The retainers of water in the soil can favor nitrogen (N) use efficiency in oat yield. The aim of the study was to determine if the conditions of use of the biopolymer hydrogel increase the fertilizer-N use efficiency in oat yield in succession systems of high and low residual-N release. In each succession system (soybean/oat, corn/oat), two experiments were conducted in 2014 and 2015, one to quantify biomass yield and the other to estimate grain yield and lodging. The design was randomized blocks with four replicates in a 4 x 4 factorial scheme for hydrogel doses (0, 30, 60 and 120 kg ha-1), added in the furrow with the seed, and N fertilizer doses (0, 30, 60 and 120 kg ha-1) applied in the fourth-expanded-leaf stage. The use of hydrogel increases N use efficiency in oat yield, especially under the conditions of 30 to 60 kg ha-1 of biopolymer; however, this effect is dependent on the succession system and on weather conditions.

The supply of glutamic acid-based biostimulants may represent an innovative technology to increase oat grain yield and quality. The objective of this study is to measure the effect of different biostimulants based on concentrations of glutamic acid and nutrients and their application on indicators of productivity and industrial and chemical quality of oat grains. The study was conducted in 2016 and 2017 in a randomized block design with four replications, considering 10 combinations of treatments for different application conditions and types of glutamic acid-based biostimulants, which were: 1. Control; 2. Zinplex (seed) + Biomol (grain filling); 3. Zinplex (seed) + Glutamin Extra (grain filling); 4. Zinplex (seed) + Biomol (thinning); 5. Glutamin Extra (1st fungicide application) + Glutamin Extra (2nd fungicide application); 6. Biomol (1st fungicide application) + Biomol (2nd fungicide application); 7. Zinplex (seed) + Vorax (grain filling); 8. Vorax (1st fungicide application) + Vorax (2nd fungicide application); 9. Biomol (thinning) + Vorax (grain filling) and 10. Biomol (thinning) + Glutamin Extra (grain filling). The foliar application of biostimulants with the presence of glutamic acid and nutrients may have positive effects on variables related to productivity and industrial and chemical quality of oat grains, however, depending on the agricultural year conditions. The application of Glutamin Extra in the 1st and 2nd fungicide application shows the best results in the vast majority of grain yield and quality variables, but the costs involving only biostimulants do not guarantee economic viability.

A B S T R A C TNitrogen use efficiency in wheat biomass and grain yields can be favored by the biopolymer hydrogel. The objective of the study was to analyze the use of the biopolymer hydrogel applied to the seed in the optimization of fertilizer-N on wheat biomass and grain yields, under different conditions of agricultural year and succession systems of high and reduced release of residual-N. In the study, two experiments were conducted, with different farming systems, soybean/wheat and maize/wheat, one to quantify the biomass yield rate and the other to determine grain yield. The experiments were conducted in the years 2014 and 2015, in a randomized block design with four replicates in a 4 x 4 factorial scheme, corresponding to hydrogel doses (0, 30, 60 and 120 kg ha ), applied as top-dressing. It is possible to improve the fertilizer-N efficiency by wheat using the biopolymer hydrogel for the production of biomass and grains. The highest wheat yield per kilogram of N supplied is obtained with 30 and 60 kg ha -1 of hydrogel, regardless of the year and succession system.Eficiência do nitrogênio na produtividade do trigo pelo biopolímero hidrogel ) aplicadas em cobertura, respectivamente, no sistema de sucessão soja/trigo e milho/trigo. É possível melhorar a eficiência de N-fertilizante pelo trigo com o uso do biopolímero hidrogel à produção de biomassa e grãos. A maior produtividade de trigo por quilograma de nitrogênio fornecido é obtida com 30 e 60 kg ha -1 de hidrogel, independente do ano e do sistema de sucessão. R E S U M O IntroductionWheat is one of the most produced cereals in the world (Arenhardt et al., 2015;Brezolin et al., 2017). Nitrogen (N) is essential to guarantee high yield of the wheat crop (Teixeira Filho et al., 2010;Prando et al., 2013), but is easily leached in rainy years (Teixeira Filho et al., 2010; Mantai et al., 2015) or volatilized in dry years (Rojas et al., 2012;Arenhardt et al., 2015). Thus, N use efficiency by wheat is eventually compromised, decreasing the yield and increasing the losses to the environment (Prando et al., 2013. Technologies that allow to improve yield with greater sustainability are necessary, especially in the increase of N use efficiency in the agricultural processes (Pinnow et al., 2013; Mantai et al., 2015).One of the ways to improve N absorption by plants is the maintenance of soil moisture, since the N supply depends, among other factors, on moisture, aeration and temperature, which interact in the cultivation systems (Rocha et al., 2008;Silva et al., 2015). The use of the biopolymer hydrogel may represent a technology to regulate soil water availability to crops, which would favor the efficiency of absorption of nutrients and improve the yield (Azevedo et al., 2008;Mendonça et al., 2013). Hydrogels are biodegradable threedimensional polymeric networks that retain water in their structure, forming a gel, which is capable of hydrating and releasing water over time (Kaewpirom & Boonsang, 2006;Venturoli & Venturoli, 2011).The objective of the study was t...

A B S T R A C TThe simulation of oat development cycle can be used in the planning of agricultural practices. The aim of the study was to simulate and validate the duration of oat development cycle by photoperiod, temperature and coefficients of development of wheat for use in the WEStreck model, considering different doses of N-fertilizer and systems of succession of high and low C/N ratio. The study was conducted in 2015 in a randomized block design with four replicates in a 4 x 2 factorial scheme, corresponding to N rates (0, 30, 60 and 120 kg ha -1 ) and oat cultivars (Barbarasul and Brisasul), respectively, in the soybean/oat and maize/ oat systems. The duration of the stages from emergence to anthesis and from anthesis to maturation of oats was simulated in the WE-Streck model. The minimum, optimum and maximum temperatures that effectively simulate the oat development cycle were 4, 22 and 30 °C from emergence to anthesis and 15, 25 and 35 °C from anthesis to maturation, respectively. The intermediate-cycle oat development was efficiently simulated by the WEStreck model using coefficients developed for wheat, with vegetative and reproductive cycles estimated at 89 and 43 days, respectively. Simulação do ciclo de desenvolvimento da aveia por fotoperíodo e temperatura R E S U M OA simulação do ciclo de desenvolvimento da aveia pode ser utilizada no planejamento de práticas agrícolas. Objetivou-se simular e validar a duração do ciclo de desenvolvimento da aveia por intermédio de fotoperíodo, temperatura e coeficientes de desenvolvimento do trigo para uso no modelo WE-Streck, considerando diferentes doses de N-fertilizante e sistemas de sucessão de alta e reduzida relação C/N. O estudo foi conduzido em 2015, em delineamento de blocos casualizados com 4 repetições em esquema fatorial 4 x 2 para doses de nitrogênio (0, 30, 60 e 120 kg ha -1 ) e cultivares de aveia (Barbarasul e Brisasul), respectivamente, no sistema soja/aveia e milho/aveia. No modelo WE-Streck foi simulada a duração das fases emergência à antese e antese à maturação da aveia. As temperaturas mínima, ótima e máxima que simulam com eficiência o ciclo de desenvolvimento da aveia da emergência à antese, foram 4, 22 e 30 °C, respectivamente e da antese à maturação 15, 25 e 35 °C, respectivamente. A simulação do desenvolvimento da aveia de ciclo médio pelo modelo WE-Streck foi eficiente usando coeficientes desenvolvidos para o trigo, com ciclo vegetativo e reprodutivo estimado em 89 e 43 dias, respectivamente.

Nitrogen fertilizer management modifies oat (Avena sativa) panicle components and its grain yield. The work aims to study the potential of the variables of oat (A. sativa) panicle with N-fertilizer, and to simulatate its grain yield using multiple linear regression in succession systems of high and reduced Nresidual release. The study was done in 2013 and 2014. The experiment was done in a complete randomized block of 4×2 factorial design, with four replications. The treatments include: nitrogen fertilizer of four doses (0, 30, 60 and 120 kg ha-1), oat (A. sativa) cultivars at two levels (Barbarasul and Brisasul) and succession system at two levels (soybean/oat (A. sativa) and corn/oat (A. sativa). The multiple linear models were efficient in the harvest index of panicle of soybean/oat (A. sativa) system, regardless of the dose evaluated. However, at high doses, the number of grain per panicle was included. In the corn/oat (Avena sativa) system, the harvest index of panicle, the number of grains and spikelets panicle were adjusted based on the model. The multiple linear regression efficiently simulates N-fertilizer to affect the grain yield of oat (Avena sativa) and one or more potential variables of panicle in the succession systems.