GROWTH OF ETIOLATED AVENA SEEDLINGS IN RELATION TO PHOSPHORUS NUTRITION

The effects of carbon dioxide, of phosphate, and of nitrate nutrition on the growth of etiolated oat seedlings in relation to the amounts of reserves and of phosphorus translocated from the endosperm, have been studied in a 23 factorially arranged experiment.For each mg of translocate 4.37 μg of phosphorus were transferred in the untreated seedlings, and this rate was slightly increased by nitrates, reduced by phosphates, and hardly changed by carbon dioxide, at the concentrations used.Under treatment with phosphates a high content of phosphorus was quickly built up in the roots, but there was an initial reduction in the quantity found in the coleoptile and leaves. Apparently, upward transport from the roots took place only slowly; the phosphorus in the coleoptile and leaves may therefore have come preferentially from the endosperm.Although nitrate supply increased the flow of phosphorus from the endosperm, it decreased the content in the plants. This effect appears to be due to a smaller uptake of phosphorus in the presence of nitrates. © 1969 OXFORD UNIVERSITY PRESS.