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1.
Genetically modified (GM) cassava is currently being developed to address problems of diseases that threaten the food security of farmers in developing countries. The technologies are aimed at smallholder farmers, in hopes of reducing the vulnerability of cassava production to these diseases. In this paper we examine barriers to farmers’ voice in the development of GM cassava. We also examine the role of a translational research process to enhance farmers’ voice, to understand the sources of vulnerability farmers in a group in Kenya’s Coast face, and to determine if their concerns are consistent with those of the scientists in agriculture addressing farmers’ needs. A two-way communication participatory process provided insights into the complex vulnerability context of farmers, their primary concerns with processing and markets of cassava in order to improve livelihoods, the lack of networks with two way communication flows, and the lack of information on GM technologies. The translational research engaged farmers and scientists in an iterative process where scientists are learning what farmers need, and farmers are learning about the potential benefits and risks from GM technologies, while at the same time expressing their concerns.  相似文献   
2.
Water infiltration is an important hydrological process that influences runoff and soil loss patterns in mountain ecosystems. In this paper, we present results on spatial variation in infiltration in croplands on the volcanic soils of Mt. Elgon, in Eastern Uganda. Twelve experimental sites with slope gradients ranging from 12 to 32% were established. Infiltration tests were carried out with a double ring infiltrometer and three measurements were taken at the upper, middle and lower sections of each experimental site to assess the local variability of infiltration. In addition soil information was collected on each experimental site. The soil infiltration data were then evaluated to fit to four commonly used water infiltration models: (1) Philip (1957), (2) Green–Ampt (1911), (3) Horton (1940) and (4) Kostiakov (1932). The twelve experimental sites cover two cropping systems: annual (6 sites) and perennial (6 sites) crops. Based on the results, we examine the spatial variability of infiltration, the relationship of infiltration to landscape position, and the influence of soil composition on infiltration rates on the slopes. The factors affecting spatial variability of soil infiltration were analysed using correlation and regression techniques. Steady state infiltration rates generally increased with the slope gradient and were crop type independent (P < 0.05). The performance of the four applied water infiltration models was generally good with mean R2 values ranging from 0.79 to 0.87, although all the models tended to over-predict the steady state infiltration rates at most sites. Overall, the Philip's and Kostiakov gave better results than the Horton and Green–Ampt models in reproducing the infiltration process on Mt. Elgon.  相似文献   
3.
Twenty-four Large White × Landrace crossbreed primigravid pigs, aged 7.50 to 8.00 months weighing between 86.15 and 88.24 kg were used to study the effects of feeding graded levels of soya bean meal (SBM) replaced blood meal (BM) diets on serum biochemical profile in gestating pigs. The pigs were randomly allotted to four finisher diets formulated such that BM replaced SBM at 0.0, 50.0, 75.0 and 100.0 %, respectively. The diets were T1 (100.0 % SBM, 0.0 % BM), T2 (50.0 % SBM, 50.0 % BM), T3 (25.0 % SBM, 75.0 % BM) and T4 (0.0 % SBM, 100.0 % BM). Individual animal’s daily ration of the test diets was 2.20, 2.00 and 2.50 kg at stages one, two and three of gestation. Blood sampling and analysis for the effects of the test diets on biochemical profile of the experimental animals were carried out prior to conception, at weeks 3, 7 and 11 of gestation, respectively. The result showed no significant (P?≥?0.05) dietary treatment effects on total protein, albumin, globulin fraction, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, creatinine and urea profile of the pigs fed with BM diets when compared to the control fed with 100.0 % SBM. There was however a significant (P?≤?0.05) variation in these biochemical indices in all the experimental groups at different stages of gestation. It was concluded that BM can replace 100.0 % of SBM in the diets of pregnant pigs in the tropical humid environment without any deleterious effect on their health.  相似文献   
4.
Rotation of nitrogen-fixing woody legumes with maize has been widely promoted to reduce the loss of soil organic matter and decline in soil biological fertility in maize cropping systems in Africa. The objective of this study was to determine the effect of maize-fallow rotations with pure stands, two-species legume mixtures and mixed vegetation fallows on the richness and abundance of soil macrofauna and mineral nitrogen (N) dynamics. Pure stands of sesbania (Sesbania sesban), pigeon pea (Cajanus cajan), tephrosia (Tephrosia vogelii), 1:1 mixtures of sesbania + pigeon pea and sesbania + tephrosia, and a mixed vegetation fallow were compared with a continuously cropped monoculture maize receiving the recommended fertilizer rate, which was used as the control. The legume mixtures did not differ from the respective pure stands in leaf, litter and recycled biomass, soil Ca, Mg and K. Sesbania + pigeon pea mixtures consistently increased richness in soil macrofauna, and abundance of earthworms and millipedes compared with the maize monoculture (control). The nitrate-N, ammonium-N and total mineral N concentration of the till layer soil (upper 20 cm) of pure stands and mixed-species legume plots were comparable with the control plots. Sesbania + pigeon pea mixtures also gave higher maize grain yield compared with the pure stands of legume species and mixed vegetation fallows. It is concluded that maize-legume rotations increase soil macrofaunal richness and abundance compared with continuously cropped maize, and that further research is needed to better understand the interaction effect of macrofauna and mixtures of organic resources from legumes on soil microbial communities and nutrient fluxes in such agro-ecosystems.  相似文献   
5.

The aim of this study was to reveal communal farmer’s knowledge, attitudes and practice on ticks and tick-borne diseases affecting cattle, tick control methods used and their knowledge on acaricide resistance. A total of 160 structured questionnaires are prepared and randomly administered to cattle farmers in Sinqu and Elundini communities in the Eastern Cape Province, South Africa. Associations between the area, gender, age, employment, source of income, level of education and farming experience were statistically tested using Chi-square test. Gall sickness (63%) was the most prevailing tick-borne disease in cattle during the summer season (61%). About 59% of the farmers had no knowledge of the effect of tick-borne diseases on cattle production, and 78% of respondents reported that ticks are the major challenge to cattle farming. Pour-on (61%) was the most commonly used acaricidal treatment system with every fortnight (40%) treatment frequency during the summer season and (31%) during the winter season. Pyrethroids (73%) were the most used acaricide compounds to control ticks, and about 65% of respondents perceived to have no knowledge of the use of ethnoveterinary medicines used to control ticks. Inefficacy of acaricide (44%) and undipped animals (42%) were regarded as the major contributing factors to the increased tick population and acaricide resistance. About 85% of respondents perceived that they do not practice acaricide rotation and 88% of the respondents had no knowledge of the acaricide resistance. Within the context of this study, ticks and tick-associated diseases are perceived by these farmers as the most important disease problem their cattle face. Thus, knowledge regarding the epidemiology of ticks and tick-borne diseases is key to control strategies, and farmer training should be encouraged to achieve better control of ticks and the diseases they transmit.

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6.
Examination of callus micro-grafts in Uapaca kirkiana Müell Arg. was carried out with the objective of determining early signs of graft compatibility. Leaves from U. kirkiana, U. nitida and Jatropha curcas trees were used for callus induction. Two pieces of callus were co-cultured on Murashige and Skoog (MS) medium with different supplements. Co-cultured calli were embedded in paraffin wax and dissected. The specimens were stained in safranin and fast green before viewing under a light microscope. Results showed that MS medium with 0.1 mg l−1 thidiazuron (TDZ) and 0.5 mg l−1 naphthaleneacetic acid (NAA) or 1.0 mg l−1 dichlorophenoxyacetic acid (2,4-D) and 0.5 mg l−1 NAA was effective for callus induction. There were no necrotic layers at the unions within U. kirkiana clones and provenances, but a differential growth (irregularity) between U. kirkiana and U. nitida co-cultured calli. Phenol deposits were observed at the union interfaces of U. kirkiana combinations and were high on calli derived from mature trees. Phenol deposits were absent at the union of J. curcas heterografts. Necrotic layers developed at the unions of U. kirkiana and J. curcas micro-grafts and indicating an outright graft incompatibility. Accumulation of phenol deposits at the union interfaces inhibited graft compatibility in many U. kirkiana combinations. Callus fusion technique can be used to identify partners with an outright graft incompatibility, especially for distant related plant species.  相似文献   
7.
The use of biochar (BC) has been suggested for remediation of contaminated soils. This study aims to investigate the role of microorganisms in sorption of PAH to BC-amended soils. Fungi, especially the wood and litter-degrading fungi, have shown the ability for humification and to degrade recalcitrant molecules, and are thus suitable model organisms. Haplic Arenosol with high organic matter content was chosen to highlight the importance of soil organic matter (SOM) in PAH sorption, possibly to form non-extractable residue. Basidiomycetous fungi Agrocybe praecox and Phanerochaete velutina grown on pine bark were inoculated in organic matter (OM)-rich Haplic Arenosol and OM-poor sandy loam with either BC or chemically activated BC (ABC) and 14C-labelled pyrene for 60 days. Fungi did not mineralize pyrene, but increased sorption up to 47–56% in BC-amended Haplic Arenosol in comparison with controls (13–25%) without a fungus irrespective of the presence of an adsorbent. In OM-poor sandy loam, only 9–12% of pyrene was sorbed to amended soil in the presence of fungus and adsorbent. The results suggest that BC and fungal amendment increased sorption of pyrene, especially to Haplic Arenosol more than by either BC or fungi alone.  相似文献   
8.
Fertilizer trees, the nitrogen-fixing legumes, such as gliricidia (Gliricidia sepium) and tephrosia (Tephrosia spp.) have been used to improve soil fertility for higher crop yields in nitrogen deficient soils. Many studies have focused on how these fertilizer trees improve maize yield, but there has been a dearth of information on the effect of fertilizer tree species on cotton growth and yield. A study was undertaken for two cropping seasons (2012/13 and 2013/14) with the objective of assessing IRM 81 cotton growth and yield responses to tephrosia and/or gliricidia biomass with or without inorganic fertilizer application. Boll opening significantly varied (P < 0.0001) with treatments and early boll opening was observed in plots where only inorganic fertilizer was applied. Higher lint yield (mean of 1397 kg/ha) was obtained in the second cropping season than in the first cropping season (480 kg/ha) and the application of gliricidia biomass with fertilizer gave the highest lint yield (2121 kg/ha). The lowest lint and seed yields were obtained from plots where tephrosia biomass only was applied. It is concluded that the use of gliricidia biomass with inorganic fertilizer improved cotton yields. The high amount of gliricidia biomass (due to prolific coppicing) applied contributed to higher cotton lint yields with reduced rates of inorganic fertilizer application, making gliricidia-cotton intercropping a cost-effective option to smallholder farmers.  相似文献   
9.
The production of paprika (Capsicum annum L.) under small-scale farm conditions in southern Africa is constrained by low soil fertility and lack of appropriate cultivars. The objective of this study was to determine the growth responses and fruit yields of six cultivars of paprika to organic and inorganic nutrient sources. The study was conducted in 2007 and 2008 at Chitedze Agricultural Research Station in Malawi. A combination of six paprika cultivars and four nutrient sources, namely (1) organic input from Gliricidia, (Gliricidia sepium) biomass, (2) inorganic fertilizer, (3) integrated nutrient input (Gliricidia biomass + inorganic fertilizer), and (4) control (no nutrient input) were compared. Each combination was replicated five times. A split-plot design was used where nutrient sources formed the main plot and cultivars the sub-plots. Plant height differed due to nutrient source in 2007 and 2008, while differences due to cultivar were minor. The control plots produced the shortest plants (height < 50 cm), while plots receiving the integrated nutrient input produced the tallest plants (height > 60 cm). Numbers of branches and fruits per plant differed due to nutrient source and cultivar during most of the study period. Plants receiving either organic inputs (Gliricidia biomass) alone or the integrated nutrient input alone had significantly higher stem, leaf and fruit weight compared with the control. Average fruit yield was lower in control plots than in plots receiving the organic input alone or the integrated nutrient input. Among cultivars, Papri-King, Papri-Supreme and Papri-Queen produced higher dry fruit yield. The ASTA and RAL colour rating was within the internationally accepted range for fruit from the treatments.  相似文献   
10.
Agroforestry Tree Seed Production and Supply Systems in Malawi   总被引:1,自引:1,他引:0  
A sustainable agroforestry tree germplasm supply system is vital to resource-constrained smallholder farmers who depend on agroforestry to improve the productivity of their farm enterprises. Successful adoption of agroforestry hinges on the development of a sustainable agroforestry tree germplasm supply system. This paper reviews the agroforestry tree seed supply system in Malawi, with a view to determining its sustainability and quality. Currently, more than 90% of the documented agroforestry tree seed distributed to farmers is produced by smallholder farmers collected mainly from scattered farmland trees, the remainder being produced from seed orchards and seed stands owned or controlled by research organizations. Three organizations—namely the Land Resources Centre (LRC), National Tree Seed Centre (NTSC) of the Forestry Research Institute of Malawi (FRIM) and the World Agroforestry Centre (ICRAF)—were identified as major procurers of agroforestry tree seed produced by smallholder farmers. Agroforestry germplasm is distributed to farmers by non-governmental organizations (NGOs) and government agricultural and forestry extension departments. The procurement and distribution of germplasm to farmers is in general effective. The major challenge to sustainability of agroforestry tree germplasm distribution in Malawi is dependence on donor funding. The agroforestry tree seed system is, to some extent, sustainable with regards to production, although the genetic quality of the germplasm is low. Germplasm storage facilities at national level are available and possibly adequate, but knowledge and information on effective low-cost tree germplasm storage systems at household level are limited. Sustainability could be enhanced by strengthening of grass-root organizations involved in tree seed production to institutionalize the distribution through farmer–farmer exchange. There is also a need to support the development, promotion and adoption of low-cost tree germplasm storage facilities by smallholder farmers.  相似文献   
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