乙烯利浓度和喷施时期对上部烟叶耐烤性的影响及生理机理研究

The Effect of Ethephon Concentration and Spraying Time on the Resistance of Upper Tobacco Leaf and Its Physiological Mechanism

为探索乙烯利对烤烟上部叶耐烤性的影响,研究了不同浓度乙烯利处理(0、1000和1500 mg/L)以及喷后不同时间采收(喷施后3、5、7 d采收)的烟叶烘烤过程中多酚氧化酶(Polyphenol oxidase, PPO)活性、暗箱烟叶变褐时间、丙二醛(Malondialdehyde,MDA)含量和相对电导率变化规律。结果表明:乙烯利处理浓度和喷后采收时间均显著促进烟叶田间落黄,提高烘烤期间烟叶PPO活性,缩短暗箱烟叶变褐时间,导致耐烤性降低。乙烯利处理还导致变黄后期至定色初期烟叶MDA含量和细胞膜透性显著提高,膜脂过氧化进度和膜损伤发生时间较正常成熟烟叶提前。从耐烤性角度考虑,1000 mg/L乙烯利处理后3~5 d采收烟叶有利于其外观质量的提升。论文可为更好地在烟叶生产中应用乙烯利促进烟叶成熟以及制定与之相适应的烘烤工艺提供依据。

In order to explore the effect of ethephon on the endurable curing potential of flue-cured tobaccoupper leaves,The effect of different concentrations of ethephon treatment(0 mg/L, 1000 mg/L and 1500 mg/L, respectively) and different harvesting time after spraying(harvested on 7 d, 5 d and 3 d after spraying, respectively) on the activity of polyphenol oxidase(PPO), the browning time under dark condition, the content of malondialdehyde(MDA) and the relative conductivity of tobacco leaves during curing were studied. The results showed that both of the concentration of ethephon treatmentand the harvesting time after spraying significantly promoted the yellowing of tobacco leaves, increased their PPO activity during curing, shortened their browning time under dark condition, thus the treatments decreased of endurable curing potential. Ethephon treatment also significantly increased MDA content and cell membrane permeability from the late stage of yellowing to the early stage of color fixation. Membrane lipid peroxidation progress and membrane damage occurred earlier than normal mature tobacco leaves.Harvesting tobacco leaves in 3 to 5 days after 1000 mg/L ethephon treatment was beneficial to improvement of appearance qualityfrom the perspective of endurable curing potential. The results will provide a basis for a better application of ethephon in tobacco leaf production to promotetobacco lea fmaturity and formulate a suitable baking process.