Mineral Distribution in Relation to Fruit Development and Monocarpic Senescence in Anoka Soybeans

The changes in distribution of several important mineral nutrients (N, K, Ca, Mg, Mn, and Fe) were studied in relation to monocarpic senescence (measured as leaf yellowing) and fruit development in hydroponically‐grown (and to a lesser extent field‐grown) Anoka soybeans with particular emphasis on the leaves and seeds. Only N shows a clear redistribution from the leaves to the seeds as the seeds grow, and this transfer starts before visible leaf yellowing. K, Ca, Mn and Fe do not seem to redistribute, but Mg may undergo limited redistribution. Depodding prevents the drop in the amounts of minerals in attached leaves by blocking leaf shedding and/or redistribution and also creates some quantitative changes in mineral distribution. On a g fresh weight basis, only the N content of leaf blades decreases during yellowing; the K, Mg, Ca, Mn and Fe contents do not decrease. Therefore, depletion of the latter minerals from the leaves cannot be responsible for their yellowing. Although N deficiency alone could cause foliar chlorosis, the monocarpic yellowing pattern is distinctly different from that induced by N deprivation.