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14 C‐Studies on Apple Trees. VIII. The Seasonal Variation and Nature of Reserves
Author(s) -
HANSEN POUL,
GRAUSLUND JØRGEN
Publication year - 1973
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1973.tb01146.x
Subject(s) - xylem , dry matter , sorbitol , chemistry , fraction (chemistry) , zoology , starch , malus , carbohydrate , botany , horticulture , biology , food science , chromatography , biochemistry
The nature, seasonal variation and mobilization of reserves in Malus × domestica have been studied by means of 14 C, carbohydrate analyses and extractions of xylem sap. Following exposure to 14 CO 2 in the autumn, the majority of the 14 C absorbed is found in the root. During the winter and in particular the spring the amounts of 14 C in the top and root are reduced to approximately 40 per cent of the autumn values; in the root the amount of dry matter was also considerably reduced. In the tops, most of the 14 C absorbed was found as methanol (80 %)‐soluble 14 C which also showed the greatest seasonal reduction; sorbitol, sucrose or glucose in particular are responsible for the decrease in concentration within this fraction. Maximum values for methanol‐insoluble 14 C were found in March. In the root, the highest values for absolute changes were found for methanolinsoluble 14 C. Hydrolysis of this fraction showed considerable activity in glucose. In the root there was also considerable activity in a precipitated fraction of the methanol extract. Eluates of xylem sap from apple branches contained primarily sorbitol, the highest concentration of which was found at the beginning of March. For a tree with a dry matter weight of about 300 g, the utilization of reserves from the tree in the spring was calculated to be at least 13 g of dry matter. However, only a minor part (less than 25 per cent) of the latter appears to serve as building material for new growth.