the presentation deals with the response of plants to drought at various time scales

1. Short and long term impacts of water deficits and droughts on perennial grasses in grasslands Jean-Louis Durand Marc Ghesquière Jean-Paul Sampoux

3. Projection of 2 French meteorological models for annual rainfalls in A 2 scenario (2000-2100) Livre blanc Escrime ed. 2009

5. 1. The plant response to water deficits Potential volume growth rate * carbon costs (g mm -3 d -1 ) Roots Leaves stems Absorbed PAR LAI Carbon demand Partitioning according to environmentally dependant hierarchy. Photosynthesis - Respiration Carbon supply MORPHOGENESIS ENERGY ASSIMILATION genotype, water genotype, water

6. Adaptive responses to insure survival and competition Leaf area morphogenesis Rooting depth Plant water status T A MAXIMISE MAXIMISE MAXIMISE MINIMISE 1. The plant response to water deficits Trade off ENERGY WATER

10. DURAND J.L., & al 1997 Eur. J. Agronomy 7: 99-107. Depth of water extraction, as a quantitative trait Lm LmFg (4x) Fg 1. The plant response to water deficits

11. g S T A 1. The plant response to water deficits Transpiration use efficiency as an integrated estimate of water status and resource acquisition

13. How do populations change under dry conditions on the longer term? Under high competition, high water and nitrogen status, the frequency of individuals exhibiting vegetative growth is enhanced in a plot sawn 20 years before.

14. The EFEST design (Genetic E volution of Fest ulolium populations under summer water deficit) March 2005 June 2006 Sept. 2006 June 2007 Sowing Seed harvest Plant sampling Seed harvest rain fed rain fed 4x- BC1 pop. Amphi. pop.

15. Delta 18 O soil water profiles in the spaced-plant trial for clonal assessment (sampled vs initial plants)

16.  18 O plant water in spaced-plant trial with response of plants sampled in sward compared to the initial seed batch of the Festulolium population Lolium Festuca Initial Sampled

17. Estimation of plant selection within the Festulolium population in sward because of drought δ 18 O in the plants sampled in the rain fed sward has shifted by 0.4 phenotypic standard deviation of the initial population as if 10 % of the least deeply rooted plants (δ 18 O > - 0.10 o/oo ) disappeared because of drought

20. 3. Long term evolution and speciation Festuca nigrescens Festuca rubra ssp fallax Festuca ovina

21. 3. Long term evolution and speciation Modelled ecological probability of presence of Festuca nigrescens (Sampoux and Badeau, 2009)