Élaboration de modèles allométriques d’Acacia Sénéga

La présente étude s’est appesantie sur l’élaboration de modèles allométriques d’une espèce soudanosahélienne (Acacia Sénégal ) dans le but d’asseoir une base de calcul des stocks de carbone. La recherche s’est effectuée en zone sylvopastorale, au nord du Sénégal. Au préalable, l’étude a tenté d’approfondir les connaissances sur la dendrométrie de Acacia Sénégal. Sur le terrain, les paramètres suivants ont été mesurés et fait l’objet d’analyses et interprétations : diamètre à la base, hauteur totale de l’arbre, longueur du tronc, diamètre à hauteur de poitrine, circonférence à hauteur de poitrine et largeur du houppier. La pesée des échantillons de chaque partie (tronc, branche, rameau) de l’échantillon d’arbres composés de 38 pieds d’Acacia Sénégal et leur séchage à l’étuve ont permis de connaître la biomasse sèche de chaque sujet. Ensuite, des modèles allométriques spécifiques (entre la biomasse sèche et les paramètres dendrométriques) ont été générés et les coefficients de corrélation déterminés. Les différentes analyses ont permis d’affirmer que le diamètre à hauteur de poitrine (DHP) est la variable qui offre la meilleure corrélation avec la biomasse aérienne. Parmi les modèles, et par ordre décroissant, nous avons obtenu la relation polynomiale, logarithmique et de puissance. Les modèles retenus ont comme entrée le DBH. De ce fait, le modèle polynomiale (y = 0,032DBH3 - 1,016DBH2 + 10,87DBH + 7,429) présente la meilleure corrélation (R² = 0,963), suivi du modèle logarithmique (y = 13,61ln(DBH) + 17,89) avec une corrélation R² = 0,933 et du modèle de puissance (y = 22,23DBH0,357) pour une corrélation R² = 0,909. L’étude a confirmé l’hypothèse selon laquelle, au sein d’une même espèce, l’élaboration de modèle spécifique reflète plus la réalité et permet de faire une quantification des stocks de carbone plus proche de la réalité que le modèle générique.Mots-clés : modèle allométrique, grande muraille verte, Acacia Sénégal, séquestration de carbone

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Background: Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. // Methods: We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung's disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. // Findings: We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung's disease) from 264 hospitals (89 in high-income countries, 166 in middle-income countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in low-income countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. // Interpretation: Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between low-income, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Performances agronomiques de quatre variétés de riz pluvial NERICA de plateau semées à différentes dates en zone soudano-sahélienne au Sénégal

Objectif: Le Sénégal est à 80% tributaire du marché international pour satisfaire sa demande intérieure en riz. Pourtant cet aliment occupe une place de premier choix dans l’alimentation quotidienne des sénégalais. Les autorités et les partenaires au développement oeuvrent alors, depuis ces deux dernières décennies, à réduire la dépendance du pays vis-à-vis du riz importé à travers l’augmentation de la production nationale. Le présent travail s’inscrit dans cette dynamique. Elle s’intéresse particulièrement à l’étude, en conditions strictement pluviales, des performances agronomiques de deux variétés de riz NERICA à cycle de 75-85 jours (NERICA 8 et NERICA 11) et de deux variétés de riz NERICA à cycle de 95-100 jours (NERICA 1 et NERICA 4).Méthodologie et résultats: Pour ce faire, deux essais ont été semés à Sinthiou Malème , pendant la saison des pluies, à des dates décalées en 2013 et répétés en 2014. Chaque année, le semis du premier essai a été effectué pendant la cinquième pentade du mois de juillet et le deuxième pendant la deuxième pentade du mois d’août. Les résultats ont montré que la saison des pluies a duré 110 jours et a été caractérisée par des périodes de déficit hydrique qui ont coïncidé avec la phase reproductive des variétés de riz étudiées. Ce déficit hydrique a perturbé la formation des panicules et la fécondation des épillets. L’effet de ce déficit hydrique a été plus prononcé sur les semis tardifs d’une part (baisse de rendement grains de 75 à 79%) et sur les variétés à cycle plus long d’autre part (baisse de rendement grains pouvant atteindre 42%).Conclusion et application des résultats: Les quatre variétés de riz NERICA pluvial étudiées peuvent certes être cultivées dans la zone soudano-sahélienne de Sinthiou Malème mais il faut préférer les variétés très précoces de 75-85 jours (NERICA 8 et NERICA 11) et les semer avant la cinquième pentade du mois de juillet pour ne pas compromettre les rendements grains.Mots-clés: date de semis, zone soudano-sahélienne, NERICA, performances agronomiques, riz pluvial, SénégalEnglish AbstractObjective: Senegal imports every year 80 % of its rice for consumption. Since the last two decades, current policies are trying to reduce the dependence of the country towards the international market by increasing the national rice production. One of the alternatives for the increase of national rice production is the development of rainfed rice in soudano-sahelian areas of the country. Therefore, the present study aimed to measure the agronomic traits of four upland rainfed rice NERICA (NERICA 1 and NERICA 4 (95-100 days); NERICA 8 and NERICA 11 (75-85 days)) in a soudano-sahelian zone.Methodology and results: Two trials were carried out in 2013 and 2014 at Sinthiou Malème (13°50’N; 13°55’W; 22 m) during the raining season and no water was given through irrigation. Each year, the first trial was sown during the month of July and the second one, during the second one in the month of August. The results showed that the raining season lasted 110 days and dry spells occurred during the flowering stage of the rice varieties. Those drought periods affected negatively the panicle formation and the spikelet pollination. This phenomenon was severe on the latest trials (grain yields decreased of 75-79 %) and on the longest cycle length, varieties (grain yields decreased of 42 %).Conclusion and application: The four rice varieties (NERICA 1, NERICA 4, NERICA 8 and NERICA 11) can be cultivated in the soudano-sahelian zone of Sinthiou Malème but it is advantageous to choose NERICA 8 and NERICA 11 for their shortest cycle length and they must been sown before the fifth decade of July.Keywords: Sowing date, soudano-sahelian zone, NERICA, agronomic traits, rainfed rice, Senega

Dynamics of agricultural land and the risk to food insecurity in the <i>Niayes</i> region of Diamniadio, West Senegal

Food security is a serious challenge facing West African countries because most croplands are being degraded. Consequently, agricultural production is being exceeded by rapid population growth. This study relates the dynamics of agricultural lands to the level of capacity building for resilience in response to low productivity and hence to food insecurity in the Niayes region, Senegal, where lands are presumably suitable for crop production. Factors influencing changes in surface areas, soil quality and level of resilience were examined using quantitative and qualitative research methods. Findings showed strong relationships between a significant decrease (65.25% – 35.54%) in productive agricultural lands with a range of soil physical and chemical properties (clay to loamy soil texture; soil pH: 7.0–8.0; soil organic carbon [SOC]: 5.0 g kg−1 – 25.0 g kg−1; effective cations exchangeable capacity [ECEC]: 4.5 Cmol kg−1 – 39.0 Cmol kg−1; cation exchange capacity [CEC]: 8.0 Cmol kg−1 – 34.0 Cmol kg−1) and food insecurity levels. In the last 5 years, urbanisation and industrialisation processes have reduced the farmlands by about 26.51% through uncontrolled construction of buildings and companies, leading to a disappearance of lands. Such dynamics raises the issue of a risk to food security in a region that usually provides more than 70% of fruits and vegetables demand for consumption. These results underline a need for a greater understanding of resilience for a better management design with a risk prevention plan to ensure food security

Research activities under COST C1 at the Departement MSM of the University of Liège

peer reviewe

Impact of irrigation water quality on soil nitrifying and total bacterial communities

Disturbance induced by two contrasting irrigation regimes (groundwater versus urban wastewater) was evaluated on a sandy agricultural soil through chemical and microbial analyses. Contrary to wastewater, groundwater displayed very high nitrate contents but small amounts of ammonium and organic matter. Despite these strong compositional shifts, soil organic carbon and nitrogen, nitrate and ammonium contents were not significantly different in both types of irrigated plot. Moreover, neither microbial biomass nor its activity, determined as fluorescein diacetate hydrolysis activity, was influenced by irrigation regimes. Bacterial community structure, assessed by denaturing gradient gel electrophoresis (DGGE) of 16S ribosomal DNA fragments, was also weakly impacted as molecular fingerprints shared an overall similarity of 85%. Ammonia-oxidizing bacterial community (AOB) was monitored by DGGE of the functional molecular marker amoA gene (alpha subunit of the ammonia monooxygenase). Surprisingly, no amoA signals were obtained from plots irrigated with groundwater, whereas signal intensities were high in all plots under wastewater. Among the last, compositional shifts of the AOB community were weak. Overall, impact of irrigation water quality on soil chemistry could not be evidenced, whereas effects were low on the total bacterial compartment but marked on the AOB community

The High Red/Far-Red Ratio Supports the Acclimation of Fern Platycerium bifurcatum to High Light

Background and aims: High light causes disturbances in photosynthetic phosphorylation or damage to the photosystem II (PSII) structure or even assimilation tissues. The value of the red/far-red ratio (R/FR) provides the plant with information on the environmental light conditions, regulating, among others, photosynthetic activity and pigment composition of the plant. The response of the photosynthetic apparatus of the sporotrophophylls and nest leaves of Platycerium bifurcatum, grown for 6 months at the low or high R/FR ratio, were studied. Later, the plants were transferred to high light (1,200 μmol quantum·m−2 · s−1). Methods: Changes in PSII photochemical activity were determined based on non-destructive methods of chlorophyll a fluorescence kinetics analysis. The measurement of radiation reflectance from the leaves allowed to determine the content of selected pigments related to the photosynthesis process and to assess changes in the Photochemical Reflectance Index. The calculation of reflectance difference and sensitivity analysis was used to identify so-called “stress-sensitive wavelengths”. Results and discussion: Plant growth at high R/FR ratio prepares photosynthetic apparatus of ferns to high light and enables more efficient conversion of absorbed photons. The increase in the amount of photoprotective compounds allows the protection against photoinhibition in the sporotrophophyll leaves that play key roles in plant nutrition and reproduction

Are poor responses to praziquantel for the treatment of Schistosoma mansoni infections in Senegal due to resistance? An overview of the evidence

The definitive version is available at www3.interscience.wiley.comThis paper summarizes and concludes in-depth field investigations on suspected resistance of Schistosoma mansoni to praziquantel in northern Senegal. Praziquantel at 40 mg/kg usually cures 70–90% of S. mansoni infections. In an initial trial in an epidemic S. mansoni focus in northern Senegal, only 18% of the cases became parasitologically negative 12 weeks after treatment, although the reduction in mean egg counts was within normal ranges (86%). Among other hypotheses to explain the observed low cure rate in this focus, the possibility of drug resistance or tolerance had to be considered. Subsequent field trials with a shorter follow-up period (6–8 weeks) yielded cure rates of 31–36%. Increasing the dose to 2 × 30 mg/kg did not significantly improve cure rates, whereas treatment with oxamniquine at 20 mg/kg resulted in a normal cure rate of 79%. The efficacy of praziquantel in this focus could be related to age and pre-treatment intensity but not to other host factors, including immune profiles and water contact patterns. Treatment with praziquantel of individuals from the area residing temporarily in an urban region with no transmission, and re-treatment after 3 weeks of non-cured individuals within the area resulted in normal cure rates (78–88%). The application of an epidemiological model taking into account the relation between egg counts and actual worm numbers indicated that the low cure rates in this Senegalese focus could be explained by assuming a 90% worm reduction after treatment with praziquantel; in average endemic situations, such a drug efficacy would result in normal cure rates. Laboratory studies by others on the presence or absence of praziquantel resistance in Senegalese schistosome strains have so far been inconclusive. We conclude that there is no convincing evidence for praziquantel-resistant S. mansoni in Senegal, and that the low cure rates can be attributed to high initial worm loads and intense transmission in this area