Agronomic performance of 27 Populus clones evaluated after two 3‐year coppice rotations in Henan, China

Selecting superior clones is the first step for commercial short-rotation coppice cultures to provide biomass and bioenergy. Till date, such selection for hybrid Populus clones in middle China is absent. Here we describe the growth, aboveground biomass production and cell wall composition of 27 hybrid poplar clones in Henan, China for two 3-year rotations. Significant variation in these three characteristics over two triennial rotation coppices among the 27 poplar clones was observed. During two 3-year rotation coppices, clones '276', '02-17', and '599' showed relatively higher tree heights and larger basal diameters than those of the other clones. However, the most productive clones were '36' and '01-30'. At the end of the second triennial rotation, the aboveground biomass production reached 18 Mg ha(-1) year(-1). For the cell wall composition analysis, the cellulose contents of clones '01-243' and '2001' were relatively high, while the xylose contents of clones '01-30' and '65' were relatively high. Cluster analysis based on height, basal diameter, biomass, heat value, cellulose content, and survival rate revealed five growth potential classes. Accordingly, clones '03-332', '36', and '599' exhibited high biomass and growth and had the greatest potential to serve as excellent biomass producers in Henan, China. In addition, the expression patterns of 20 key regulatory genes were analyzed, and an integrated coexpression network was constructed. This field trial provides a comprehensive quantification and evaluation of the agronomic performance of 27 poplar clones in Henan, China. The results of this study and the analytical strategies provide an efficient mechanism for selecting clones that will perform well agronomically in local environments. The expression of key genes and the integrated coexpression network provide the molecular mechanisms of poplar biomass performance.