Effet de la salinité sur la germination graines et la croissance des semis de treize cultivars africains de sésame (Sesamum indicum L.)

Le sésame (Sesamum indicum L.), une plante annuelle autoféconde originaire d’Afrique et d’Inde, est très sensible aux stades de germination et de semis mais modérément tolérant aux stress hydrique et salin. Cette étude menée en serre a pour objectif d’évaluer l’effet de différentes concentrations de NaCl sur la germination des graines et la croissance des semis de treize cultivars africains de sésame provenant du Sénégal, du Burkina Faso, du Cameroun et du Soudan. Un dispositif à blocs randomisés avec deux facteurs et trois répétitions a été utilisé . Les résultats montrent un effet négatif du gradient de salinité sur les taux de germination, de survie, la biomasse fraiche, la biomasse sèche, le diamètre au collet et la longueur de la tige. Les cultivars AS09, AS13, AS14, AS15, AS19 et AS25 ont été moins affectés par la salinité. L’importance de l’effet dépressif dépend de la concentration de sel et de la variété de cultivar de sésame. Sesame (Sesamum indicum L.), an annual self-pollinating plant native to Africa and India, is very sensitive to the stages of germination and sowing but moderately tolerant to water and salt stress. The objective of this greenhouse study is to assess the effect of different NaCl concentrations on seed germination and seedling growth of thirteen African sesame cultivars from Senegal, Burkina Faso, Cameroon and Sudan. A randomized block device with two factors and three replicates was used. The results show a negative effect of the salinity gradient on the germination rate, survival, fresh biomass, dry biomass, diameter at the collar and length of the stem. Cultivars AS09, AS13, AS14, AS15, AS19 and AS25 were less affected by salinity. The magnitude of the depressive effect depends on the concentration of salt and the sesame cultivar. &nbsp

General characteristics of the study cohort.

<p>General characteristics of the study cohort.</p

Baseline <i>S</i>. <i>haematobium</i> infection, efficacy of three treatments of praziquantel and reinfection levels over three years in nine villages of the Niakhar study area.

<p>Baseline <i>S</i>. <i>haematobium</i> infection, efficacy of three treatments of praziquantel and reinfection levels over three years in nine villages of the Niakhar study area.</p

Map of the study area of Niakhar showing the villages studied and the snail sampling sites in the fresh-water ponds and backwaters.

<p>Map of the study area of Niakhar showing the villages studied and the snail sampling sites in the fresh-water ponds and backwaters.</p

Global results of the malacological survey in water bodies from 2011 to 2013 in the nine villages selected in the Niakhar study area.

<p>Global results of the malacological survey in water bodies from 2011 to 2013 in the nine villages selected in the Niakhar study area.</p

Baseline <i>S</i>. <i>haematobium</i> infection, efficacy of three treatments of praziquantel and reinfection levels over three years according to age group and sex.

<p>Baseline <i>S</i>. <i>haematobium</i> infection, efficacy of three treatments of praziquantel and reinfection levels over three years according to age group and sex.</p

Efficacy of praziquantel against urinary schistosomiasis and reinfection in Senegalese school children where there is a single well-defined transmission period

Background: Human schistosomiasis is a significant health problem in Sub-Saharan Africa. In Niakhar, West central Senegal, the transmission of S. haematobium occurs seasonally between July and November. No control measures have been implemented despite high prevalence reported in previous studies. This aim of this study was to i) determine the current prevalence of S. haematobium in children at Niakhar, ii) assess the efficacy of one dose of PZQ (40 mg/kg) against S. haematobium and iii) monitor reinfection. Methods: The current study was carried out in a cohort of 329 children aged five to 15 years enrolled from six villages in Niakhar to determine the efficacy of one dose of PZQ, as well as reinfection. Parasitological screening was performed in June 2011 to determine the baseline prevalence of S. haematobium, and then a single dose of PZQ was administered to all selected subjects in the transmission season in August 2011. The efficacy of PZQ treatment and reinfection were monitored respectively five weeks after in September 2011 and from February to March 2012. Results: At baseline, the overall prevalence and the heavy intensity of infection were 73.2 % and 356.1eggs/10 ml of urine. Significant differences in the prevalence and intensity of S. haematobium infection were noted between villages. A single dose of PZQ significantly reduced the prevalence of S. haematobium infection from 73.2 % to 4.6 % and the geometric mean intensity of infection from 356.1 to 43.3 eggs/10 ml of urine. The cure rates ranged from 89.4 % to 100 %. The egg reduction rates also ranged from 77.6 % to 100 %. Two to three months after the period of transmission, the overall rate of reinfection was 12.6 % and was significantly higher in male children than in female children. The overall prevalence at this period was 13.8 %, which was significantly lower than the prevalence at baseline (73.2 %). Conclusion: The Niakhar study area remains a hot spot of urinary schistosomiasis in Senegal with differences in transmission between villages. This study suggests that when transmission is strictly seasonal, Praziquantel shows the expected efficacy in reducing the prevalence and intensity of infection, but also a significant effect on the occurrence of reinfection