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ABSTRACT:The nitrogen use efficiency (NUE) is defined as the capacity of a given genotype in take advantage of the applied nitrogen (N) and transform it in biomass and grains. The objective of this study was to evaluate 12 wheat cultivars as to the NUE and its components. The experiment was conducted in a controlled environment, in a randomized block design with three replications.

Several studies have shown a significant increase in wheat (Triticum aestivum L.) grain yield (GY) worldwide during the 20th century as a result of genetic and environmental improvement. The objective of this study was to measure the genetic gains achieved in a wheat breeding program maintained by the Central Cooperative of Agricultural Research (COODETEC) in Brazil through the annual evaluation of lines in multienvironment trials. The dataset was composed of 836 advanced trials and was evaluated in 40 representative locations to assess the value for cultivation and use (VCU) regions in the south, southeast, and central‐west areas of the country from 2004 to 2013. Each trial consisted of 25 treatments (lines + checks) in a randomized complete block design with three replicates. A linear mixed model was fitted to predict the genetic values of each genotype per year and a restricted maximum likelihood algorithm to estimate the variance components. These genetic values were used to compute the genetic gain over the years. The overall estimated genetic gain of the breeding program was 61.59 kg ha−1 yr−1 (1.68% yr−1) for GY, although it was partially counterbalanced by the estimated negative environmental effects. The genetic gain per VCU region ranged from 31.38 (VCU 4) to 115.33 kg ha−1 yr−1 (VCU 1). After accounting for the environmental changes over years, the yield gain was 39.40 kg ha−1 yr−1 (1.10% yr−1), ranging from −0.82 (VCU 3) to 3.35% yr−1 (VCU 1). The assessment of Brazilian cultivars released between 1998 and 2014 showed genetic gains in GY of 34.8 kg ha−1 yr−1 (1% yr−1), demonstrating that the efforts of Brazilian research institutions to develop cultivars have produced additive results. The implications of genetic gain estimates on breeding programs are discussed.

Soybean [Glycine max (L.) Merr.] maturity group (MG) is an important concept used to determine the most suitable macroregion and edaphoclimatic region (ECR) in which soybean can best use the available resources. This classification is based on the number of days between sowing and maturation in the soybean life cycle. The MG is related to photoperiod; thus, the longer the photoperiod, the shorter the MG of cultivars must be to have an adequate life cycle. However, there is no consensus on which MGs are the most suitable for each region to improve grain yield. The objective of this study was to identify suitable soybean MGs for cultivation in the macroregions and ECRs in Brazil. During 4 yr of evaluation, grain yield data from 247 yield trials over 83 locations, encompassing four macroregions and 14 ECRs in Brazil, were used. Cultivars were grouped according to their MG for statistical analyses. Using these groups, the ideal genotypes and performance according to local analyses were determined. The best adapted and most productive cultivars were those with an intermediate MG in their predefined adaptation region (both macroregions and ECR). The maturities that performed the best in each macroregion were as follows: M1 (cultivars in MGs 5.3–5.9) M2 (cultivars in MGs 6.0–7.0), M3 (cultivars in MGs 7.1–7.9), and M4 (cultivars in MGs 7.7–8.4). A lower productivity was observed in cultivars in extreme MGs for each macroregion. Breeding program efforts should target the MGs identified as ideal for each ECR to develop cultivars with a greater chance of achieving high yields and with greater adaptability to the specific region.

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Nitrogen (N) management in wheat crop is one of the most studied agricultural practices in Brazil; however, there are few reports on its use efficiency. The objective of this study was to characterize 18 Brazilian wheat cultivars, which are representative and have been recently released to cultivation, for nitrogen use efficiency (NUE). The experiments were carried out in Pato Branco, Paraná, and Coxilha, Rio Grande do Sul, during the 2011 crop season. It was used a randomized block design with three replications, in factorial scheme (2 environments × 18 cultivars). Genetic variability was observed for nitrogen utilization efficiency by grains (NUtEg=47.6 to 81.1 kg kg -1 ) and nitrogen harvest index (NHI=71.3 to 84.6%) with significant effects relating to the environment of cultivation and performance of these traits. The evaluation of the protein concentration of grain by near infrared spectrometry (GPC N ) produced equivalent results to the direct analytical method of Kjeldahl (GPC K ), in Pato Branco (r=0.56) and Coxilha (RS) (r=0.80). However the CPG N overestimated the protein values by 16.85%. The GPC and protein yield were positively correlated with NUtEg and NHI. The best performance for the traits associated with NUE was observed for the following cultivars: Mirante, Quartzo, Fundacep Cristalino, Fundacep Raízes and CD 150. This is the first report of differences between Brazilian wheat cultivars for nitrogen use efficiency.Key words: Triticum aestivum L., grain yield, nitrogen harvest index, SDS sedimentation, grain protein concentration. Caracterização de cultivares de trigo em termos de eficiência do uso do nitrogênioResumo O manejo do nitrogênio (N) na cultura do trigo é uma das práticas agrícolas mais estudadas no Brasil, entretanto ainda são poucos os relatos sobre a sua eficiência de uso. O objetivo deste estudo foi caracterizar 18 cultivares de trigo brasileiras representativas e recentemente disponibilizados para cultivo quanto à eficiência do uso do N (EUN). Os experimentos foram executados em Pato Branco, PR, e Coxilha, RS, na safra agrícola de 2011. O delineamento experimental utilizado foi em blocos casualizados em esquema fatorial (2 ambientes × 18 cultivares), em três repetições. Foi possível identificar variabilidade genética para a eficiência do uso do nitrogênio pelos grãos (EUNg = 47,6 a 81,1 kg kg -1 N) e índice de colheita de nitrogênio (ICN = 71,3 a 84,6%), com efeito do local de cultivo sobre o desempenho desses parâmetros. A avaliação da concentração proteica dos grãos por espectrometria de infravermelho próximo (CPG N ) produziu resultados equivalentes ao método analítico direto de Kjeldahl (CPG K ), em Pato Branco, PR (r = 0,56), e Coxilha, RS (r = 0,80), porém o CPG N superestimou os resultados em 16,85%. A CPG K e o rendimento de proteína (RP) foram positivamente associados com a EUNg. As cultivares Mirante, Quartzo, Fundacep Cristalino, Fundacep Raízes e CD 150 apresentaram melhor desempenho para os caracteres associados à EUN. Esse é o primeiro relato que mostra di...

Soybean is an important oil and protein source for human and animal food, as well as being used in the production of biofuel. Brazilian soybean is known for its quality, especially with regard to its high protein content. This work aimed to present a screening of Brazilian soybean cropped at different locations, to assess the composition of seed with regard to the protein, oil and fatty acid contents. We screened 46 cultivars, which represent more than 50% of the soybean cultivars produced in the South-Center region of Brazil in recent years, analyzed under six environments. In order to conduct the analysis, a grain sample was used to determine seed protein, oil and fatty acid contents, which was accomplished using near infrared spectroscopy (NIR). All the traits presented a genotype x environment interaction (GEI) (p<0.01). A mean oil content of 20.35% was identified for all the evaluated cultivars. This was superior to that obtained in other countries. The mean protein content was 40.20%, which was expected for the Brazilian soybean. This higher oil content is doubly favorable in Brazilian soybean: firstly, for its use as cooking oil and biofuel; secondly, for the production of high protein soybean meal, once all the oil is removed. The cultivars which presented the highest oil contents were also stable across the evaluated environments. On the other hand, the genotypes with the highest protein content presented low stability across the environments. Regarding the fatty acid composition, Brazilian soybean stands out for its low linoleic acid content, which gives a high oxidative stability to the resulting oil and biofuel. Trait associations were dependent on the location, thus breeders can select plants for specific traits at different locations. Brazilian cultivars present interesting characteristics for use in human and animal food products, and for biofuel production.

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