Interactions of potassium with nitrogen and their influence on growth and yield potential in maize.
Stromberger J.A. | Tsai C.Y. | Huber D.M.
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.
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