Short rotation coppices, grasses and other herbaceous crops: Productivity and yield energy value versus 26 genotypes

Short rotation woody crops where the most resistant to environmental conditions, whereas grasses and some herbaceous genotypes were the most prone to lodging. The three willow varieties (Ekotur, Żubr and Start) gave the highest average yield (over 15 Mg ha−1 y−1 d.m.) and they yielded over 20 Mg ha−1 y−1 d.m. in 2013, which in terms of energy was equivalent to 350 GJ ha−1 y−1. Poplars gave more than three times and black locust up to five times lower yield compared to the highest-yielding willows. The highest yield among herbaceous plants was obtained from Helianthus salicifolius, and among grasses - from Miscanthus sacchariflorus (on average 9 Mg ha−1 y−1 d.m.). The yield energy value of these genotypes was approx. twice lower compared to the best willow varieties. It was found that of the 26 genotypes of perennial plants, new willow varieties proved the most valuable in terms of yield and energy in the initial three years under the environmental conditions of north-eastern Poland.