Evaluation of tall fescue (Festuca arundinacea Schreb.) varieties and wild ecotypes as feedstock for biogas production.

Research was done at the Lithuanian Institute of Agriculture in the experimental fields of the Grass Breeding Department and in the Chemical Research Laboratory during 2008–2010. The genetic collection of tall fescue composed of 4 varieties and 9 wild ecotypes was studied for a complex of agrobiological traits and characters and dry matter (DM) chemical composition. The varieties ‛Navas DS’, ‛Kora’ and ‛Bariane’ were distinguished for DM yield per plant. The average annual DM yield per plant (1st cut + aftermath) for these varieties was 198, 158, and 156 g, respectively. The average annual DM yield per plant for the variety ‛Navas DS’ was significantly (P < 0.05) or 28.5% higher than the trial average. Tall fescue DM yield per plant of the aftermath (2nd + 3rd cut) accounted for on average 53.7% of the annual yield and ranged from 51.4% (wild ecotype No. 20) to 56.4% (wild ecotype No. 22). At the beginning of heading stage, wild ecotypes Nos 21, 17, 22 and 19 were noted for high nitrogen content in DM – 23.0, 21.9, 21.7 and 20.4 g kg-1 DM, respectively. The highest water soluble carbohydrate (WSC) content was measured for wild ecotype No. 25 and the variety ‛Bariane’ – 210.0 and 197.0 g kg-1 DM, respectively. According to DM’s neutral detergent fibre (NDF) quality composition, wild ecotype No. 25 and cv. ‛Bariane’ were noted for low lignin (22.8 and 20.7, respectively), cellulose (261.2 and 293.3) and hemicellulose (265.0 and 281.0) contents g kg-1 DM. The DM of productive varieties ‛Navas DS’ and ‛Bariane’ at the beginning of heading stage had a C:N ratio of 25.5 and 27.9, which is optimal for biogas production.