The research is financed by Swedish Research Council (Vetenskapsradet) U-Forsk2013, "Deployment of molecular durum breeding to the Senegal Basin: capacity building to face global warming". AbstractThe Senegal River basin (Guinea, Mali, Mauritania, and Senegal) is a key agricultural production area in sub-Saharan Africa. Here, rice fields are left fallow during the cooler winter season, when the night temperatures reach 16 °C but the maximum daily temperatures remain above 30 °C. This season was used for the first time to conduct multi-environmental trials of durum wheat. Twenty-four elite breeding lines and cultivars were tested for adaptation during seasons 2014-15 and 2015-16 at two stations: Kaedi, Mauritania and Fanaye, Senegal. Phenological traits, grain yield and its components were recorded. Top grain yield was recorded at 5,330 kg ha -1 and the average yield at 2,484 kg ha -1 . The season lasted just 90 days from sowing to harvest. Dissection of the yield in its components revealed that biomass and spike fertility (i.e. number of seeds produced per spike) were the most critical traits for adaptation to these warm conditions. This second trait was confirmed in a validation experiment conducted in 2016-17 at the same two sites. Genotype × environment interaction was dissected by AMMI model, and the derived IPC values used to derive an 'AMMI wide adaptation index' (AWAI) to asses yield stability. The use of a selection index that combined adjusted means of yield and AWAI identified three genotypes as the most stable and high yielding: 'Bani Suef 5', 'DAWRyT118', and 'DAWRyT123'. The last two genotypes were also confirmed among the best in a validation trial conducted in season 2016-17. The data presented here are meant to introduce to the breeding community the use of these two research stations along the Senegal River for assessing heat tolerance of wheat or other winter cereals, as well as presenting two new ideal germplasm sources for heat tolerance, and the identification of spike fertility as the key trait controlling adaptation to heat stress.

Global warming may cause +4 • C temperature increases before the end of this century. Heat tolerant bred-germplasm remains the most promising method to ensure farm productivity under this scenario. A global set of 384 durum wheat accessions were exposed to very high temperatures occurring along the Senegal River at two sites for two years. The goal was to identify germplasm with enhanced tolerance to heat. There was significant variation for all traits. The genetic (G) effect accounted for >15% of the total variation, while the genotype by environment interaction (G × E) reached 25%. A selection index that combines G and a G × E wide adaptation index was used to identify stable high yielding germplasm. Forty-eight accessions had a stable grain yield above the average (2.7 t ha −1 ), with the three top lines above 3.5 t ha −1 . Flowering time, spike fertility and harvest index were the most critical traits for heat tolerance, while 1000-kernel weight and spike density only had environment-specific effects. Testing of six subpopulations for grain yield across heat-prone sites revealed an even distribution among clusters, thus showing the potential of this panel for dissecting heat tolerance via association genetics.

L’objectif de cette étude était de collecter, trier et étudier la diversité phénotypique des accessions de maïs de décrue sur la base de quelques variables sélectionnées, parmi les descripteurs du maïs. Cent soixante-deux (162) accessions de maïs de décrue collectées dans la haute et moyenne vallée du fleuve Sénégal ont été ainsi triées et évaluées au plan morphologique. Parmi ces 162 accessions, 64,81% sont collectées au niveau de la haute vallée et 35,19 % dans la moyenne vallée. En se basant sur trois caractères morphologiques du maïs, (couleurs des grains, texture des grains et couleur de la rafle), le tri de cette collection a montré une très grande variabilité en morphotypes (15), avec la dominance du morphotype Jaune-Corné-Blanc (J-C-B) dans la collection avec un effectif (85/162). Les morphotypes avérés très rares ne dépassent pas l’effectif 1 dans la collection. La caractérisation sur épis de ces morphotypes en fonction de certains caractères (poids de l’épi et le poids de 100 graines, longueur de l’épi,…), liés au rendement a montré une diversité phénotypique très importante. En effet, le poids de l’épi varie de 63,03g pour les morphotypes à petits épis à 290 g pour les morphotypes à gros épis de même que pour la longueur de l’épi qui varie de 10,5 cm à 26 cm. Cette diversité offre une grande possibilité de choix des géniteurs pour la création de variétés améliorées de maïs ayant un potentiel de rendement élevé et adaptées à différentes zones agro-écologiques de la vallée du fleuve Sénégal. ABSTRACT The objective of this study was to collect, sort and study the phenotypic diversity of flood recession maize accessions based on a few selected variables, among the maize descriptors. One hundred and sixty-two (162) flood recession maize accessions collected in the high and medium valley of the Senegal River were thus sorted and evaluated morphologically.Among these 162 accessions, 64.81% are collected in the upper valley and 35.18% in the middle valley. Based on three morphological characteristics of the maize (grain colors, texture and color of the stalk), the sorting of this collection showed a great variability in morphotypes (15), with the dominance of the morphotype Yellow-Corné-Blanc (JCB) in the collection with a strength (85/162). The morphotypes found to bevery rare do not exceed the number 1 in the collection. Characterization on the ears of these morphotypes according to some characteristics (weight of the ear and the weight of 100 g, length of the ear), related to the yield showed a very important phenotypic diversity. In fact, the weight of the ear varies from 63.03 g for short-eared morphotypes to 290 g for coarse-cut morphotypes as well as for spike length ranging from 10.5 cm to 26 cm. This diversity offers a great opportunity for brood stock selection for the creation of improved maize varieties with high yield potential and adapted to different agro-ecological zones of the Senegal River Valley.