Efeito da época de semeadura na produção de grãos e nos teores de óleo e proteína em cultivares de soja

Soybean (Glycine max) is originally from the China and considered one of the oldest cultivated plants. In Tocantins came to gaining ground and it became one of the most important crops for the state's economy. Its economic importance is directly related to its broad and diverse utilization, either by the agricultural industry, chemical industry or food industry. The levels of oil and protein in soybean grain are controlled for genetic factors, and greatly influenced by the environment. The planting season influences the agronomic characteristics of culture and may modify the production values and oil and protein content of the grain. Thus, were conducted four trials planting season in the crops 2014/15 and 2015/16 , aiming to assess the effect of sowing time on grain yield and oil content and protein. The experimental design used was randomized blocks with three replications. Each test was consisted for seven treatments (commercial cultivars) and planting was conducted in two distinct locations; Porto Nacional and Santa Rosa, with two different season; the first corresponding to the opening of planting, and the second varying the maximum of 15 days of the first. The characteristics evaluated were: plant height, height of the 1st pod, number of pods / plant , number of grains / pod , thousand seeds weight (g), grain yield (kg ha-1), oil content and protein (%) and the respective yields (kg ha-1). After obtaining the data was carried individual variance analysis and right after carried out a joint analysis of the trials, the averages were compared by the Scott and Knott test at 5% probability. In Porto Nacional, the cultivars showed the best performance for the production of grain and for contents and yields of oil and protein. When sowing soybean was delayed, there was an increase in protein content and a decrease in yield potential and oil content. The cultivar 8579RSF IPRO showed the highest yield of grain and higher contents and yields of oil. On the other hand, M9144 RR presented higher protein content in the grains.A época de semeadura exerce influência sobre as características agronômicas e químicas da cultura da soja, refletindo no rendimento agronômico e industrial. Neste sentido, foram realizados oito ensaios de competição de cultivares, sendo quatro na safra 2014/15 e quatro na safra 2015/16, em Porto Nacional e Santa Rosa - TO. O delineamento experimental utilizado em cada ensaio foi de blocos ao acaso com três repetições e oito tratamentos, representados por sete cultivares. As características avaliadas foram: altura de planta, altura da 1° vagem, número de vagens/planta, número grãos/vagem, peso de mil sementes (g), produção de grãos (kg.ha-1), teor de óleo e proteína (%) e seus respectivos rendimentos (kg.ha-1). Após a obtenção dos dados foi realizada a análise de variância individual e em seguida a análise conjunta dos ensaios, sendo as médias comparadas pelo teste de Scott & Knott a 5% de probabilidade. Em Porto Nacional, as cultivares apresentaram os melhores desempenhos para a produção de grãos e para os teores e rendimentos de óleo e proteína. À medida que a semeadura da soja foi atrasada, ocorreu incremento nos teores de proteína e queda no potencial produtivo e nos teores de óleo. A cultivar 8579RSF IPRO apresentou as maiores produtividades e um maior teor e rendimento de óleo. Por outro lado, M9144 RR apresentou maior conteúdo proteico nos grãos