Nitrogen rate and source affects leaf elemental concentration and plant growth in muscadine grapes
1993
Spier, J.M. | Braswell, J.H.
Leaf concentrations of nitrogen (N), phosphorus (P), potassium (K), iron (Fe), and manganese (Mn) in 'Sterling' muscadine grapes (Vitis rotundifolia Michaux) grown for two years in sand culture were not influenced by different N-fertilizer sources. Leaf zinc (Zn) and copper (Cu) were higher with ammonium nitrate (NH4NO3) than ammonium sulfate [(NH4)2SO4]. Shoot growth was greatest with NH4NO3. Leaf Ca, Mg, Mn, and Cu content decreased and leaf N increased as N-fertilizer rates were raised. Plant growth was positively correlated with leaf N, but was negatively correlated with leaf Ca, Mg, Fe, Cu, and Mn content. Percent Mg in the leaves was reduced when N levels, regardless of N source, were raised from the low (1.8 mM) to the middle (5.4 mM) rate. High leaf-N levels were correlated with lower Ca and Mg in the leaves, indicating a relationship between N fertilization and the late-season Mg deficiency often observed in muscadine grapes.
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