DIURNAL CHANGES AND GROWTH RATES AS ASSOCIATED WITH ASCORBIC ACID, TITRATABLE ACIDITY, CARBOHYDRATE AND NITROGENOUS FRACTIONS IN THE LEAVES OF ANANAS COMOSUS (L.) MERR

Abstract

The variations in ascorbic acid content appeared to be connected with changes in the carbohydrate level. Sugars increased all day, while acidity decreased; this inverse relation suggests that acids are generated after oxidation of sugars. Soluble N increased and residual N decreased in daylight. The concentrations of acid in the chlorophyllous tissues at different diurnal intervals varied slightly. Titratable acidity of the tissues, composed mostly of malic and citric acids, increased at night, but decreased in day; being highest at 6 A.M. and lowest at 6 P.M. Total sugars decreased at night, but increased in day, being lowest at 6 A.M. and highest at 6 P.M. Higher acidity (about 13%) was obtained on a day when sunlight level was high (Aug. 2) than on a day of 50% lower sun as measured by white bulb-black bulb temperature differential. Titrable acidity was inversely related to total sugars, suggesting possible generation of acidity and negatively with total sugars. Residual nitrogen, i.e., the insoluble fraction in macerated tissues after extraction of the water soluble fraction, was greater from tissues collected at intervals at night, than in day, but extractable nitrogen, in the water soluble fraction, was reversed.