Chemical Characteristics of Isotopes and Ph of Treating Solutions Isotopes Chemical Specific Ph of Isotop Chform Activity Treating Solutions

One criterion of the effectiveness of nutritional sprays is the rate at which the foliar applied nutrients are absorbed by the leaf and translocated to other plant parts including the roots. Two distinct but not easily separated processes, absorption and transport, are involved. Initial penetration most likely involves passage through the cuticle and epidermal cells (17, 20); stomata may also play a minor role (15). Transport of foliar absorbed nutrients undoubtedly occurs via the phloem (2, 3, 4, 14). While the rate and amount of transport varies with each element, it parallels the phenomenon of nutrient redistribution as described by Biddulph (2) and Williams (19). The extent of redistribution (mobility, phloem transport) of each nutrient in the plant is an important consideration in foliar applications of fertilizer to satisfy nutrient needs of plants (20), in assaying the capacity of meristems to initiate "internal starvation" (19), and in "keying-out" nutritional deficiencies (2). Symptoms of malnutrition may arise from lack of mobility as well as lack of initial absorption. Only in a few instances and with a limited number of the essential elements have rates of foliar absorption and transport been reported (2, 7, 14, 15, 20). As with herbicides (8, 17) isotopic labeling offers a unique approach to studies of nutrient absorption, transport (export) from leaves, and mobility. The rates of absorption, by the primary leaves of the bean, of several isotopically labeled nutrient elements, and their subsequent mobilities and partitioning within plant parts are herein presented.