Changes in the Chlorophyll and Carotene Contents of Curing Burley Tobacco Cut at Different Stages of Maturity

Abstract

IntroductionChanges in the chemical composition of burley tobacco which take place in curing are being investigated at the Kentucky Agricultural Experiment Station in an attempt to understand the physiology of curing and its effect on leaf quality. Color is recognized as one of the most important factors in the determination of leaf quality, any retention of green pigment in the cured leaf greatly reducing its value. The chlorophylls are the green pigments in normal tobacco, and the investigations reported in this paper were made primarily to determine the rate and amount of change in these pigments during air curing on the stalk of tobacco cut at three stages of maturity. The development of a method for determining carotene from the same solution used in the chlorophyll determinations made possible the study of this constituent.This study of the catabolic changes of plant pigments is of general biochemical and physiological interest. Numerous articles have appeared reporting the rates of formation of these pigments under different conditions, but studies on pigment disappearance are rare. In 1918 WILLSTXTTER and STOLL (5) reported that the chlorophyll content of yellowed leaves was less than of green leaves. They did not, however, follow closely the loss of either chlorophyll or carotenoids. GUTHRIE (2) investigated the pigment changes in potted plants when placed in the dark as compared with others remaining in the light. His results indicated that tomato plants lost about 25% of their chlorophyll in four days, soybean plants about 70%o in eight days, and yellow coleus practically none in eight days.

Quantitative Investigations of Leaf Pigments From Their Inception in Buds Through Autumn Coloration to Decomposition in Falling Leaves

“…Studies of Willstatter and Stoll (1918) revealed no change in the ratio of chlorophyll a to chlorophyll b in autumn leaves. The more rapid breakdown of chlorophyll a as compared to chlorophyll b under a variety of circumstances involving the decay of green plant tissue has since been demonstrated, however (Rudolf 1934, Nagel 1940, Seybold 1943, Egle 1944, Jeffrey and Griffith 1947, Strain 1949, Wolf and Wolf 1955, Wolf 1956, Goodwin 1958, so it appears that the earlier views of Willstatter and Stoll were wrong. Egle ( 1944), from his studies on silage, concluded that acids arising during fermentation constituted an important factor in chlorophyll destruction, with chlorophyll a less resistant than b.…”

The Chlorophyll Content of Certain Flue‐Cured and Turkish Tobacco Varieties

“…Subsequently Jeffrey and Griffith ( 6) studied the changes in concentrations of chlorophylls during air curing of the Burley variety Kentucky 16. They used 3 sets of samples, one from plants cut 10 days before maturity, another when mature, and the third when 10 days overmature.…”