Improve Crops in Arid Regions and future climates

Experimental setups - The load cell platform at IRD-Montpellier is now fully installed, completing a diversified experimental setup (hydroponic system, pressure pots, 3D scanning) to undertake physiological research at IRD. Similar efforts are on the way at CERAAS in Senegal.  

In WP1, developing pearl millet CRISPR-CAS9 lines failed because of the regeneration difficulty in that species. Efforts have been re-oriented toward Setaria italica. Testing the functional role of aquaporin genes is unlikely to happen in the timeframe of the project. A recent paper (Burridge et al., 2022) posits that traits measured at a cell level are likely to face compensation effects at an organ or plant level. A re-focus has been put on phenotyping higher level phenes, i.e. phenotypes at a higher level of plant organization, in WP2 and WP3.

In WP2-a, three important results came up: (i) plants with a smaller leaf to root area ratio restricted transpiration more; (ii) the leaf to root area ratio was larger in sorghum than in pearl millet, and within-specie variations were larger in pearl millet than in sorghum; (iii) Soil had no major influence on the leaf to root area ratios in sorgho, but plants grown in the sandy soil restricted transpiration more under high evaporative demand. These results reinforce our hypothesis that the leaf to root area ratios play an important role in the transpiration restriction under high evaporative demand, and that the soil also influences the transpiration response.

In WP2-b, the positive effect of increasing sowing density on pearl millet productivity has been published (Pilloni et al., 2022). A related paper in sorghum and other papers are pending. A PhD student has graduated from that work (R Pilloni). These results open two avenues. The first is the opportunity of a direct application on the ground - a pilot test is planned for 2023 in farmer’s field (see next section). The second is about deciphering canopy architecture traits that explain the relationships between the positive response to sowing density, the higher in water use efficiency, and the better light distribution within the canopy. This work is now the main focus of the project and combines nicely applied and upstream research.

In WP3, the analysis of pearl millet transpiration efficiency (TE) data is underway. TE results on that large germplasm panel were quite different from earlier data in sorghum, especially with a much narrower range of variation. Higher TE was found in hybrid lines bred for a wetter environment of India than for hybrids bred for dry zones. Although TE showed relatively high heritability, few SNPs only for TE have been found, suggesting a multigenic determinism of TE in pearl millet. Phenotyping of traits underlying the transpiration restriction is underway.

In WP4, as mentioned earlier, a version of a crop model working for pearl millet genotypes adapted to the Sahel region is about to be ready. Data are still being produced to have sufficient agronomic data to validate the crop model.

In connection to the project, i keep coordinating the collaboration between France and the CGIAR on climate change. This initiative offers a scope to connect MOPGA’s work to a more holistic view on water use efficiency and a paper will soon come up. I also chaired the International Interdrought conference, held in Dakar this time, first time in Africa (ID7).