Translocation of Carbohydrates in the Cuthbert Raspberry

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Abstract
Seasonal fluctuations in reducing sugars, sucrose, starch, acid hydrolyzable carbohydrates, total carbohydrates and the residual polysaccharides are recorded. Only the lst-year or vegetative canes were used. Ringing was used to check movements of sugars. Double rings were used, one 15 cm. and another 30 cm. above the ground. Plants were ringed and others tagged for controls on May 15, again on June 23, and finally on July 16. The plants treated on May 15 were harvested on June 23; those treated on June 23 and July 16 were harvested on July 16 and Aug. 9 respectively. Total carbohydrates accumulated above the rings and decreased between and below the rings. Sucrose, although low in conc. made the largest increases above and below the rings, in percentage of the normal cones., of all fractions. It decreased between the rings from 75 to 100%. Reducing sugars increased above the rings, but in percentage of the normal, only half that of sucrose. They decreased between and below the rings. All carbohydrate gradients were positive, sugars moving downward with a positive gradient. The gradients of acid hydrolyzable substances and starch were static. Ringing increased the positive gradient of reducing sugars. The slight gradient of sucrose was increased; if this sugar were moving only downward, a decrease in gradient would be expected. This effect, coupled with the great accumulation above and below the rings, suggests that in the early development of the young shoot there is a movement of sucrose from the perennial, carbohydrate-gorged roots into the young canc. during the growth period of the 1st season the roots-to-shoot gradient gradually disappears owing to the increased production of sugars by the rapidly enlarging foliage region of the cane; there is a counterbalancing of the upward movement from the roots by a downward movement of sucrose from the foliage; and the effect of the rings is to remove the influence of the opposing source in each case. The residual substances consist of those polysaccharides, small quantities of fats, minerals, and organic N which remain after the total carbohydrates, including acid hydrolyzable substances, are subtracted from the dry weight. The residual polysaccharides fluctuate as the total carbohydrates, particularly reducing sugars and the hemicelluloses fluctuate, and in the same direction.