Assessment of mutagenized giant reed clones for yield, drought resistance and biomass quality

Given the sterility of giant reed (Arundo donax L.), mutagenesis can be a valid strategy to increase genetic diversity in the species and to enable the selection of superior genotypes with new agronomic and qualitative characteristics. The objective of this study was to evaluate the quantitative and qualitative traits of selected three-year old giant reed mutants (UniBO3; Line10; and Line11). The mutants' performance was evaluated in comparison to the local non-mutagenized ecotype (Arun11) under irrigated and rainfed conditions. Yield differences among mutants were significant: Line11 produced the highest (24 Mg ha−1), and UniBO3 the lowest (19 Mg ha−1) biomass yield, while Line10 showed intermediate yield (22 Mg ha−1). Such variable yields were in line with tiller density and WUE. Besides that, Line11 showed and enhanced plasticity in its water uptake sources and drought resistance. However, the effects of the irrigation and the genotype by irrigation treatment interaction were not significant. The irrigation treatment did not change either the qualitative characteristics of Line11: the cellulose content (42%) was higher than in the control and UniBO3 mutant. Whereas the hemicellulose and lignin contents remained unvaried, suggesting Line11 as a promising feedstock for conversion to advanced biofuels. As for the mineral composition, Line11 showed the most marked changes, especially in terms of K, Si, and Si/K ratio, suggesting a lowered quality for thermochemical conversion. The induced variability shows some promising characteristics that could lead to new specialized mutant lines with improved suitability to specific environmental conditions and conversion technologies.