Arundo donax water use efficiency and photosynthetic response to drought

• Author(s): Garreiro, Andreia
• Date: 2014
• Persistent ID: http://hdl.handle.net/10362/25110
• Origin: Repositório Institucional da UNL
• Subject(s): Domínio/Área Científica::Engenharia e Tecnologia::Outras Engenharias e Tecnologias
• Document Type: Master thesis
• Language: English
• Advisor(s): Mont, Andrea; Fernando, Ana
• Contributor(s): RUN

Description

Arundo donax L., commonly known as giant reed or Giant reed, has been identified as an excellent biomass feedstock, because of its high yields delivered from low nutrient inputs. Two criticisms of cultivating Arundo donax are that it has a history of biological invasion, and also that it may require great quantities of water to sustain its rapid growth. Yet, there is little research reported quantifying the water-use requirements. The objective of this study was to better understand the deep water uptake ability and water use efficiency (WUE) of Arundo donax. Moreover, it was possible to evaluate the effects of drought on the photosynthetic efficiency of Arundo donax. Durable transient drought stress period were imposed a long time to top soil layers and compared with well watered plants. Twelve cylindrical transparent rhizotrons, separated in two parts by a Vaseline layer allowed to follow the evolution of this experiment. Soil moisture was adjusted to well-watered and drought conditions in the upper (topsoil) layer, while the lower (deep) layer was always wet. WUE was significantly increased in plants of Arundo donax by drought and the photosynthetic efficiency was not affect by drought. Relative water uptake from deep soil layers and water use efficiency of deep roots were signifi-cantly increased by drought in top soil layers. However, the increase of RLD in deep roots was not observed. In conclusion, the drought resistance of Arundo donax and the maintenance of the photosynthetic apparatus are explained by higher WUE and higher WUE of deep soil layers but not because deep soil roots enhanced root length density.