Nutrients composition of calyces and seeds of three Roselle (Hibiscus sabdariffa L.) ecotypes from Niger

The chemical composition of calyces and seeds of three ecotypes of Roselle from Niger was compared. The results indicate that calcium (Ca), potassium (K), sodium (Na), magnesium (Mg) and protein contents in calyces are significantly different (P<0.005) among ecotypes. The highest concentrations of K, Na, Mg and protein in calyces were recorded for ecotype E7 (35.66, 3.40, 6.01 and 101 mg/g d.w., respectively). Ecotype E9 had the highest Ca content in calyces (34.41 mg/g d.w.); while E3 and E7 had similar and lower contents. The protein content in calyces for E9 (52 mg/g d.w.) was approximately halved compared to those of E3 and E7. For all ecotypes, the concentrations of Ca, K, Mn, Na and Fe in the calyces were higher compared to those in the seeds. In contrast, P content was higher in seeds. The highest K, Na, Mg and P concentrations in seeds were registered for E7 and the lowest ones for E9. Ecotypes E3 and E9 recorded higher and similar Cu, Fe and Mn contents in calyces and in seeds compared to E7. The highest Zn concentrations in seeds were obtained for E3 and E7.Keywords: Niger, Roselle, seeds, calyces, protein, composition, micronutrients, macronutrientsAfrican Journal of Biotechnology Vol. 12(26), pp. 4174-417

Agricultural impacts of large-scale variability of the West African monsoon

Agriculture in the Sudano-Sahelian zone is heavily dependent on the seasonal characteristics of rainfall. This study seeks to characterise components of regional climatic variability and their impact on simulated, attainable, plot level yields of millet. First we describe at a regional scale two main events in the seasonal pattern of the monsoon over West Africa by using a daily rainfall dataset over the 1968-1990 period, that is, (i) the onset of the summer monsoon characterised by an abrupt northward shift of the ITCZ from 5°N to 10°N around 24 June, and (ii) large and coherent intra-seasonal rainfall fluctuations at two different time scales, around 15 and 40 days. Second, we investigate the impact of these regional phenomena on local crop yields using SARRAH, a crop model simulating attainable yield, i.e. water and climate limited but not nutrient limited yield, by means of sensitivity analyses. The response of attainable yield to sowing date is studied for 19 years of the 1968-1990 period for a 90-day millet crop at Niamey. The results indicate that information on regional climate dynamics might help improve crop production locally. It is shown that the regional onset of the monsoon is very close to the ideal sowing date, derived from simulations, at Niamey and that simulated yields are much higher for these dates than for those identified with the traditional rule based on local rainfall. Taking into account the regional onset of monsoon thus seems to improve the relationship between water available and water used by the plant, and thus seems to potentially increase crop water use. Where attainable, simulated yields using the monsoon onset criterion are low, they are generally caused by intra-seasonal dry spells that have differential impact depending on phenological stage of the crop. (Résumé d'auteur

Perception et observation : les principaux risques agro-climatique de l’agriculture pluviale dans l’ouest du Niger

Climate variability and change are challenges for rainfed agriculture in the Sahel. The objective of this study was to identify and prioritize agroclimatic risks, their impacts and adaptive strategies through community perception and analysis of observed data. A survey of 361 household heads from 12 villages was conducted in the Sahelian and Sahelo-sudanian areas of Niger. Precipitation and wind data from 2 weather stations were analyzed. The results show that communities are aware of the existence of agro-climatic risks, including early cessation of the rainy season, early season sand winds, and dry spells that are the most frequent and most severe weather events. The perceptions on winds and dry spells agree with the results of the analysis of observed data, whereas in the case of early cessation of the rainy season, analysis of the observed data reveals a return to a better situation, which remains non-perceptible by the communities, due to the high intra- and inter-annual variability. The immediate impacts are loss of seedlings and crops and the development of crop pests. These impacts in turn lead to animal weakness and food insecurity. Although they develop adaptation strategies such as improved crop varieties and water conservation and soil protection/restoration techniques, communities seem to be overwhelmed by the phenomenon. In the short term, the proposed adaptation strategies to the risks identified by the communities will help to cope with the effects of variability and climate change on rainfed agriculture in the Sahel

Perception et observation : les principaux risques agro-climatique de l’agriculture pluviale dans l’ouest du Niger

La variabilité et le changement climatiques constituent un défi pour l’agriculture pluviale au Sahel. L’objectif de cette étude était d’identifier et de hiérarchiser les risques agroclimatiques, leurs impacts et les stratégies d’adaptation, à travers la perception communautaire et l’analyse des données observées. Une enquête a été conduite au Niger auprès de 361 chefs de ménage de 12 villages des zones sahéliennes et sahélo-soudaniennes. Les données de précipitations et de vents de 2 stations météorologiques ont été analysées. Les résultats montrent que les communautés sont conscientes de l’existence des risques agroclimatiques, à savoir la fin précoce des pluies, les vents de sable en début de saison et les séquences sèches qui sont les événements météorologiques les plus fréquents et les plus sévères. Les perceptions sur les vents et les séquences sèches s’accordent avec les résultats de l’analyse des données observées, alors qu’en ce qui concerne la fin précoce des pluies, l’analyse des données observées révèle un retour à une meilleure situation, qui demeure cependant non perceptible par les communautés, du fait de la forte variabilité intra et interannuelle. Les impacts immédiats sont les pertes de semis et de récoltes et le développement des ravageurs de cultures. Ces impacts entrainent à leur tour l’affaiblissement des animaux et l’insécurité alimentaire. Bien qu’elles développent des stratégies d’adaptation, telles que les variétés améliorées et les techniques de conservation des eaux et de défense et de restauration des sols, les communautés semblent être désarmées par le phénomène. Dans l’immédiat, la proposition de stratégies d’adaptation face aux risques identifiés par les communautés aiderait à faire face aux effets des variabilités et changements climatiques sur l’agriculture pluviale au Sahel.Climate variability and change are challenges for rainfed agriculture in the Sahel. The objective of this study was to identify and prioritize agroclimatic risks, their impacts and adaptive strategies through community perception and analysis of observed data. A survey of 361 household heads from 12 villages was conducted in the Sahelian and Sahelo-sudanian areas of Niger. Precipitation and wind data from 2 weather stations were analyzed. The results show that communities are aware of the existence of agro-climatic risks, including early cessation of the rainy season, early season sand winds, and dry spells that are the most frequent and most severe weather events. The perceptions on winds and dry spells agree with the results of the analysis of observed data, whereas in the case of early cessation of the rainy season, analysis of the observed data reveals a return to a better situation, which remains non-perceptible by the communities, due to the high intra- and inter-annual variability. The immediate impacts are loss of seedlings and crops and the development of crop pests. These impacts in turn lead to animal weakness and food insecurity. Although they develop adaptation strategies such as improved crop varieties and water conservation and soil protection/restoration techniques, communities seem to be overwhelmed by the phenomenon. In the short term, the proposed adaptation strategies to the risks identified by the communities will help to cope with the effects of variability and climate change on rainfed agriculture in the Sahel

Perception et observation : les principaux risques agro-climatique de l’agriculture pluviale dans l’ouest du Niger

La variabilité et le changement climatiques constituent un défi pour l’agriculture pluviale au Sahel. L’objectif de cette étude était d’identifier et de hiérarchiser les risques agroclimatiques, leurs impacts et les stratégies d’adaptation, à travers la perception communautaire et l’analyse des données observées. Une enquête a été conduite au Niger auprès de 361 chefs de ménage de 12 villages des zones sahéliennes et sahélo-soudaniennes. Les données de précipitations et de vents de 2 stations météorologiques ont été analysées. Les résultats montrent que les communautés sont conscientes de l’existence des risques agroclimatiques, à savoir la fin précoce des pluies, les vents de sable en début de saison et les séquences sèches qui sont les événements météorologiques les plus fréquents et les plus sévères. Les perceptions sur les vents et les séquences sèches s’accordent avec les résultats de l’analyse des données observées, alors qu’en ce qui concerne la fin précoce des pluies, l’analyse des données observées révèle un retour à une meilleure situation, qui demeure cependant non perceptible par les communautés, du fait de la forte variabilité intra et interannuelle. Les impacts immédiats sont les pertes de semis et de récoltes et le développement des ravageurs de cultures. Ces impacts entrainent à leur tour l’affaiblissement des animaux et l’insécurité alimentaire. Bien qu’elles développent des stratégies d’adaptation, telles que les variétés améliorées et les techniques de conservation des eaux et de défense et de restauration des sols, les communautés semblent être désarmées par le phénomène. Dans l’immédiat, la proposition de stratégies d’adaptation face aux risques identifiés par les communautés aiderait à faire face aux effets des variabilités et changements climatiques sur l’agriculture pluviale au Sahel.Climate variability and change are challenges for rainfed agriculture in the Sahel. The objective of this study was to identify and prioritize agroclimatic risks, their impacts and adaptive strategies through community perception and analysis of observed data. A survey of 361 household heads from 12 villages was conducted in the Sahelian and Sahelo-sudanian areas of Niger. Precipitation and wind data from 2 weather stations were analyzed. The results show that communities are aware of the existence of agro-climatic risks, including early cessation of the rainy season, early season sand winds, and dry spells that are the most frequent and most severe weather events. The perceptions on winds and dry spells agree with the results of the analysis of observed data, whereas in the case of early cessation of the rainy season, analysis of the observed data reveals a return to a better situation, which remains non-perceptible by the communities, due to the high intra- and inter-annual variability. The immediate impacts are loss of seedlings and crops and the development of crop pests. These impacts in turn lead to animal weakness and food insecurity. Although they develop adaptation strategies such as improved crop varieties and water conservation and soil protection/restoration techniques, communities seem to be overwhelmed by the phenomenon. In the short term, the proposed adaptation strategies to the risks identified by the communities will help to cope with the effects of variability and climate change on rainfed agriculture in the Sahel

Les conséquences géomorphologiques de l'occupation du sol et des changements climatiques dans un bassin-versant rural sahélien

International audienceDepuis 1994, le Kori Mountséka situé dans l'Adar Doutchi au centre-sud du Niger est redevenu fonctionnel sur 70 km. Avant cette date, les écoulements étaient pertur-bés par des verrous constitués de dépôts de sable éolien et de cônes de déjection. Il se formait ainsi des mares, particulièrement dans la partie amont, alors que, dans la partie médiane et aval, le lit servait comme champ de culture de mil. Les observations directes sur le terrain ont permis de mettre en évidence que ce bassin-versant est soumis à une dynamique hydroérosive intense liée à l'érodibilité des sols et à la faiblesse du couvert végétal. Le traitement des données pluviométriques relève l'importance des extrêmes pluvieux. Enfin, les cartes de répartition spatiale des pro-cessus d'érosion hydrique en relation avec l'occupation des sols en 1986 et en 2000 confirment cet état de fait. Abstract Geomorphological consequences of land use and climate change in a sahelian rural catchment basi

Response of Pearl Millet to nitrogen as affected by water deficit

In the Sahelian zone, low soil N could be as limiting as drought in pearl millet production. Although growth and crop productivity depend on several biochemical reactions in which the nitrogen metabolism plays a great role, there is little information available on how N uptake and key enzymes, nitrate reductase and glutamine synthetase, are affected by nitrogen and water interaction in millet. For this purpose, the millet variety cv. Souna III was grown in the field during the dry season under three levels of nitrogen fertilization (NO = 0.0, N1 = 17.13, and N2 = 68.50 kg N ha-1) and different water regimes (well-watered and water-stressed) in a split-plot experimental design. Irrigation was stopped for water-stressed plants during tillering, and the grain formation and filling phases, thereby giving rise to two water deficit cycles. A major quantity of mobilized N (79-100%) was taken up before flowering in all N treatments. Nitrogen uptake declined significantly only during the second water deficit cycle. During the first water deficit cycle, aboveground biomass was reduced and the maintenance of the N uptake resulted in increased N and nitrate concentrations. The water deficit reduced nitrate reductase activity jn all treatments and the effect was greater under high N. The increase in nitrate concentration under water deficit conditions showed that the reduction in nitrate reductase activity was probably not due to limiting nitrates. Glutamine synthetase activity was higher under the low N treatments, N1 and N0, showing the absence of a stimulating effect of glutamine synthetase activity by nitrate or ammonium. These results are discussed on the basis of their effect on grain N and grain yield.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Revue des outils de suivi agropétérologique et des méthodes utilisés dans le Sahel de l'Afrique de l'Ouest

Agrometeorological monitoring in the Sahelian countries consists of collecting, processing, and analyzing various data and information that can affect the outcome of the agricultural season. It combines observational data from national meteorological, hydrological, agricultural extension, plant protection, and livestock breeding offices, as well as satellite data provided by the AGRHYMET Center. From May until the end of October, multidisciplinary working groups (MWGs) in each country publish dekadal and monthly bulletins. At the regional level in the AGRHYMET Center, data and information coming from the national components are combined with satellite data to elaborate regional syntheses that are published at different time steps. In these publications, the current situation is analyzed and compared with that of the previous period, the previous year, and the average. Forecasts of seasonal rainfall and crop yields, that are refined from month to month, are also given. Color maps illustrates the amounts of rainfall, sowing dates, crop water requirements, satisfaction indices, yield estimates, zones with particular pests, and the advance of the vegetation front. Hard copies and electronic versions of these publications are mailed to subscribers. They are also posted on the Center’s website: www.agrhymet.ne