RESUMO A produção de biomassa de aveia voltada à elaboração de silagem de qualidade é dependente de elementos climáticos e nitrogênio sem ocorrência de acamamento. O objetivo do presente estudo é a definição da dose ideal do regulador de crescimento que possibilite, no máximo, 5% de acamamento de plantas de aveia, bem como a identificação das variáveis potenciais para composição do modelo de regressão linear múltipla com simulação da produtividade de biomassa à elaboração de silagem nas condições de uso do regulador, em reduzida, alta e muito alta fertilização com nitrogênio. O estudo foi conduzido em 2013, 2014 e 2015, em delineamento de blocos ao acaso, com quatro repetições em esquema fatorial 4x3, para doses de regulador (0, 200, 400 e 600mL ha-1) e doses de nitrogênio (30, 90 e 150kg ha-1), respectivamente. A dose de 495mL ha-1 de regulador se mostra eficiente na redução do acamamento de plantas de aveia em condição de reduzida, alta e muito alta fertilização com nitrogênio. A soma térmica, a precipitação, a radiação, a dose de regulador e o nitrogênio qualificam a composição do modelo de regressão linear múltipla, tornando eficiente a simulação da produtividade de biomassa da aveia para silagem ao longo do ciclo.

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...

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The sowing density adjustment in oatcan maximize the productivity expression.The aim of this study is to define the behavior of productivity expression of biomass, grains, straw andharvest indexthrough increasing sowing density in the main biotype cultivated in Southern Brazil. It proposesthe possibility of indicating higher sowing density to the productivity maximization of biomass and grains.With the densityadjusted to the grain productivity to simulate the reflexes on the biological and straw productivity and harvest index compared to recommendeddensity, considering high and reduced tillering cultivars in different succession systems.The study was carried out in 2013, 2014 and 2015 in randomized blockdesign with four replications in a 4 × 2 factorial scheme, for sowing density (100, 200, 300, 600 and 900 m -2 ) and oat cultivars (Brisasul and URS Taura), respectively, in the corn/oat and soybean/oat succession system.With the increase in sowing density, the biological and straw productivity evidence alinear behavior and the grain productivity and harvest index ofquadratic behavior, regardless of the cultivar,agricultural year and succession system. It is possible to indicate a higher sowing density to the biomass and grain productivity maximization with sowing density close to 500 seeds m -2 in the main succession systems.In high and reduced tillering cultivars, the adjusted density compared tothe recommended increasedthe biological and straw productivity, regardless of agricultural year and succession systems.

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