Chemical Investigation of "Trashy" Leaf Phenomenon in Australian-Grown Flue-Cured Tobacco

Abstract

SummaryCarbohydrates and nitrogen distribution in flue-cured tobacco leaves described as "trashy" were determined. Sugars in "trashy" leaf were as low as 3 per cent. and in "good" leaf as high as 28 per cent. "Trashy" leaf, relatively to normal leaf, had large total N, protein N, and ammonia N contents and low amide N values, while its weight per unit area was about 30 to 50 per cent. less than that of "good" leaf. Uncured "affected" ,leaf also had low sugar and high N values and low weight per unit area.It is believed that trashiness is due to processes associated with carbohydrate impoverishment in leaves on the plant and· that its development is conditioned by constraints such as soil nitrogen (N), temperature (T), and sunlight (L). It is suggested that effects of the N-L-T constraints on compounds available to the plant for degradation as "foods," can be expressed in simplified form as ~ R ex: NT, where ~ R is the total energy "spent" irreversibly (i.e. become nonavailable for various liying processes) by the plant in unit time.. If ~ E is the total available energy from all sources during the same time, then for certain values of ~'E -~ R "sugars" will dEicrease with corresponding approach to tpe state ot exhaustion of other compounds and onset of trashiness.Inagticultural practice it is suggested that, when considering measures for control of trashiness, attention should be' given to plant spacing, nitrogen supply, number of :hours of sunshine, and night temperatures: