IC4R006-Phenomics-2015-26104576

Project Title

• Field phenomics for response of a rice diversity panel to tenenvironments in Senegal and Madagascar. 1. Plant phenological traits

The Background of This Project

• The GRiSP Global Rice Phenotyping Network seeks to assemble a multi-environment, multi-trait phe-nomics resource for rice (Oryza sativa L.) diversity panels in order to understand existing genetic diversityand identify genes/alleles conveying adaptation and yield potential. Phenology is central to plant adap-tation and productivity in different agro-ecologies.

Plant Materials & Treatment

• The population taken from the ORYTAGE species-wide (O.sativa L.) diversity panel of Cirad (http://ricephenonetwork.irri.org/diversity-panels/orytage-diversity-panels) which is also aresource for the GRiSP Global Rice Phenotyping Network (http://ricephenonetwork.irri.org). For the present study, a sub-sample of189 indica accessions was grown, augmented for comparative pur-poses with 20 genotypes representing other genetic groups (3 aus,3 temperate japonica, 12 tropical japonica, and 2 aromatic acces-sions). The indica population covered improved and traditionalvarieties from all tropical regions but had large sub-populationsfrom Madagascar (34) and W-Africa (44, thereof 30 improved linesfrom AfricaRice bred in Senegal) to capture adaptations to theclimatic constraints at the experimental sites. Twenty improvedvarieties and lines were from IRRI (Philippines). A complete list ofaccessions’ geographic origin and seed sources is presented in TableS1.

Research Findings

• The environmentsThe six sowing dates in Senegal subjected the crop to very differ-ent weather and day length conditions (Fig. 1). Weather variablesare presented in Fig. 1A as averages for the initial 80 d of the cropas a rough measure of conditions during pre-floral developmentstages. The first three sowing dates were associated with low min-imum air humidity (RHmin) averaging less than 30%, while meanminimum meanminimum temperature increased from 16.4 (February crop) to 19.0(April crop)℃. Mean and maximal temperatures increased at a sim-ilar rate, with a constant mean diurnal temperature amplitude ofabout 15℃. Astronomic day length varied between 11.05 h in winter and12.97 h in summer (wet season) (Fig. 1B). The July crop had thelongest days at sowing but experienced decreasing day lengththroughout its life cycle. Conversely, the February crop had theshortest days at sowing but experienced increasing day lengththroughout its cycle.

Fig. 1. Graph A: Weather variables averaged for the period from sowing to 80 d after sowing at the Senegal site. Tmax, Tmean, Tminare maximum, mean and minimum airtemperature at 2 m, respectively. RH is minimum daily relative air humidity. PET is potential evaporation according to FAO standard. The recommended sowing dates for thehot–dry season (HDS) and the wet season (WS) are indicated. Graph B: Astronomic day length at sowing

• floweringSenegal. Only four check varieties were replicated for each ofthe 6 sowing dates in the augmented design of the experimentin Senegal. No block (replication) effects were observed accordingto ANOVA, whereas genotype, sowing date and date X genotypeeffects were highly significant (P < 0.0001) (Table 2A). Broad-senseheritability on the basis of family means was high at h2= 0.95(Table 2C).Madagascar. All 209 accessions were replicated in both yearsand locations. There was a significant block (replication) effecton time to flowering (P < 0.0001, F = 6.0) but it was negligiblein size as compared to the year (F = 156), location (F = 30783)and genotype (F = 367) effects, which were also highly significant(P < 0.0001) (Table 2B). Broad-sense heritability of time to floweringwas h2= 0.98 (Table 2C).

Fig. 2. Duration from sowing to maximum flowering for four check genotypes. (A) Observations for 6 sowing dates in Senegal in 2009 (means and SEM for 6 replications).(B) Observations for Madagascar at mid altitude (857 m asl) and high altitude (1497 m asl) for 2009 and 2010 (means and SEM of 3 replications. The straight lines connectthe 2-year means for two altitudes. No data for cv. Chomrong were available for high altitude.

Labs working on this Project

• Cirad, Umr AGAP (Dept. BIOS) and Upr AIDA (Dept. ES), F-34398, Montpellier, France
• IRRI, CESD Division, DAPO Box 7777, Metro Manila, Philippines
• Africa Rice Center, Sahel Station, P.B. 96, St. Louis, Senegal
• Université d’Antananarivo, Département de Biologie et Ecologie Végétales, BP 906, Antananarivo 101, Madagascar
• SRR FOFIFA, BP 230, Antsirabe 110, Madagascara

Corresponding Author

• M. Dingkuhn: m.dingkuhn@irri.org