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Factors Affecting Aflatoxin Contamination of Harvested Maize in the Three Agroecological Zones of Uganda  [PDF]
A.N. Kaaya,W. Kyamuhangire,S. Kyamanywa
Journal of Applied Sciences , 2006,
Abstract: A survey was conducted in 2003 to establish aflatoxin levels in maize and the associated farmer practices in the three agroecological zones of Uganda. Maize kernels obtained from farmers in the Mid-Altitude (moist) zone had the highest aflatoxin contaminated samples (83%) and mean aflatoxin levels of 9.7 ppb followed by those from the Mid-Altitude (dry) where 70% were contaminated with a mean of 7.7 ppb, while the kernels sampled from the Highland zone had the least contaminated samples (55%) and mean aflatoxin levels of 3.9 ppb. Aflatoxin contamination in maize grain was positively related to leaving maize to dry in the field for more than three weeks, drying maize without husks, drying maize on bare ground, shelling maize by beating, heaping maize on the floor during storage and use of baskets for storage of maize. The practices that negatively impacted on aflatoxin development in maize in the agroecological zones were sorting before storage, storage of maize in shelled form, storage of maize in bags, use of improved granary as storage structures, storage of maize above fireplace and use of synthetic pesticides. Thus, those practices that reduce aflatoxin contamination of maize should be adopted by all farmers in Uganda to reduce the health hazards associated with consumption of contaminated maize grain.
Trait Association and Path Analysis for Cassava Genotypes in Four Agroecological Zones of Nigeria
O.O. Aina,A.G.O. Dixon,E.A. Akinrinde
Journal of Biological Sciences , 2007,
Abstract: The associations among different traits and their direct and indirect influence on yield using the path analysis and correlation procedures were examined in 20 broad-based cassava genotypes to understand how inter-character relationships influences root yield. Field evaluation was carried out in 4 agroecological zones of Nigeria for two cropping seasons. Data were collected on morphological and yield parameters such as plant height, stem girth, canopy volume, shoot weight, leaf size, number of roots, root size and root yield. Results showed that root parameters such as medium-sized roots with correlation coefficient (r) of 0.95, number of roots (r = 0.91) and small-sized roots (r = 0.77) were highly significantly (p< 0.001) correlated) with root yield. Path analysis revealed that number of roots had the largest direct effect on root yield with a direct path coefficient effect (P) of 0.61, accounting for 86% of the total direct + indirect effects, followed by number of medium-sized roots (p = 0.23), that accounted for 79.2% of the total direct + indirect effects. Small-sized roots had a negative direct effect on root yield (p = -1.21) but a positive indirect effect (p = 1.91) via number of roots. Number of storage roots and medium-sized roots both contributed the largest influence on storage root yield in cassava. These parameters should, therefore, be considered together while selecting for cassava genotypes with higher storage root yield potentials.
Genetic Diversity of Parkia biglobosa from Different Agroecological Zones of Nigeria Using RAPD Markers  [PDF]
Oluwafemi Amusa,Adenubi Adesoye,Adebayo Ogunkanmi,Ojobo Omoche,Olumayowa Olowe,Solomon Akinyosoye,Taiwo Omodele
International Journal of Biodiversity , 2014, DOI: 10.1155/2014/457309
Abstract: Parkia biglobosa (Jacq.) is an important leguminous tree crop in the African Savannahs useful to the natives where it is found, for domestic use. Previous diversity studies on this tree crop had been majorly on morphological and biochemical analysis. In order to capture the maximum diversity not obtained by previous research, the study aimed at evaluating the genetic diversity of accessions of this crop in the different agroecological zones in Nigeria using RAPD markers. A total of 81 scorable bands with an average of 8.1 bands per primer were amplified among the accessions studied. Intrazonal genetic diversity analysis showed a percentage polymorphism with a range of 11.11% to 65.43% among the agroecological zones studied. Although, gene diversity was highest within Humid forest agroecological zone, a low genetic distance and high genetic similarity between the agroecological zones were observed. Cluster analysis indicated six main groups of which four groups had single accessions while the two groups clustered the remaining accessions, indicating a narrowed genetic base from the 23 accessions studied. 1. Introduction The African locust bean plant (Parkia biglobosa) is a perennial tree legume belonging to the subfamily Mimosoideae of the family Fabaceae. It is one of the thirty-four known species of the genus Parkia whose centre of origin is South America. Distributed in a belt between latitudes 5°N and 15°N, and longitudes 16°W and 32°W, from the Atlantic coast in Senegal to Southern Sudan and Northern Uganda in the African continent, it has its greatest belt (about 800?Km) in West Africa and narrows to the east [1, 2]. Aside from its ecological role in cycling of nutrients [3, 4], it is a valuable source of food especially the seeds which serves as a source of useful spices for cooking [1, 5, 6]. Kwon-Ndung et al. [7] reported that it is a very important tree crop in the Africa Savannas where the natives use it as medicine, glaze for ceramic pots, fodder, firewood, and charcoal production. Parkia tree is also used as timber for making pestles, mortars, bows, hoe handles, and seats [8, 9] while the husks and pods are good food for livestock [10]. Previously, studies on diversity within this species focused on accessions from West African countries like Burkina Faso, Benin, and Uganda with only three accessions collected from the Southern Guinea Savanna in Nigeria [11–13]. These studies dealt majorly with phenotypic and anatomical diversity within species of the plant. P. biglobosa is however known to occur in diverse agroecological zones in Nigeria
Assessment of Aflatoxin Contamination of Maize, Peanut Meal and Poultry Feed Mixtures from Different Agroecological Zones in Cameroon  [PDF]
Jean Rapha?l Kana,Benoit Gbemenou Joselin Gnonlonfin,Jagger Harvey,James Wainaina,Immaculate Wanjuki,Robert A. Skilton,Alexis Teguia
Toxins , 2013, DOI: 10.3390/toxins5050884
Abstract: Mycotoxins affect poultry production by being present in the feed and directly causing a negative impact on bird performance. Carry-over rates of mycotoxins in animal products are, in general, small (except for aflatoxins in milk and eggs) therefore representing a small source of mycotoxins for humans. Mycotoxins present directly in human food represent a much higher risk. The contamination of poultry feed by aflatoxins was determined as a first assessment of this risk in Cameroon. A total of 201 samples of maize, peanut meal, broiler and layer feeds were collected directly at poultry farms, poultry production sites and poultry feed dealers in three agroecological zones (AEZs) of Cameroon and analyzed for moisture content and aflatoxin levels. The results indicate that the mean of the moisture content of maize (14.1%) was significantly ( P < 0.05) higher than all other commodities (10.0%–12.7%). Approximately 9% of maize samples were positive for aflatoxin, with concentrations overall ranging from <2 to 42 μg/kg. Most of the samples of peanut meal (100%), broiler (93.3%) and layer feeds (83.0%) were positive with concentrations of positive samples ranging from 39 to 950 μg/kg for peanut meal, 2 to 52 μg/kg for broiler feed and 2 to 23 μg/kg for layer feed. The aflatoxin content of layer feed did not vary by AEZ, while the highest (16.8 μg/kg) and the lowest (8.2 μg/kg) aflatoxin content of broiler feed were respectively recorded in Western High Plateau and in Rainforest agroecological zones. These results suggest that peanut meal is likely to be a high risk feed, and further investigation is needed to guide promotion of safe feeds for poultry in Cameroon.
Distribui o dos agregados e carbono organico influenciados por manejos agroecológicos = Aggregate and organic carbon distribution influenced by agroecological handling
Arcangelo Loss,Marcos Gervasio Pereira,Nivaldo Schultz,Edilene Pereira Ferreira
Acta Scientiarum : Agronomy , 2009,
Abstract: O objetivo deste estudo foi verificar a influência do manejo agroecológico na distribui o dos agregados estáveis em água e no teor de carbono organico dos agregados em diferentes coberturas vegetais. Foram selecionadas cinco áreas, a saber: sistema agroflorestal; cultivo de figo (Ficus carica L.); consórcio maracujá (Passiflora edulis S.)–Desmodium sp.; cultivo de feij o (Phaseolus vulgaris L.), em manejo convencional, e cultivo de milho (Zeamays L.), em plantio direto. Em cada área, foram coletadas amostras de terra indeformadas, nas profundidades de 0 - 5 e 5 - 10 cm, e avaliada a estabilidade dos agregados e o teor de carbono organico nos agregados (COAGR). A maior massa de agregados encontra-se naclasse de 2,00 mm, em ambas as profundidades, com exce o do cultivo de feij o. Nas duas profundidades, a classe de 2,00 mm apresentou os maiores valores de COAGR para a área do consórcio macaracujá - Desmodium sp. The objective of this study was to verify the influence ofagroecological handling in the distribution of stable aggregates in water and in the levels of aggregate organic carbon under different vegetable covers. Five areas were selected: agroflorestal system; fig cultivation (Ficus carica L.); passion fruit (Passiflora edulis S.) and Desmodium sp. consortium; bean cultivation (Phaseolus vulgaris L), under conventional system; and corn (Zea mays), in no-tillage system. In each area, undisturbed samples were collected, in 0-5 and 5-10 cm depths, and water aggregate distribution and organic carbon ofaggregate (OCAGR) were quantified. The highest aggregate mass was observed in the 2.00 mm aggregate class, in both depths, except for the bean cultivation area. In both depths, the class with greater diameter showed the highest OCAGR values for the area of passion fruit– Desmodium sp. consortium.
Population Levels of Indigenous Bradyrhizobia Nodulating Promiscuous Soybean in two Kenyan Soils of the Semi-arid and Semi-humid Agroecological Zones  [PDF]
John M. Maingi,Nkanata M. Gitonga,Chris A. Shisanya,Berthold Hornetz
Journal of Agriculture and Rural Development in the Tropics and Subtropics , 2006,
Abstract: Soybeans grown in Africa have been selected to nodulate effectively with indigenous Bradyrhizobium spp. populations since Bradyrhizobium japonicum populations are considered absent or in very low numbers in African soils. The major objective of this study was to estimate total population of Bradyrhizobia specific to soybean in two agro-ecologically different study sites, Kiboko in Makueni District, Southeast Kenya (semi-arid to arid conditions) and Kaguru in Meru District, East Kenya (semi-humid climate) . The population of the indigenous rhizobia specific to soybeans was determined using the Most Probable Number (MPN) plant infection technique. In these experiments, the total Bradyrhizobia populations, the population sizes of taxonomically defined slow-growing Bradyrhizobia specific to soybean and the population sizes of Bradyrhizobia spp. specific to tropical Glycine Cross (TGx) varieties were determined for the two study sites. Cowpea, Vigna unguiculata, cultivar Ken Kunde I was used to estimate the total Bradyrhizobia spp. population. Clark soybean, Glycine max, was used to estimate the population sizes of taxonomically defined slow-growing Bradyrhizobia spp. specific to soybean while a TGx genotype, SB12-TGx1869-31E was used to determine the population sizes of Bradyrhizobia spp. specific to TGx varieties. The results of the MPN counts indicated that the total Bradyrhizobia population in Kiboko was between 2.59x104 and 1.89x105. The population size of taxonomically defined slowgrowing Bradyrhizobia in Kiboko was between 2.59x102 and 1.89x103 cells per gram of soil sample while the approximate Bradyrhizobia population specific to TGx genotype was between 7.81x102 and 5.67x103 cells per gram of soil. In Kaguru, the approximate total Bradyrhizobia population was between 1.04x102 and 7.56x103 cells per gram of soil. The population size of taxonomically defined slow-growing Bradyrhizobia was between 1.33x102 and 9.72x102 cells per gram of soil while the approximate Bradyrhizobia population specific toTGx genotype was between 2.37x102 and 1.73x103 per gram of soil. These populations were adequate to give satisfactory results on nodulation and nitrogen fixation in the two study sites.
Connectance of Brazilian social bee: food plant networks is influenced by habitat, but not by latitude, altitude or network size
Biesmeijer, Jacobus C.;Slaa, E. Judith;Castro, Marina Siqueira de;Viana, Blandina Felipe;Kleinert, Astrid de M. P.;Imperatriz-Fonseca, Vera L.;
Biota Neotropica , 2005, DOI: 10.1590/S1676-06032005000100010
Abstract: several recent studies suggest that the level of generalization (measured as percentage connectance) of plant-pollinator networks has several ecological correlates, e.g. latitude and altitude. here we report on levels of generalization in 27 two-mode networks of social bees and their food plants in various brazilian habitats and urban environments. social bees are generalist foragers and are among the most abundant flower visitors in brazil. they probably account for 30-50% of all plant - flower visitor interactions. connectance was significantly influenced by habitat. cerrado forests showed lower connectance than the dry dune habitats, with atlantic rain forest and urban sites taking intermediate position and arid caatinga being similar to dunes. this shows that generalization in a plant - flower visitor community can be influenced by habitat even within a group of generalist flower visitors, in our case social bees. we show that the strength of the interactions is not different between cerrado and semi-arid habitats (dunes and caatinga) and discuss other explanations for our findings.
Evaluation des critères physiques des fèves de caféier Robusta (Coffea canephora P.) introduit dans les zones de basse altitude au Cameroun
Fallo, J.,Ngongang Nono, JC.
Tropicultura , 2005,
Abstract: Evaluation of Physical Criteria of Introduced Coffee Robusta (Coffea canephora P.) Beans in Low Altitude of Cameroon. A study based on physical criteria of Robusta coffee beans (Coffea canephora P.) was performed in two agro-ecological areas of IRAD (Institute of Agricultural Research for Development), at Nkolbisson in the centre and Barombi-Kang in the south west Cameroon. Eight clones (B5, B11 and B42 from the Republic of Central Africa, C5 and C6 from Ivory Coast, J13 and J21 from Java, M5 from Madagascar) were the study material. Harvested cherries were evaluated for the rate of caracolis, bean size distribution and weight of one hundred beans. Mean weights of hundred beans are between 19.14 and 10.99 grams. The rate of caracolis at Barombi-Kang is 23.5% for the clone C5 and 10.6% for M5. The rates of the others are minor than 5%. At Nkolbisson, four clones have their rate of caracolis between 35 and 60% (C5, J13, J21 and M5). The results showed a highly significant difference (P< 0.01) among clones for bean size distribution and rate of caracolis. Only one group was found homogenous according to Newman-Keuls test, despite significant difference observed for caracolis rate. The results showed also that globally observed parameters depend nor to location, nor to clone.
Cas pratique : Utilisation du système d'information géographique comme outil de gestion de zones humides d'altitude : le cas du domaine skiable de Val Thorens
Stéphanie Gaucherand et Francis Isselin-Nondedeu
Sciences Eaux & Territoires : la Revue du IRSTEA , 2011,
Abstract: Dans quelle mesure l’utilisation d’un système d’information géographique peut-elle aider à la gestion des zones humides de montagne ? Quel est l’intérêt d’un outil de cartographie dans la définition des mesures de gestion et de restauration ? Premiers éléments de réponse et perspectives d’utilisation pour les gestionnaires des zones humides d’altitude du domaine skiable de Val Thorens.
Effect of nitrogen and phosphorous on Farm Plantations in various agroecological zones of Punjab, Pakistan
SMA Rahim, S Hasnain, J Farkhanda
African Journal of Environmental Science and Technology , 2011,
Abstract: Against a world average of 25% area under forests, Pakistan has around 5% and Punjab has only 2% area under manageable and productive forests. The present deteriorating condition of the forests in Punjab has bleak prospects of improvement and expansion in near future due to ever increasing demand for agriculture produce. In view of the present situation the best possible solution seems to be offered by Farm forestry/agroforestry that models planting trees and agricultural crops together, which unfortunately, has not been utilized to its full potential. Based on physiographic, climate and ecology, Pakistan is divided into nine major ecological or vegetative zones, which are further sub-divided into 18 habitat types – an arrangement for the development of protected areas system in terms of representative ecotypes. During the survey of farm plantations about 400 soil samples were collected and their physical and chemical analysis was conducted for the comparison of the four Agro ecological zones of the Punjab Province of Pakistan with regards to agroforestry. A comparison of the characteristics of soils taken from various farm plantations necessitated a prior evaluation of nitrogen and phosphorous as well as their composition in order to ascertain whether the soils were texturally similar or not. In case of Agroforestry, the type of soil is one of the major factors for the classification of different suitable species of plants. The results of the soil analysis of various Agro ecological zones and the consequent recommendation of the associated suitable species, aids the agrofarmers to pick out the best possible option.
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