ChileanJAR

The characterization ofthe physiological nitrogen use efficiency (PNUE) ofwheat cultivars and maize hybrids growing under different N-fertilizer rates and N-sources was determined. At low nitrogen fertilizer supply, the wheat cultivars and maize hybrids evaluated produced grain with the highest physiological Nuseefficiency, 54-80 kg and 60-72 kg ofgrain per kg ofnitrogen absorbed, respectively. Under the highest N-fertilizer applications, PNUE was the lowest, 25-31 and 20-30 kg of grain per kg of nitrogen absorbed for wheat and maize respectively. PNUE showed higher sensitivity than agron0mic and recovery N use efficiency to sample genotypic and/or environmental effect. Wheat demonstrated genotypic effects intheir PNUE responses, whereas maize hybrids demonstrated genotypic and environmental effects in their PNUE responses. Some ofthese highest PNUE values were presented along with higher grain yield which must be seen as a possibility to select N-efficient material adapted to sustainable agriculture. The presente work relies on one of the concept of sustainable agriculture, which takes into account the general inputoutput ratio achieved in terms of improved use efficiency of nutrientes by crops.