Fluxo de energia solar e produtividade em cultivo de capim-sudão BRS Estribo em diferentes espaçamentos e épocas de semeadura

Abstract

The large-scale use of Sudan grass BRS Estribo, an annual summer grass, as forage for animal feed is relatively new in south Brazil. When grazing is conducted in a wellused in all regions of our country. For the best use of the crop and greater production, some management characteristics need to be understood, such as sowing date and spacing between rows, as they define the productive characteristics of this forage, such as the total number of cuts and tillering capacity. However, in the literature there are no studies that clarify about the spacing between rows that should be used in the cultivation of Sudan grass, nor the best time for its sowing. Thus, the objectives of this study were to evaluate the influence of different sowing dates and different spacing between rows on the albedo and accumulation of green and dry matter of Sudan grass in the region of Pelotas-RS. Five different sowing dates were used (November 2016, January 2017, November 2017, December 2017, and January 2018), three row spacing (0.17, 0.34 and 0.51 m) with four repetitions in two agricultural years (2016/2017 and 2017/2018). The albedo was determined from the relation of global and reflected solar radiation data, obtained by the solarimeter tubes installed in the experiment. And the production of green and dry matter was determined by sampling the plants in the three different treatments. The sowing dates in which sowing occurred earlier were the ones with the highest production of green and dry matter in relation to the others, in the two agricultural years evaluated. The smallest spacing between rows had the highest production of green and dry matter, compared to the other spacings, regardless of the sowing date. On a sunny day, the albedo was 0.31, 0.29 and 0.27 in the spacings of 0.17, 0.34 and 0.51 m respectively. On the cloudy day, the albedo was 0.28, 0.27 and 0.23 at 0.17, 0.34 and 0.51 m spacings, respectively.