烤烟不同成熟期色素含量变化及其与叶绿体超微结构的关系探究

为明确烤烟成熟过程中色素含量变化及其与叶绿体超微结构的关系，以3个烤烟品种为试验材料，针对未熟、适熟和过熟的中部叶叶片，进行了活体叶绿素SPAD值、叶绿素含量、叶绿素酶活性测定，并对叶绿体超微结构进行观察和分析。结果表明：3个烤烟品种中部叶的叶绿素含量、活体叶绿素SPAD值及叶绿素酶活性均随着烟叶成熟过程呈现出下降趋势。随着成熟度的提升，叶绿体结构由完整到破裂，淀粉粒和嗜锇颗粒增多、体积增大，基粒片层由紧凑变为疏松，结构紊乱扭曲，基质片层和基粒片层间的界限明显度也下降，淀粉粒和嗜锇颗粒向着细胞中部游离，叶绿体被膜逐步破损。基粒片层数和片层垛叠数也随着成熟度的加深不断减少。相关分析表明，烤烟成熟期中部叶的色素含量与叶绿体超微结构间存在较强的相关性，这使得从色素、SPAD值判定成熟度有了内在依据，因而能够更好地判定成熟度并在最佳采收期采收。

Study on Changes of Pigment Content in Flue-cured Tobacco at Different Maturity Stage and Its Relationship with Chloroplast Ultrastructure

In order to clarify the change of pigment content and its relationship with chloroplast ultrastructure in the process of flue-cured tobacco ripening, three flue-cured tobacco varieties were used as experimental materials to measure the SPAD value of chlorophyll in vivo, the content of chlorophyll and the activity of chlorophyllase in the unripe, ripe and overripe middle leaves, and the ultrastructure of chloroplast was observed and analyzed. The results showed that the content of chlorophyll, the SPAD value of chlorophyll and the activity of chlorophyllase in the middle leaves of three flue-cured tobacco varieties decreased with the extension of maturity period. With the increase of maturity level, the structure of chloroplast changed from integrity to rupture, starch granules and eosinophil granules increased, the volume increased, the lamellar layer of basal granules changed from compact to loose, the structure was disordered and twisted, the boundary between the lamellar layer of matrix and the lamellar layer of basal granules also decreased significantly, starch granules and eosinophilic granules dissociated towards the middle of cell, and the membrane of chloroplast was damaged step by step. Correlation analysis showed that there was a strong correlation between pigment content and chloroplast ultrastructure in the middle leaf of flue-cured tobacco. This made it possible to determine maturity level from pigment and SPAD value, thus it was betterly understood the maturity of tobacco leaves, so as to harvest them in optimal harvest period.