Removal of Cu2+ and Cd2+ from Aqueous Solution by Bentonite Clay Modified with Binary Mixture of Goethite and Humic Acid

Pre-modification of bentonite clay with goethite, humic acid, and a binary mixture of goethite and humic acid reagents increased its cation exchange capacity from 95 to 105.32, 120.4, and 125.8 meq/100 g of bentonite clay, respectively. The effective pre-modification of bentonite clay with goethite, humic acid, and goethite–humic acid reagents was confirmed from their Fourier transform infrared spectra which suggested that modification was effective on the AlAlOH and Si–O sites for goethite and humic acid modification and AlAlOH for goethite–humic acid modification. The presence of 0.001 M NaNO₃ electrolyte increased the adsorption capacity of bentonite clay. Temperature was observed to favor the adsorption of Cu²⁺ and Cd²⁺ onto both the raw and modified bentonite clay samples. The goethite–humic acid-modified bentonite gave the best adsorption capacity of ≈10 and 16 mg/g at 30 and 50°C, respectively, for both metal ions. The inner sphere complexation mechanism was suggested for the adsorption of both metal ions onto the modified adsorbents. Modifying bentonite clay with a binary mixture of goethite and humic acid reduced the selectivity of bentonite clay for either Cu²⁺ or Cd²⁺. Preadsorbed goethite and humic acid on bentonite clay will further reduce the mobility of heavy metal ions in soils and in aquatic environments.     

Host–pathogen interaction of maize (Zea mays L.) and Aspergillus niger as influenced by arbuscular mycorrhizal fungi (Glomus deserticola)

This study was carried out to investigate the interaction of maize and Aspergillus niger as influenced by arbuscular mycorrhizal fungi (AMF). Three quality protein maize (QPM) genotypes (ILE1-OB, ART-98-SW5-OB and ART-98-SW6-OB) and two market accessions (Ilishan and Shagamu) were evaluated in a pot experiment conducted under natural environment conditions at the Research and Teaching Farm of Babcock University, Ogun State, Nigeria. AMF (Glomus deserticola) in mixtures of soil and root fragments was inoculated at the rate of 15 g per plant, while maize was artificially infected with A. niger (15 cfu ml^?1) in each designated pots. The coefficient of emergence (COV), percentage emergence (% E) and disease severity were determined using standard methods. Generally, plants treated with AMF only produced the highest cumulative cob yield (18 g), followed by plants treated with AMF and A. niger (15 g) and then control (12 g), while the least was recorded for only A. niger-treated plants (4 g).     

Control of common bacterial blight disease of cowpea (Vigna unguiculata [L.] Walp) with certain plant extracts in Abeokuta,Nigeria

Common bacterial blight disease of cowpea, caused by Xanthomonas axonopodis pv phaseoli, has been identified as the most important biotic constraint to cowpea production worldwide. Continuous and indiscriminate application of chemical pesticides has necessitated the search for an environment friendly method of control. Azadirachta indica (neem), Acalypha wilkisiana (red acalypha) and Carica papaya (pawpaw) extracts were field-tested against common bacterial blight disease. The experiment was laid out as a randomized complete-block design (RCBD) with three replicates. Cold extracts of 6.67% concentration of the plant leaves were sprayed on cowpea (variety ‘Ife brown’) foliage. Streptomycin sulfate of 0.2% concentration was applied as a positive control and sterile distilled water as a negative control. Incidence of common bacterial blight ranged from 20.00 to 43.74% and severity from 1.02 to 2.00 on a 1–6 scale, where 1 = no symptoms of common bacterial blight and 6 = necrotic lesions on more than 75% of the leaf area. A combination of extracts of pawpaw, neem and red acalypha reduced disease incidence by 73.68% and improved yield by 1.58 tons/ha (a 73.49% increase) compared with untreated control. Azadirachta indica, Acalypha wilkisiana and Carica papaya extracts, both singly and in combination (Pawpaw + neem + Acalypha, Pawpaw + neem, Pawpaw + Acalypha and neem + Acalypha), reduced incidence and severity of common bacterial blight disease and increased yield of cowpea. Thus, these plant extracts could serve as viable alternative to synthetic chemicals to control Xanthomonas-caused diseases in cowpea.     

Use of Aqueous Extracts of Avocado Pear,Pyrus Communis,Leaf as Anaesthetic in Gonadectomy of African Catfish,Clarias gariepinus

This study was carried out to determine the efficacy and effective concentration of avocado pear (Pyrus communis) leaf extract as an anaesthetic in gonadectomy of Clarias gariepinus broodstocks. Fresh avocado leaves were harvested, water extracted, and applied at 0 (control), 100, 130, 160, and 190ml/l to C. gariepinus broodstocks. Onset of individual phases of anaesthesia and recovery rate was determined. Gonadectomy was then carried out on individual anaesthetized fish and the time taken was recorded. Aqueous extracts of avocado pear leaf at concentrations ranging from 130–190 ml/l induced general anaesthesia. The recovery rate was concentration-dependent but non-linear, with a significant threshold in efficacy between 130 and 190 ml/l. There was no mortality recorded during the experimental period. The effective concentration of avocado pear leaf extracts that best sustained the gonadectomy was 190 ml/l with a recovery time of 12 minutes.     

Effects of detoxified Jatropha curcas protein isolate on growth performance,nutrient digestibility and physio‐metabolic response of Labeo rohita fingerlings

Jatropha protein isolate was prepared following the principle of isoelectric precipitation. The isolated protein is low in fibre, lipid and ash, and high in protein and gross energy contents. The antinutritional factors such as phytic acid, tannin and trypsin inhibitor were found to decrease after protein extraction except phorbol esters (PEs), which remain bounded to the protein matrix. Thus, the protein isolate was detoxified and the PEs content reduced significantly. For the feeding trial, six isonitrogenous diets were formulated as DJP 0, DJP 25, DJP 50, DJP 75, DJP 100, or DJP 100 + lysine with detoxified Jatropha protein isolate (DJP) in replacement for soybean protein isolate (SPI) and fed to L. rohita fingerlings (3.25 ± 0.02 g) for 60 days. The weight gain percentage (WG %), specific growth rate and metabolic growth rate values among the groups showed no significant difference (p > .05), except DJP 100 fed group. The feed conversion ratio, protein efficiency ratio, protein productive value, and survival, digestive and hepatic aminotransferase enzymes activities were not significantly affected, whereas intestinal alkaline phosphatase and serum alanine transaminase differ significantly (p < .05). Thus, this study revealed that DJP supplemented with lysine could replace 100% SPI protein without causing any significant effects on fish performance and organ integrity.     

Agroforestry potential of Dacryodes edulis in the oil palm-cassava belt of southeastern Nigeria

Between June 1993 and June 1994, 112 farmers in the oil palm (Elaeis guineensis)-cassava (Manihot esclentus) belt of southeastern Nigeria were interviewed to determine the status and agroforestry potential of Dacryodes edulis. Between 50% and 100% of respondents in different states within the belt owned D. edulis trees. On average, a farmer owned 9.3 trees, the largest number being 16, by farmers in Imo State. Twenty percent of farmers in the system rated D. edulis their best farm tree. It was present in all the farm niches: homegardens (51.4%), tree crop plots (20.7%) food crop plots (11.4%), secondary forest/fallow (14.2%) and virgin forest (2.5%). The tree is planted primarily for home consumption and sale to generate cash. At the current densities, on-farm D. edulis trees generally did not decrease yield of companion crops or trees. Except for ring weeding around the stem, D. edulis trees received little or no management attention. More than 50% of the trees produced 33 to 50 kg of fruit tree⁻¹ annually. This is valued at US $0.4 to 0.8 kg⁻¹. Farmers were willing to plant more D. edulis trees provided trees with traits such as less height for easy harvesting of fruits, larger fruit, more fruits, sweeter fruits and year round production of fruits were available. Possible agroforestry technologies into which D. edulis may fit include live fences, scattered trees in food crop fields, shade trees in tree crop plots and contour bund or hedgerow planting. Research is required to determine best tree accessions, canopy management strategies, optimum tree population and improved methods on post- harvest handling of fruits. This revised version was published online in June 2006 with corrections to the Cover Date.     

Correlation of Chemical Compositions of Cassava Varieties to Their Resistance to Prostephanus truncatus Horn (Coleoptera: Bostrichidae)

The preference of cassava as a major host by Prostephanus truncatus Horn is a major constraint to ample production of cassava, Manihot esculenta Crantz and storage. This study analyzed the nutritional and secondary metabolite compositions in 15 cassava varieties, evaluated levels of damage and reproduction by P. truncatus, and assessed their resistance to attack. One hundred grams of dried cassava chips in 250-ml Kilner jars were infested with 10 adult larger grain borerof 0–10 days old and held for 3 months. The nutritional and secondary metabolites compositions of the dry cassava chips were determined using the method of Association of Analytical Chemists . Chip perforation rates in the cassava varieties ranged from 17.7 to 71.6%. The weight of cassava powder varied by about threefold. The final number of larger grain borer in the cassava varieties varied by about sixfold with 63 in 01/0040 and 379 in 01/1368. Hydrocyanic acid content content varied by over 10-fold and correlated negatively with number of larger grain borer. Flavonoid content varied by ∼10%. Tannins and saponin content of the cassava negatively correlated with number of adult P. truncatus. The cassava varieties 95/0166, 92/0326, 01/0040, 05/0024, and 34 91934 had selection index <0.8 and were classified as resistant to larger grain borer damage, while others with selection index >0.8 were classified as susceptible. The resistance to high damage in the resistant varieties was conferred by secondary metabolites such as tannins, saponins, alkaloids, and hydrocyanic acid content. The genetic variation in cassava varieties could be explored to breed resistant cassava varieties for use in larger grain borer-endemic areas.     

Determinants of stem form: Application to Tectona grandis (Linn. F) stands

ABSTRACT

Stem form information can enhance rapid estimation of stem volume. Studies on important determinants of stem form in pure stands are scanty. This study aimed at identifying determinants of stem form using Tectona grandis stands in Omo Forest Reserve, Nigeria. Twenty 0.04 ha square plots were randomly selected across four stand ages. Crown diameter, total and merchantable heights (MH), diameters at breast height (DBH), at 5.27 m tree height and at midpoint from breast height to tip of tree were measured in each plot. Measured trees were classified into four canopy layers (CL)—dominant, codominant, intermediate, and suppressed. Merchantable volume, basal area (BA), form factor (F_f), normal form quotient (Q_n), Girard form class (Q_G), absolute form quotient (Q_a), ratio of diameter at merchantable limit to diameter at the base (D_t/D_b), and tree slenderness coefficient were derived from the data. Analysis of variance, correlation, and regression analyses were used to analyze the data. Significant differences were observed in stem form and tree size variables under different canopy layers. The DBH, BA, MHT, and CL were identified as important variables associated with stem form. Inclusion of Q_a improved most the predictive ability of the selected stem volume equation.