Cultivares de trigo duplo propósito submetidos ao manejo nitrogenado e a regimes de corte

Abstract

Cultivares de trigo duplo propósito submetidos ao manejo nitrogenado e a regimes de corte [Dual- RESUMOAvaliaram-se a produção e a qualidade da forragem em cultivares de trigo duplo propósito submetidos a doses de nitrogênio e a regimes de corte. O delineamento experimental foi o de blocos ao acaso com três repetições. Os tratamentos constituíram-se de quatro cultivares de trigo duplo propósito − BRS Figueira, BRS Umbu, BRS Guatambu e BRS Tarumã −, cinco doses de nitrogênio − 0, 45, 90, 135 e 180kg ha -1 − e três manejos de corte − sem corte, um e dois cortes. As variáveis avaliadas foram: produção de forragem, relação de folhas, proteína bruta, digestibilidade in vitro da matéria orgânica e nutrientes digestíveis totais. A adubação nitrogenada apresentou comportamento linear crescente sobre a produção de massa e proteína da forragem e não houve efeito sobre as demais variáveis. A produção de forragem aumentou no segundo corte e sua qualidade decresceu. Os resultados quantitativos e qualitativos da forragem foram distintos entre os cultivares. Os cultivares de trigo duplo propósito de ciclo mais longo apresentaram maior qualidade forrageira e menor produção de forragem.Palavras-chave: trigo, Triticum aestivum, integração lavoura-pecuária, recurso forrageiro ABSTRACTProduction and quality of forage were evaluated in four dual-purpose wheat cultivars submitted to nitrogen fertilization and cutting regimes. The experimental design was randomized blocks with three replicates. The treatments consisted of four dual purpose wheat (BRS Figueira, BRS Umbu, BRS Guatambu, and BRS Tarumã), five nitrogen doses (0, 45, 90, 135, and 180kg ha -1 ), and three cutting managements (no cuts, one and two cuts). The studied variables were: forage production, leaf ratio, crude protein, in vitro digestibility of organic matter and total digestible nutrients. The nitrogen fertilizer showed a linear increase on the fodder yield and protein and there was no effect on other variables. Forage production increased in the second harvest and its quality decreased. The quantitative and qualitative results of the forage were different among cultivars. The longer cycle dual-purpose wheat had higher nutritional quality and lower forage production.

Dual-purpose wheat grain and animal production under different grazing periods

“…These results are related to changes in the forage sward as the length of the grazing season increased, including the decrease of the leaf:stem ratio and more lignified cell walls. Similar changes were reported by Hastenpflug et al (2011).…”

Agronomic performance of wheat BRS Tarumã under different sowing densities, nitrogen fertilization and cutting managements

“…Hastenpflug et al (2011) observed a similar result to this work regarding the average crude protein content for the cultivar BRS Tarumã and linear increases up to the nitrogen rate of 90 and 120 kg ha -1 in the forage dry matter production and crude protein content with 1 cut and 2 cuts, respectively. It should be noted that in the present study, the nitrogen rates evaluated were higher (80 to 240 kg ha -1 ) and the lowest dose was sufficient for the cultivar to reach maximum forage and crude protein yield.…”

“…Another aspect related to the regrowth and tillering ability is the nutritional status of the plant, especially with regard to nitrogen. In dual-purpose wheat, higher nitrogen doses can be used to increase forage and grain yield without presenting the risk of lodging due to the size reduction caused by cuts (Hastenpflug et al, 2011). Wheat grain yield is highly related to nitrogen management (Sangoi et al, 2007).…”

“…According to Espindula et al (2010), the 40, 60, 80, 100 and 120 kg N ha -1 rates promoted a quadratic response in wheat grain yield, with a maximum point of 5.032 kg ha -1 , estimated at 96.8 kg N ha -1 rate. Hastenpflug et al (2011) reported increased forage dry matter yield in dual-purpose wheat cultivars as a function of the application of nitrogen rates up to 120 kg ha -1 .…”

Adubação nitrogenada na produção de grãos e matéria seca de cultivares de trigo de duplo propósito

“…FONTANELLI (2007) destaca que N é importante para a rebrota rápida da planta após a desfolha, sendo determinante para reduzir o tempo entre pastejos sucessivos. HASTENPFLUG et al (2011) demonstraram que materiais de trigo para duplo propósito apresentam resposta direta à aplicação de N quando se trata de produção de biomassa.…”