Rice (Oryza sativa. L) genetic diversity for early vigor and drought ...

IntroductionThe second data set was generated in a greenhouse experiment (Exp2) on Panel 2 (see details below)performed in 2009 at CIRAD (Montpellier, France) between 9 February and 8 May 2009 (late winterand early spring).The greenhouse was S2 type (for GMO cultivation) equipped with a double glass roof interceptingmuch of natural sunlight. It was thus equipped with supplemental light sources (halogen lamps at 1.5m spacing). Air humidity and temperature were regulated by adiabatic method and were set to25°C/22°C (day/night) and 50%/90% air humidity. Seed was grown in a germination chamber at 29°C,then transplanted 3 days after germination in 1 litre drained pots (5 seeds per pot) when seedlingswere about 3 cm tall. The date of transplanting was variable depending on the genotype and its timeof germination. Pots were placed on flooded tables at 30 pots m -2 with 5 cm water depth. Plantpopulations were thinned to 1 plant per pot at 4-leaf stage. Pots contained about 450 g (dry weight)of a mixed soil consisting of 20% peat and 80% loamy sandy clay soil (loam: 45%, sand: 30% and clay:25%, sampled at 0-40 cm depth in a field at Lavalette experimental site of Agro Montpellier, France),supplied on the day before transplanting with 2g of a coated fertilizer Basacote Plus 6Mcomplemented in oligo-elements (Compo GmbH & Co. KG, Münster, Germany containing 11, 9 and19% of N, P 2 0 5 and K 2 0 respectively). The experiment included a drought treatment that will bereported elsewhere and only well-watered treatment results are presented here. Because of highplant number and limited space the replications were implemented successively and notsimultaneous, resulting in different radiation environments in the greenhouse.Genetic materialsPanel 1 (169 O. sativa L. genotypes) was a subset of the rice core collection of the GenerationChallenge Programme (GCP 2005). It consisted of 130 indica, 23 tropical japonica, 8 temperatejaponica, 10 aus, 15 aromatic rices, 4 deep-water rices and 2 intermediate accessions obtained fromthe International Rice Genebank at IRRI.Panel 2 (190 genotypes) consisted of 173 tropical japonica accessions composed to capture thegenetic diversity of the sub-species, and an additional set of 17 reference accessions (extendedPerlegen population) covering all genetic groups of the species (7 indica, 3 tropical japonica, 3temperate japonica, 2 aus, 2 aromatic). The Perlegen population corresponds to the OryzaSNP panelcurrently used to develop a high-density SNP chip for genotyping (McNally et al. 2009).Both panels were composed with the objective to conduct genetic association studies on droughttolerance and early vigor traits in the context of the Generation Challenge Programme (GCP).35