Effect of amino acid fertilization on nitrate assimilation of leafy radish and soil chemical properties in high nitrate soil

The objective of the present work was to investigate the corresponding uptake and assimilation of nitrate (NO3-) in leafy radish and effects on soil chemical properties by foliar application of amino acid fertilizer (AAF). The activity of the enzymes related to the process of NO3- reduction (NR: nitrate reductase; NiR: nitrite reductase; GS: glutamine synthetase) and the content of NO3-, total N, and the end products of this process (amino acids and proteins) were analyzed. The soils were sampled twice, and some chemical properties were analyzed. The results of this study showed that application of AAF increased biomass production, and nitrogen (N) utilization in the treatment of a low rate of AAF increased 55% over the control. In addition, the activities of the enzymes were affected differently depending on applied rate of AAF. Furthermore, the NO3- content was reduced 4-24%, and total N content was increased 14-32% by AAF treatments. Finally, application of AAF improved uptake efficiency of N from soil and prevented N loss by leaching.