FIELD PERFORMANCE OF NEW ENERGY POPLAR CLONES IN COMBINATION WITH DIFFERENT PLANTING DENSITY

摘要

Among the woody species, poplar (Populus ssp.) in SRF appears to a be the best suited energy crop forthe environmental conditions of Northern Italy. Nevertheless, it should be considered that productivity of poplar SRFis often modest, when compared to other energy crops. For this reason, a substantial effort in breeding is on progress,with the purpose of obtaining clones selected for energy purposes. The scope of the present study was to evaluate theperformance of recently developed clones in combination with several planting distances. In the period from 2004 to2009 a field experiment on poplar SRF was carried out in Anzola dell’Emilia (Bologna), Po Valley, Northern Italy.The experiment compared two new poplar clones (AF2 and AF6) in combination with two distances between rows(240 and 280 cm) and three distances within rows (40, 60 and 80 cm). The experimental design was a split-split-plotwith three replication, with the clones in the whole plots, distance between rows in the sub plots and distances withinrows in the sub-sub plots. Biomass harvest was performed every two years, in the winter of 2006, 2008 and 2010.The following observations were collected on each individual plot: i) number of plants; ii) number of stems per plant;iii) stem height; iv) stem diameter at 1.3 m height; v) fresh weight of stems and branches; vi) moisture content ofstems and branches (oven dry at 105 °C); vii) dry matter yield per unit area. The average biennial productivity ofthe clone AF2 was 36 Mg DM ha~(-1), much higher than 29 Mg DM ha~(-1) observed for the clone AF6. This is consistentwith the observed dimensions of stems for AF2, +45 cm height and + 5 mm diameter compared to AF6. The plantingdistance between- and within-rows had little influence on biomass productivity.