Rural societies in the face of climatic and environmental changes in West Africa, 2017
Introduction Sanio millet has reappeared in villages in the Sine, between Bambey, Diourbel and Fa... more Introduction Sanio millet has reappeared in villages in the Sine, between Bambey, Diourbel and Fatick, since the mid-2000s. However, this long cycle millet had disappeared from farms in the northern half of Senegal in the 1970s because of the sudden decrease in rainfall. It was still present further south in the wetter regions of Saloum and beyond as far as the Casamance. As rainfall depths increased from the mid-1990s everywhere in Senegal (Salack et al., 2011), we put forward the hypothesis..
The future of West Africa depends on the capacity of its agriculture to ensure the food security ... more The future of West Africa depends on the capacity of its agriculture to ensure the food security of the population, which should double in the next 20 years, while facing up to the new risks resulting from climate warming. Indeed, the changes in temperature and precipitations already operating and that should become more marked will have serious effects on agricultural production and water resources in this part of Africa in the near future. One of the keys to meeting this new challenge is the adaptation of rural societies to climate risks. To gain better knowledge of the potential, processes and barriers, this book analyses recent and ongoing trends in the climate and the environment and examines how rural societies perceive and integrate them: what are the impacts of these changes, what vulnerabilities are there but also what new opportunities do they bring ? How do the populations adapt and what innovations do they implement - while the climate-induced effects interact with the social, political, economic and technical changes that are in motion in Africa ? By associating French and African scientists (climatologists, agronomists, hydrologists, ecologists, demographers, geographers, anthropologists, sociologists and others) in a multidisciplinary approach, the book makes a valuable contribution to better anticipation of climatic risks and the evaluation of African societies to stand up to them
Studying seasonal adaptation is of great importance for understanding crop diversification. The b... more Studying seasonal adaptation is of great importance for understanding crop diversification. The biological process of seasonal adaptation of sorghum (Sorghum bicolor (L.) Moench.) allowed the development of flood recession agrosystems in the Sahel (West and Central Africa). To analyze the patterns of trait variation linked to this poorly documented process, we evaluated and compared four eco-seasonal groups of sorghum originating from seasonally diversified agrosystems in the same cropping conditions. The muskuwaari and samme groups are composed of landraces adapted to flood recession agrosystems in the Lake Chad Basin (43 accessions) and the Senegal River Valley (14 accessions), respectively. The other two groups are composed of varieties commonly grown in the rainy season (19 accessions from the Lake Chad Basin and 24 accessions from the Senegal River Valley and and surrounding regions). Multivariate analyses based on ten agro-morphological traits structured the sample in two main...
Pearl millet, unlike other cereals, is able to withstand dry and hot conditions and plays an impo... more Pearl millet, unlike other cereals, is able to withstand dry and hot conditions and plays an important role for food security in arid and semi-arid areas of Africa and India. However, low soil fertility and drought constrain pearl millet yield. One of the main targets to address these constraints through agricultural practices or breeding is root system architecture. In this study, in order to easily phenotype the root system in field conditions, we developed a model to predict root length density (RLD) of pearl millet plants from root intersection densities (RID) counted on a trench profile in field conditions. We identified root orientation as an important parameter to improve the relationship between RID and RLD. Root orientation was notably found to differ between thick roots (more anisotropic with depth) and fine roots (isotropic at all depths). We used our model to study pearl millet root system response to drought and showed that pearl millet reorients its root growth toward ...
Les sociétés rurales face aux changements climatiques et environnementaux en Afrique de l’Ouest
contrainte hydrique on procèderait à l'élimination de certains poquets (par exemple tu sèmes à 50... more contrainte hydrique on procèderait à l'élimination de certains poquets (par exemple tu sèmes à 50 cm et ensuite tu élimines 1 e ligne sur 2) pour que les restants aient de l'eau pour terminer leur cycle. Il serait aussi intéressant de savoir jusqu'à quel stade de développement l'application d'engrais pourrait avoir un effet significatif sur le développement du mil. Cela permettrait de jouer, en plus de la densité, sur la fertilisation pour gérer le niveau de développement de la culture en fonction des pluies reçues et des prévisions pour la fin du cycle.
Rice production faces the challenge to be enhanced by 50% by year 2030 to meet the growth of the ... more Rice production faces the challenge to be enhanced by 50% by year 2030 to meet the growth of the population in rice-eating countries. Whereas yield of cereal crops tend to reach plateaus and a yield is likely to be deeply affected by climate instability and resource scarcity in the coming decades, building rice cultivars harboring root systems that can maintain performance by capturing water and nutrient resources unevenly distributed is a major breeding target. Taking advantage of gathering a community of rice root biologists in a Global Rice Science Partnership workshop held in Montpellier, France, we present here the recent progresses accomplished in this area and focal points where an international network of laboratories should direct their efforts.
Abstract: The root length density (RLD) distri-bution in the soil is a key factor for water and n... more Abstract: The root length density (RLD) distri-bution in the soil is a key factor for water and nutrient uptake but its direct assessment is not easy. A field method is presented here to assess RLD of sorghum (Sorghum bicolor L. Moench) from the root intersection density (RID) and taking root orientations into account. The method was developed with four varieties cropped in 2006 in Bambey (Senegal) on a sandy soil, and validated on the basis of independent data obtained on two other varieties cropped in 2008 in Thiès in Senegal on a sandy loam soil. Sets of 1 × 10-3 m3 cubic undisturbed soil samples were collected at different positions and at three different dates for the four varieties during the
Sequencias do DNA de uma regiao em comum de multiplos individuos de uma populacao podem revelar p... more Sequencias do DNA de uma regiao em comum de multiplos individuos de uma populacao podem revelar polimorfismos que permitem o estudo da evolucao do genoma e suas historias de selecoes, migracoes e recombinacoes. Adicionando-se a esses polimorfismos da populacao informacoes quanto a origem geografica, viabiliza-se um estudo filogeografico que permite a elaboracao de cenarios de evolucao apos a domesticacao; bem como quais eventos (mutacoes ou recombinacoes) mais influenciaram a diversidade genetica (DG) desta populacao, para aquela regiao do DNA em estudo. Por outro lado, a associacao desses polimorfismos das sequencias com as caracteristicas de interesse estabelece um estudo de associacao. Neste contexto, este trabalho visou mostrar a aplicacao do polimorfismo de sequencias de DNA em um estudo de filogeografia e de associacao. Para ambos os estudos foram utilizados dezenove segmentos de seis genes candidatos (Sh2, Bt2, Sssl, Ael, Wx e 02) em uma colecao de sorgo (Sorghum bicolor L. M...
Root architecture of two sorghum varieties, fitted in #Durra race# and with different response in... more Root architecture of two sorghum varieties, fitted in #Durra race# and with different response in drought conditions, has been studied on hydroponic system, pot and in situ on field. These varieties have similar aerial agro-morphological characteristics in optimal growth conditions. In pre-flowering drought stress condition, tolerant variety (SSM1611), has a stable and higher yield than the non-tolerant one (IS16101). On hydroponics conditions and pot growth, varieties are studied at young stage. On field, observations concerned the whole plant cycle. Frequent observations of the aerial system have been made in all the trials, with counting of emerged leaves number and measuring stem height. Adventitious roots number and adventitious roots ranks number have been daily observed on hydroponic system and observations was not destructive. Spatial root disposition on stem was observed on hydroponic condition. On pot and field, these observations were destructive and realised once a week....
Drought is a major constraint on plant productivity globally. Sorghum (Sorghum bicolor) landraces... more Drought is a major constraint on plant productivity globally. Sorghum (Sorghum bicolor) landraces have evolved in drought-prone regions, but the genetics of their adaptation is not yet understood. Loci underlying stay-green post-flowering drought tolerance (Stg), have been identified in a temperate breeding line, but their role in drought adaptation of tropical sorghum is to be elucidated. We phenotyped 590 diverse sorghum accessions from West Africa under field-based managed drought stress, pre-flowering (WS1) and post-flowering (WS2) over several years and conducted genome-wide association studies (GWAS). Broad-sense heritability for grain and biomass yield components was high (33-92%) across environments. There was a significant correlation between stress tolerance index (STI) for grain weight across WS1 and WS2. GWAS revealed that SbZfl1 and SbCN12, orthologs of maize flowering genes, likely underlie flowering time variation under these conditions. GWAS further identified associations (n = 134) for STI and drought effects on yield components, including 16 putative pleiotropic associations. Thirty of the associations colocalized with Stg1–4 loci and had large effects. Seven lead associations, including some within Stg1, overlapped with positive selection outliers. Our findings reveal natural genetic variation for drought tolerance-related traits, and suggest a broad role of Stg loci in drought adaptation of sorghum.
Drought is one of the largest factors limiting yield of sorghum in semi-arid areas like in Senega... more Drought is one of the largest factors limiting yield of sorghum in semi-arid areas like in Senegal. With the improvement of farming techniques, identification and/or creation of varieties better adapted to drought could increase sorghum production in drought prone areas. Plant material used in selection and research programs, is usually from local provenance and has a low genetic diversity and limited performances under drought conditions. Thus, these work aim at evaluate agro-morphological characteristics of a core collection of 210 accessions issued from the world collection maintained at ICRISAT-Pantechuru, under three water regimes and screen varieties with contrasted responses to drought stress. Three experiments were conducted; one under non-limiting watering conditions (ETM), one with a water stress applied at pre-flowering stage (STRpre) and one with a stress at post-flowering stage (STRpost). Results show that, under any water regime, the core collection exhibits a large di...
Journal of Agriculture and Ecology Research International, 2020
Jatropha (Jatropha curcas L.) is a potential biodiesel plant that gained much attention in non-oi... more Jatropha (Jatropha curcas L.) is a potential biodiesel plant that gained much attention in non-oil production countries. We investigated the ability of the species to cope with water deficit occurring in semi-arid zones like Senegal climatic conditions. The layout of the experiment was a randomized complete blocks design with two factors (level and frequency of irrigation) and 6 repetitions. The trial was conducted from December 2012 to June 2013 in CERAAS/ISRA at Thiès, Senegal. Potted Jatropha seedlings were exposed, after three months under similar well-watered conditions, to three water regimes (100%, 50% and 25% of field capacity, respectively C100, C50 and C25) and two frequency of watering once and twice watering a week(F1 and F2, respectively). The different treatments didn’t affect significantly collar diameter and plant height during the time of the experimentation. Nevertheless, the trend line is up for collar diameter and plant height in wellwatered plants. For the same ...
Depuis le milieu des années 2000, le mil de type sanio1 est réapparu dans plusieurs villages du S... more Depuis le milieu des années 2000, le mil de type sanio1 est réapparu dans plusieurs villages du Sine, entre Bambey, Diourbel et Fatick. Pourtant, ce mil à cycle long avait disparu des paysages agraires de la moitié nord du Sénégal au cours des années 1970 en raison de la raréfaction brutale des pluies, pour se maintenir plus au sud, dans les régions arrosées du Saloum et au-delà jusqu’en Casamance. Étant donné que la quantité des pluies a augmenté à partir du milieu des années 1990 partout au Sénégal (SALACK et al., 2011), nous avons formulé l’hypothèse que cette résurgence pourrait constituer un « marqueur » agronomique robuste de l’évolution pluviométrique récente dans le centre-ouest du Sénégal et témoigner de la capacité des paysans à s’adapter rapidement et de façon autonome, i. e. sans l’appui de l’ingénierie agronomique2, aux changements de leur environnement.
The interactions between plant roots and the associated microbiota impact soil aggregation, water... more The interactions between plant roots and the associated microbiota impact soil aggregation, water retention and plant nutrient availability. Thus, selection of plant genotypes that promote microbial species involved in root-adhering soil aggregation and rhizosheath formation could help improve yield sustainably. Here, we tested pearl millet genotypic variation in both root-adhering soil aggregation, microbiological and biochemical characteristics. A collection of 181 pearl millet inbred lines was phenotyped for their rhizosheath size, and 13 contrasting genotypes were selected and grown under field conditions, and their root-adhering soil (RAS) was sampled. Microbial biomass, pH, mineral N content and six enzymatic activities involved in main nutrients cycles were analyzed, and metabarcoding of 16S rDNA and ITS were performed for bacterial and fungal diversity. Enzymatic activities (chitinase, acid phosphomonoesterase, FDA-hydrolysis and β-glucosidase) were higher in RAS of larger rhizosheath lines than that of smaller rhizosheath one. Bacterial β-diversity showed a separation of the most contrasting lines in the principal coordinate analysis performed with the Bray-Curtis distance matrix. Some bacteria from the Gaiellaceae and Sphingomonadaceae families and the Bradyrhizobium and Mesorhizobium genera were associated with the large rhizosheath phenotype. Concerning the fungal community, we noticed a negative correlation between the specific richness and the rhizosheath size and Trichoderma genus was positively associated to the rhizosheath size. This study demonstrates that in pearl millet, the rhizosheath size is related to soil nutrient dynamics and microbiota diversity. However, it also shows that other factors shape this trait and their relative importance must be determined.
Sorghum is the fifth most important cereal crop world-wide and feeds millions of people in the Sa... more Sorghum is the fifth most important cereal crop world-wide and feeds millions of people in the Sahel. However, it often faces early-stage water deficit due to false onsets of rainy seasons resulting in production decrease. Therefore, developing early drought tolerant material becomes a necessity but requires a good knowledge of adaptation mechanisms, which remains to be elucidated. The present study aimed at assessing the effects of early drought stress on ten elite sorghum varieties tested over two years (2018–2019) at the National Agronomic Research Centre (CNRA) of Bambey (Senegal, West Africa). Two different water regimes (well-watered and drought stress) were applied during the dry season. Water stress was applied by withholding irrigation 25 days after sowing for one month, followed by optimal irrigation until maturity. Soil moisture measurements were performed and allowed to follow the level of stress (down to a fraction of transpirable soil water (FTSW) of 0.30 at the end of...
Heterotic grouping based on combining ability for traits of interest, in addition to plant perfor... more Heterotic grouping based on combining ability for traits of interest, in addition to plant performance and genetic relationship among germplasm, would be useful in planning crosses in breeding programmes. This study aimed at determining the combining abilities of selected landraces for morphological and physiological traits under contrasted environments and identifying the suitable heterotic grouping method for superior hybrid production. For this purpose, nineteen accessions representing different origins and population structure among West African Sorghum Accessions Panel (WASAP) and two female lines, were used in « Line x tester » mating design to produce thirtyeight (38) hybrids. Analysis of variance showed significant general combining ability and specific combining ability effects for grain weight, plant height, days to flowering, panicle length and chlorophyll content implying existence of heterotic responses for these traits. Both additive and non-additive gene effects were important in controlling the inheritance of the traits. Parents K31.3, K37 and Ni331 were the best combiners for grain weight, providing the opportunity for breeders to improve grain yield under diverse environments. AVG-1 x K31.3 and AVG-1 x Tg148 were the superior hybrids. Combining ability based heterotic grouping methods classified sorghum accessions into four groups. The heterotic group's specific and general combining ability (HSGCA) method was the suitable in predicting hybrid superiority. This combining abilities based heterotic grouping study is an additional tool that breeders could use to identify the best parents for superior hybrids development in West Africa.
Rural societies in the face of climatic and environmental changes in West Africa, 2017
Introduction Sanio millet has reappeared in villages in the Sine, between Bambey, Diourbel and Fa... more Introduction Sanio millet has reappeared in villages in the Sine, between Bambey, Diourbel and Fatick, since the mid-2000s. However, this long cycle millet had disappeared from farms in the northern half of Senegal in the 1970s because of the sudden decrease in rainfall. It was still present further south in the wetter regions of Saloum and beyond as far as the Casamance. As rainfall depths increased from the mid-1990s everywhere in Senegal (Salack et al., 2011), we put forward the hypothesis..
The future of West Africa depends on the capacity of its agriculture to ensure the food security ... more The future of West Africa depends on the capacity of its agriculture to ensure the food security of the population, which should double in the next 20 years, while facing up to the new risks resulting from climate warming. Indeed, the changes in temperature and precipitations already operating and that should become more marked will have serious effects on agricultural production and water resources in this part of Africa in the near future. One of the keys to meeting this new challenge is the adaptation of rural societies to climate risks. To gain better knowledge of the potential, processes and barriers, this book analyses recent and ongoing trends in the climate and the environment and examines how rural societies perceive and integrate them: what are the impacts of these changes, what vulnerabilities are there but also what new opportunities do they bring ? How do the populations adapt and what innovations do they implement - while the climate-induced effects interact with the social, political, economic and technical changes that are in motion in Africa ? By associating French and African scientists (climatologists, agronomists, hydrologists, ecologists, demographers, geographers, anthropologists, sociologists and others) in a multidisciplinary approach, the book makes a valuable contribution to better anticipation of climatic risks and the evaluation of African societies to stand up to them
Studying seasonal adaptation is of great importance for understanding crop diversification. The b... more Studying seasonal adaptation is of great importance for understanding crop diversification. The biological process of seasonal adaptation of sorghum (Sorghum bicolor (L.) Moench.) allowed the development of flood recession agrosystems in the Sahel (West and Central Africa). To analyze the patterns of trait variation linked to this poorly documented process, we evaluated and compared four eco-seasonal groups of sorghum originating from seasonally diversified agrosystems in the same cropping conditions. The muskuwaari and samme groups are composed of landraces adapted to flood recession agrosystems in the Lake Chad Basin (43 accessions) and the Senegal River Valley (14 accessions), respectively. The other two groups are composed of varieties commonly grown in the rainy season (19 accessions from the Lake Chad Basin and 24 accessions from the Senegal River Valley and and surrounding regions). Multivariate analyses based on ten agro-morphological traits structured the sample in two main...
Pearl millet, unlike other cereals, is able to withstand dry and hot conditions and plays an impo... more Pearl millet, unlike other cereals, is able to withstand dry and hot conditions and plays an important role for food security in arid and semi-arid areas of Africa and India. However, low soil fertility and drought constrain pearl millet yield. One of the main targets to address these constraints through agricultural practices or breeding is root system architecture. In this study, in order to easily phenotype the root system in field conditions, we developed a model to predict root length density (RLD) of pearl millet plants from root intersection densities (RID) counted on a trench profile in field conditions. We identified root orientation as an important parameter to improve the relationship between RID and RLD. Root orientation was notably found to differ between thick roots (more anisotropic with depth) and fine roots (isotropic at all depths). We used our model to study pearl millet root system response to drought and showed that pearl millet reorients its root growth toward ...
Les sociétés rurales face aux changements climatiques et environnementaux en Afrique de l’Ouest
contrainte hydrique on procèderait à l'élimination de certains poquets (par exemple tu sèmes à 50... more contrainte hydrique on procèderait à l'élimination de certains poquets (par exemple tu sèmes à 50 cm et ensuite tu élimines 1 e ligne sur 2) pour que les restants aient de l'eau pour terminer leur cycle. Il serait aussi intéressant de savoir jusqu'à quel stade de développement l'application d'engrais pourrait avoir un effet significatif sur le développement du mil. Cela permettrait de jouer, en plus de la densité, sur la fertilisation pour gérer le niveau de développement de la culture en fonction des pluies reçues et des prévisions pour la fin du cycle.
Rice production faces the challenge to be enhanced by 50% by year 2030 to meet the growth of the ... more Rice production faces the challenge to be enhanced by 50% by year 2030 to meet the growth of the population in rice-eating countries. Whereas yield of cereal crops tend to reach plateaus and a yield is likely to be deeply affected by climate instability and resource scarcity in the coming decades, building rice cultivars harboring root systems that can maintain performance by capturing water and nutrient resources unevenly distributed is a major breeding target. Taking advantage of gathering a community of rice root biologists in a Global Rice Science Partnership workshop held in Montpellier, France, we present here the recent progresses accomplished in this area and focal points where an international network of laboratories should direct their efforts.
Abstract: The root length density (RLD) distri-bution in the soil is a key factor for water and n... more Abstract: The root length density (RLD) distri-bution in the soil is a key factor for water and nutrient uptake but its direct assessment is not easy. A field method is presented here to assess RLD of sorghum (Sorghum bicolor L. Moench) from the root intersection density (RID) and taking root orientations into account. The method was developed with four varieties cropped in 2006 in Bambey (Senegal) on a sandy soil, and validated on the basis of independent data obtained on two other varieties cropped in 2008 in Thiès in Senegal on a sandy loam soil. Sets of 1 × 10-3 m3 cubic undisturbed soil samples were collected at different positions and at three different dates for the four varieties during the
Sequencias do DNA de uma regiao em comum de multiplos individuos de uma populacao podem revelar p... more Sequencias do DNA de uma regiao em comum de multiplos individuos de uma populacao podem revelar polimorfismos que permitem o estudo da evolucao do genoma e suas historias de selecoes, migracoes e recombinacoes. Adicionando-se a esses polimorfismos da populacao informacoes quanto a origem geografica, viabiliza-se um estudo filogeografico que permite a elaboracao de cenarios de evolucao apos a domesticacao; bem como quais eventos (mutacoes ou recombinacoes) mais influenciaram a diversidade genetica (DG) desta populacao, para aquela regiao do DNA em estudo. Por outro lado, a associacao desses polimorfismos das sequencias com as caracteristicas de interesse estabelece um estudo de associacao. Neste contexto, este trabalho visou mostrar a aplicacao do polimorfismo de sequencias de DNA em um estudo de filogeografia e de associacao. Para ambos os estudos foram utilizados dezenove segmentos de seis genes candidatos (Sh2, Bt2, Sssl, Ael, Wx e 02) em uma colecao de sorgo (Sorghum bicolor L. M...
Root architecture of two sorghum varieties, fitted in #Durra race# and with different response in... more Root architecture of two sorghum varieties, fitted in #Durra race# and with different response in drought conditions, has been studied on hydroponic system, pot and in situ on field. These varieties have similar aerial agro-morphological characteristics in optimal growth conditions. In pre-flowering drought stress condition, tolerant variety (SSM1611), has a stable and higher yield than the non-tolerant one (IS16101). On hydroponics conditions and pot growth, varieties are studied at young stage. On field, observations concerned the whole plant cycle. Frequent observations of the aerial system have been made in all the trials, with counting of emerged leaves number and measuring stem height. Adventitious roots number and adventitious roots ranks number have been daily observed on hydroponic system and observations was not destructive. Spatial root disposition on stem was observed on hydroponic condition. On pot and field, these observations were destructive and realised once a week....
Drought is a major constraint on plant productivity globally. Sorghum (Sorghum bicolor) landraces... more Drought is a major constraint on plant productivity globally. Sorghum (Sorghum bicolor) landraces have evolved in drought-prone regions, but the genetics of their adaptation is not yet understood. Loci underlying stay-green post-flowering drought tolerance (Stg), have been identified in a temperate breeding line, but their role in drought adaptation of tropical sorghum is to be elucidated. We phenotyped 590 diverse sorghum accessions from West Africa under field-based managed drought stress, pre-flowering (WS1) and post-flowering (WS2) over several years and conducted genome-wide association studies (GWAS). Broad-sense heritability for grain and biomass yield components was high (33-92%) across environments. There was a significant correlation between stress tolerance index (STI) for grain weight across WS1 and WS2. GWAS revealed that SbZfl1 and SbCN12, orthologs of maize flowering genes, likely underlie flowering time variation under these conditions. GWAS further identified associations (n = 134) for STI and drought effects on yield components, including 16 putative pleiotropic associations. Thirty of the associations colocalized with Stg1–4 loci and had large effects. Seven lead associations, including some within Stg1, overlapped with positive selection outliers. Our findings reveal natural genetic variation for drought tolerance-related traits, and suggest a broad role of Stg loci in drought adaptation of sorghum.
Drought is one of the largest factors limiting yield of sorghum in semi-arid areas like in Senega... more Drought is one of the largest factors limiting yield of sorghum in semi-arid areas like in Senegal. With the improvement of farming techniques, identification and/or creation of varieties better adapted to drought could increase sorghum production in drought prone areas. Plant material used in selection and research programs, is usually from local provenance and has a low genetic diversity and limited performances under drought conditions. Thus, these work aim at evaluate agro-morphological characteristics of a core collection of 210 accessions issued from the world collection maintained at ICRISAT-Pantechuru, under three water regimes and screen varieties with contrasted responses to drought stress. Three experiments were conducted; one under non-limiting watering conditions (ETM), one with a water stress applied at pre-flowering stage (STRpre) and one with a stress at post-flowering stage (STRpost). Results show that, under any water regime, the core collection exhibits a large di...
Journal of Agriculture and Ecology Research International, 2020
Jatropha (Jatropha curcas L.) is a potential biodiesel plant that gained much attention in non-oi... more Jatropha (Jatropha curcas L.) is a potential biodiesel plant that gained much attention in non-oil production countries. We investigated the ability of the species to cope with water deficit occurring in semi-arid zones like Senegal climatic conditions. The layout of the experiment was a randomized complete blocks design with two factors (level and frequency of irrigation) and 6 repetitions. The trial was conducted from December 2012 to June 2013 in CERAAS/ISRA at Thiès, Senegal. Potted Jatropha seedlings were exposed, after three months under similar well-watered conditions, to three water regimes (100%, 50% and 25% of field capacity, respectively C100, C50 and C25) and two frequency of watering once and twice watering a week(F1 and F2, respectively). The different treatments didn’t affect significantly collar diameter and plant height during the time of the experimentation. Nevertheless, the trend line is up for collar diameter and plant height in wellwatered plants. For the same ...
Depuis le milieu des années 2000, le mil de type sanio1 est réapparu dans plusieurs villages du S... more Depuis le milieu des années 2000, le mil de type sanio1 est réapparu dans plusieurs villages du Sine, entre Bambey, Diourbel et Fatick. Pourtant, ce mil à cycle long avait disparu des paysages agraires de la moitié nord du Sénégal au cours des années 1970 en raison de la raréfaction brutale des pluies, pour se maintenir plus au sud, dans les régions arrosées du Saloum et au-delà jusqu’en Casamance. Étant donné que la quantité des pluies a augmenté à partir du milieu des années 1990 partout au Sénégal (SALACK et al., 2011), nous avons formulé l’hypothèse que cette résurgence pourrait constituer un « marqueur » agronomique robuste de l’évolution pluviométrique récente dans le centre-ouest du Sénégal et témoigner de la capacité des paysans à s’adapter rapidement et de façon autonome, i. e. sans l’appui de l’ingénierie agronomique2, aux changements de leur environnement.
The interactions between plant roots and the associated microbiota impact soil aggregation, water... more The interactions between plant roots and the associated microbiota impact soil aggregation, water retention and plant nutrient availability. Thus, selection of plant genotypes that promote microbial species involved in root-adhering soil aggregation and rhizosheath formation could help improve yield sustainably. Here, we tested pearl millet genotypic variation in both root-adhering soil aggregation, microbiological and biochemical characteristics. A collection of 181 pearl millet inbred lines was phenotyped for their rhizosheath size, and 13 contrasting genotypes were selected and grown under field conditions, and their root-adhering soil (RAS) was sampled. Microbial biomass, pH, mineral N content and six enzymatic activities involved in main nutrients cycles were analyzed, and metabarcoding of 16S rDNA and ITS were performed for bacterial and fungal diversity. Enzymatic activities (chitinase, acid phosphomonoesterase, FDA-hydrolysis and β-glucosidase) were higher in RAS of larger rhizosheath lines than that of smaller rhizosheath one. Bacterial β-diversity showed a separation of the most contrasting lines in the principal coordinate analysis performed with the Bray-Curtis distance matrix. Some bacteria from the Gaiellaceae and Sphingomonadaceae families and the Bradyrhizobium and Mesorhizobium genera were associated with the large rhizosheath phenotype. Concerning the fungal community, we noticed a negative correlation between the specific richness and the rhizosheath size and Trichoderma genus was positively associated to the rhizosheath size. This study demonstrates that in pearl millet, the rhizosheath size is related to soil nutrient dynamics and microbiota diversity. However, it also shows that other factors shape this trait and their relative importance must be determined.
Sorghum is the fifth most important cereal crop world-wide and feeds millions of people in the Sa... more Sorghum is the fifth most important cereal crop world-wide and feeds millions of people in the Sahel. However, it often faces early-stage water deficit due to false onsets of rainy seasons resulting in production decrease. Therefore, developing early drought tolerant material becomes a necessity but requires a good knowledge of adaptation mechanisms, which remains to be elucidated. The present study aimed at assessing the effects of early drought stress on ten elite sorghum varieties tested over two years (2018–2019) at the National Agronomic Research Centre (CNRA) of Bambey (Senegal, West Africa). Two different water regimes (well-watered and drought stress) were applied during the dry season. Water stress was applied by withholding irrigation 25 days after sowing for one month, followed by optimal irrigation until maturity. Soil moisture measurements were performed and allowed to follow the level of stress (down to a fraction of transpirable soil water (FTSW) of 0.30 at the end of...
Heterotic grouping based on combining ability for traits of interest, in addition to plant perfor... more Heterotic grouping based on combining ability for traits of interest, in addition to plant performance and genetic relationship among germplasm, would be useful in planning crosses in breeding programmes. This study aimed at determining the combining abilities of selected landraces for morphological and physiological traits under contrasted environments and identifying the suitable heterotic grouping method for superior hybrid production. For this purpose, nineteen accessions representing different origins and population structure among West African Sorghum Accessions Panel (WASAP) and two female lines, were used in « Line x tester » mating design to produce thirtyeight (38) hybrids. Analysis of variance showed significant general combining ability and specific combining ability effects for grain weight, plant height, days to flowering, panicle length and chlorophyll content implying existence of heterotic responses for these traits. Both additive and non-additive gene effects were important in controlling the inheritance of the traits. Parents K31.3, K37 and Ni331 were the best combiners for grain weight, providing the opportunity for breeders to improve grain yield under diverse environments. AVG-1 x K31.3 and AVG-1 x Tg148 were the superior hybrids. Combining ability based heterotic grouping methods classified sorghum accessions into four groups. The heterotic group's specific and general combining ability (HSGCA) method was the suitable in predicting hybrid superiority. This combining abilities based heterotic grouping study is an additional tool that breeders could use to identify the best parents for superior hybrids development in West Africa.
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Papers by Bassirou Sine