Morphological traits, yield and chemical composition of forage sorghum genotypes, grown under different nitrogen rates

Abstract

In order to reduce total costs on farms and to sustain agricultural production, it is necessary to provide a new approach to this problem on a global level. The biomass of silage sorghum [Sorghum bicolor (L.) Moench] may replace maize, whose profitability decreases in semi-arid regions of the world. Growing forage sorghum as an alternative to silage maize and utilising smaller amounts of nitrogen allows using natural resources more rationally and increases production efficiency. A 2-year study was conducted to investigate the effects of using different amounts of nitrogen (low 105 kg ha(-1), intermediate 150 kg ha(-1) and high 180 kg ha(-1)) on morphological traits (MT), yield (Y) and chemical composition of biomass (CCB) in Sudan grass (cv. Zora), forage sorghum (cv. NS-Dzin) and their interspecies hybrid (cv. Siloking). The standard technology for the production of forage sorghum was applied and ammonium nitrate was applied to the soil before planting. Results indicated that these genotypes have a high yield potential for ground biomass. The genotype Siloking gave the highest ground biomass yield, 90.22 t ha(-1), and the genotype Zora the lowest, 85.41 t ha(-1). Yield variations were also significant in relation to nitrogen plant nutrition. The lowest average yield was in the control. In the year with more favourable rainfall distribution (2010), ground biomass yield (Y) was, on average, higher by about 15%. The genotype had the greatest influence on morphological traits. Intensified nitrogen plant nutrition caused an increase of stem length, stem mass and leaf mass, as well as an increase of leaf portion of total ground biomass. Nitrogen had a two-fold effect on the quality of biomass, as a bulk livestock feed, through an increased proportion of leaf in total ground biomass, and through higher total protein content. Using more intensive nitrate nutrition, the percentage of nitrogen-free extract (NFE) decreased.