Improving rice for drought-prone upland environments
1999
Courtois, Brigitte | Lafitte, Renée Honor
Drought is the main cause of yield instability in upland rice. But this general statement has to be put into perspective. Four different production systems of upland rice (shifting cultivation, integrated rice-based, perennial-based, and cash-based) are encountered in Asia. They correspond to three different agroecological zones with different risks of drought and sets of additional specific constraints. We define different breeding priorities for the different production systems and present the available germplasm in the light of improvement of resistance to water deficit. We discuss some important points for upland rice improvement, notably the strong G x E interactions and their implications for decentralization of breeding work, and the tradeoff between productivity and stability. More specifically, we present the current breeding strategy for drought resistance, highlighting the difficulties involved in establishing relevant drought conditions and choosing relevant selection criteria. We emphasize the use of molecular markers to improve selection efficiency. We chose to focus on improving individual traits rather than on performance under stress. We are developing near-isogenic lines by introgressing QTLs for structural root system and osmotic adjustment into elite backgrounds. This approach allows us to reconcile the need for rapid impact and the testing of physiological hypotheses on the value of the various traits. (Résumé d'auteur)
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