Architecture racinaire et aptitude au drageonnage de trois espèces forestières

Les systèmes racinaires de Balanites aegyptiaca (L.) Del., Sclerocarya birrea (A. Rich.) Hochst. et Diospyros mespiliformis Hochst. ex A. Rich. ont été caractérisés par une analyse détaillée de leur architecture dans des sols de texture différente en Région Centre-Sud du Burkina Faso. Ils ont été étudiés à partir de plants d’âges divers, certains prélevés en pépinière et d’autres partiellement excavés en forêt. Des tests d’induction de drageonnage par sectionnement complet de racines traçantes ont également été effectués sur ces espèces. Les données obtenues indiquent que ces trois espèces semblent montrer une certaine plasticité en fonction des textures de sols et de leur âge. B. aegyptiaca et S. birrea exhibent une tubérisation très nette de leur pivotante dans le jeune âge. En forêt, des drageons ont été observés sur les racines de B. aegyptiaca et D.  mespiliformis. L’induction artificielle de drageons en août, presqu’en fin de la saison des pluies, a donné des résultats positifs surtout pour S. birrea et dans une moindre mesure pour D. mespiliformis, mais pas pour B.  aegyptiaca.Mots clés : Système racinaire, multiplication végétative, Burkina Faso

Efficient cloud tracing: From very high level to very low level

With the increase of cloud infrastructure complexity, the origin of service deterioration is difficult to detect because issues may occur at the different layer of the system. We propose a multi-layer tracing approach to gather all the relevant information needed for a full workflow analysis. The idea is to collect trace events from all the cloud nodes to follow users' requests from the cloud interface to their execution on the hardware. Our approach involves tracing OpenStack's interfaces, the virtualization layer, and the host kernel space to perform analysis and show abnormal tasks and the main causes of latency or failures in the system. Experimental results about virtual machines live migration confirm that we are able to analyse services efficiency by locating platforms' weakest links

Effects of phosphorus on yield of cowpea cultivars intercropped with pearl millet on Psammentic paleustalf in Niger

Phosphorus (P) is the most limiting soil nutrient in the sandy soils of Niger and farmers rarely use chemical fertilizers in producing pearl millet and cowpea. A 3-yr study was conducted in farmer's fields at two locations in South Western Niger to investigate yield response of six cowpea cultivars to applied P-fertilizer (0, 8, 16 kg ha(-1)) when intercropped with millet. Significant yield differences were found between cultivars for their seed and dry fodder yield at all rates of applied P. Cultivars responded differently to the application of P. Millet grain was more than doubled with the addition of 8 to 16 kg P ha(-1). Cowpea cultivars did not have significant differential effect on millet yields. Cowpea cultivars differed significantly in the accumulation of P in fodder with the highest yielding cultivars taking up more P than the low yielding ones. The results have important implications for breeding and selection of cowpea cultivars that are adapted to a range of fertility levels

Rotation and nitrogen fertilizer effects on pearl millet, cowpea and groundnut yield and soil chemical properties in a sandy soil in the semi-arid tropics, West Africa

A 5-year study was conducted from 1988 to 1992 at three sites in Niger to determine the effects of crop rotation of a cereal and legumes and nitrogen fertilizer on chemical properties of the soil (0-20 cm) and yield of pearl millet (Pennisetum glaucum), cowpea (Vigna unguiculata), and groundnut (Arachis hypogaea). Four N levels (0-45 kg N/ha) and rotation treatments including continuous fallow were investigated. Soil samples taken from the top 20 cm depth at the end of the experiment from treatments without nitrogen application which included continuous fallow, fallow-millet rotation, groundnut-millet rotation, cowpea-millet rotation, and continuous millet were analysed for soil pH, organic carbon, total nitrogen and exchangeable bases. Fertilizer N significantly increased yield of pearl millet, cowpea and groundnut. Continuous monocropping of pearl millet resulted in lower yields across N levels compared to legume-millet rotations. Legume yields were also consistently lower in monoculture than when rotated with millet. There was a decline in organic matter under continuous millet, cowpea-millet rotation and groundnut-millet rotation. The fallow-millet rotation supplied more mineral N than the legume-millet rotations. Nitrogen availability was greater in cowpea-millet rotation than continuous millet. Crop rotation was more productive than the continuous monoculture but did not differ in maintaining soil organic matter. The legume-millet rotation at 30 kg/ha N appears to be the most viable for millet production. Research should focus on understanding the effect of legume/cereal intercrops and rotations on soil productivity

Physiological determinants of cowpea seed yield as affected by phosphorus fertilizer and sowing dates in intercrop with millet

The interaction of cowpea (Vigna unguiculata (L.) Walp.) cultivars with management factors and environments was analyzed in terms of parameters of a simple physiological model. In one set of experiments seven cultivars were sown at three rates of phosphorus (P) fertilizer (0, 8 and 16 kg P ha−1). In another set, five cultivars were sown on two dates relative to sowing of millet (Pennisetum glaucum (L.) R.Br.). All experiments involved factorial combinations of management and cultivar treatments, and were conducted in 1988 and 1989 at two sites in western Niger. Seed yield, shoot dry matter, vegetative (Dv) and reproductive (Dr) durations were determined and crop growth rate (C) and partitioning (p) to seed estimated Application of P increased seed yield by increasing C. As sowing was delayed from 1 to 3 weeks after the millet was sown, there was a reduction in seed yield due to decreases in C, Dv and Dr. Variation in cultivar performance across years was mainly a function of C and partitioning. In both experiments the C of the landrace Sadore Local was greater than that of other cultivars, although the partitioning to seed of this cultivar was unstable due to variable control of insect pest damage It is concluded that the primary causes of G × E interactions were differential canopy development and insect damage effects. Therefore in the development of cowpea cultivars for intercropping with millet, emphasis should focus on light capture capabilities. Improved yields would then seem possible with most cultivars, providing insect damage is controlled

Soil fertility management and cowpea production in the semiarid tropics

Cowpea (Vigna unguiculata [L.] Walp.) is an important grain legume in the semiarid zone of West Africa as it is a major source of dietary protein for the people. It is usually grown as an intercrop with the major cereals, namely millet and sorghum. Despite its importance, its yields are very low due to several constraints including poor soil, insect pests, and drought. The soils in semiarid West Africa are inherently low in nitrogen and phosphorus. Soil, water, and nutrient management practices are inadequate to sustain food production and to meet the food requirements of the fast growing population. Research results show that proper management of organic amendments such as crop residues and manure, which are essential complements to mineral phosphorus fertilizers, can increase yields of cowpea and associated cereals more than three fold. Direct application of indigenous phosphate rocks can be an economical alternative to the use of imported, more expensive soluble phosphorus fertilizers for cowpea production in the region. The agronomic effectiveness of indigenous phosphate rock is about 50% compared to the imported single superphosphate. Furthermore, when the unreactive phosphate rocks are partially acidulated at 50%, their agronomic effectiveness can increase to more than 70%. Studies on cereal–cowpea rotation revealed that yields of cereals succeeding cowpea could, in some cases, double compared to continuous cereal cultivation. With effi cient soil fertility management, cowpea can fi x up to 88 kg N/ha and this results in an increase of nitrogen use effi ciency on the succeeding cereal crop from 20% in the continuous cereal monoculture to 28% when cereals are in rotation with cowpea. Furthermore, the use of soil nitrogen increased from 39 kg N/ha in the continuous cereal monoculture to 62 kg N/ha in the rotation systems. Future research needs to focus on understanding the factors affecting phosphorus uptake from different sources of natural rock phosphate. There is also a need to quantify the below-ground nitrogen fi xed by different cowpea cultivars. The increase of cowpea productivity in the cropping systems in this region will improve the nutrition of people, increase the feed quantity and quality for livestock, and contribute to soil fertility maintenance. This should contribute to reduction in poverty and environmental degradation

Improving soil fertility through the use of organic and inorganic plant nutrient and crop rotation in Niger

Food production can be increased through the integration of organic and inorganic nutrient sources coupled with proper land management. Niger is one of the poorest countries in the Sahelian zone of West Africa where soil fertility and rainfall are the most limiting factors for crop production. The majority of the people in this region depend on subsistence agriculture for their livelihood. The population pressure has decreased the availability of arable land and the use of extended fallow periods to restore soil fertility is not possible. Research results have shown that yields can be increased up to five times with the improvement of soil fertility using a combination of soil tillage, organic and inorganic fertilizers than under traditional practice. Crop yields have also been shown to increase substantially using rotation of cereals with legume or intercropping. Yields of pearl millet can be doubled following cowpea as compared to continuous pearl millet cultivation. These combinations can improve soil properties such as Organic carbon content, Cation Exchange Capacity (CEC) and pH..

Performance evaluation of various agroforestry species used in short duration improved fallows to enhance soil fertility and sorghum yields in Mali

The general soil fertility and crop yield decline constraints have guided the Malian agricultural research institute (Institut d’ Economie Rurale, IER), the Sahel Program of the World Agroforestry Centre (ICRAF) and the International Crops Research Institute for the Semi Arid Tropics (ICRISAT) to join efforts and undertake research activities aimed at mitigating the constraints in Mali. Thus, from the year 2000, 14 different trees and shrubs are being tested in improved fallow systems to find which ones perform best to replenish soils and improve crop yields. The results have (i) identified most suited species for 1 or 2 yr improved fallows, (ii) determined their impact on sorghum grain yields and (iii) documented the remnant effects of their impact on soil fertility and crop yields..

Improving cereal productivity and farmers’ income using a strategic application of fertilizers in West Africa

In the past two years, ICRISAT, in collaboration with other International Agricultural Research Centres, National Agricultural Research and Extension Systems, has been evaluating and promoting point or hill application of fertilizer along with “Warrantage” in three West African countries, namely, Burkina Faso, Mali and Niger. The hill application of fertilizers consists of applying small doses of fertilizer in the planting hills of millet and sorghum. The combination of strategic hill application of fertilizer with complementary institutional and market linkages, through an inventory credit system (known as “Warrantage”) offers a good opportunity to improve crop productivity and farmers’ incomes. Results from the two year on-farm trials showed that, on average, in all the three countries, grain yields of millet and sorghum were greater by 44 to 120% while incomes of farmers increased by 52 to 134% when using hill application of fertilizer than with the earlier recommended fertilizer broadcasting methods and farmers’ practice. Substantial net profits were obtained by farmers using “Warrantage”. Farmers’ access to credit and inputs was improved substantially through the “Warrantage” system. The technology has reached up to 12650 farm households in the three countries and efforts are in progress to further scale-up and out the technology to wider geographical area