The role of oxalic acid and polygalacturonase in the pathogenicity ofPythium aphanidermatum on different cowpea varieties

The amounts of oxalic acid and polygalacturonase (PG) produced in the tissues of cowpea (Vigna unguiculata Walp.) plants infected byPythium aphanidermatum were higher in vars. IT81D-1020 and VITA 5 than in vars. IT82E-32 and TVX3236. Oxalic acid accumulated early at the infective stage of the disease but its production decreased as the plants became older or as the disease developed. At the peak of oxalic acid and PG production (8–10 days after infection) the pH of the tissue fell from 7.2 to 3.1 and thereafter rose to 4.3 (within 18 days). It seems, therefore, that the combination of oxalic acid and PG and the accompanying reduced pH of infected tissue play an important role in the pathogenesis of susceptible varieties of cowpea byP. aphanidermatum. In the two varieties found to be resistant in this study, oxalic acid and PG production were lower than in the susceptible varieties and the pH did not fall as low. Early accumulation of oxalic acid in cowpea tissue during pathogenesis may be a useful tool for monitoring disease severity, and hence susceptibility or resistance toP. aphanidermatum, when there is a compatible interaction between host and pathogen.     

Effects of nutrients omission on maize growth and nutrient uptake in three dominant soil types of southwestern Nigeria

Abstract

A pot experiment was conducted to determine most limiting nutrients for maize performance using nutrient omission treatments in three soil types of southwestern Nigeria. There were six treatments; full nutrient [120?kg nitrogen (N)/ha, 40?kg phosphorus (P)/ha, 80?kg potassium (K)/ha, 10?kg molybdenum (Mo)/ha, and 5?kg zinc (Zn)/ha]; full nutrient minus N, P, K, Mo, and Zn including control was replicated thrice. Treatments were arranged as split plot in a complete randomized design. Data were collected on growth parameters, shoot, root dry weights, and NPK uptakes. Data were subjected to analysis of variance and means separated using LSD_0.05. Majeroku and Egbeda soils and full nutrient supported better maize growth and NPK uptakes. Shoot weight was higher in Egbeda while root weight was higher in Itagunmodi soil. Phosphorus was the most limiting in Egbeda and Itagunmodi soils, and nitrogen in Majeroku soil. In conclusion, maize growth, nutrient uptake and most limiting nutrient varied with soil types.     

Study on the susceptibility of Sahel goats to experimental Trypanosoma vivax infection

Sahel goats, also known as Borno whites are found in the northern semi-arid, tsetse free Sahel region of Nigeria. They are transported alongside cattle from this zone to all other zones in the country, including the tsetse-infested zones, for commercial purposes and are kept for some time in these tsetse-infested zones until they are sold. This study therefore assessed the susceptibility of this breed of goats to trypanosome infection and its response to treatment with Berenil. Six bucks were inoculated intravenously with Trypanosoma vivax through the jugular vein while two served as uninfected control. The mean pre-patent period was 4.5 days and increasing parasitaemia followed the establishment of infection. Onset of parasitaemia was associated with increase in rectal temperature in all the infected goats and the temperature peak coincided with the only parasitaemic peak second week post-infection. The infected goats were treated with Berenil (Hoechst, Germany) 3.5mg/kg body weight at 4 weeks post-infection. The packed cell volume (PCV) continued to fall from a mean 30.73+/-0.01% pre-infection to a mean 13.21+/-0.18% at 1 week post-treatment. Deaths were recorded for 4 of the infected goats 1 week post-treatment while the remaining two died 2 weeks post-treatment, not responding to treatment.     

Chemical compositions, feed intakes and digestibilities of crop residue based rations in non-lactating Red Sokoto goats in the subhumid zone of Nigeria

The present study was conducted to evaluate the chemical composition, intake and digestibility of crop residue based rations by Red Sokoto goats maintained on natural pastures and Digitaria smutsii hay during the dry season of the year. Twenty‐eight non‐lactating does were blocked for weight and assigned to 7 treatment groups comprising 4 does each in a completely randomized design. Ration A, the conventional concentrate ration, was used as the positive control, Rations B and C were the two crop residue based test rations, while Ration D, the unsupplemented treatment, was used as the negative control. Each of the supplementation rations was fed at 1% and 2% of the doe's body weight. Ration A had the highest crude protein percentage of 17.19% while Rations B and C had 9.54 and 10.38%, respectively. The naturally grazed pastures and Digitaria smutsii hay (Ration D) contained the least protein: 2.76 and 4.75%, respectively. Ration D also had the highest percentages of acid detergent fiber, neutral detergent fiber and lignin (49.14, 74.73 and 9.49% in hay and 50.29, 8.27 and 11.5% in grazed pastures, respectively). Ration A on the other hand, had the lowest percentages of acid detergent fiber (20.00%), neutral detergent fiber (40.01%) and lignin (4.64%). The results indicated that the supplemented group of does had significantly higher (P < 0.05) dry matter and crude protein intakes as well as nutrient digestibilities than the unsupplemented groups. A comparison of the unsupplemented animals with all the other treatment groups revealed that dry matter digestibility improved by a range of 4.1–27.9%, while crude protein digestibility improved by 17.1–42.2%, the highest value being in does on Ration A. It was concluded that goats were able to subsist and make appreciable gains in the long dry season on crop‐based diets that compared favorably with the conventional concentrate rations. Of the two tested crop residue based rations, Ration C is a better supplementation package than Ration B.     

Scrotal circumference, bodyweight and serum testosterone concentration of Red Sokoto weaner bucks as influenced by dry season crop-residue supplementation

The effect of dry season supplementation with crop‐residue‐based rations on bodyweight, scrotal circumference and serum testosterone concentrations in Red Sokoto weaner bucks at 5, 6 and 7 months of age was investigated in the present study. There were 7 treatment groups which were fed a positive control ration (conventional concentrate) fed at 1 and 2% of the bucks’ bodyweights (Rations 1A and 2A), two crop‐residue‐based test rations each fed at 1 and 2% of bodyweight (1B, 2B, 1C and 2C), and a negative control that was unsupplemented (Ration D). All treatment groups had ad libitum access to natural pastures and Digitaria smutsii hay as a basal diet. Bodyweight and scrotal circumference of the bucks significantly increased (P < 0.05) with age from 5.9 kg to 10.2 kg, and 4.40 cm to 6.95 cm, at 5 and 7 months of age, respectively. Bucks on Ration D (unsupplemented group) had the lowest bodyweight and scrotal circumference. Bucks on Ration 2A showed a significant increase in basal testosterone concentration from 0.32 ng/mL at 5 months of age to 0.65 ng/mL at 7 months of age. Peak testosterone concentration also increased from 1.0 ng/mL at 5 months to 2.8 ng/mL at 7 months of age. Bucks on test Ration 2C had higher bodyweights (6.75, 8.00 and 10.00 kg at 5, 6 and 7 months of age, respectively) than bucks on the other test Ration B (6.20, 7.20 and 8.50 kg, respectively). There were no significant differences between the two test rations with regard to scrotal circumferences of the bucks at all ages. However, at 7 months of age, bucks on test Ration 2C had significantly higher peak testosterone concentration (1.80 ng/mL) than their counterparts on test Ration 2B (1.30 ng/mL). The secretory patterns of testosterone were episodic and pulsatile in nature. It was concluded that crop‐residue supplementation in prepubertal Red Sokoto bucks has a significant influence on their bodyweight, scrotal circumference and testosterone production. Test Ration C was a cheap, affordable and better crop‐residue‐based ration for optimal reproductive performance than test Ration B.     

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.     

Liming and Fertilizer Potentials of Some Underutilized Plant Materials in Southwestern Nigeria

Soil acidification and phosphorus deficiency are a major constraint to crop production in tropical soils.Use of conventional liming materials is associated with some limitations viz:inability to solely improve nitrogen and available phosphorus in soils,loss of soil organic carbon and soil aggregate stability.Liming and fertilizer potentials of leaves from three plant materials(Tithonia diversifolia(TL),Imperata cylindrica(SG)and Gliricidia sepium(GL))widely growing in Ogbomoso,southwest Nigeria,were tested under incubation condition.Each of the plant material was applied at the rate of 10 t·hm~(-2) with and without 50%concentration of NPK 15:15:15-urea mix in 500 g acidic soil.Sole lime applied at 1 t·hm~(-2),sole NPK 15:15:15 applied at 60 kg·hm~(-2) mixed with urea at 60 kg N·hm~(-2) and an unamended soil were compared in completely randomized design in three replicates.The treated soils were incubated for 12 weeks.Thereafter,maize seeds were raised in each pot for a period of 3 weeks.Data collected were subjected to analysis of variance.Regression analysis was used to predict contributions of increased soil p H in plant material treated soils to exchangeable Al,H,dry root weight of maize and available phosphorus.Results indicated that sole plant materials were the order SGTLGL significantly(p0.05)reduced exchangeable acidity compared to unamended and sole NPK.Sole NPK had the highest exchangeable acidity(4.7 cmol·kg~(-1))compared to unamended soil(3.3 cmol·kg~(-1))and sole lime(2.7 cmol·kg~(-1)).Application of sole Tithonia diversifolia increased available phosphorus by 214%and 97%compared to unamended and sole NPK treated soils respectively.Sole plant materials increased maize root weight by 33%compared to sole NPK.Increasing soil p H at harvesting in plant material treated soils significantly reduced exchangeable H and A_1.Soil p H was responsible for up to 33%and 53%reductions in exchangeable Al and H,respectively.This culminated into up to 22%increases in dry root weight of maize seedling.Present results showed ability of the plant materials tested to ameliorate soil acidity and improved soil available phosphorus.The plant materials should be explored for using as green manure and composting feedstock.It will go a long way to reduce high dosage use of conventional liming and fertilizer materials on acidic nutrient degraded soils.