Interactions of potassium with nitrogen and their influence on growth and yield potential in maize

Abstract

Abstract Although potassium (K) is not a structural component of plants, it is involved in numerous biochemical and physiological processes. This study was conducted to examine interactions of K with nitrogen (N) levels and N sources as they affect both growth and yield in maize. The role of K in sucrose and amino acid transport into endosperm tissue also was investigated, since maize yield increases are heavily dependent on inputs of inorganic N and K fertilizers. Plants of four maize hybrids were grown in a greenhouse in sand/soil culture. Pots were supplemented to provide 168, 336, or 672 kg/ha K and 168 or 336 kg/ha N as NH4NO3, Ca(NO3)2, or (NH4)2SO4. Plants were harvested at midsilk, and dry weights and kernel primordia were determined. High levels of K promoted more vigorous growth when mixed‐N treatments were averaged across all N rates. High K in conjunction with mixed‐N generally enhanced dry matter accumulation and kernel primordia number for all hybrids. However, high K with either ammonium (NH4 +) or nitrate (NO3 −) generally had a negative effect on dry matter accumulation and primordia number. Hybrids tended to respond differently to these interactions. In vitro movement of L‐glutamine into endosperms was enhanced with 25 or 50 mM K, but K levels in excess of 50 mM were inhibitory. Sucrose uptake was strongly enhanced by K and followed the same pattern as L‐glutamine, but required higher levels of K.