The effect of Aging on Ion Uptake by Excised Barley Roots

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Abstract
When excised barley (Hodeum Vulgare L.) roots were aged, the rate of uptake of K and C1 increased raching a maximum in about 14 to 18 h. At its maximum the uptake rate was approxiamately twice that of the freshly excised root materila. Respiratory activity declined markedly during the aging period. Although excision was an essential requirement for uptake enhancement, washing was not. Both the uptake and aging processes were shown ot be unresponsive to the presence or absence of Ca in the tratment solutions. Because of cation exchange properties, the change in the total cation content of the root material was a more meaningful measure of the metabolically mediated cation uptake than was the change in content of the test cation itself. The pluggin of xylem vessels with protein and pectin‐like substances was observed to increase with aging. It is proposed that the occlusion of the vessels may account for an apparent increaase in uptake since the obstruction could reduce a concurrent loss of ions through the cut ends of the root segments.