Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, Udine, Italy.
Department of Agricultural, Forest and Food Sciences, University of Torino, Grugliasco, Italy.
Plant Physiol Biochem. 2021 May;162:613-623. doi: 10.1016/j.plaphy.2021.03.037. Epub 2021 Mar 20.
Despite the wide use of urea and ammonium as N-fertilizers, no information is available about the proper ratio useful to maximize the efficiency of their acquisition by crops. Ionomic analyses of maize seedlings fed with five different mixes of urea and ammonium indicated that after 7 days of treatment, the elemental composition of plant tissues was more influenced by ammonium in the nutrient solution than by urea. Within 24 h, similar high affinity influx rates of ammonium were measured in ammonium-treated seedlings, independently from the amount of the cation present in the nutrient solution (from 0.5 to 2.0 mM N), and it was confirmed by the similar accumulation of N derived from ammonium source. After 7 days, some changes in ammonium acquisition occurred among treatments, with the highest ammonium uptake efficiency when the urea-to-ammonium ratio was 3:1. Gene expression analyses of enzymes and transporters involved in N nutrition highlight a preferential induction of the cytosolic N-assimilatory pathway (via GS, ASNS) when both urea and ammonium were supplied in conjunction, this response might explain the higher N-acquisition efficiency when both sources are applied. In conclusion, this study provides new insights on plant responses to mixes of N sources that maximize the N-uptake efficiency by crops and thus could allow to adapt agronomic practices in order to limit the economic and environmental impact of N-fertilization.
尽管尿素和铵是广泛使用的氮肥料，但关于最大限度提高作物吸收效率的最佳比例，尚无信息可用。对用五种不同尿素和铵混合物喂养的玉米幼苗进行的离子组分析表明，在处理 7 天后，植物组织的元素组成受营养溶液中铵的影响大于尿素。在 24 小时内，无论营养溶液中存在的阳离子数量（从 0.5 到 2.0 mM N）如何，铵处理的幼苗中都可以测量到类似的高亲和力铵流入率，并且可以通过来自铵源的 N 的类似积累来证实。7 天后，处理之间的铵吸收发生了一些变化，当尿素与铵的比例为 3:1 时，铵的吸收效率最高。参与氮营养的酶和转运蛋白的基因表达分析突出了细胞溶质氮同化途径（通过 GS、ASNS）的优先诱导，当同时供应尿素和铵时，这种反应可能解释了当两种来源同时应用时更高的氮吸收效率。总之，这项研究为植物对氮源混合物的反应提供了新的见解，这些反应可以最大限度地提高作物的氮吸收效率，从而可以调整农业实践，以限制氮施肥的经济和环境影响。
