Laboratory evaluation of freshly prepared juice from garlic (Allium sativum L.) Liliaceae as protectants against the maize weevil, Sitophilus zeamais (Motsch.) [Coleoptera: Curculionidae]

Fresh prepared garlic (Allium sativum L.) juice, containing the antimicrobial allicin, was evaluated as a possible grain protectant against the maize weevil, Sitophilus zeamais (Motsch.). Each experiment was set out in completely randomized design (CRD) with four replications and a control treatment. Adult mortality and percentage weight loss were investigated. There was an observed increase in adult mortality following days of exposure in all treatments. Statistically significant (P<0.05) reduced grain loss was also observed in all the treatments when compared with the control. The juice prepared from an indigenous Nigerian garlic cultivar (GUN) was more lethal (causing 93% adult mortality), when applied topically on the freshly emerged S. zeamais adults, compared to the juice prepared from a clove of garlic purchased at a supermarket in Germany (GAG). High performance liquid chromatography (HPLC) analysis indicated that the amount of allicin in GUN was 1883.2 μg/ml while that in GAG was 3500.93 μg/ml. This study highlights the potential of A. sativum containing allicin for biorational control of maize grains against S. zeamais infestation and damage. Keywords: Allicin, Allium sativum, biopesticide, biorational control, crop protectant, Sitophilus zeamais, stored productAfrican Journal of Biotechnology, Vol. 13(10), pp. 1123-1130, 5 March, 201

Effect of Cu AND Zn On Maize (Zea Mays L.) Yield and Nutrient Uptake in Coastal Plain Sand Derived Soils of Southeastern Nigeria

Micronutrients, which are often found to be lacking in coastal plain sand derived soils, can lead to higher crop yields in this area. The use of Cu and Zn as fertilizers could be a variable option to fulfill the demand for these elements and also to increase its contents in maize grains. In this study, laboratory, greenhouse and field studies were undertaken to investigate the status of Cu and Zn and to find out whether the addition of these nutrient elements would increase maize grain yields and yield components and also, remediate their constraints in coastal plain sand derived soil of southeastern Nigeria, for optimization of maize (Zea mays L.) yields. Dry matter yields, plant concentrations, plant uptake, and maize grain yield was used to evaluate the effects of Cu and Zn levels. In both the greenhouse and field experiments, hydrated Cu and Zn sulphate fertilizers were applied to the soils in separate experiments at seven levels (0, 2, 4, 6, 8, 10 and 12 kg ha-1) for Cu and Zn respectively. A recommended N, P, and K at rates of 120, 60, 30 kg ha-1, respectively, were also used as basal application. The status of available Cu and Zn by 0.1 HCl were found to be low in the soil. The application of Cu and Zn into the soils significantly (P<0.05) increased both maize DM and grain yields. Maximum grain yields and uptake in maize were established at 10 kg Cu ha-1 and 8 kg Zn ha-1, respectively. The estimated optimum rates for Cu and Zn under greenhouse environments were also established at 10 kg Cu ha-1 and 8 kg Zn ha-1, respectively. However, maize response curve showed that for optimum grain yield, concentration for Cu was determined to be 35.9 mg kg-1, while for Zn it was 32.1 mg kg-1. The current study showed that though the soils has a severe Cu and Zn deficiency, which could be due to their strong sorption capacity, and nutrients mining, due to intensive cropping, maize production can still be increased considerably in this soil and other similar soils in the same agroecological zone within a coastal plain sand derived soil by applying Cu and Zn at rates of 10 kg Cu ha-1 and 8 kg Zn ha-1, respectively

Characterization of two benchmark soils of contrasting parent materials in Abia State, Southeastern Nigeria

Detailed characterization of two important agricultural soils of contrasting parent materials, found in southeastern Nigeria was carried out. The Amakama soil formed over Coastal Plain Sands has a deep, well drained profile greater than 240cm deep. The soil texture varies from loamy sand in the surface layer to sandy clay loam down the profile. The Ibeku soil formed over Bende-Ameki (clay shale) formation has a deep profile that is gravelly in the upper 60cm and clayey in the lower horizons. Bulk density on oven dry basis ranged from 1.3 to 1.66 g cm-3 in the Ibeku soil and from 1.43 to1.52 g cm-3 in the Amakama soil. Water content at 33 kPa ranged from 13.7 to 14.9 in the Amakama soil and from 27.8 to 48.4 in the Ibeku soil. Chemically, the Amakama soil is deficient in basic cations with aluminum saturation being greater than 83%. The soils are very acidic (pH 4.5 – 4.9) and low in organic carbon, total nitrogen and available phosphorus. In contrast, the Ibeku soil has high levels of calcium, sum of basic cations that range from 9.2 to 23.5 cmol(+) kg-1 and aluminum saturation of 25 - 40%. Total nitrogen and organic carbon are medium and available phosphorus is low in this soil. The mineralogy of clay sized particles showed a dominance of kaolinite in both soils with some quantities of montmorillonite that increased down the profile. In the Ibeku soil, the mineralogy of coarse silt fractions showed that goethite and quartz were the dominant minerals in upper horizons (< 1 m) while potassium feldspar and goethite dominated the lower horizons. Amakama soil was classified as Fine loamy, siliceous, isohyperthermic, Rhodic Haplustox while Ajata –Ibeku soil was classified as very fine, kaolinitic, isohyperthermic, Aquertic Paleustalf.KEY WORDS: Benchmark soil, Mineralogy, Morphology, Soil properties

Enhanced root yield and β-carotene content of orange fleshed sweetpotato using integrated nutrient management

This study was conducted in 2014 and 2015planting season at the Research farm of National Root Crops Research Institute Umudike, southeastern, Nigeria to determine the effect of integrated nutrient management on root yield and total carotenoid content of orange fleshed sweetpotato. The experiment was a 5x4 factorial laid out in randomized complete block design (RCBD). The treatment comprises of five levels of composite manure (Pig manure, cowdung and poultry manure) applied at the rate of 0, 2, 4, 6 and 8t/ha and mineral fertilizer (NPK 15:15:15) applied at the rate of 0, 200, 400 and 600kg/ha. Combined application of mineral fertilizer and composite manure significantly (p&lt;0.05) increased the total and marketable root yield of orange fleshed sweetpotato. Application of 4t/ha composite manure + 400kg/ha NPK gave the highest mean root yield of 15.90t/ha relative to control. The β-content increased generally with increasing rate of the treatment combinations with application of 8t/ha composite manure + 200kg/ha NPK giving the highest β-carotenoid content of 733.2μg/g. Results of the regression analysis showed that Organic matter, total nitrogen, available phosphorous, effective cation exchange capacity and percentage base saturation are the major soil chemical properties that contributes to increase in the β-carotene content of the orange fleshed sweetpotato. From the results obtained, application of 4t/ha composite manure + 400kg/ha NPK is recommended for good root yield while application of 8t/ha composite manure + 200kg NPK is recommended for farmers who wish to improve the carotenoid content of orange fleshed sweetpotato.Keywords: Composite manure, mineral fertilizer, root yield, orange fleshed sweetpotato and carotenoi

Control of field insect pests of mung bean (<i>Vigna radiata</i> L. Wilczek) using some plant extracts in Umudike, Nigeria

Field trials were conducted at Umudike, Nigeria, during the 2015 and 2016 cropping seasons to determine the efficacy of plant extracts from seven plant species against field insect pests of mung bean, Vigna radiata L. Wilczek. The extracts tested were obtained from scent leaf (Ocimum gratissimum), neem leaf (Azadirachta indica), bitter leaf (Vernonia amygdalina), garlic (Allium sativum), turmeric (Curcuma longa), plantain (Musa paradisiaca) peel and Negro pepper (Xylopia aethiopica). Karate (Lambda-cyhalothrin EC) at 50 mL was introduced as a check in the trials. The experimental design was a randomised complete block design (RCBD) with three replicates. Data were collected weekly on the insect population densities, yield and yield components. The results indicated that all the treatments were effective against mung bean insect pests (Aphis craccivora [aphid], Bemisia tabaci [whitefly], Amrasca biguttula biguttula [jassid] and Zonocerus variegatus[grasshopper]). There was a significant (p ≤ 0.05) reduction in the population of insects on the plots treated with plant extracts and karate in 2015 and 2016 cropping seasons. The population densities of grasshoppers in 2015 and whitefly in 2016 were significantly lower in the treated plots compared with the control plots. Azadirachta indica and C. longa extracts recorded the highest seed yield of 50.00 kg/ha and 42.33 kg/ha in 2015 and 2016, respectively. No significant differences were observed between the plant extracts and karate, which recorded significantly higher yields when compared with the control (23.30 kg/ha). All the plant extracts used exhibited insecticidal activity against the insect pests of mung bean. It is, therefore, recommended that these plant extracts can be used for the control of mung bean insect pests to achieve sustainable production, food security and quality

EFFECT OF RELATIVE SOWING TIME ON GROWTH AND YIELD OF VEGETABLE COWPEA (VIGNA UNGUICULATA (L.) WALP) AND MAIZE (ZEA MAYS L.) IN VEGETABLE COWPEA/MAIZE INTERCROPPING SYSTEM

Improved varieties of both vegetable cowpea (IT92KD-263-4-1) and maize (OBA 98) were grown in mixture at Michael Okpara University of Agriculture, Umudike research farm for two cropping seasons (2006 and 2007) in order to determine the suitable relative sowing time of the component crops. The experiment was laid out in a randomized complete block design and with three replicates. The treatments were vegetable cowpea and maize separately planted in their pure stands, vegetable cowpea and maize simultaneously sown on the same day, vegetable cowpea sown 2, 3, 4 weeks before maize and vegetable cowpea introduced 2, 3 and 4 weeks after maize was sown. Widest leaf area, heaviest total aboveground dry matter and nodules per plant of vegetable cowpea were attributed to the vegetable cowpea sown 4 weeks before maize. Similarly, maize leaf area index, aboveground dry matter, number of grains per cob, 100-seed weight and grain yield per hectare were highest when maize was sown 4 weeks before introducing vegetable cowpea. The highest LER of 1.61 and 1.58 in 2006 and 2007, respectively were attributed to the vegetable cowpea sown 4 weeks after maize. It was therefore, recommended that the resource poor rural farmers should introduce the vegetable cowpea 4 weeks after sowing the maize seeds since they usually target the combined yield from the component crops of the farmlandÂ

New ‘stimuli-enriched’ laboratory bioassay used to identify improved botanical repellent treatment, Lem-ocimum, to control the stored-grain pest Tribolium castaneum

A laboratory study of Tribolium castaneum, a major pest of stored grain, was conducted to develop a more efficient and effective ‘choice’ bioassay for identification of new repellent botanical treatments. Standard bioassays to test the repellency of candidate plants include pit-fall traps and open arena choice tests, environments lacking in some of the most important natural stimuli that guide the movement of food-searching beetles, e.g., 1) materials they can burrow through, which stimulate ‘positive thigmotaxis’, 2) a range of light and dark areas, which stimulate ‘negative phototaxis’ and 3) three-dimensional habitats, which stimulate ‘positive geotaxis.’ The lack of these stimuli can lead to two common problems; ‘low efficiency’ (high proportion of beetles remain in the area that surrounds treatments without making a ‘choice’), and ‘low efficacy’ (high variability in proportions found in control and treated samples). The new ‘stimuli-enriched’ bioassay, which included all three of the above stimuli, was significantly more efficient (P < 0.0001) and effective than three standard bioassays. The stimuli-enriched bioassay was used to compare the repellency of four candidate plants; Ocimum basilicum (Sweet Basil) and Cymbopogon nardus (Lemongrass) were significantly more repellent than Vernonia amygdalina or Nauclea diderrichii (Tukey Contrasts; P < 0.01). A novel method of applying repellent material (a paste of repellent plant is applied between the layers of double bagged grain) was tested on the most promising repellent plants materials; a combination of C. nardus and O. basilicum (‘Lem-ocimum’) at 0.5% w/w of each was significantly more effective than O. basilicum on its own (Tukey Contrasts; P < 0.05). These results show that the stimuli-enriched bioassay provides more consistent and accurate assessments than the standard bioassays of the repellency of candidate botanicals, and that Lem-ocimum treated double-bags are a promising new method of protecting sorghum from T. castaneum

Pesticidal plant extracts improve yield and reduce insect pests on legume crops without harming beneficial arthropods

In the fight against arthropod crop pests using plant secondary metabolites, most research has focussed on the identification of bioactive molecules. Several hundred candidate plant species and compounds are now known to have pesticidal properties against a range of arthropod pest species. Despite this growing body of research, few natural products are commercialised for pest management whilst on-farm use of existing botanically-based pesticides remains a small, but growing, component of crop protection practice. Uptake of natural pesticides is at least partly constrained by limited data on the trade-offs of their use on farm. The research presented here assessed the potential trade-offs of using pesticidal plant extracts on legume crop yields and the regulating ecosystem services of natural pests enemies. The application of six established pesticidal plants (Bidens pilosa, Lantana camara, Lippia javanica, Tephrosia vogelii, Tithonia diversifolia and Vernonia amygdalina) were compared to positive and negative controls for their impact on yields of bean (Phaseolus vulgaris), cowpea (Vigna unguiculata) and pigeon pea (Cajanus cajan) crops and the abundance of key indicator pest and predatory arthropod species. Analysis of field trials showed that pesticidal plant treatments often resulted in crop yields that were comparable to the use of a synthetic pesticide (lambda-cyhalothrin). The best-performing plant species were Tephrosia vogelii, Tithonia diversifolia and Lippia javanica. The abundance of pests was very low when using the synthetic pesticide, whilst the plant extracts generally had a higher number of pests than the synthetic but lower numbers than observed on the negative controls. Beneficial arthropod numbers were low with synthetic treated crops, whereas the pesticidal plant treatments appeared to have little effect on beneficials when compared to the negative controls. The outcomes of this research suggest that using extracts of pesticidal plants to control pests can be as effective as synthetic insecticides in terms of crop yields while tritrophic effects were reduced, conserving the non-target arthropods that provide important ecosystem services such as pollination and pest regulation. Thus managing crop pests using plant secondary metabolites can be more easily integrated in to agro-ecologically sustainable crop production systems