Poplar biomass production in short rotation under irrigation: A case study in the Mediterranean

In this study we analyzed the behavior of four poplar genotypes growing in the field under Mediterranean climatic conditions and different watering treatments ranging from optimal to deficient conditions. Behavior was assessed in relation to productivity, water-use efficiency, foliar nitrogen concentration as well as the relationship between these traits. Total aboveground biomass (Bt) was recorded at the end of the first rotation, while other variables such as carbon isotope discrimination (Δ13), net photosynthetic rate (A), stomatal conductance (gs), specific leaf area (SLA) and nitrogen concentration (NA) were also measured during the growth periods. 'AF2' and 'Monviso' were the most productive genotypes and also displayed the higher water-use efficiency. In contrast, 'I-214' and 'Pegaso' were significantly less productive and less efficient. However, these less productive genotypes displayed lower biomass reductions under non-optimal water conditions, probably due to their higher stomatal conductance and higher leaf nitrogen concentration under deficient water scenarios. The relationship between productivity and water use efficiency is analyzed and discussed. Biomass production was also modeled for the different watering scenarios. The study outcomes provided in this article will aid the development of appropriate management strategies as regards the establishment and management of poplar short rotation coppice (SRC) under scenarios with reduced water availability. It will also contribute towards identifying the most suitable genotypes for biomass production in the Mediterranean region and aid the selection of future lines for tree genetic improvements in the context of water scarcity.