The role of the leaves in the accumulation of nitrogen by wheat during ear development

Abstract

When wheat plants were deprived of nitrogen in the rooting medium at anthesis there was a small, but significant, increase in the nitrogen content of the grain at maturity. It was shown that there was a greater migration of nitrogen from the leaves and stem to the ear in plants deprived of nitrogen than in those plants supplied with nitrogen throughout ear development.

In an examination of the effects on grain nitrogen content of leaf removal at anthesis, it was shown that this treatment reduces the uptake of nitrogen into the culm and the nitrogen content of the grain at maturity.

Ear shading treatments significantly reduced the total nitrogen content of the grain in one experiment. Ear shading also decreased the amino nitrogen, and increased the nitrate nitrogen, content of the ear.

Variation of the grain dry weight per ear, induced by shading, by defoliation treatments, or by differences in variety, were positively correlated with grain nitrogen content. Either the movement of dry matter and nitrogen into the ear are interdependent, or they are both promoted by some external factor, such as rate of growth of the ear.

The possible importance of the leaves of the wheat plant in promoting the uptake of nitrogen into the culm and in supplying nitrogen to the grain is discussed.