Influence of humic acid derived from composted wastes of Nigeria origin on oxidative and antioxidant status of African mud catfish (Clarias gariepinus)

The utilization of organic fertilizer, a product of composted organic wastes, is being advocated in Nigeria as a solid waste management alternative. The application of such products near surface water could increase organic matter load of the aquatic environment, thus increasing the humic substance concentration that influence metal speciation and bioavailability in water. In this study, Humic Acid (HA), a major humic substance fraction, derived from composted organic wastes of Nigeria origin was evaluated for effects on the oxidative and antioxidant status of African Mud Catfish (Clarias gariepinus) exposed to different HA (100, 250, 500 and 1000 mg L(-1)) concentrations in static water culture. Lipid peroxidation was estimated via malondialdehyde (MDA) using thiobarbituric acid assay while oxidative stress was assessed spectrophotometrically, via superoxide dismutase (SOD), glutathione (GSH) and catalase (CAT) using standard enzymatic assay techniques. Results showed that treatments increased MDA by 20 to 70% but decreased SOD, CAT and GSH by 10 to 42.56%, 43.62 to 64.09% and 9.84 to 67.68%, respectively. Negative coefficient (r) was obtained for CAT (r = - 0.491; p > 0.10), GSH (r = - 0.551; p > 0.10) versus HA concentration but correlation was positive for MDA (r = 0.998; p = 0.012) and the latter. Study revealed humic acid-mediated oxidative stress and lipid oxidation in the fish. The adverse impact was a function of humic acid concentration and an assessment of heavy metal-humic acid mixture effect on the oxidative and antioxidant status of fresh water fish is recommended.     

Studies on multipurpose fodder trees and shrubs in West Africa: variation in determinants of forage quality in Albizia and Paraserianthes species

We investigated variation in forage production, in sacco dry matter (DM) and nitrogen (N) degradations, and in vitro gas production characteristics of four Albizia (A. lebbeck N 864, A. procera N 865, A. saman N 825) and Paraserianthes falcataria (N 783) provenances obtained from The Nitrogen Fixing Tree Association. After one year of establishment forage production was assessed by harvesting trees at 0.5 m above ground in the main wet (April–August) minor-wet (September–November) and dry (December–March) seasons at Ibadan, southwestern Nigeria. Forage samples from the main-wet and dry seasons were incubated for 6, 12, 48, 72 and 96 h in rumen-fistulated cattle to estimate in sacco DM and N degradation characteristics. In vitro gas production was estimated over 3, 6, 12, 24, 48, 72 and 96 h of incubation. Forage production of A. procera was significantly higher than the other species in all seasons. Cell-wall components were comparatively higher in A. procera than the other species. Potential DM and N degradations of A. lebbeck and A. saman were significantly higher than P. falcataria and A. procera. The results suggest that A. lebbeck and A. saman provenances used in this study have relatively higher feed value than A. procera and P. falcataria.     

Preliminary studies on the renaturation of denatured catfish (Clarias gariepinus) glutathione transferase

Purified juvenile catfish (Clarias gariepinus) glutathione transferase (cgGST) was denatured in vitro and renatured in the absence and presence of different concentrations of endogenous or xenobiotic model substrates. Protein transitions during unfolding and refolding were monitored by activity measurement as well as changes in protein conformation using UV difference spectra at 230 nm. Gdn-HCl at 0.22 M caused 50 % inactivation of the enzyme and at 1.1 M, the enzyme was completely unfolded. Refolding of cgGST main isozyme was not completely reversible at higher concentrations of Gdn-HCl and is dependent on protein concentration. An enzyme concentration of 30 μg/ml yielded 40 % percentage residual activity in the presence of glutathione (GSH), regardless of the concentration that was present as opposed to 30 % obtained in its absence. The xenobiotic model substrate, lindane, appears to have no effect on the refolding of the enzyme. In summary, our results show that GSH assists in the refolding of cgGST in a concentration-independent manner and may be involved in the same function in vivo whereas the xenobiotic model substrate does not.     

Genetic analysis of drought-adaptive traits at seedling stage in early-maturing maize inbred lines and field performance under stress conditions

Maize hybrids that are tolerant to drought at the seedling stage are needed to boost productivity in the rainforest agro-ecology of West Africa. Genetics of tolerance of maize seedling to drought stress is not well understood and is poorly documented. The objectives of this study were to screen early-maturing maize lines for seedling drought tolerance, determine the inheritance and the combining ability of selected inbred lines, and evaluate the performance of seedling drought-tolerant hybrids under field conditions. Forty-nine early maize lines were screened for drought tolerance at the seedling stage. Ten drought-tolerant and two susceptible inbred lines were selected and used in diallel crosses to generate 66 hybrids. The twelve inbred lines and their hybrids were evaluated under induced drought at seedling stage in the screen house and under marginal growing conditions on the field for two seasons. Data collected were subjected to analysis of variance using the DIALLEL-SAS program. Mean squares for both GCA and SCA were significant for most traits in all research environments, indicating that additive and non-additive gene actions are controlling seedling traits under stress conditions. However, for most traits, SCA was preponderant over GCA in all environments, indicating overdominating effect of non-additive gene action. Which in turn implied that the best improvement method for the traits is hybridization. Inbred TZEI 7 had the best GCA effect for seedling traits under screenhouse conditions and for grain yield and other agronomic traits under drought conditions in the field. Hybrids TZEI 357?×?TZEI 411 and TZEI 380?×?TZEI 410 showed superior SCA effects under screen house conditions. In conclusion, the study established wide genetic variability for drought tolerance at seedling stage among tropical early-maturing maize germplasm however, the non-additive gene action was more important for most seedling traits.     

Influence of Cocoa Pod Husk-Based Compost on Nutrient Uptake of Okra (Abelmoschus esculentus (L.) MOENCH) and soil properties on an Alfisol

This experiment evaluated the potentials of cocoa pod husk (CPH)-based compost on okra and soil chemical properties. Three CPH-based compost: CPH+ Neem leaf (CPH+ NL), CPH+ Poultry manure (CPH+ PM) and CPH+ PM+ NL were prepared. The treatments; 25, 50, 75, 100 kg N/ha of each compost and NPK mineral fertilizer at 40, 50, 60 kg N/ha and control, were applied to 5 kg soil each and arranged in a completely randomized design in three replicates. Two varieties of okra (NH47-4 and LD88) were grown for six weeks and residual effect evaluated. The Nitrogen, Phosphorus, and Potassium uptake of okra were determined. Pre- and post-cropping soil analyses were done. Data were analyzed using ANOVA and means separated by Duncan Multiple Range Test at α_0.05. The results showed that the nutrient uptake of okra consistently increased with CPH-based compost compared to control in both main and residual cropping. Nitrogen uptake ranged from 53.6 (60 kg N/ha NPK) to 106.7 (50 kg N/ha CPH+ PM) and 16.10 (50 kg N/ha NPK) to 55.06 (25 kg N/ha CPH+ PM+ NL); Phosphorus uptake ranged from 6.9 (25 kg N/ha CPH+ NL) to 24.1 (60 kg N/ha NPK) and 3.70 (25 kg N/ha CPH+ NL) to 9.98 (50 kg N/ha CPH+ PM+ NL), while potassium uptake ranged from 166.4 (25 kg N/ha CPH+ NL) to 244.48 (25 kg N/ha CPH+ PM+ NL) and 64.06 (40 kg N/ha NPK) to 122.29 (75 kg N/ha CPH+ NL) mg/plant in main and residual cropping, respectively. Organic carbon, pH, nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg) and sodium (Na) were also significantly increased by the CPH-based compost. It could, therefore, be concluded that CPH-based compost could be a good fertilizer for okra production.     

尼加拉瓜西南部热带雨林生态系统木材生产速率及其对可持续森林经营的启示

积累木材采运数据对森林可持续经营是非常必要的,但这些数据在一些发展中国家却非常缺乏。本文收集和分析了尼加拉瓜Ondo州森林保护区和非保护区内木材生产速率的数据。数据来源于州林业主管部门的官方数据、年度报告和相关文件,包括2003年至2005年间以月采伐量为单位的不同经济术材的物种、材积量和立木数。对收集的数据进T检验和一维方差分析。结果表明:3年间,非保护区内采伐木材的物种数、科数和立木量均高于森林保护区内采伐的。但是,保护区内被砍伐的树木材积总量要显著高于非保护区的(p<0.05)。非保护区内,有25个植物科的60种阔叶树种被砍伐:森林保护区内有23个科的57种阔叶树种被砍伐。3年间,Ondo州森林系统内被砍伐树林共111,377株,材积量约295 089.67m3。年平均伐木数和材积量分别是37,125株和98 363.22 m3。月平均伐木数和材积量分别是3 094和8 196m3。T检验结果表明,森林保护区和非保护区内被砍伐的树木株数和材积量显著不同(p<0.05)。一维方差分析结果表明,03年和04年伐木活动显著增加,但05年有所下降。说明森林系统中经济木材树种正在减少,伐木活动对森林生态系统产生了...