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ISHS Acta Horticulturae 932: XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Plant Physiology from Cell to Fruit Production System

ACCUMULATION OF TOTAL AND REDUCING SUGARS IN THE GREEN LEAVES AND BULB TISSUES DURING GROWING AND BULBING OF ONION (ALLIUM CEPA L.)

Author:   N. Benkeblia
Keywords:   growth, development
DOI:   10.17660/ActaHortic.2012.932.42
Abstract:
The accumulation of reducing and total sugars in the green leaves and bulb of onion (Allium cepa L.) tissues during growing and bulbing was investigated. Total sugars (TS) and reducing sugars (RS) were analyzed spectrophotometrically by the method of Nelson and Somogyi. RS in green leaves increased from 10 to 16 weeks, and then decreased after 18 weeks. In bulbs, RS showed a progressive increase from week 10 to week 14, but they increased sharply during the last four weeks. TS varied similarly to RS in green leaves, and increased progressively from week 10 to 14, and then sharply by two-fold after week 16. During the last two weeks of growing, TS decreased in week 18. In bulb, TS increased progressively from week 10 to 14, and then increased sharply during the last four weeks and were 66.3 and 70.7 mg g-1 FW after week 16 and week 18, respectively. The bulb to leaf ratio of reducing and total sugar contents was estimated in leaves and bulb during growing, and we noted that the ratio increased from 1 to 1.7 and 1.6 at week 12 for RS and TS, respectively. From week 12 to 16, the ratio decreased to values close to those observed at the beginning, and afterwards it increased sharply at week 18 to 1.7 and 2.2 for RS and TS, respectively. This indicates that during the maturity stage, there is a massive export of carbohydrate reserves from the leaves to the bulb.

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