorophenoxyacetic acid (2,4-D) on seed germination, growth and physiological and biochemical changes of seedlings in cucumber cv. Tezao and Jinza 4 were investigated in this experiment. The results were as follows.Response surface analysis (RSA) and principal component analysis (PCA) were combined to optimize the combination of GA₃ concentration in film coating and storage time of coated seed in cucumber. According to the RSA design, the cucumber seeds were treated by 14 combinations of different GA₃ concentration in film coating and coated seed storage time each with five levels. After that, the germination test of treated seeds was conducted. Shoot height, chlorophyll content and root vigor were measured. These parameters were used for PCA, then principal component vector was analyzed by RSA. Finally, an optimal combination of GA₃ concentration in film coating and storage time of coated seed in cucumber was obtained that is the GA₃ concentration was 193 mg/L, the storage time was 115.3h.After coated with GA₃, there were no significant effects on energy of germination, germination percentage, germination index and root dry weight. Significant increase in vigor index, length and dry weight of hypocotyl and cotyledon, chlorophyll concentration, soluble sugar concentration and activity of POD and CAT was observed. Coated with GA₃ signficantly reduced mean germination time, increased root length in Tezao, but there were no significant effects on root length of Jinza 4. Coated with GA₃ improved the growth of shoot and dry weight.After coated with 6-BA, there were no significant effects on seed germination parameters, however vigor index was increased in both cucumber varieties. Seed film coated with 6-BA increased the length of cotyledon, had no significant effects on the length of hypocotyls and roots. There were significant increases in dry weight of roots, hypocotyls and cotyledons, root vigor, concentration of chlorophyll and soluble sugar, activities of POD and SOD.Seed film coating with 2,4-D had no significant effects on energy of germination, germination percentage and germination index, but improved seed vigor index. Coated with 2,4-D significantly increased the dry weight of root, hypocotyls and cotyledon, the length of hypocotyls and cotyledon length. Seed film coating with 2,4-D increased root vigor, soluble sugar concentration, but there were no significant effects on soluble protein concentration. Coated with 2,4-D significantly increased the activities of POD, CAT and SOD in Jinza 4, but didn't reached the significant effects in Tezao. Coated with 2,4-Dsignificantly reduced the mean germination time, significantly increased root length and chlorophyll concentration in Tezao, however, didn't have such significant effects in Jinza 4.