Yield and chemical composition of plant parts of silage maize (Zea mays L) hybrids and their interest for biogas production

Silage maize (Zea mays L) hybrids bred in Martonvásár were tested for morphological traits, yield and chemical composition of the whole plant and the plant parts in three years (2010-2012). Biogas production of the hybrids was investigated in 2009 and 2010. The dry matter, protein, starch, water soluble carbohydrates, neutral detergent fibre, acid detergent fibre, lignin and in vitro digestible organic matter contents were measured by NIR spectroscopy. The ratio of ear attachment height to plant height was smaller, the leaf number above the ear and the proportion of the leaves in the total plant dry matter was greater for leafy hybrids. It was concluded that the differences in the chemical composition of the parts of the same genotype were greater than between the same parts of different genotypes. The leaves had the greatest protein content. The starch and WSC content in the ear was significantly higher than in the other plant parts. The ear had the lowest lignin content and the highest IVDOM content compared to other plant parts. NDF and ADF contents were greatest in the stalk below the ear. Significant differences were found for WSC content of the plant parts of leafy and non-leafy hybrids. Digestible dry matter yield (DDMY) was calculated from individual dry matter production, plant number per hectare and digestible organic matter content. The highest DDMY value was recorded for Siloking (19.18 t ha-1). Biogas yield was highest for Mv Massil (659 l kg-1 DM) with 61.38% methane concentration. Leafy hybrids produced significantly more biogas than conventional hybrids. Biogas yield proved to have significant positive correlations with starch and WSC content, and negative correlations with protein and lignin content