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Abstract Agroecosystems in the tropics include growing two or more crops in diverse polycultural patterns. In Kenya, cowpea Vigna unguiculata (Walp.) is grown in combination with cereals such as maize and sorghum, perennial legumes such as pigeon peas and root crops such as cassava and sweet potatoes. In the present investigations, field experiments were conducted to study the incidence and damage caused by Clavigralla tomentoscollis Germ, and C. shadabi after flowering, on cowpea intercropped with maize. It was evident from the present studies that C. tomentoscollis and C. shadabi were more prevalent on cowpea during the first season rather than during the second season. Both species had a preference for feeding on cowpea intercropped with maize than when it was grown in pure stands. Consequently more pod damage was recorded on cowpea planted with maize. It was therefore concluded that this agricultural system, which is commonly practised by small‐scale farmers in Kenya, is undesirable from the point of view of bug damage. 相似文献
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An in-vitro growth system for investigating the behaviour of S. gesnerioides on cowpea has been developed. The roots of young cowpea plants were spread over glass fibre filter paper in a shallow plastic tray, and a known number of germinated Striga seeds were placed on the cowpea root surface. This allowed the infection process of the parasite to be quantified. Good access to the host-parasite association enabled the entire infection process to be easily monitored and tissue removed for cytological studies. Observations revealed for the first time that contact of S. gesnerioides radicles with host roots stimulated the development of radicular hairs and swelling of the tip of these radicles. Furthermore, penetration of cowpea roots by Striga was shown to be localized and to cause very little damage to the host roots. Swollen parasite tubercles developed on the surface of the roots only after the host stele had been penetrated by invading Striga cells. This growth system is suitable for in-vestigating the mechanisms of host resistance. and also for rapidly screening cowpea germplasm for new sources of resistance to the Parasite. Resistant cowpea cultivars offer the best potential solution for control of this Parasite. 相似文献
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Abstract A method was devised for estimating large populations of cowpea aphid Aphis craccivora Koch (Hemiptera: Aphididae) on cowpea. The densities of the aphid on stem, leaves and pod were first estimated in the laboratory for use in the field later. The densities were estimated in three arbitrary classes of infestation, viz. heavy, medium and low, determined visually based on the intensity of colonization. The densities of the aphid per cm2 on stems were 108.50, 49.77 and 2503, while on pods they were 80.68, 44.46 and 23.20, in the three classes of infestation respectively. The aphid did not show any preference for the thickness of stems whereas young pods were preferred to old pods for colonization. The mean aphid densities on leaflets of topmost leaves were 62.10, 36–35 and 18–50, while on leaflets of top 2nd and 3rd leaves they were 124–60, 69–35 and 38.20, in the three infestation classes respectively. Comparisons made between the aphid densities on different parts of cowpea plant showed that the aphid colonized them in descending order of preference as stem > pod > top most leaf > top 2nd and 3rd leaves. 相似文献
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Simulation study of the competitive ability of erect, semi-erect and prostrate cowpea (Vigna unguiculata) genotypes 总被引：1，自引：1，他引：1
Ecophysiological simulation models provide a quantitative method to predict the effects of management practices, plant characteristics and environmental factors on crop and weed growth and competition. The INTERCOM interplant competition model was parameterised, calibrated by monoculture data for three cowpea (Vigna unguiculata) genotypes that differed in growth habit, common sunflower (Helianthus annuus) and common purslane (Portulaca oleracea), and used to simulate competition of cowpea cover crops with sunflower or purslane. The simulation results were compared with observations from field competition experiments in 2003 and 2004. INTERCOM more accurately simulated actual field data for the competition of cowpea genotypes and sunflower than companion field experiments for the competition of cowpea and purslane. The validated simulation model of cowpea and sunflower at two densities was used to study the effects of cowpea growth habit on final biomass production of cowpea and sunflower. The model suggested that erect growth habit was more competitive than semi‐erect and prostrate growth habit, when cowpea genotypes were grown with sunflower. Cowpea leaf area distribution was important to higher cowpea biomass production, while cowpea height growth was important to reduce sunflower biomass. Our simulation approach is suggested as a method for crop breeders to gauge the likely success of selection for competitive crops before undertaking expensive long‐term breeding experiments. 相似文献
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Abstract The efficacy of two application rates of powdered fruits of four types of peppers (Capsicum spp.) was evaluated for the control of Callosobruchus maculatus (F). The various pepper powders at 2.5 g‐5.0 g per 250 g of seed were effective in reducing oviposition and damage to cowpea seeds. The pepper type Capsicum frutescens var. yarmunchi was the most effective in discouraging oviposition and minimizing damage to the seed, as indicated by the significantly lower number of emergence holes. The seed quality and viability were not affected by the powdered pepper fruit treatment. The result is indicative of the potential for the use of powdered fruits of some peppertypes in protecting stored cowpea seeds against C. maculatus. 相似文献
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The present study was carried out to assess the field efficacy of 10 isolates of entomofungal pathogens on management of cowpea aphid, Aphis craccivora. All the tested isolates showed suppressive effect on aphid population. Two-year pooled data revealed lower incidence of 19.37–40.81 aphids/plant in the entomofungal pathogen treated plots compared to higher incidence of 88.07 aphids/plant in untreated control. Among the 10 isolates tested, Vl-8 isolate of Lecanicillium lecanii, Ma-6 isolate of Metarhizium anisopliae and Bb-5a isolate of Beauveria bassiana showed 78.01%, 77.42% and 76.91% reduction of aphid population, respectively, over control and were on par with each other. Significantly higher yields were recorded in the plots treated with Bb-5a, Ma-6 and Vl-8 isolates (1252, 1225 and 1208 kg/ha, respectively) compared to untreated control (916 kg/ha). The predatory coccinellid populations of Cheilomenes sexmaculata and Micromus timidus in entomofungal treated and untreated control plots were almost similar and found statistically non-significant, indicating the safety of fungal pathogens to these coccinellid predators. 相似文献
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Summary Although the angiospermous parasitic weed Alectra vogelii is a major biotic constraint to cowpea production in Africa, there is little information on the host:parasite association between them. Accordingly, the dry matter production and partitioning in a cowpea: A. vogelii association was studied over the growth cycle. Cowpea was grown in pots containing 1350, 2700 or 4000 A. vogelii seeds kg−1 top soil and with uninfected controls. Alectra vogelii attachment on to cowpea roots was first detected 30 d after crop emergence, and the first shoots emerged 44 d after crop emergence. New A. vogelii attachments on to cowpea roots continued to be produced throughout the growth of the crop. Alectra vogelii infection did not decrease cowpea dry matter production, but it significantly altered dry matter partitioning by increasing the proportion of root dry matter. Alectra vogelii infection significantly reduced dry matter accumulation in cowpea pods. The loss of dry matter in cowpea pods was largely accounted for by dry matter gain in A. vogelii shoots. The data are discussed in relation to how A. vogelii and other parasitic plants influence dry matter partitioning in their hosts. 相似文献
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为了明确豌豆修尾蚜Megoura crassicauda和豆蚜Aphis craccivora在蚕豆上适合度的差异,从中选出适合度较高的蚜虫用于天敌昆虫的大规模繁殖,对两种蚜虫在蚕豆上的发育参数进行了观察并建立了生命表。结果表明：2种蚜虫的成虫历期和世代周期差异虽不显著,但豌豆修尾蚜的若虫历期6.66 d显著低于豆蚜的7.86 d。产蚜量曲线中,豌豆修尾蚜的产蚜量在前期虽迅速增加,但2种蚜虫的生殖力参数差异均不显著。存活率曲线中,豌豆修尾蚜在蚕豆上14～30.5 d时的存活率低于豆蚜,30.5 d后开始高于豆蚜,且其整体存活率曲线比较稳定。生命参数表中,豌豆修尾蚜的周限增长率和内禀增长率分别为1.38和0.32,均高于豆蚜的1.33和0.29。综上,相较豆蚜,豌豆修尾蚜在蚕豆苗上的适合度、存活稳定性更高,更适合在蚕豆上大量扩繁,在蚜虫天敌规模化生产中具有一定的应用潜力。 相似文献
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Cowpea (Vigna unguiculata) is one of the most important legumes cultivated in many parts of the world. The diseases caused by Cowpea severe mosaic virus (CPSMV) and Cowpea aphid‐borne mosaic virus (CABMV) are considered among the most important constraints on yield and quality, especially in Latin America and Africa. Here, the concept of using an RNA interference construct to silence the CPSMV proteinase cofactor gene and the CABMV coat protein gene is explored, in order to generate resistant transgenic cowpea plants. Ten cowpea transgenic lines were produced, presenting a normal phenotype and transferring the transgene to the next generation. Plants were tested for resistance to both CABMV and CPSMV by mechanical co‐inoculation. Seven lines presented milder symptoms when compared to the control and three lines presented enhanced resistance to both viruses. Northern analyses were carried out to detect the transgene‐derived small interfering RNA (siRNA) in leaves and revealed no correlation between siRNA levels and virus resistance. Additionally, in the symptomless resistant lines the resistance was homozygosis‐dependent. Only homozygous plants remained uninfected while hemizygous plants presented milder symptoms. 相似文献
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Fifty-one cowpea ( Vigna unguiculata ) cultivars and lines were tested by mechanical inoculation against seven geographically and pathogenically diverse isolates of blackeye cowpea mosaic potyvirus (BICMV), to identify genetic resources with comprehensive BICMV resistance. Five genotypes, IT 80S 2049, Big Boy, Corona, Serido, and Tennessee Cream #8 were immune from all seven isolates, and an additional three genotypes, TVu-2657, TVu-2740, and TVu-3433, were immune from all isolates except PU-7B, an aberrant B1CMV isolate. The diversity among BICMV isolates was illustrated by the range of responses to inoculation among cowpea genotypes, many of which were either immune from or tolerant of individual B1CMV isolates. 相似文献
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豇豆Vigna unguiculata 喜温喜光,是一种适合在我国南方种植的豆科蔬菜。长期以来,豇豆病虫害多发重发,其中,蓟马是豇豆上最主要和最顽固的害虫之一。传统的化学防治方法对蓟马的防治效果常常不理想,并易造成农药残留问题。本文概述了我国豇豆产业的种植情况和以蓟马为主的病虫害问题及豇豆蓟马研究现状,并从农艺措施、理化诱控、生物防治、化学防治和抗性治理角度总结了豇豆蓟马的综合防治技术。最后,从构建豇豆蓟马的有害生物综合治理(integrated pest management, IPM)技术体系、加强基础研究和防控技术产品开发、建立科学用药和农药监管制度3个方面提出建议,以期为我国豇豆产业的绿色可持续发展提供参考。 相似文献
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Muhammad Bashir R. O. Hampton 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(5):411-419
Fifty-one cowpea (Vigna unguiculata (L.) Walp.) genotypes were tested by mechanical inoculation with seven geographically diverse isolates of cowpea aphid-borne mosaic potyvirus to identify resistant sources. Of 51 genotypes three, TVu-401, TVu-1582 and TVu-1593 were found immune to all the seven isolates. Forty-five genotypes gave different reactions to individual isolates. Several immune, resistant and tolerant genotypes against each isolate were identified. A considerable evidence of pathogenic variability among the virus isolates was also observed. 相似文献
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Arakere Chunchegowda Udaya Shankar Siddaiah Chandra Nayaka Sathyanarayana Niranjan‐Raj Hanumanthaiah Bhuvanendra Kumar Munagala S Reddy Siddapura Ramachandrappa Niranjana Harishchandra Sripathy Prakash 《Pest management science》2009,65(10):1059-1064
BACKGROUND: The present study investigated the effect of seven Bacillus‐species plant‐growth‐promoting rhizobacteria (PGPR) seed treatments on the induction of disease resistance in cowpea against mosaic disease caused by the blackeye cowpea mosaic strain of bean common mosaic virus (BCMV). RESULTS: Initially, although all PGPR strains recorded significant enhancement of seed germination and seedling vigour, GBO3 and T4 strains were very promising. In general, all strains gave reduced BCMV incidence compared with the non‐bacterised control, both under screen‐house and under field conditions. Cowpea seeds treated with Bacillus pumilus (T4) and Bacillus subtilis (GBO3) strains offered protection of 42 and 41% against BCMV under screen‐house conditions. Under field conditions, strain GBO3 offered 34% protection against BCMV. The protection offered by PGPR strains against BCMV was evaluated by indirect enzyme‐linked immunosorbent assay (ELISA), with lowest immunoreactive values recorded in cowpea seeds treated with strains GBO3 and T4 in comparison with the non‐bacterised control. In addition, it was observed that strain combination worked better in inducing resistance than individual strains. Cowpea seeds treated with a combination of strains GBO3 + T4 registered the highest protection against BCMV. CONCLUSION: PGPR strains were effective in protecting cowpea plants against BCMV under both screen‐house and field conditions by inducing resistance against the virus. Thus, it is proposed that PGPR strains, particularly GBO3, could be potential inducers against BCMV and growth enhancers in cowpea. Copyright © 2009 Society of Chemical Industry 相似文献
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The effect of mixed infection of cowpea aphid-borne mosaic (CAMV) and cucumber mosaic (CMV) viruses on cowpea yield varied with the resistance levels of cowpea lines, since there was a strong interaction between the latter and virus infection types atP ≤ 0.01. In cowpea line TVu 3629, with low resistance to both viruses, mixed infection significantly(P ≤ 0.05) reduced most yield components as compared with single infections and uninoculated controls. However, in line TVu 15656, which is highly resistant to both viruses, the effect of mixed infections was not significantly different from that of single infections or from the control. Between these two extremes were cowpea lines TVu 13683 and TVu 410, which were mildly resistant to CMV and CAMV, respectively; single infections significantly reduced the yield components relative to control, although these were generally not different from mixed infections. CMV, hitherto considered to be not economically important in cowpea in Nigeria, could induce severe yield losses when present in mixed infection with CAMV in cowpea lines with low resistance to both viruses. However, since mixed infection did not affect the yield of the highly doubly-resistant TVu 15656 cowpea line, it may be possible to breed for combined resistance to both viruses. 相似文献
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Seedlings from 182 cowpea ( Vigna unguiculata ) pre-introductions/germplasm accessions from 12 countries were tested under greenhouse conditions for six seed-borne viruses. Twenty-one (13.3%) accessions from eight countries were found to be seed-infected with one of the three following viruses: blackeye cowpea mosaic (BlCMV) and cowpea aphid-borne mosaic (CABMV) potyviruses, and cucumber mosaic cucumovirus (CMV). Natural seed transmission incidence of 0–6.9%, 0–13.3%, and 0–2.0% were determined for BlCMV, CABMV and CMV respectively. Another set of 2930 cowpea germplasm accessions, mostly from Botswana and Senegal (Africa), were examined under field conditions for detection and identification of seed-borne viruses. Only CABMV was detected in this material. Most of the lines were free from other viruses reported in cowpea seed. Eight isolates of BlCMV and 28 isolates of CABMV were derived from cowpea pre-introductions/germplasm accessions evaluated under greenhouse and field conditions. 相似文献
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氯虫苯甲酰胺和高效氯氟氰菊酯在豇豆和土壤中的残留行为 总被引：2，自引：1，他引：1
建立了采用分散固相萃取法进行样品前处理,分别用液相色谱-质谱联用和气相色谱检测14%氯虫苯甲酰胺·高效氯氟氰菊酯微囊悬浮剂中2种有效成分在豇豆和土壤中的残留量及消解动态的方法。结果表明:豇豆和土壤中分别添加0.005～1 mg/kg 4个水平的氯虫苯甲酰胺和高效氯氟氰菊酯,其平均回收率为80%～105%,相对标准偏差为0.70%～9.5%。北京和海南2地氯虫苯甲酰胺和高效氯氟氰菊酯在豇豆中的半衰期为4～6 d,土壤中的为10～24 d。成熟时采收,豇豆中氯虫苯甲酰胺和高效氯氟氰菊酯的残留量均低于0.2 mg/kg。推荐14%氯虫苯甲酰胺·高效氯氟氰菊酯微囊悬浮剂在豇豆上的使用剂量为有效成分45 g/hm2,使用方式为喷雾,施药次数不超过3次,施药间隔期为7 d,安全间隔期为5 d。 相似文献
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The role of cowpea ( Vigna unguiculata) debris as a primary source of inoculum for Sphaceloma sp., the pathogen of cowpea scab, was studied in field experiments. Three fields were selected in 1993 and three in 1994, in which cowpea had been grown 1, 2 or 3 years previously as part of a crop rotation. Polyethylene mulch was spread over the soil to prevent soil/debris splash in half of the plots. No scab symptoms were observed on the primary leaves. It took an average of 25 days for primary symptoms to be observed in each field, irrespective of mulching. Mulching had a significant effect on disease severity only in the two sites where cowpeas were last grown a year before the trial (sites 1a and 1b). In both years, interaction between time (days after sowing) and site (fields in which cowpea had been grown 1–3 years earlier) had a significant effect on disease incidence while in 1994, interaction between time, site and mulching was also significant ( P < 0.05). Higher disease incidence was observed in 1994 than in 1993. In all fields, there were increases in disease incidence over time. Rain splashing may have contributed to higher disease incidence in plots without mulch. The presence of scab in the mulched plots in fields last sown to cowpea 3 years before the trial suggests that the pathogen may survive on infected cowpea debris, which acts as one of the sources of primary inoculum. Hence longer periods of crop rotation with nonhosts may be required to control the disease. 相似文献