Plant species response to ammonium‐nitrate concentration ratios

Abstract

Most plants can use either nitrate (NO₃) or ammonium (NH₄) as a source of nitrogen. However, the degree of effectiveness of these two forms on plant growth and nutrient uptake is dependent on plant species and NH₄.: NO₃ ratio. The 77: 77 ppm NH₄: NO₃‐N concentration ratio in solution caused the most growth reduction for cabbage, melon, and corn, with corn being least affected. Bean seems to be well adapted to the use of NH₄, and was unaffected by equal concentrations of NH₄: NO₃‐N. The presence of 28 ppm NH₄‐N in the mixture reduced only cabbage growth, whereas growth of melon, bean and com was not affected. All of the species studied responded to the NH4 concentration increase by an increase in anion content in their leaf tissues. The K content in melon and corn leaf was increased with NH₄‐N up to 28 ppm. The K content in tomato and cabbage tissue was reduced at 28 ppm NH₄. The K content in all the species tested was reduced with 77: 77 ppm NH₄: NO₃‐N concentration treatment. Calcium composition reduction in all the plant species was affected at 28 ppm NH₄‐N with reduction to 50% that of all NO₃ nutrition at 77 ppm NH₄‐N. Magnesium composition of corn tissue was most severely reduced by the 77: 77 ppm NH₄: NO₃‐N nutrition. Bean Mg composition was not affected by the NH₄‐N concentration in the 14 to 77 ppm range. Magnesium was reduced in cabbage, melon, and corn by NH₄‐N concentrations above 28 ppm.