Showing papers in "Physiologia Plantarum in 1963"

CHANGES IN THE PERMEABILITY OF CARROT TISSUES DUE TO $gamma$ IRRADIATION AND OTHER PHYSICAL AND CHEMICAL TREATMENTS

Abstract: The effect of Co/sup 60/ radiation on the permeability of carrot tissue and the possibility of reducing this effect by means of CaCl/sub 2/ were studied. In addition, the radiation effect was compared to the effects of freezing and treatment with various fixing fluids. Carrots of the Nantes variety were used, and gamma irradiation was carried out at 4 deg C with doses varying from 35 to 1450 krad. The loss of sugar and ions in water and the uptake of sucrose from solution were shown to increase strongly with increasing doses. The weight loss in molar sucrose plus the weight loss in water, as compared to untreated samples, were reduced considerably with increasing doses of radiation. In the presence of 0.01M CaCl/sub 2/ the uptake of sucrose was considerably lower and the weight loss was considerably higher in molar sucrose, but the overall course of the curves was the same as in the absence of CaCl/sub 2/. Gains and losses of matter proceeded exponentially with increasing doses. The weight loss in sucrose was accompanied at low doses by shrinking andd plasmolysis of the cells. At higher doses there was no such reaction. In addition, it was shown that themore » rates of uptake and release of matter were dependent on temperature and on the area of cut surface/volume ratio, while the final result was independent of these values. The extent of exudation through the periderm was very slight at low (< 250 krad) doses. It was also shown that Ca induced rigidity of the cell walls and reduced the permeability of cells to sucrose. Na had a reverse effect. Low pH values ( approximates 2) caused a direct loss of matter from the cells to water. It was not possible to demonstrate any certain effect of oxalate ions (0.01M) on the uptake of water. Freezing of the tissue gave the same curves as the highest dose of radiation used, but the effects on its structure were different. Fixing fluids had the reverse effect of irradiation on permeability. Respiration experiments showed the respiration to decrease simultaneously with a marked increase in permeability. It is concluded that the combination of the radioinduced injuries to the tissues (impairment of the wound healing, deterioration of cell walls, and increased permeability) provide saprophytes with the same growth possibilities afforded the parasites on untreated carrots, and that treatment with low concentrations of CaCl/sub 2/ reduce the deleterious effects of radiation. (BBB)« less