Résumé
Drought is one of the major constraints for rice production when cropped in lowland conditions. Lowland rice indeed depends only on rainfall and thus suffers from frequent water deficits. AfricaRice leads a GCP supported project to develop rice varieties for rainfed lowland conditions combining high yield potential and drought tolerance using marker assisted recurrent selection in collaboration with national partners in Burkina Faso, Mali and Nigeria. Among methods used for characterizing plant response to drought, canopy temperature is known to be related to plant transpiration and thus drought tolerance. This study aims to confirm the relevance of a drought phenotyping method base on infrared thermography standardized with the Crop Water Stress Index (CSWI). In 2013 and 2014, 250 lines coming from the cross between IR64 X IITA212 were phenotyped in 2 West African locations. Drought was applied for 15 days at reproductive stage ( 45 days after sowing) and characterized soil humidity (monitoring with diviner). Drought response was evaluated with canopy temperature using a numerical infrared thermographie camera. Canopy temperature was normalized (CWSI) according to micro-meteorological variation collected through an on-site weather station. Results confirm the relationship between water deficit and canopy temperature. A large genetic variability of the drought response (CWSI) was observed in each site revealing some drought tolerant and sensitive lines. Sorne lines showed a stable tolerance and response to drought across the three sites. A classification of the lines with respect to their sensitivity to stress could be established by the use of the Crops Water Stress Index (CWSI).This strategy, once adopted, will enable a high throughput field phenotyping of a large number of genotypes and be useful to plant breeders. (Résumé d'auteur)