烘烤过程中烟叶主脉腐烂及霉变症状分析

Midrib mildew and rot symptoms of tobacco leaves during flue-curing

为明确腐烂和霉变烟叶的主脉微观结构变化和主要元素含量状况,以云烟85中部叶为试验材料,通过扫描电镜观测了鲜烟叶和烘烤过程中腐烂和霉变烟叶的主脉,并采用能谱仪检测烟叶主脉和晶体Na、O、C、Ca、P元素含量(质量分数)。结果表明,与烟叶霉变相比,烟叶发生腐烂的时间早、扩散速度快,烟叶腐烂和霉变首先发生在叶脉,之后向其两侧叶肉延伸;烟叶腐烂时,主脉产生草酸钙砂晶,晶体中含有大量Ca元素(30.34%),可促进烟叶霉变,且晶体中还含有一定量P元素(24.92%),可调控晶体形态;细胞底壁、细胞侧壁和草酸钙砂晶均含有Na、O和Ca元素,细胞底壁和细胞侧壁含有C元素,细胞侧壁和草酸钙砂晶均含有P元素,以草酸钙砂晶的Ca和P元素含量最高。烟叶腐烂和霉变主要发生在叶基部叶脉,烟叶腐烂产生含Ca的草酸钙砂晶促进了烟叶的霉变。

In order to study the microstructure variation and main element contents in midribs of moldy and rotten tobacco leaves, the middle leaves of cv. Yunyan 85 were taken as the experimental material, scanning electron microscopy was used to observe the midribs of fresh leaves and leaves mildewed and rotted during flue-curing. Energy dispersive spectrometer was used to detect the contents of Na, O, C, Ca and P in midribs and crystals of tobacco leaves. The results showed that tobacco leaves rotted earlier and spread faster than leaves mildewed. The rot and mildew of tobacco leaf appeared in its midrib first, and then extended to both sides of the midrib. When tobacco leaves rotted, their midribs produced calcium oxalate crystal sands which contained a large amount of Ca (30.34%) to accelerate the mildew of tobacco leaves and some P (24.92%) to regulate crystal morphology. Cell bottom wall, cell sidewall and calcium oxalate crystal sands contained Na, O and Ca, cell bottom wall and cell sidewall contained C, and cell sidewall and calcium oxalate crystal sands contained P. The contents of Ca and P in calcium oxalate crystal sands were the highest. The mildew and rot of tobacco leaves mainly occurred on the midrib of leaf base. Rotten tobacco leaves produced calcium oxalate crystal sands, which accelerated the mildew of tobacco leaves.