烟叶成熟过程中主要酶活性的变化规律

Study on Activity of Major Enzymes During Maturity Process of Tobacco

为了给烟叶成熟采收提供理论依据，采用完全随机区组设计，研究了烤烟品种云烟85下、中、上部烟叶的成熟度脂氧合酶（LOX）、超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）活性以及丙二醛（MDA）含量变化规律。结果表明：POD、CAT活性随烟叶部位的升高而升高，随成熟度的提高而显著下降；随着成熟度的提高，LOX、SOD活性呈先升高后降低的趋势；MDA含量则逐渐升高，M2期以后升高速度加快，4种酶活性绝对值表现均为下部叶＜中部叶＜上部叶。根据酶活性水平变化规律，建议云烟85下部烟叶以M1到M2（叶面变黄程度达30％，主脉约1/2变白，支脉1/3～1/2变白）期、中部叶以M3（叶面整体变黄程度达60％，主脉2/3～3/4变白，支脉1/2～2/3变白）期，上部叶以 M3期（叶面变黄程度达80％，3/4～4/5变白，2/3至3/4变白）采收为宜。

The activity of LOX,SOD,POD,CAT and MDA of lower,middle and upper tobacco leaves with different maturity degree was determined by using the completely randomized block design to provide the theoretical basis for tobacco harvest.The results showed that the POD and CAT activity rose with increase of leaf position and significantly decreased with increase of maturity degree,the LOX and SOD activity presented a first rise and decline trend with increase of maturity degree,the MDA content rose gradually with increase of maturity degree and the increase velocity speeded up after M2 period,and the activity absolute value of four enzymes was lower leaf＆lt; middle leaf＆lt; upper leaf.The proper harvest period for lower leaves,middle leaves and upper leaves of Yunyan 85 is from M1 to M2,M3 and M3 period separately.