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Abstract:
Increased rice yields due to rising levels of atmospheric carbon dioxide (CO 2 ), known as the CO 2 fertilisation effect (CFE), play an important role in sustaining global food security. However, model projections on future rice yields are still uncertain, partly owing to the lack of knowledge on how CFE varies between rice cultivars and sub-species. Here we show, through synthesis of hundreds of observations from field experiments, a significant difference in CFE between two main rice sub-species; CFE was ~12.4% 100 ppm-1 for Indica rice, twice that of Japonica rice with 6.2% 100 ppm-1 . A pot study suggests that the higher CFE for Indica rice can be explained by higher photosynthetic acclimation of Japonica rice compared to Indica rice during the reproductive stage. After accounting for differences in sub-species, crop models project substantial regional discrepancies of CFE, which are not captured by original models. Together, these results suggest a strong influence of genotype on crop yield responses to increasing CO 2 , and highlight the need for crop models to consider sub-species and genotypes to improve projections of regional and global crop yield in the context of climate change.
