Variacoes diurnas no teor de amido e de acucares solúveis em folhas de cacau (Theobroma cacao L.)

The starch and total sugar contents results from prevalent photosynthesis in cocoa leaves were determined. Cocoa seedlings of 'Catongo' grown in a greenhouse were utilized. The plants were submitted to a dark period of 48 hours to reduce the stored carbohydrates level in the leaves. Leaf discs were collected for carbohydrates determination before and after the darking and daily at intervals of two and tree hours from 8:00 and at 18:00 and 19:00 hours, respectively. There was no significant difference for starch contents between leaves of different ages. A significant difference between the youngest and the oldest leaves was observed for soluble sugar content. Generally, the highest levels of starch and soluble sugar were observed at 8:00 and 11:00 hours. From then the soluble sugar level remained stable while starch level increase gradually until - 17:00 hours. The starch accumulation between 8:00 and 17:00 h was about 4.2 mg.dm exponent -2 of leaf, which represented, on average, about 30 percent of the non structural carbohydrate accumulated in the leaves in this time period. The highest rate of soluble sugar loss occurred during the night and was about 12,0 mg.dm exponent -2 of leaf. The results showed that soluble sugars are the predominant form of non-structural carbohydrates in cocoa leaves during the photosynthetic period.

Bibliographic Details

Main Authors:	89073 Machado, R.C.R., 97348 Muller, M.W., 46744 Barretto, W.S.
Format:	biblioteca
Published:	1989
Subjects:	THEOBROMA CACAO, HOJAS, COMPOSICION QUIMICA, CONTENIDO DE CARBOHIDRATOS, AZUCARES, BROTACION, CULTIVAR CATONGO,
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