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1.
Asante Maxwell Darko Adjah Kossi Lorimpo Annan-Afful Ebenezer 《Journal of Crop Science and Biotechnology》2019,22(2):123-130
Journal of Crop Science and Biotechnology - Even though there are abundant rice genetic resources, only a fraction is used in breeding programs leading to a narrow genetic base for improved... 相似文献
2.
Akesse-Ransford Geoffrey Owusu Ebenezer Oduro Kyerematen Rosina Adu-Acheampong Samuel 《Agroforestry Systems》2021,95(5):791-803
Diversity of insect communities can be used as bioindicators for change in the environment especially in farms under different management systems. In line with that, we conducted a research on insect species associated with cocoa under organic and conventional management systems in the Eastern and Central regions of Ghana. Insect collection was done using Hand height visual count, Canopy, and “Knock down”, pitfall, coloured bowl and fruit-baited traps. A total of 13,742 individual insects belonging to 138 species from 63 families and 12 orders were recorded in the study. Insect abundance and diversity were generally higher in organic farms compared to conventional farms with Oecophylla longinoda as the most dominant species in both management systems and especially more dominant in organic cocoa farms. Our study revealed that most of the insect species recorded were known cocoa pests although there was high abundance of beneficial insects too. Some of the pest species were Planococoides njalensis, Salhbergella singularis, Helopeltis spp and Pseudococus spp, while some of the beneficial insects recorded were Pheidole spp, Tegenaria spp, Camponotus spp, Crematogaster spp. We can conclude that cocoa farms are potential habitats for insect biodiversity conservation. We recommend that management and/or agronomic practices used in cocoa farms should be geared towards protecting beneficial organisms for instance pollinators and natural enemies by effectively suppressing insect pest populations while enhancing good seed production.
相似文献3.
Sutter NB Bustamante CD Chase K Gray MM Zhao K Zhu L Padhukasahasram B Karlins E Davis S Jones PG Quignon P Johnson GS Parker HG Fretwell N Mosher DS Lawler DF Satyaraj E Nordborg M Lark KG Wayne RK Ostrander EA 《Science (New York, N.Y.)》2007,316(5821):112-115
The domestic dog exhibits greater diversity in body size than any other terrestrial vertebrate. We used a strategy that exploits the breed structure of dogs to investigate the genetic basis of size. First, through a genome-wide scan, we identified a major quantitative trait locus (QTL) on chromosome 15 influencing size variation within a single breed. Second, we examined genetic variation in the 15-megabase interval surrounding the QTL in small and giant breeds and found marked evidence for a selective sweep spanning a single gene (IGF1), encoding insulin-like growth factor 1. A single IGF1 single-nucleotide polymorphism haplotype is common to all small breeds and nearly absent from giant breeds, suggesting that the same causal sequence variant is a major contributor to body size in all small dogs. 相似文献
4.
M. A. Dadzie A. Oppong K. Ofori J. S. Y. Eleblu B. E. Ifie E. T. Blay E. Obeng-Bio Z. Appiah-Kubi M. L. Warburton 《Plant pathology》2019,68(8):1565-1576
Fungal mycotoxins are important contaminants of agricultural commodities that pose serious concerns to producers, consumers and exporters. Aflatoxin is a carcinogenic metabolite produced by the fungi Aspergillus flavus and A. parasiticus. These fungi and other mould species living in the soil contaminate several crops including maize. This study was undertaken with the following objectives: (i) to assess the presence of A. flavus and other moulds in Ghanaian soil; (ii) to determine the distribution and density of A. flavus under three agro-ecologies noted for major maize production; and (iii) to assess the effect of percentage of carbon (C) and nitrogen (N) and soil pH on A. flavus population densities and diversity in the isolates found across the agro-ecologies. The data showed seven moulds that were common across the agro-ecologies. Significant differences (P < 0.05) were observed in the A. flavus density and distribution within and across these agro-ecologies. Fumesua soils recorded the highest levels of A. flavus (1.185 × 103 cfu g−1) while Akomadan recorded the least (9.76 × 102 cfu g−1). Percentage available C, N and soil pH did not significantly influence A. flavus density. The A. flavus isolates identified in this study varied in genetic sequence within the aflatoxin gene cluster, but these differences were not distinguishable by origin. 相似文献
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Biochars are,amongst other available amendment materials,considered as an attractive tool in agriculture for carbon sequestration and improvement of soil functions.The latter is widely discussed as a consequence of improved physical quality of the amended soil.However,the mechanisms for this improvement are still poorly understood.This study investigated the effect of woodchip biochar amendment on micro-structural development,micro-and macro-structural stability,and resilience of two differently textured soils,fine sand (FS) and sandy loam (SL).Test substrates were prepared by adding 50 or 100 g kg-1 biochar to FS or SL.Total porosity and plant available water were significantly increased in both soils.Moreover,compressive strength of the aggregates was significantly decreased when biochar amount was doubled.Mechanical resilience of the aggregates at both micro-and macro-scale was improved in the biochar-amended soils,impacting the cohesion and compressive behavior.A combination of these effects will result in an improved pore structure and aeration.Consequently,the physicochemical environment for plants and microbes is improved.Furthermore,the improved stability properties will result in better capacity of the biochar-amended soil to recover from the myriad of mechanical stresses imposed under arable systems,including vehicle traffic,to the weight of overburden soil.However,it was noted that doubling the amendment rate did not in any case offer any remarkable additional improvement in these properties,suggesting a further need to investigate the optimal amendment rate. 相似文献
7.
Ebenezer Annan-Afful Noriko Iwashima Ernest Otoo Kwame Osafredu Asubonteng Daisuke Kubota Akira Kamidohzono 《Soil Science and Plant Nutrition》2013,59(5):649-664
The bulk density and nutrient distribution in soil profiles as affected by various land use systems were studied. Mean bulk densities of the various soil profiles, 0-20, 20-40, and 4060 cm in the selected five land use systems along the upland / lowland topo-sequences were, 1.26, 1.73, and 1.44 Mg m-3 for the primary forest (PF) plot in the upland area, 1.13, 1.51, and 1.50 Mg m-3 for the cacao farm (CP) plot, 1.16, 1.63, and 1.26 Mg m-3 for the mixed cropping (MC) plot, 1.39, 1.61, and 1.50 Mg m-a for the fallow (Fallow) plot, all three land use systems being in the upland / fringe areas, and 1.46, 1.72, and 1.60 Mg m-3 for the lowland traditional rice farming (TR) plot, respectively. The very high bulk density of the second layer, especially in the PF plot, may be related to the hardening of the iron / quartz stone layer due to prolonged dry conditions, which may affect plant growth and hydrological cycles in the benchmark inland valley watersheds. The TC contents of the topsoil samples were 43, 32, 24, 26, 18, and 15 g kgm-1 for the PF, CP, Fallow, MC, TR, and sawah (Sawah) plots, respectively. The C / N ratios of the topsoil samples were 10, 10, 9.8, 9.1, 8.8, and 8.8 for the CP, Fallow, MC, Sawah, TR, and PF plots, respectively, displaying a higher natural fertility, especially for the N supply in the PF plot in the upland area. The available phosphorus levels were low even for the topsoil samples, 1.8 to 3.4 mg kg-1 for the upland soils while the lowland TR and Sawah plots recorded values of 4.4 and 4.9 mg kg-1, respectively. The contents of exchangeable K, 0.1-0.4 cmole kg-1, of the topsoil samples were in the range of those of normal inland valley soils in West Africa. In contrast to the content of available P, although the MC plot showed a depletion, the PF, Fallow, and CP plots showed a replenishment of available K through biological nutrient cycling. The levels of exchangeable Ca and Mg as well as eCEC, were also relatively high compared to those of mean inland valley soils in West Africa. The major component of eCEC was Ex. Ca. The levels of Ex. Ca in the topsoil samples were 11.1, 9.1, 7.8, 4.7, 5.1, and 3.9 cmolc kg-1 for the PF, CP, Fallow, MC, TR, and Sawah plots, respectively. The distinctive feature of Ex. Mg was its large distribution in the upper soil profiles in the CP plot, indicating that in the cacao farms, Ex. Mg was enriched, probably due to the high level of Mg in the leaf litter. The lowland soils, normally, should have been enriched in exchangeable bases such as Ca, K, and Mg, leading to a higher eCEC value and higher general fertility through the process of geological fertilization, Le., nutrient flows from upland to lowland areas, as in the case of lowland sawah in monsoon Asia. At the benchmark sites, however, the effects of the geological fertilization process were not evident. This is one of the most important characteristics of West African inland valley watersheds. 相似文献
8.
Dhana Raj Boina Ebenezer O Onagbola Masoud Salyani Lukasz L Stelinski 《Pest management science》2009,65(8):870-877
BACKGROUND: Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, transmits the causal bacteria of the devastating citrus disease huanglongbing (HLB). Because of the variation in spatial and temporal uptake and systemic distribution of imidacloprid applied to citrus trees and its degradation over time in citrus trees, ACP adults and nymphs are exposed to concentrations that may not cause immediate mortality but rather sublethal effects. The objective of this laboratory study was to determine the effects of sublethal concentrations of imidacloprid on ACP life stages. RESULTS: Feeding by ACP adults and nymphs on plants treated daily with a sublethal concentration (0.1 µg mL?1) of imidacloprid significantly decreased adult longevity (8 days), fecundity (33%) and fertility (6%), as well as nymph survival (12%) and developmental rate compared with untreated controls. The magnitude of these negative effects was directly related to exposure duration and concentration. Furthermore, ACP adults that fed on citrus leaves treated systemically with lethal and sublethal concentrations of imidacloprid excreted significantly less honeydew (7–94%) compared with controls in a concentration‐dependent manner suggesting antifeedant activity of imidacloprid. CONCLUSIONS: Sublethal concentrations of imidacloprid negatively affect development, reproduction, survival and longevity of ACP, which likely contributes to population reductions over time. Also, reduced feeding by ACP adults on plants treated with sublethal concentrations of imidacloprid may potentially decrease the capacity of ACP to successfully acquire and transmit the HLB causal pathogen. Copyright © 2009 Society of Chemical Industry 相似文献
9.
Roger R.B. Leakey Zacharie Tchoundjeu Rognvald I. Smith Robert C. Munro Jean-Marie Fondoun Joseph Kengue Paul O. Anegbeh Alain R. Atangana Annabelle N. Waruhiu Ebenezer Asaah Cecilia Usoro Victoria Ukafor 《Agroforestry Systems》2004,60(2):101-111
Ten fruit and kernel traits were measured in 152 Irvingia gabonensis and 293 Dacryodes edulis trees from 6 villages in Cameroon and Nigeria. Frequency distribution curves were used to examine the range of variation
of each trait of each species in each village and aggregated into national and regional populations. There were differences
between the village sub-populations, with regard to the normality (e.g., mean kernel mass of D. edulis) or skewness (e.g., mean flesh depth of D. edulis) of the distribution curves and in the degree of separation between the individual village populations along the x axis,
resulting in the development of a bimodal distribution in the regional population. For all traits, populations of both species
differed significantly between countries, but only in D. edulis were there significant differences between the Cameroon populations. On the basis of the results of this study, D. edulis can be said to be virtually wild in Nigeria but semi-domesticated in Cameroon, while I. gabonensis is wild in Cameroon and semi-domesticated in Nigeria. These results are discussed with regard to a hypothesis that the range
and frequency of variation in the different populations can be used to identify five stages of domestication. From a comparison
of the frequency distribution curves of desirable versus undesirable traits, and statistically identifyable changes in skewness and kurtosis, it is concluded that as a result of
the farmers’ own efforts by truncated selection, D. edulis is between Stages 2 and 3 of domestication (with a 67% relative gain in flesh depth) in Cameroon, while I. gabonensis in Nigeria is at Stage 2 (with a 44% relative gain in flesh depth). In this study, genetic diversity seems to have been increased,
and not reduced, by domestication.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
10.
Ayodele Ebenezer Ajayi Moacir de Souza Dias Junior Nilton Curi Cezar Francisco Araujo Junior Thiago Tadeu Teixeira Souza Alberto Vasconcellos Inda Junior 《Soil & Tillage Research》2009,105(1):122-127
In this study, strength attributes and compaction susceptibility of the main classes of Brazilian Latosols (Oxisols), under native vegetation, were studied using the load bearing capacity models relating precompression stress, compression index and water potential through statistical regression models. These models were developed based on the results of the analysis of undisturbed soil samples collected at the B horizon at the different sites. The results showed that the maximum value of the compression index was 0.53 for the Acric Red Latosol, indicating its higher susceptibility to soil compaction. The Dystrocohesive Yellow Latosol had the highest load bearing capacity, while the Acric Red Latosol had the lowest one. The Dystrocohesive Yellow Latosol due to its high load bearing capacity and bulk density (mechanical resistance) behave similarly to hardsetting soil, in which the plants root system has severe physical restrictions to explore deeper horizons during the dry periods. Differences in the load bearing capacity and compaction susceptibility were found to be influenced by soil structure which is associated with clay mineralogy in these very weathered-leached soils and water potential. The study also showed that soil compression index is influenced by water potential and clay mineralogy also. Our work has laid a foundation for estimation of compaction susceptibility of Latosols. 相似文献