Schoppach, Rémy
[UCL]
In order to satisfy increasing wheat demands, scaling up wheat production will require boosting yield in suboptimal, drought-prone areas. This increase will be particularly challenging since in several major agricultural regions of the world, yield stagnation has been observed during last decades. Moreover, warmer climates are already contributing to significant decreases in worldwide wheat yields, highlighting the need for more adapted germplasm. Under rain-fed environments, one promising option is the identification of traits allowing for soil water conservation. The aim of this thesis was the identification of the physiological and genetic bases of these water-saving traits in wheat. We have shown that genotypes with conservative water use in their response to high atmospheric demand were also conservative in response to soil drying invoking an adapted sensitivity of transpiration rate (TR) to both sources of drought. This thesis revealed a large genetic variability in the responses of TR to VPD with a significant effect of day and night atmospheric conditions during growth affecting compensation mechanisms between leaf areas and TR sensitivities to VPD. Nighttime TR was shown to be highly significant in wheat and strongly correlated to daytime TR process, revealing that tolerance strategies such as conservative water use do also exists under night-time environments. The exceptional drought tolerance of the conservative breeding line RAC875 was linked to a root-based hydraulic restriction that requires potentially heritable functional (AQP-based processes) and anatomical features. Finally, we highlighted a total of 68 mostly trait-specific QTL. Six QTL were identified for the TR response to VPD, with one QTL individually explaining 25.4% of the genetic variance. This QTL harbored several genes previously reported to be involved in drought tolerance and plant hydraulics.
Bibliographic reference |
Schoppach, Rémy. Physiological and genetic bases of water-saving traits in wheat. Prom. : Sadok, Walid ; Javaux, Mathieu |
Permanent URL |
http://hdl.handle.net/2078.1/182158 |