Are genetically diverse wheat populations more resilient to water stress than monocultures ? Assessment by modelling, with a focus on the role of roots

Details

Supervisors

Lobet, Guillaume

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en sciences et technologies de l'environnement, à finalité spécialisée

Abstract

Today more than ever, agriculture faces increasing environmental pressures like drought, cutting yields and causing economic losses and food scarcity. This study focuses on wheat, one of most widely grown crops across the world, accounting for 8% of the total production of primary crops worldwide, with 0.8 billion tonnes. Researchers are now looking for ways to make crops more resilient to water stress and drought conditions. Genetic diversity across crop fields is sometimes an overlooked aspect but might very well be a key to increasing plant performance under drought conditions. Indeed, many studies have shown that functional diversity across a population leads to better adaptation to biotic and abiotic pressures, compared to monocultures. A modelling approach with a focus on the role of roots was chosen to answer the following question “Are genetically diverse wheat populations more resilient to water stress than monocultures ?” The model used is called Virtual Grassland (VGL) and integrates complex plant morphogenetic and growth processes through the L-system formalism, allowing for realistic plant modelling despite simple rules and low computational costs. A very useful perk of VGL for this study is its ability to apply variance over chosen parameters. Therefore, it was used to assess the impact of increasing values in coefficient of variation across five plant parameters, mostly related to root architecture, on several field outputs, including total biomass. Results overall did not confirm the hypothesis of the research question, with roots parameters variability leading to either a statu-quo or decrease in biomass. However, diversity in leaf length across the population led to a small but noticeable increase in biomass, while diversity in root elongation rate and inter-branching distance led to increase in total root length. Rooting depth was shown to decrease for all tested parameters variance. Some reasons behind this biomass result, which opposes previous literature findings and our hypothesis, could be the lack of time in the simulation, which would allow selection of the most adapted individuals in crop fields, or the lack of multi-criterion variability analysis, making these subjects an interesting axis for further research.