Bemisia tabaci is a polyphagous herbivore that feeds on a wide range of horticultural and ornamental crops cultivated under diverse ecological zones. In Sierra Leone, B. tabaci is found to infest a wide range of veget...Bemisia tabaci is a polyphagous herbivore that feeds on a wide range of horticultural and ornamental crops cultivated under diverse ecological zones. In Sierra Leone, B. tabaci is found to infest a wide range of vegetable crops by directly feeding on phloem sap thereby inducing physiological disorders, and also serve as a vector to gemini viruses. Invariably the destructive feeding of B. tabaci affects the productivity and aesthetic values of vegetables and other horticultural crops and hence is considered a serious economic pest. A bioassay experiment was carried out by rearing B. tabaci populations on four vegetable crops under controlled laboratory conditions to determine its life table and demographic parameters. Results showed that the intrinsic rate of growth which measures the population size and growth pattern was highest for populations reared on tomato crops with the following values: rm 0.145 female female−1 day−1, the gross reproduction rate (Ro), and finite growth rate λ were highest for population reared on tomato, correspondingly the development period from egg-adult emergence was shortest with a value of 26 d. Conversely, the computed demographical parameters rm, λ and Ro for the population reared on sweet pepper were 0.106 female female−1 day−1 respectively, with a corresponding development period egg-adult emergence as 36d. The computed biological parameters for okra and garden egg varied with intermediary values between tomato and pepper host materials. The survivorship rates were quite significant for the smaller instars (Instars 1-III) with over 80% surviving to pre-pupa and pupa stage for the populations reared for all the test materials. High mortality was noticed for the pre-pupa and pupa stages as their survival rates were significantly low compared to the high survival rates of the smaller instars. Less than 50% of pupae failed to emerge to adults except for populations reared on tomato test materials where 52% emerged to adults. The study indicated tomato as the most suitable host among the four vegetable crops. Although life table and demographic parameters are invaluable information for forecasting pest populations and help in designing pest management efforts, further investigations such as the economic threshold and economic injury levels of B. tabaci population are requisite decision tools for sound pest management decisions of B. tabaci on these vegetable crops. The information obtained from this investigation would be quite relevant for extension service and pest management practitioners where mixed vegetable farming is a common practice.展开更多
Fields experiments were conducted at the Department of Crop Protection, Faculty of Agriculture, University of Maiduguri Teaching and Research Farm, Maiduguri during 2010 and 2011 cropping seasons to investigate the ef...Fields experiments were conducted at the Department of Crop Protection, Faculty of Agriculture, University of Maiduguri Teaching and Research Farm, Maiduguri during 2010 and 2011 cropping seasons to investigate the effects of intercropping pattern on stem borer pest infestation in pearl millet (Pennisetum glaucum L.) intercropped with ground nut (Arachis hypogea L.). A split-plot design was used to test the intercrop pattern of 1:0 ratio (sole millet), 1:1 ratio (1 millet row to 1 ground nut row), 2:1 ratio (2 millet rows to 1 ground nut row) and 1:2 ratio (1 millet row to 2 ground nut rows). The results obtained showed that the intercrop pattern of 1:2 ratio and 1:1 ratio yielded less stem borer infestation and abundance in pearl millet, and as well supported high panicle weight and grain yield. In addition to recommending either of these two intercropping patterns to pearl millet farmers for more effective stem borer pest management, results further show the need for identification of effective intercropping patterns in other cropping systems.展开更多
The use of plant extracts as insecticides against vector insects serves as a perfect alternative to conventional methods.This study was carried out to assess the chemical composition and efficacy of Chromolaena odorat...The use of plant extracts as insecticides against vector insects serves as a perfect alternative to conventional methods.This study was carried out to assess the chemical composition and efficacy of Chromolaena odorata L.and Ocimum gratissimum L.in the control of adult houseflies.C.odorata and O.gratissimum were extracted with cold water and applied at four concentrations(5,10,40 and 100%v/v)in different bioassays(contact,fumigant and feeding-deterrent).A synthetic insecticide(Lambdacyhalothrin)and an untreated control were included in the treatments.The treatments were arranged in a completely randomized design with three replicates.The phytochemical compositions of the tested plant extracts were determined via gas chromatography‒mass spectrometry(GC‒MS).Mortality data were recorded at the stipulated times(1,2,4,6,8 and 24 h),and the means were separated via Duncan’s multiple range test at a 5%probability.GC‒MS revealed different chemical compounds,and eugenol,n-hexadecanoic acid,caryophyllene,phytol,humulene,9,12,15-octadecatrienoic acid,(Z,Z,Z)-,squalene,and stigmasterol compounds,among others,were identified as active insecticidal compounds.The tested plant extracts were effective against the studied insects,which suggested synergistic action of the observed natural chemicals in the plant extracts used.Moreover,the two plant extracts did not kill the studied insects faster than the synthetic insecticide did,but 100%mortality was observed after 12 h of exposure to the plant extracts.The mode of application and concentration played a significant role in the toxicity of the plant extracts,with the feeding mode of application resulting in greater toxicity effects than the fumigant and contact bioassays at the highest concentration.However,O.gratissimum exhibited better insecticidal control than C.odorata extracts did.Therefore,the use of crude plant extracts as insecticides could serve as substitutes for lambdachyalothrin in the control of houseflies,especially in animal rearing facilities and in the human population.展开更多
Floral structures of six cowpea （Vigna unguiculata） cultivars were analysed for secondary plant metabolites （polyphenols, terpenoids and flavonoids） to study their relationships with resistance to Megalurothrips s...Floral structures of six cowpea （Vigna unguiculata） cultivars were analysed for secondary plant metabolites （polyphenols, terpenoids and flavonoids） to study their relationships with resistance to Megalurothrips sjostedti （Trybom）. Polyphenols varied significantly （P 〈 0.001） among the floral structures of the cultivars at the same growth stage. Significant negative correlations were obtained between polyphenols and damage indices （r = -0.57）, mean adult counts （r = -0.56） and mean larval counts （r = -0.64） of resistant cowpea cultivars especially in the late season, indicating that polyphenols play a significant role in cowpea resistance to M. sjostedti. High levels of polyphenols obtained from Sanzibanili and Sewe cultivars, coupled with highly significant correlations between the polyphenols and thrips population on resistant cultivars, and their damage indices, suggests that these polyphenols could be inhibitors or deterrents in this case. Terpenoid extracts （10 mg/mL） of IT90K-277-2, Sewe, Sanzibanili, TVu 1509 and KV - 404-8-1 racemes; KV ~ 404-8-I and TVu 1509 floral buds; IT90K-277-2, Sewe and Sanzibanili flowers caused significant （P 〈 0.001） larval mortalities, since mortality ranged between 56.7%-96.7%. Hence terpenoid extracts from floral structures of the cultivars are biologically active and confers antibiotic resistance to M. sjostedti larvae; this compound could be promising candidates for genetic transformation of cowpea cultivars.展开更多
Mutagenesis is used for creating new genetic variability in cultivar improvement. Optimal mutagenic treatment is required for effective mutation induction in crop species. Therefore, radio-sensitivity of cowpea access...Mutagenesis is used for creating new genetic variability in cultivar improvement. Optimal mutagenic treatment is required for effective mutation induction in crop species. Therefore, radio-sensitivity of cowpea accessions to gamma irradiation was investigated. Seeds of eight cowpea accessions were irradiated with <sup>60</sup>Co gamma radiation doses of 100, 200, 300, 400 and 500 Gy. The seeds were sown in pots to evaluate the treatment effects on seed germination (SG), seedling survival (SS) and growth habits of M1 generation. Data were analyzed using descriptive statistics. Low rates of SG (10% - 45%) were recorded at higher doses (500 - 400 Gy) in Ife Brown (IB) and its derivatives, whereas high SG rates (74% - 94%) were observed in IT90K-284-2 across all treatments. Percentage SS was inversely related to gamma dosage. A wide range of LD<sub>50</sub> for SG (329 - 1054 Gy) and SS (149 - 620 Gy) were observed across the cowpea accessions. Low LD<sub>50</sub> scores for SG (329 - 516 Gy) and SS (149 - 357 Gy) were observed among cowpea with rough seed coat, whereas cowpea with smooth seed coat recorded higher LD<sub>50</sub> for SG (521 and 1054 Gy) and SS (449 and 620 Gy). Seed germination LD<sub>50</sub> and SS LD<sub>50</sub> were highly correlated with mean coat thickness (0.899 and 0.937) than mean seed weight (0.621 and 0.678). Gamma irradiation of cowpea seed at low dosage (100 Gy) increased the vigor of M<sub>1</sub> seedlings with respect to primary leaf area, terminal leaflet area, seedling height and plant height at six weeks. Doses of 200 Gy and above resulted in a progressive reduction in vigor of plant and seed setting of cowpea. Radio-sensitivity varied with cowpea genotype and was associated with seed testa texture, thickness and seed weight. Low gamma irradiation treatment (100 Gy) may be used to enhance seedling vigor, vegetative growth and yield of cowpea at M<sub>1</sub> generation.展开更多
Pod-sucking bugs (PSBs) infestation by Ano-plocnemissp./ Riptortussp./Clavigrallasp./Nezaraviridula( Linnaeus) greatly limits cowpea (Vignaunguiculata (L.) Walp) production throughout sub-Saharan Africa. The efficacy ...Pod-sucking bugs (PSBs) infestation by Ano-plocnemissp./ Riptortussp./Clavigrallasp./Nezaraviridula( Linnaeus) greatly limits cowpea (Vignaunguiculata (L.) Walp) production throughout sub-Saharan Africa. The efficacy of aqueous leaf extracts (ALEs) (5 percent weight/volume concentration) of three botanicals and one synthetic insecticide against PSBs infestation was thus evaluated. The botanicals tested include Aza- dirachtaindicaA. Juss, Chromolaenaodorata (L.) and Ricinuscommunis (L.), whilst the synthetic insecticide was Uppercot 500 EC ( Lambda cyhalothrin 30 g + Dimethoate 250 g ). The effects of these treatments on the number of PSBs/ pods/seeds, pod/seed weight and grain yield were assessed during 2008 and 2009 rainy seasons in Bayo, Borno State, Guinea Savanna region, Nigeria. The number of PSBs was lower on crops treated with Uppercot 500 EC (0.00 - 0.31). This was followed by crops treated with the ALEs ofA.indica/C.odorata (0.31 - 1.33) and R.communis (0.72 - 3.72) than the untreated (3.06 - 5.64) ones.The number of pods/pod weight per plant, seeds/seed weight per pod and total grain yield were generally higher on cowpea crops treated with Uppercot 500 EC (26/17 g, 14/19 g and 1618 kg). This was followed bycrops treated with the ALEs of A.indica/C.odorata (23 - 25/14 - 15 g, 12 - 13/15 g and 1268 - 1310 kg) and R.communis( 21/13 g, 11/14 g and 972 kg) than the untreated (16/9 g, 7/10 g and 312 kg) ones. Although Uppercot 500 EC was most effective inprotecting cowpea against PSBs attack, theALEs of A.indica and C.odorata appreciably protected treated crops against infestation, giving relatively high total grain yield. Both botanical scan thus serve as alternatives to synthetic insecticides for managing PSBs attack on cowpea.展开更多
Compost has been used to stabilise lead (Pb) in soil. However, compost contains a high level of dissolved organic matter (DOM) which may make Pb bioavailable in plant and thereby limiting its effectiveness and applica...Compost has been used to stabilise lead (Pb) in soil. However, compost contains a high level of dissolved organic matter (DOM) which may make Pb bioavailable in plant and thereby limiting its effectiveness and application. Addition of biochar to compost can reduce this effect. Rice husk (RH) and Cashew nut shell (CNS) biochars and compost-modified biochars were used in comparison to compost for stabilizing Pb in lead smelting slag (LSS)-contaminated soil (Pb = 18,300 mg/kg) in Nigeria. Efficiency of Pb stabilisation in control and amended soils was assessed using CaCl2 batch leaching experiment and plant performance. In pot experiments, maize plant was grown on the contaminated soil and on soil treated with minimum and optimum doses of the amendments singly and in combination for 6 weeks. Agronomical and chemical parameters of the plants were measured. CaCl2-extractable Pb in the untreated soil was reduced from 60 mg/kg to 0.55 mg/kg in RHB amended soils and non-detectable in other amended soils. RH-biochar/compost increased plant height, number of leaf and leaf area more than the others. Similarly, at minimum rate, it reduced root and shoot Pb by 91% and 86.0% respectively. Compost-modified rice husk biocharstabilised Pb in lead smelting slag contaminated soil reduced Pb plant uptake and improved plant growth. Lead stabilisation through the use of rice husk biochar with compost may be a green method for remediation of lead smelting slag-contaminated soil.展开更多
This study determined the effects of initial infestation of cowpea seeds （Ife brown variety） with different insect densities （0, 2, 4 and 6 pairs per 50 g seeds） of Callosobruchus maculatus （F.） and evaluated th...This study determined the effects of initial infestation of cowpea seeds （Ife brown variety） with different insect densities （0, 2, 4 and 6 pairs per 50 g seeds） of Callosobruchus maculatus （F.） and evaluated the effects of aqueous leaf extract of Nicotiana tabacum L. on C. maculatus in the laboratory. It was observed that adult beetle population increased significantly （p〈0.05） with increase in insect density. The increase in population of beetles and corresponding weight loss of the seeds in different levels of infestation showed that the cowpea variety was susceptible to beetle infestation, emergence and survival of progeny. Significantly more adults emerged on higher infestation compared to lower and no infestation. In Nigeria, Nicotiana tabacum L. is a locally available plant, with known insecticidal properties. The plant leaf extract was easily extracted with water and confirmed its effectiveness as a protective agent for stored cowpea seeds. Experiment was conducted to assess the effects of aqueous extracts ofN. tabacum at 0, 0.1, 0.2 and 0.3 mL＂ 50 g-1 cowpea seeds on C. maculatus. Data was recorded and showed varying levels of effectiveness against C. maculatus. Result showed that seed appearance was dependent on levels of insect population, while N. tabacum aqueous extract exerted effects on survival of C. maculatus. Aqueous leaf extract of N. tabacum probably contained some insecticidal properties which might have significantly conferred beetle mortality and reduced beetle emergence leading to a decrease in seed weight loss.展开更多
Stunt nematodes(Tylenchorhynchus spp.)are obligate migratory root ecto-parasitic nematodes found in the fields of many cultivated crops.These nematodes,with phyto-sanitary potential,are frequently ignored or misdiagno...Stunt nematodes(Tylenchorhynchus spp.)are obligate migratory root ecto-parasitic nematodes found in the fields of many cultivated crops.These nematodes,with phyto-sanitary potential,are frequently ignored or misdiagnosed as pests,and this may pose a threat to food security.The accuracy of its identification based on a morphological approach has been challenged recently,due to the overlapping of the morphological and morphometric characters of the species.Consequently,the objective of this study is to identify and characterize stunt nematodes present in 54 fields cultivated with cereal crops(wheat,maize and rice)in the savannahs of northern Nigeria,using integrative taxonomy and molecular approaches.The molecular and morphological studies identified and confirmed the presence of T.annulatus as the occurring specie in the savannahs of northern Nigeria.The phylogenetic analysis was carried out using the internal transcribed spacer(ITS)and 28S genes of ribosomal DNA further confirmed the presence of T.annulatus.The first molecular characterization and sequences of the ITS and 28S rDNA gene for T.annulatus from Nigeria were provided by this research.Also,according to our literature search,this is the first report on T.annulatus in wheat,maize and rice in the savannahs of northern Nigeria.Further study to test the pathogenicity of the parasitic nematode species found in this survey is recommended for the prioritization and development of efficient management strategies.展开更多
An investigation of effect of Latana camara, Tephrosia vogelii and Zingiber officinale applied at 5%, 10% and 25% concentrations on flea beetle of cabbage was conducted on the Teaching and Research Farm of the Ladoke ...An investigation of effect of Latana camara, Tephrosia vogelii and Zingiber officinale applied at 5%, 10% and 25% concentrations on flea beetle of cabbage was conducted on the Teaching and Research Farm of the Ladoke Akintola University of Technology Ogbomoso in the early seasons of 2011 and 2012. The experiment consisted of 11 treatments laid in a Randomized Complete Block Design （RCBD） with three replications. Data were subjected to analysis of variance and significant means were compared using the Least Significant Difference （LSD） at p〈0.05. All the tested plant extracts exhibited moderate efficacy in the control of flea beetle. The treatment plant extracts performed as well as synthetic insecticides （0.76±0.05 and 0.76±0.05, respectively）. It was discovered that 25% w/v of Z. officinale gave the best yield of 0.50 kg · hm-2. The result showed that extract of T. vogelii （0.71±0.00） and L. camara （0.96±0.23） could suppress flea beetle population at different hours of spraying, while Z. officinale showed an effect at 48 HAS （0.71±0.00） and 72 HAS （0.76±0.05） alter spraying.展开更多
The insecticidal potential of seed powders of Capsicum chinense Jacq. （Solanaceae） and Aframomum melegueta K. Schum. （Zingiberaceae） was tested against Trogoderma granarium （Coleoptera： Dermestidae） in the labo...The insecticidal potential of seed powders of Capsicum chinense Jacq. （Solanaceae） and Aframomum melegueta K. Schum. （Zingiberaceae） was tested against Trogoderma granarium （Coleoptera： Dermestidae） in the laboratory at （28±2）℃ and 70%± 5% relative humidity. The seed powders were tested at the rates of 0.0%, 0.5%, 1.0% and 1.5% （w/w） of groundnut seeds replicated three times. At the highest rate of treatment, C. chinense caused 56.7% and 76.8% larval mortality at 3 and 7 days post treatment （DPT） respectively while A. melegueta exerted 53.4% and 73.8% larval mortality at 3 and 7 DPT, respectively. Results showed that insecticidal potential of the seed powders against adult mortality of T. granarium and seed damage followed similar trend. The various rates of C. chinense seed powder performed better than .4. melegueta seed powder in causing larval and adult mortality and in reducing seed damage. The activity of the seed powders on mortality of the insect, seed weight loss and seed damage were exposure time and rate dependent. A significant reduction （p〈0.05） in seed weight loss and seed damage was recorded among the treatments and maximum reduction was observed in the seeds treated with the highest rate of C. chinense seed powder. Percentage seed damage significantly （p〈0.05） decreased with increase in the rate of treatment while the highest seed weight loss and seed damage were obtained in the control. The study showed that C. chinense seed powder had higher activity against the test insect pest than .4. melegueta seed powder. The two seed powders had high bio-activity against the insect and therefore could be used in formulating environment friendly plant-derived insecticide.展开更多
A study was carried out to determine the relative susceptibility of six maize(Zea mays L.) varieties to maize weevil,Sitophilus zeamais Motschulsky(Coleoptera: Curculionidae). It was conducted at Department of Crop Pr...A study was carried out to determine the relative susceptibility of six maize(Zea mays L.) varieties to maize weevil,Sitophilus zeamais Motschulsky(Coleoptera: Curculionidae). It was conducted at Department of Crop Protection Laboratory,University of Ilorin, Nigeria at ambient temperature of 28±2℃ and 68%±3% relative humidity. Samples of the varieties were infestedwith five pairs of S. zeamais adults in their respective containers arranged in completely randomized design with three replications.Data were collected on moisture content, adult mortality, adult emergence, grain loss and grain damage. The index of susceptibilityand means of damage parameters were used to determine susceptibility of the maize varieties. The results showed that 2008 SYNEE W DT STR was highly resistant and 2004 TZE-W POP STR C4 was moderately resistant, while 2004 TZE-Y-POP STR C4,99 TZEE-Y-STR, EV99 QPM and TZE-Y-POP DT STR QPM C_0S1 were susceptible. Under artificial infestation, the weevils hadsignificantly longer survival period in the susceptible varieties than those in the resistant genotype. It could be concluded that thesusceptible varieties already released to farmers should be protected from maize weevil damage.展开更多
Heterodera filipjevi continues to be a major threat to wheat production worldwide.Rapid detection and quantification of cyst nematodes are essential for more effective control against this nematode disease.In the pres...Heterodera filipjevi continues to be a major threat to wheat production worldwide.Rapid detection and quantification of cyst nematodes are essential for more effective control against this nematode disease.In the present study,a TaqManminor groove binder(TaqMan-MGB)probe-based fluorescence quantitative real-time PCR(qPCR)was successfully developed and used for quantifying H.filipjevi from DNA extracts of soil.The primers and probe designed from the obtained RAPD-SCAR marker fragments of H.filipjevi showed high specificity to H.filipjevi using DNA from isolatesconfirmed species of 23 Heterodera spp.,1 Globodera spp.and 3 Pratylenchus spp.The qPCR assay is highly sensitive and provides improved H.filipjevi detection sensitivity of as low as 4^(-3) single second-stage juvenile(J2)DNAs,10^(-3) female DNAs,and 0.01μgμL^(-1) genomic DNAs.A standard curve relating to the threshold cycle and log values of nematode numbers was generated and validated from artificially infested soils and was used to quantify H.filipjevi in naturally infested field soils.There was a high correlation between the H.filipjevi numbers estimated from 32 naturally infested field soils by both conventional methods and the numbers quantified using the qPCR assay.qPCR potentially provides a useful platform for the efficient detection and quantification of H.filipjevi directly from field soils and to quantify this species directly from DNA extracts of field soils.展开更多
A laboratory experiment was carried out to determine the response of six groundnut varieties to infestation by larvae of Trogoderma granarium Everts （Coleoptera： Dermestidae） and their nutritional constituents. The...A laboratory experiment was carried out to determine the response of six groundnut varieties to infestation by larvae of Trogoderma granarium Everts （Coleoptera： Dermestidae） and their nutritional constituents. The improved groundnut varieties used included SAMNUT 10, RMP-91, SAMNUT 19, SAMNUT 23, EX-DAKAR and RRB. The crude fat content varied significantly among the varieties from 32.7% to 53.1% in EX-DAKAR and RRB, respectively. The seed varieties were not significantly different in crude protein, ash and moisture content. The moisture content ranged between 6.6% and 8.9% in EX-DAKAR and SAMNUT 19 varieties, respectively. The crude protein content ranged between 19.7% and 31.3% in SAMNUT 19 and EX-DAKAR, respectively. The ash content varied between 3.0% and 7.4% in RRB and RMP-91 varieties, respectively. The results showed that the seeds were attacked by the 4th instar larvae of T. granarium as indicated by percentage seed weight damage, seed weight loss and dust production. SAMNUT 10 variety had the least seed damage of 33.1%, 41.4% and 43.7% in 1 month, 2 and 3 months post-infestation. In view of the damage, it was evident that SAMNUT 10 variety had the least percent seed damage and loss suggesting the possible inclusion of the variety in breeding programme against the insect pest.展开更多
The cotton leafworm is an important defoliating pest of cotton in Brazil, and occurs in all regions where the crop is cultivated. The purpose of this study was to evaluate the effect of larval densities of A. argillac...The cotton leafworm is an important defoliating pest of cotton in Brazil, and occurs in all regions where the crop is cultivated. The purpose of this study was to evaluate the effect of larval densities of A. argillacea after different infestation periods on the yield components of four cotton cultivars. The experiment was carried out in Pindorama, SP, Brazil, in the 2008/2009 growing season. The cultivars IAC-25, DeltaOPAL, Fibermax 966 and Fibermax 993 were artificially infested with A. argillacea larvae at three times (30, 60 and 90 DAE) and four densities (0, 2, 4, and 6 larvae per plant). The average boll weight (g), fiber percentage (%), 100-seed weight (g) and yield (kg·ha-1) were evaluated. With increasing infestation density of A. argillacea, the cotton yield of the cultivars decreased. The presence of larvae significantly reduced the weight of 100 seeds of cultivar Fibermax 966. Initial infestations reduced the boll weight of IAC-25 and DeltaOPAL, while cultivars Fibermax 966 and Fibermax 993 were most affected by late infestations. Early infestation compromised fiber percentage of cultivar DeltaOPAL and late infestations were most harmful to cultivar Fibermax 966. Early A. argillacea infestation reduced the yield of DeltaOPAL, while infestations 60 DAE caused the most damage to IAC-25, and the other cultivars were not affected by the moment of infestation.展开更多
Environmental factors such as relative humidity and rainfall generally have been found to increase the incidence, rate of spread and severity of diseases thereby reducing yield of crops. Study was conducted on five co...Environmental factors such as relative humidity and rainfall generally have been found to increase the incidence, rate of spread and severity of diseases thereby reducing yield of crops. Study was conducted on five cotton varieties, which were artificially inoculated with bacterial blight pathogen to determine the effects of rainfall and relative humidity on incidence and severity of angular leaf spot (ALS) and yield of seed cotton in Yola and Mubi. Results showed that the severity of ALS was higher in Yola (58.65%) at 13 WAS assumed to be due to higher relative humidity range of 76% - 87% and low rainfall of 2 - 40.6 mm. This is assumed to have favoured disease development as against that of Mubi location which recorded lower severity (51.11%) due to lower relative humidity (42% - 55%) and rainfall (37 - 73 mm). Results further revealed that at 13 WAS, SAMCOT-8 had low incidence (66%) and severity (39%) in Yola. This was against the much higher corresponding incidence and severity of 82% and 42% respectively that was observed in Mubi during the same period. SAMCOT-10 and SAMCOT-9 varieties were found to be highly susceptible to the disease at the same period. SAMCOT-8 recorded the highest yield of 390.00 kg?ha?1 in Yola and 868.09 kg?ha?1 in Mubi while the lowest yields of 227.17 kg?ha?1 was observed on SAMCOT-10 in Yola while 461.61 kg?ha?1 was obtained on SAMCOT-9 in Mubi. The variation in yield among these varieties might be due to the differences in their reactions to the disease. There is a need to conduct further trials in these locations to confirm the level of resistance or other aspects of these varieties to the disease.展开更多
Application of inorganic fertilizers improves crop yields but costs and adverse health effects often discourage their applications. This study therefore aims at evaluating the combined effects of cassava peel compost ...Application of inorganic fertilizers improves crop yields but costs and adverse health effects often discourage their applications. This study therefore aims at evaluating the combined effects of cassava peel compost with poultry manure and mineral fertilizer on growth and yields of Corchorus olitorius. Pots （factorial laid out in a randomized complete block design） and field （split-plot with fertilizer being the main effect and the varieties the sub plot effect） experiments were carried out during rainy season at Ibadan, Nigeria. Treatments consisted of 0, 5, l0 and 20 t/ha composts prepared from cassava peel and poultry manure in ratio 3：1 and mineral fertilizer （NPK 15：15：15） at the rate of 250 kg/ha, using two varieties of C. olitorius. Five and six weeks after planting （WAP）, plants were assessed for growth and yields in pot and field experiments respectively, and also in residual studies. Application of compost significantly improved growth （heights） （36.50-41.56 cm）, while morphological and dry weight values increased with increase in compost. Marketable yield increase of 13.2%, 22.3%, 32.1% and 29.3% were recorded using 5, 10, 20 t/ha compost and NPK fertilizer respectively in the field. Corresponding increase when ratooned were 40.0%, 42.9%, 57.1% and 52.0%, respectively. Application of compost at the rate of 20 t/ha performed better in the main and residual effect experiments compared to NPK fertilizer and other compost rates. Application of cassavas peels compost at the rate of 20 t/ha proved to be adequate for optimum growth and yield performance of C. olitorius.展开更多
Genetic diversity evaluation of mutant lines is essential to facilitate their conservation and utility in breeding programs. Characterization of plant genotypes using morphological markers has limitations which make t...Genetic diversity evaluation of mutant lines is essential to facilitate their conservation and utility in breeding programs. Characterization of plant genotypes using morphological markers has limitations which make the procedure inefficient. Application of molecular tools for characterization and diversity assessment has been found useful to complement phenotypic evaluation of plant population. Therefore genetic diversity of some cowpea mutant lines was studied using simple sequence repeats (SSR) markers. DNA barcoding marker, ribulose-1,5-bisphosphate carboxylase(rbcL) of the chloroplast DNA (cpDNA) was also used for characterization and identification of the mutants to species level. The mean polymorphic information content (0.51) obtained from the microsatellites showed high polymorphism in accessing wide genetic diversity among the mutants and their parents. Dendrogram generated revealed 8 groups with most mutants clustered separately from their parents. Sequence analysis revealed insertions/deletions (InDels) and base substitutions as the two main classes of mutations induced in the plastid DNA of the mutants studied. The nucleotide frequencies were 26.95% (A), 34.43% (T), 24.09% (C) and 14.53% (G). A total of 61.38% AT rich region was identified, while GC rich region was found to be 38.62%. Highest rate of mutations were observed in region 3 - 4 indicating that the region is less conserved in cowpea rbcL gene. The present study proved that SSR markers are useful for the genetic diversity assessment of cowpea mutants. It also proved the efficiency of rbcL markers in mutants’ identification. The results indicate that the mutants are valuable genetic resources that have been developed to widen cowpea genetic base.展开更多
An experiment was carried out to evaluate the fungitoxic effect of Trichoderma longibrachiatum (Rifai) metabolite on F. oxysporum, A. niger and A. tamarii. The fungi were collected from the International Institute of ...An experiment was carried out to evaluate the fungitoxic effect of Trichoderma longibrachiatum (Rifai) metabolite on F. oxysporum, A. niger and A. tamarii. The fungi were collected from the International Institute of Tropical Agriculture (IITA) and Nigerian Institute of Science Laboratory Technology (NISLT). T. longibrachiatum was cultured on 1/4 strength Potato Dextrose Broth (PDB) following standard procedures. Its metabolite was extracted using 50 ml n-hexane with 50 ml Potato Dextrose Broth (PDB). The metabolite was purified by filter sterilization using a sterile 0.22 millipore filter disc after centrifuging at 900 rpm for 20 minutes. Petri plates of each fungus were later impregnated in triplicates with the T. longibrachiatum metabolites using four concentrations (10%, 25%, 50% and 100%), and three volumes (1 ml, 2 ml, and 3 ml). Petri plates of fungi without the metabolite and Petri Plates of fungi with n-hexane and PDB served as control. All Petri Plates were incubated at 28°C for 7 days. Radial and diametric growth of each fungus on all Petri Plates were taken daily at 24 hours intervals. Data obtained were analysed using SAS (version 9.3). Growth inhibition of F. oxysporum, A. niger and A. tamarii was significantly higher than in control in that order (P ≤ 0.05). Inhibition of the fungi by metabolites extracted with both PDB and n-hexane was significantly better than in control. Generally, inhibition by metabolite extracted with PDB was better than that extracted with n-hexane. Growth inhibition at all the concentrations of the metabolite was significantly better than in the control (P ≤ 0.05). Generally, inhibition at 100%, 50% and 25% concentrations was better than that at 10% concentration of the metabolite. Trichoderma longibrachiatum metabolite can thus be said to possess promising fungitoxic potential even at concentrations as low as 25%. Both PDB and n-hexane are good extraction media for the metabolite.展开更多
In this study, some Eriophyid mite species showing different morphological characters and host-plant symptoms were obtained. Five mites species collected from different localities in Khartoum State （Sudan） during th...In this study, some Eriophyid mite species showing different morphological characters and host-plant symptoms were obtained. Five mites species collected from different localities in Khartoum State （Sudan） during the period （2002-2003） which classified under family Eriophyidae from different hosts were selected and examined carefully. These were recognized as Cisaberoptus kenyae （K.） on Mango Mangifera indica, Acalitus hassani （K.） onArrak Salvadora persica, Aceria balanites （Massee） on Heglig Balanites aegyptiaca, Colomerus vitis on Grape Vitis sp. （for the first time in the Sudan） and Eriophyes tulipae （K.） on Onion Allium cepa and garlic Allium sativum respectively. The remaining six eriophyid mites were not completely described but designated as Eriophyes sp. 1, 2, 3, 4, 5 and 6 on Sidir Ziziphus spina, Aradeib Tamarindus indica, Harazz, Acacia albida, Talha Acacia seyal var. seyal, Seyal Acacia tortilis var. raddiana and Mormeet Pergia capensis respectively. The response of 12 different plant species infested artificially with Cisaberoptus kenyae （K.）, Acalitus hassani （K.） and Eriophyes tulipae （K.） were studied after two months of infestation. The results showed that onion and garlic plants were severely infested with Eriophyes tulipae （K.） while tomato was found to be susceptible for Cisaberoptus kenyae （K.） and Acalitus hassani （K.） showing moderate infestations. On the other hand, sorghum and wheat infested with Eriophyes tulipae （K.） showed moderate and light infestations respectively. On the contrary, mite infestations were not detected on the rest of plant species. The degree of infestation of Eriophyid mites species on different test plants, measured by symptoms appeared on plant leaves.展开更多
文摘Bemisia tabaci is a polyphagous herbivore that feeds on a wide range of horticultural and ornamental crops cultivated under diverse ecological zones. In Sierra Leone, B. tabaci is found to infest a wide range of vegetable crops by directly feeding on phloem sap thereby inducing physiological disorders, and also serve as a vector to gemini viruses. Invariably the destructive feeding of B. tabaci affects the productivity and aesthetic values of vegetables and other horticultural crops and hence is considered a serious economic pest. A bioassay experiment was carried out by rearing B. tabaci populations on four vegetable crops under controlled laboratory conditions to determine its life table and demographic parameters. Results showed that the intrinsic rate of growth which measures the population size and growth pattern was highest for populations reared on tomato crops with the following values: rm 0.145 female female−1 day−1, the gross reproduction rate (Ro), and finite growth rate λ were highest for population reared on tomato, correspondingly the development period from egg-adult emergence was shortest with a value of 26 d. Conversely, the computed demographical parameters rm, λ and Ro for the population reared on sweet pepper were 0.106 female female−1 day−1 respectively, with a corresponding development period egg-adult emergence as 36d. The computed biological parameters for okra and garden egg varied with intermediary values between tomato and pepper host materials. The survivorship rates were quite significant for the smaller instars (Instars 1-III) with over 80% surviving to pre-pupa and pupa stage for the populations reared for all the test materials. High mortality was noticed for the pre-pupa and pupa stages as their survival rates were significantly low compared to the high survival rates of the smaller instars. Less than 50% of pupae failed to emerge to adults except for populations reared on tomato test materials where 52% emerged to adults. The study indicated tomato as the most suitable host among the four vegetable crops. Although life table and demographic parameters are invaluable information for forecasting pest populations and help in designing pest management efforts, further investigations such as the economic threshold and economic injury levels of B. tabaci population are requisite decision tools for sound pest management decisions of B. tabaci on these vegetable crops. The information obtained from this investigation would be quite relevant for extension service and pest management practitioners where mixed vegetable farming is a common practice.
文摘Fields experiments were conducted at the Department of Crop Protection, Faculty of Agriculture, University of Maiduguri Teaching and Research Farm, Maiduguri during 2010 and 2011 cropping seasons to investigate the effects of intercropping pattern on stem borer pest infestation in pearl millet (Pennisetum glaucum L.) intercropped with ground nut (Arachis hypogea L.). A split-plot design was used to test the intercrop pattern of 1:0 ratio (sole millet), 1:1 ratio (1 millet row to 1 ground nut row), 2:1 ratio (2 millet rows to 1 ground nut row) and 1:2 ratio (1 millet row to 2 ground nut rows). The results obtained showed that the intercrop pattern of 1:2 ratio and 1:1 ratio yielded less stem borer infestation and abundance in pearl millet, and as well supported high panicle weight and grain yield. In addition to recommending either of these two intercropping patterns to pearl millet farmers for more effective stem borer pest management, results further show the need for identification of effective intercropping patterns in other cropping systems.
文摘The use of plant extracts as insecticides against vector insects serves as a perfect alternative to conventional methods.This study was carried out to assess the chemical composition and efficacy of Chromolaena odorata L.and Ocimum gratissimum L.in the control of adult houseflies.C.odorata and O.gratissimum were extracted with cold water and applied at four concentrations(5,10,40 and 100%v/v)in different bioassays(contact,fumigant and feeding-deterrent).A synthetic insecticide(Lambdacyhalothrin)and an untreated control were included in the treatments.The treatments were arranged in a completely randomized design with three replicates.The phytochemical compositions of the tested plant extracts were determined via gas chromatography‒mass spectrometry(GC‒MS).Mortality data were recorded at the stipulated times(1,2,4,6,8 and 24 h),and the means were separated via Duncan’s multiple range test at a 5%probability.GC‒MS revealed different chemical compounds,and eugenol,n-hexadecanoic acid,caryophyllene,phytol,humulene,9,12,15-octadecatrienoic acid,(Z,Z,Z)-,squalene,and stigmasterol compounds,among others,were identified as active insecticidal compounds.The tested plant extracts were effective against the studied insects,which suggested synergistic action of the observed natural chemicals in the plant extracts used.Moreover,the two plant extracts did not kill the studied insects faster than the synthetic insecticide did,but 100%mortality was observed after 12 h of exposure to the plant extracts.The mode of application and concentration played a significant role in the toxicity of the plant extracts,with the feeding mode of application resulting in greater toxicity effects than the fumigant and contact bioassays at the highest concentration.However,O.gratissimum exhibited better insecticidal control than C.odorata extracts did.Therefore,the use of crude plant extracts as insecticides could serve as substitutes for lambdachyalothrin in the control of houseflies,especially in animal rearing facilities and in the human population.
文摘Floral structures of six cowpea （Vigna unguiculata） cultivars were analysed for secondary plant metabolites （polyphenols, terpenoids and flavonoids） to study their relationships with resistance to Megalurothrips sjostedti （Trybom）. Polyphenols varied significantly （P 〈 0.001） among the floral structures of the cultivars at the same growth stage. Significant negative correlations were obtained between polyphenols and damage indices （r = -0.57）, mean adult counts （r = -0.56） and mean larval counts （r = -0.64） of resistant cowpea cultivars especially in the late season, indicating that polyphenols play a significant role in cowpea resistance to M. sjostedti. High levels of polyphenols obtained from Sanzibanili and Sewe cultivars, coupled with highly significant correlations between the polyphenols and thrips population on resistant cultivars, and their damage indices, suggests that these polyphenols could be inhibitors or deterrents in this case. Terpenoid extracts （10 mg/mL） of IT90K-277-2, Sewe, Sanzibanili, TVu 1509 and KV - 404-8-1 racemes; KV ~ 404-8-I and TVu 1509 floral buds; IT90K-277-2, Sewe and Sanzibanili flowers caused significant （P 〈 0.001） larval mortalities, since mortality ranged between 56.7%-96.7%. Hence terpenoid extracts from floral structures of the cultivars are biologically active and confers antibiotic resistance to M. sjostedti larvae; this compound could be promising candidates for genetic transformation of cowpea cultivars.
文摘Mutagenesis is used for creating new genetic variability in cultivar improvement. Optimal mutagenic treatment is required for effective mutation induction in crop species. Therefore, radio-sensitivity of cowpea accessions to gamma irradiation was investigated. Seeds of eight cowpea accessions were irradiated with <sup>60</sup>Co gamma radiation doses of 100, 200, 300, 400 and 500 Gy. The seeds were sown in pots to evaluate the treatment effects on seed germination (SG), seedling survival (SS) and growth habits of M1 generation. Data were analyzed using descriptive statistics. Low rates of SG (10% - 45%) were recorded at higher doses (500 - 400 Gy) in Ife Brown (IB) and its derivatives, whereas high SG rates (74% - 94%) were observed in IT90K-284-2 across all treatments. Percentage SS was inversely related to gamma dosage. A wide range of LD<sub>50</sub> for SG (329 - 1054 Gy) and SS (149 - 620 Gy) were observed across the cowpea accessions. Low LD<sub>50</sub> scores for SG (329 - 516 Gy) and SS (149 - 357 Gy) were observed among cowpea with rough seed coat, whereas cowpea with smooth seed coat recorded higher LD<sub>50</sub> for SG (521 and 1054 Gy) and SS (449 and 620 Gy). Seed germination LD<sub>50</sub> and SS LD<sub>50</sub> were highly correlated with mean coat thickness (0.899 and 0.937) than mean seed weight (0.621 and 0.678). Gamma irradiation of cowpea seed at low dosage (100 Gy) increased the vigor of M<sub>1</sub> seedlings with respect to primary leaf area, terminal leaflet area, seedling height and plant height at six weeks. Doses of 200 Gy and above resulted in a progressive reduction in vigor of plant and seed setting of cowpea. Radio-sensitivity varied with cowpea genotype and was associated with seed testa texture, thickness and seed weight. Low gamma irradiation treatment (100 Gy) may be used to enhance seedling vigor, vegetative growth and yield of cowpea at M<sub>1</sub> generation.
文摘Pod-sucking bugs (PSBs) infestation by Ano-plocnemissp./ Riptortussp./Clavigrallasp./Nezaraviridula( Linnaeus) greatly limits cowpea (Vignaunguiculata (L.) Walp) production throughout sub-Saharan Africa. The efficacy of aqueous leaf extracts (ALEs) (5 percent weight/volume concentration) of three botanicals and one synthetic insecticide against PSBs infestation was thus evaluated. The botanicals tested include Aza- dirachtaindicaA. Juss, Chromolaenaodorata (L.) and Ricinuscommunis (L.), whilst the synthetic insecticide was Uppercot 500 EC ( Lambda cyhalothrin 30 g + Dimethoate 250 g ). The effects of these treatments on the number of PSBs/ pods/seeds, pod/seed weight and grain yield were assessed during 2008 and 2009 rainy seasons in Bayo, Borno State, Guinea Savanna region, Nigeria. The number of PSBs was lower on crops treated with Uppercot 500 EC (0.00 - 0.31). This was followed by crops treated with the ALEs ofA.indica/C.odorata (0.31 - 1.33) and R.communis (0.72 - 3.72) than the untreated (3.06 - 5.64) ones.The number of pods/pod weight per plant, seeds/seed weight per pod and total grain yield were generally higher on cowpea crops treated with Uppercot 500 EC (26/17 g, 14/19 g and 1618 kg). This was followed bycrops treated with the ALEs of A.indica/C.odorata (23 - 25/14 - 15 g, 12 - 13/15 g and 1268 - 1310 kg) and R.communis( 21/13 g, 11/14 g and 972 kg) than the untreated (16/9 g, 7/10 g and 312 kg) ones. Although Uppercot 500 EC was most effective inprotecting cowpea against PSBs attack, theALEs of A.indica and C.odorata appreciably protected treated crops against infestation, giving relatively high total grain yield. Both botanical scan thus serve as alternatives to synthetic insecticides for managing PSBs attack on cowpea.
文摘Compost has been used to stabilise lead (Pb) in soil. However, compost contains a high level of dissolved organic matter (DOM) which may make Pb bioavailable in plant and thereby limiting its effectiveness and application. Addition of biochar to compost can reduce this effect. Rice husk (RH) and Cashew nut shell (CNS) biochars and compost-modified biochars were used in comparison to compost for stabilizing Pb in lead smelting slag (LSS)-contaminated soil (Pb = 18,300 mg/kg) in Nigeria. Efficiency of Pb stabilisation in control and amended soils was assessed using CaCl2 batch leaching experiment and plant performance. In pot experiments, maize plant was grown on the contaminated soil and on soil treated with minimum and optimum doses of the amendments singly and in combination for 6 weeks. Agronomical and chemical parameters of the plants were measured. CaCl2-extractable Pb in the untreated soil was reduced from 60 mg/kg to 0.55 mg/kg in RHB amended soils and non-detectable in other amended soils. RH-biochar/compost increased plant height, number of leaf and leaf area more than the others. Similarly, at minimum rate, it reduced root and shoot Pb by 91% and 86.0% respectively. Compost-modified rice husk biocharstabilised Pb in lead smelting slag contaminated soil reduced Pb plant uptake and improved plant growth. Lead stabilisation through the use of rice husk biochar with compost may be a green method for remediation of lead smelting slag-contaminated soil.
文摘This study determined the effects of initial infestation of cowpea seeds （Ife brown variety） with different insect densities （0, 2, 4 and 6 pairs per 50 g seeds） of Callosobruchus maculatus （F.） and evaluated the effects of aqueous leaf extract of Nicotiana tabacum L. on C. maculatus in the laboratory. It was observed that adult beetle population increased significantly （p〈0.05） with increase in insect density. The increase in population of beetles and corresponding weight loss of the seeds in different levels of infestation showed that the cowpea variety was susceptible to beetle infestation, emergence and survival of progeny. Significantly more adults emerged on higher infestation compared to lower and no infestation. In Nigeria, Nicotiana tabacum L. is a locally available plant, with known insecticidal properties. The plant leaf extract was easily extracted with water and confirmed its effectiveness as a protective agent for stored cowpea seeds. Experiment was conducted to assess the effects of aqueous extracts ofN. tabacum at 0, 0.1, 0.2 and 0.3 mL＂ 50 g-1 cowpea seeds on C. maculatus. Data was recorded and showed varying levels of effectiveness against C. maculatus. Result showed that seed appearance was dependent on levels of insect population, while N. tabacum aqueous extract exerted effects on survival of C. maculatus. Aqueous leaf extract of N. tabacum probably contained some insecticidal properties which might have significantly conferred beetle mortality and reduced beetle emergence leading to a decrease in seed weight loss.
基金funded by the National Natural Science Foundation of China(31772142)the Research Foundation for Ph D of the Graduate School of Chinese Academy of Agricultural Sciences,China(2018Y90100033)the Special Fund for Agro-Scientific Research in the Public Interest of China(210503114)。
文摘Stunt nematodes(Tylenchorhynchus spp.)are obligate migratory root ecto-parasitic nematodes found in the fields of many cultivated crops.These nematodes,with phyto-sanitary potential,are frequently ignored or misdiagnosed as pests,and this may pose a threat to food security.The accuracy of its identification based on a morphological approach has been challenged recently,due to the overlapping of the morphological and morphometric characters of the species.Consequently,the objective of this study is to identify and characterize stunt nematodes present in 54 fields cultivated with cereal crops(wheat,maize and rice)in the savannahs of northern Nigeria,using integrative taxonomy and molecular approaches.The molecular and morphological studies identified and confirmed the presence of T.annulatus as the occurring specie in the savannahs of northern Nigeria.The phylogenetic analysis was carried out using the internal transcribed spacer(ITS)and 28S genes of ribosomal DNA further confirmed the presence of T.annulatus.The first molecular characterization and sequences of the ITS and 28S rDNA gene for T.annulatus from Nigeria were provided by this research.Also,according to our literature search,this is the first report on T.annulatus in wheat,maize and rice in the savannahs of northern Nigeria.Further study to test the pathogenicity of the parasitic nematode species found in this survey is recommended for the prioritization and development of efficient management strategies.
文摘An investigation of effect of Latana camara, Tephrosia vogelii and Zingiber officinale applied at 5%, 10% and 25% concentrations on flea beetle of cabbage was conducted on the Teaching and Research Farm of the Ladoke Akintola University of Technology Ogbomoso in the early seasons of 2011 and 2012. The experiment consisted of 11 treatments laid in a Randomized Complete Block Design （RCBD） with three replications. Data were subjected to analysis of variance and significant means were compared using the Least Significant Difference （LSD） at p〈0.05. All the tested plant extracts exhibited moderate efficacy in the control of flea beetle. The treatment plant extracts performed as well as synthetic insecticides （0.76±0.05 and 0.76±0.05, respectively）. It was discovered that 25% w/v of Z. officinale gave the best yield of 0.50 kg · hm-2. The result showed that extract of T. vogelii （0.71±0.00） and L. camara （0.96±0.23） could suppress flea beetle population at different hours of spraying, while Z. officinale showed an effect at 48 HAS （0.71±0.00） and 72 HAS （0.76±0.05） alter spraying.
文摘The insecticidal potential of seed powders of Capsicum chinense Jacq. （Solanaceae） and Aframomum melegueta K. Schum. （Zingiberaceae） was tested against Trogoderma granarium （Coleoptera： Dermestidae） in the laboratory at （28±2）℃ and 70%± 5% relative humidity. The seed powders were tested at the rates of 0.0%, 0.5%, 1.0% and 1.5% （w/w） of groundnut seeds replicated three times. At the highest rate of treatment, C. chinense caused 56.7% and 76.8% larval mortality at 3 and 7 days post treatment （DPT） respectively while A. melegueta exerted 53.4% and 73.8% larval mortality at 3 and 7 DPT, respectively. Results showed that insecticidal potential of the seed powders against adult mortality of T. granarium and seed damage followed similar trend. The various rates of C. chinense seed powder performed better than .4. melegueta seed powder in causing larval and adult mortality and in reducing seed damage. The activity of the seed powders on mortality of the insect, seed weight loss and seed damage were exposure time and rate dependent. A significant reduction （p〈0.05） in seed weight loss and seed damage was recorded among the treatments and maximum reduction was observed in the seeds treated with the highest rate of C. chinense seed powder. Percentage seed damage significantly （p〈0.05） decreased with increase in the rate of treatment while the highest seed weight loss and seed damage were obtained in the control. The study showed that C. chinense seed powder had higher activity against the test insect pest than .4. melegueta seed powder. The two seed powders had high bio-activity against the insect and therefore could be used in formulating environment friendly plant-derived insecticide.
文摘A study was carried out to determine the relative susceptibility of six maize(Zea mays L.) varieties to maize weevil,Sitophilus zeamais Motschulsky(Coleoptera: Curculionidae). It was conducted at Department of Crop Protection Laboratory,University of Ilorin, Nigeria at ambient temperature of 28±2℃ and 68%±3% relative humidity. Samples of the varieties were infestedwith five pairs of S. zeamais adults in their respective containers arranged in completely randomized design with three replications.Data were collected on moisture content, adult mortality, adult emergence, grain loss and grain damage. The index of susceptibilityand means of damage parameters were used to determine susceptibility of the maize varieties. The results showed that 2008 SYNEE W DT STR was highly resistant and 2004 TZE-W POP STR C4 was moderately resistant, while 2004 TZE-Y-POP STR C4,99 TZEE-Y-STR, EV99 QPM and TZE-Y-POP DT STR QPM C_0S1 were susceptible. Under artificial infestation, the weevils hadsignificantly longer survival period in the susceptible varieties than those in the resistant genotype. It could be concluded that thesusceptible varieties already released to farmers should be protected from maize weevil damage.
基金financially supported by the National Natural Science Foundation of China(31972247)the Science and Technology Innovation Project of the Chinese Academy of Agricultural Sciences(ASTIP-2016-IPP-04)the Special Fund for Agro-scientific Research in the Public Interest,China(201503114)。
文摘Heterodera filipjevi continues to be a major threat to wheat production worldwide.Rapid detection and quantification of cyst nematodes are essential for more effective control against this nematode disease.In the present study,a TaqManminor groove binder(TaqMan-MGB)probe-based fluorescence quantitative real-time PCR(qPCR)was successfully developed and used for quantifying H.filipjevi from DNA extracts of soil.The primers and probe designed from the obtained RAPD-SCAR marker fragments of H.filipjevi showed high specificity to H.filipjevi using DNA from isolatesconfirmed species of 23 Heterodera spp.,1 Globodera spp.and 3 Pratylenchus spp.The qPCR assay is highly sensitive and provides improved H.filipjevi detection sensitivity of as low as 4^(-3) single second-stage juvenile(J2)DNAs,10^(-3) female DNAs,and 0.01μgμL^(-1) genomic DNAs.A standard curve relating to the threshold cycle and log values of nematode numbers was generated and validated from artificially infested soils and was used to quantify H.filipjevi in naturally infested field soils.There was a high correlation between the H.filipjevi numbers estimated from 32 naturally infested field soils by both conventional methods and the numbers quantified using the qPCR assay.qPCR potentially provides a useful platform for the efficient detection and quantification of H.filipjevi directly from field soils and to quantify this species directly from DNA extracts of field soils.
文摘A laboratory experiment was carried out to determine the response of six groundnut varieties to infestation by larvae of Trogoderma granarium Everts （Coleoptera： Dermestidae） and their nutritional constituents. The improved groundnut varieties used included SAMNUT 10, RMP-91, SAMNUT 19, SAMNUT 23, EX-DAKAR and RRB. The crude fat content varied significantly among the varieties from 32.7% to 53.1% in EX-DAKAR and RRB, respectively. The seed varieties were not significantly different in crude protein, ash and moisture content. The moisture content ranged between 6.6% and 8.9% in EX-DAKAR and SAMNUT 19 varieties, respectively. The crude protein content ranged between 19.7% and 31.3% in SAMNUT 19 and EX-DAKAR, respectively. The ash content varied between 3.0% and 7.4% in RRB and RMP-91 varieties, respectively. The results showed that the seeds were attacked by the 4th instar larvae of T. granarium as indicated by percentage seed weight damage, seed weight loss and dust production. SAMNUT 10 variety had the least seed damage of 33.1%, 41.4% and 43.7% in 1 month, 2 and 3 months post-infestation. In view of the damage, it was evident that SAMNUT 10 variety had the least percent seed damage and loss suggesting the possible inclusion of the variety in breeding programme against the insect pest.
文摘The cotton leafworm is an important defoliating pest of cotton in Brazil, and occurs in all regions where the crop is cultivated. The purpose of this study was to evaluate the effect of larval densities of A. argillacea after different infestation periods on the yield components of four cotton cultivars. The experiment was carried out in Pindorama, SP, Brazil, in the 2008/2009 growing season. The cultivars IAC-25, DeltaOPAL, Fibermax 966 and Fibermax 993 were artificially infested with A. argillacea larvae at three times (30, 60 and 90 DAE) and four densities (0, 2, 4, and 6 larvae per plant). The average boll weight (g), fiber percentage (%), 100-seed weight (g) and yield (kg·ha-1) were evaluated. With increasing infestation density of A. argillacea, the cotton yield of the cultivars decreased. The presence of larvae significantly reduced the weight of 100 seeds of cultivar Fibermax 966. Initial infestations reduced the boll weight of IAC-25 and DeltaOPAL, while cultivars Fibermax 966 and Fibermax 993 were most affected by late infestations. Early infestation compromised fiber percentage of cultivar DeltaOPAL and late infestations were most harmful to cultivar Fibermax 966. Early A. argillacea infestation reduced the yield of DeltaOPAL, while infestations 60 DAE caused the most damage to IAC-25, and the other cultivars were not affected by the moment of infestation.
文摘Environmental factors such as relative humidity and rainfall generally have been found to increase the incidence, rate of spread and severity of diseases thereby reducing yield of crops. Study was conducted on five cotton varieties, which were artificially inoculated with bacterial blight pathogen to determine the effects of rainfall and relative humidity on incidence and severity of angular leaf spot (ALS) and yield of seed cotton in Yola and Mubi. Results showed that the severity of ALS was higher in Yola (58.65%) at 13 WAS assumed to be due to higher relative humidity range of 76% - 87% and low rainfall of 2 - 40.6 mm. This is assumed to have favoured disease development as against that of Mubi location which recorded lower severity (51.11%) due to lower relative humidity (42% - 55%) and rainfall (37 - 73 mm). Results further revealed that at 13 WAS, SAMCOT-8 had low incidence (66%) and severity (39%) in Yola. This was against the much higher corresponding incidence and severity of 82% and 42% respectively that was observed in Mubi during the same period. SAMCOT-10 and SAMCOT-9 varieties were found to be highly susceptible to the disease at the same period. SAMCOT-8 recorded the highest yield of 390.00 kg?ha?1 in Yola and 868.09 kg?ha?1 in Mubi while the lowest yields of 227.17 kg?ha?1 was observed on SAMCOT-10 in Yola while 461.61 kg?ha?1 was obtained on SAMCOT-9 in Mubi. The variation in yield among these varieties might be due to the differences in their reactions to the disease. There is a need to conduct further trials in these locations to confirm the level of resistance or other aspects of these varieties to the disease.
文摘Application of inorganic fertilizers improves crop yields but costs and adverse health effects often discourage their applications. This study therefore aims at evaluating the combined effects of cassava peel compost with poultry manure and mineral fertilizer on growth and yields of Corchorus olitorius. Pots （factorial laid out in a randomized complete block design） and field （split-plot with fertilizer being the main effect and the varieties the sub plot effect） experiments were carried out during rainy season at Ibadan, Nigeria. Treatments consisted of 0, 5, l0 and 20 t/ha composts prepared from cassava peel and poultry manure in ratio 3：1 and mineral fertilizer （NPK 15：15：15） at the rate of 250 kg/ha, using two varieties of C. olitorius. Five and six weeks after planting （WAP）, plants were assessed for growth and yields in pot and field experiments respectively, and also in residual studies. Application of compost significantly improved growth （heights） （36.50-41.56 cm）, while morphological and dry weight values increased with increase in compost. Marketable yield increase of 13.2%, 22.3%, 32.1% and 29.3% were recorded using 5, 10, 20 t/ha compost and NPK fertilizer respectively in the field. Corresponding increase when ratooned were 40.0%, 42.9%, 57.1% and 52.0%, respectively. Application of compost at the rate of 20 t/ha performed better in the main and residual effect experiments compared to NPK fertilizer and other compost rates. Application of cassavas peels compost at the rate of 20 t/ha proved to be adequate for optimum growth and yield performance of C. olitorius.
文摘Genetic diversity evaluation of mutant lines is essential to facilitate their conservation and utility in breeding programs. Characterization of plant genotypes using morphological markers has limitations which make the procedure inefficient. Application of molecular tools for characterization and diversity assessment has been found useful to complement phenotypic evaluation of plant population. Therefore genetic diversity of some cowpea mutant lines was studied using simple sequence repeats (SSR) markers. DNA barcoding marker, ribulose-1,5-bisphosphate carboxylase(rbcL) of the chloroplast DNA (cpDNA) was also used for characterization and identification of the mutants to species level. The mean polymorphic information content (0.51) obtained from the microsatellites showed high polymorphism in accessing wide genetic diversity among the mutants and their parents. Dendrogram generated revealed 8 groups with most mutants clustered separately from their parents. Sequence analysis revealed insertions/deletions (InDels) and base substitutions as the two main classes of mutations induced in the plastid DNA of the mutants studied. The nucleotide frequencies were 26.95% (A), 34.43% (T), 24.09% (C) and 14.53% (G). A total of 61.38% AT rich region was identified, while GC rich region was found to be 38.62%. Highest rate of mutations were observed in region 3 - 4 indicating that the region is less conserved in cowpea rbcL gene. The present study proved that SSR markers are useful for the genetic diversity assessment of cowpea mutants. It also proved the efficiency of rbcL markers in mutants’ identification. The results indicate that the mutants are valuable genetic resources that have been developed to widen cowpea genetic base.
文摘An experiment was carried out to evaluate the fungitoxic effect of Trichoderma longibrachiatum (Rifai) metabolite on F. oxysporum, A. niger and A. tamarii. The fungi were collected from the International Institute of Tropical Agriculture (IITA) and Nigerian Institute of Science Laboratory Technology (NISLT). T. longibrachiatum was cultured on 1/4 strength Potato Dextrose Broth (PDB) following standard procedures. Its metabolite was extracted using 50 ml n-hexane with 50 ml Potato Dextrose Broth (PDB). The metabolite was purified by filter sterilization using a sterile 0.22 millipore filter disc after centrifuging at 900 rpm for 20 minutes. Petri plates of each fungus were later impregnated in triplicates with the T. longibrachiatum metabolites using four concentrations (10%, 25%, 50% and 100%), and three volumes (1 ml, 2 ml, and 3 ml). Petri plates of fungi without the metabolite and Petri Plates of fungi with n-hexane and PDB served as control. All Petri Plates were incubated at 28°C for 7 days. Radial and diametric growth of each fungus on all Petri Plates were taken daily at 24 hours intervals. Data obtained were analysed using SAS (version 9.3). Growth inhibition of F. oxysporum, A. niger and A. tamarii was significantly higher than in control in that order (P ≤ 0.05). Inhibition of the fungi by metabolites extracted with both PDB and n-hexane was significantly better than in control. Generally, inhibition by metabolite extracted with PDB was better than that extracted with n-hexane. Growth inhibition at all the concentrations of the metabolite was significantly better than in the control (P ≤ 0.05). Generally, inhibition at 100%, 50% and 25% concentrations was better than that at 10% concentration of the metabolite. Trichoderma longibrachiatum metabolite can thus be said to possess promising fungitoxic potential even at concentrations as low as 25%. Both PDB and n-hexane are good extraction media for the metabolite.
文摘In this study, some Eriophyid mite species showing different morphological characters and host-plant symptoms were obtained. Five mites species collected from different localities in Khartoum State （Sudan） during the period （2002-2003） which classified under family Eriophyidae from different hosts were selected and examined carefully. These were recognized as Cisaberoptus kenyae （K.） on Mango Mangifera indica, Acalitus hassani （K.） onArrak Salvadora persica, Aceria balanites （Massee） on Heglig Balanites aegyptiaca, Colomerus vitis on Grape Vitis sp. （for the first time in the Sudan） and Eriophyes tulipae （K.） on Onion Allium cepa and garlic Allium sativum respectively. The remaining six eriophyid mites were not completely described but designated as Eriophyes sp. 1, 2, 3, 4, 5 and 6 on Sidir Ziziphus spina, Aradeib Tamarindus indica, Harazz, Acacia albida, Talha Acacia seyal var. seyal, Seyal Acacia tortilis var. raddiana and Mormeet Pergia capensis respectively. The response of 12 different plant species infested artificially with Cisaberoptus kenyae （K.）, Acalitus hassani （K.） and Eriophyes tulipae （K.） were studied after two months of infestation. The results showed that onion and garlic plants were severely infested with Eriophyes tulipae （K.） while tomato was found to be susceptible for Cisaberoptus kenyae （K.） and Acalitus hassani （K.） showing moderate infestations. On the other hand, sorghum and wheat infested with Eriophyes tulipae （K.） showed moderate and light infestations respectively. On the contrary, mite infestations were not detected on the rest of plant species. The degree of infestation of Eriophyid mites species on different test plants, measured by symptoms appeared on plant leaves.
