Nitrogen Use Efficiency and Yield of Wheat Genotypes Affected by Nitrogen Fertilizing and Environmental Conditions in Southern Brazil

Nitrogen (N) is a key nutrient for plant growth and yield, but N fertilizing management is complex due to the influence of the genotype x environment interaction. This study evaluated N use efficiency and yield of wheat genotypes in response to N fertilizer rates and environmental conditions. The experiment was carried out in four environments in southern Brazil [Londrina in rainfed and irrigated conditions (L-rainfed and L-irrig), Cascavel (C-rainfed), and Ponta Grossa (PG(rainfed))] in a randomized block design with a 2 x 10 factorial arrangement, i.e. two N rates and ten wheat genotypes. The results showed that the studied wheat features (except shoot dry matter-SDM) were increased mainly due to higher water availability compared to N fertilizing. Increasing N rate from 40 to 120 kg ha(-1) N increased the density of fertile spikes by 11.5% in L-rainfed, plant lodging by an average of 12 percentage points in L-rainfed and L-irrig, N concentration in the SDM (NCSDM) by an average of 9% in L-irrig, C-rainfed and PG(rainfed), and N accumulation in the SDM (NA(SDM)) by an average of 14.6% in L-irrig and PG(rainfed). Overall, BRS Sanhaco was the genotype more responsive to N rates in terms of grain yield (average increase of 7.3% in C-rainfed and PG(rainfed)), whereas BRS Gralha-Azul, TBIO Sintonia, and Quartzo were the lower ones. The TBIO Toruk took place in the genotype group with the lower N utilization efficiency (NUtE) in all environments, with an average of 25 kg kg(-1). TBIO Sinuelo had higher NCSDM, NA(SDM), NUtE, and grain yield (averages of 17.3 g kg(-1), 163.5 kg ha(-1), 40.1 kg kg(-1), and 6436 kg ha(-1), respectively) across most of the environments. Grain yield had positive correlations with NCSDM, NA(SDM), and NUtE. Thus, we conclude that these N traits can be better explored in breeding programmes to achieve genotypes more productive and efficient in N use. In this context, TBIO Sinuelo has the potential to be used as part of an improvement strategy for spring wheat genotypes in southern Brazil.