Physical variations of tobacco maturing in field induced by exogenous ethylene

ObjectiveInfluence of exogenous ethylene on tobacco leaf physical variations during the process of matu-rity was studies in order to provide theoretical basis for promoting maturity of tobacco leaves in field and improving harvest maturity. MethodTaking spray of clean water as control(CK), ethephon solutions in dilution of 2000, 3000, 4000, 5000, and 6000 times were sprayed onto tobacco leaves during mature stage (immature). Ethylene production, respiration intensity, SPAD values, dry matter content and starch content of tobacco were measured after 0, 12, 24, 36, 48, 60 and 72 h of spray. ResultCompared with CK, after spraying ethephon of different concentrations, ethylene production and respiration intensity increased, but SPAD value declined. After 72 h of spraying, tobacco leaves sprayed by ethephon of different concentrations produced as 1.46-2.42 times ethylene as that of CK , respiration intensity was 65.00%-88.42% higher than that of 0 h spray, SPAD value was 23.47%-46.77% lower than that of 0 h spray. In 2000-3000 times dilution treatment, ethylene production and respiration intensity of tobacco grew too fast and led to uneven maturity of tobacco leaves. In 4000-6000 times dilution treatment, ethylene production and respiration intensity of tobacco increased to certain extent and tobacco matured evenly. After spray of ethephon , dry matter weight in tobacco leaf decreased as a whole. Starch con-tent of tobacco decreased compared with CK in 2000-3000 times dilution treatment whereas increased in 4000-6000 times dilution treatment. ConclusionSpray of 4000-6000 times dilution of exogenous ethylene during mature stage onto middle and upper leaves can promote maturity of tobacco in field. As dry matter content is low at lower leaves , spray of exogenous ethylene is not suitable.