Genetics evaluation of phosphorus utilization in tropical cowpea (Vigna unguiculata (L) Walp)

Genetics evaluation of phosphorus utilization in cowpea (Vigna unguiculata (L) Walp) was studied in a cross involving a tropically adapted genotype (IT90K-277-2) with a reported positive response to rock phosphate (RP) and a second genotype (IT89KD-288) that responds negatively to RP, using generation mean analysis of the parents, their F1, F2 and the two backcross generations. Highly significant differences among the six generations with respect to seed phosphorus (P) concentration and grain yield per plant were observed. The F1 progenies produced seeds with higher seed P concentration (0.31 mg/g) than the mid-parent value (0.27mg/g). Mean yield per plant in the F1(48.03g) that was significantly greater than the mid-parent value (28.85g) was also observed suggesting positive heterosis for the two traits. Backcrossing to both parents showed good convergence of genes on the recurrent parents. Possibility of transgressive segregation for seed P concentration and grain yield per plant in the F2 generation was also observed. Absence of significant reciprocal differences among individuals in the F1 and F2 populations suggested lack of maternal and cytoplasmic effects. Non-additive gene action (dominance and epistasis) made significant contributions to total genetic variations in both traits within the cross. Whereas seed P concentration was observed to be under polygenic control, number of genes for seed yield per plant was biased downward by epistasis. Observed narrow-sense heritability estimate (HN)) for seed P concentration of 50.51% and very low (0.040) expected genetic gain in the F3 over the F2 means suggested that although expected progress from selection could be lowered by non-additive gene effects, this trait could be transmitted to the offsprings of hybridization program with huge success, through backcrossing. Although, available soil P (6.03 – 8.09mg/kg) was observed to be below the critical level, phosphorus uptake in the F1 and the segregating generations was observed to be higher than what obtained in the parents to suggest that the progenies of a P-efficient x P-inefficient cross would be efficient in P utilization.Keywords: Generation mean analysis, Phosphorus uptake, Polygenes, Transgressive segregants, Tropical vigna

Identification, distribution and prevalence of ecto-parasites associated with cultured fish in Ogun State, Nigeria

Public health issues can he considered as those of direct importance to both producers and consumers of fish and include broader issues of food production, processing and delivery systems. As aquaculture assumes an expanding role in meeting consumer demands for fish and fishery products, it is natural that they meet safety and quality standards. Aquaculture is a growing industry in Nigeria and it has assumed commercial importance activity. This study was part of the project on epizootiological survey of pathogenic diseases of cultured fish species and is aimed at identifying ecto-parasite associated with cultured fish in Ogun State, Nigeria. The study which was carried out in 2012 covered fifty fish farm, spread across the three senatorial zones. Five pieces of fish were randomly picked from each farm surveyed. Participants observation and structured questionnaires were administered to fish farmers in order to gather information on source of fries, fish feeding and feed type, use of manure and its type, pond type, stocking density, pond hygiene, water source, frequency of changing water and history of diseases and mortalities of fish. Before the fish samples were collected, pond size and physicochemical water quality were assessed. Water test kits were used to measure parameters like iron, nitrate, alkalinity and ammonia. All the procedures for physicochemical water quality parameter analysis was done according to the manufacturer's instructions. Water pH was measured using a probe while dissolved oxygen and both water as well as air temperature were measured by using Hanna kit. All types of farms are included in the survey such as hatcheries, brood stock farms as well as grow out farms. The study revealed the spread of parasites across the senatorial zones. The most common encountered parasites were Trichodina sp, Gyrodactylus sp, Dactylogyrus sp and trematodes. The intensity of the parasites differed markedly

Genetics evaluation of phosphorus utilization in tropical cowpea (Vigna unguiculata (L) Walp)

Genetics evaluation of phosphorus utilization in cowpea (Vigna unguiculata (L) Walp) was studied in a cross involving a tropically adapted genotype (IT90K-277-2) with a reported positive response to rock phosphate (RP) and a second genotype (IT89KD-288) that responds negatively to RP, using generation mean analysis of the parents, their F1 , F2 and the two backcross generations. Highly significant differences among the six generations with respect to seed phosphorus (P) concentration and grain yield per plant were observed. The F1 progenies produced seeds with higher seed P concentration (0.31 mg/g) than the mid-parent value (0.27mg/g). Mean yield per plant in the F1 (48.03g) that was significantly greater than the mid-parent value (28.85g) was also observed suggesting positive heterosis for the two traits. Backcrossing to both parents showed good convergence of genes on the recurrent parents. Possibility of transgressive segregation for seed P concentration and grain yield per plant in the F2 generation was also observed. Absence of significant reciprocal differences among individuals in the F1 and F2 populations suggested lack of maternal and cytoplasmic effects. Non-additive gene action (dominance and epistasis) made significant contributions to total genetic variations in both traits within the cross. Whereas seed P concentration was observed to be under polygenic control, number of genes for seed yield per plant was biased downward by epistasis. Observed narrow-sense heritability estimate (HN)) for seed P concentration of 50.51% and very low (0.040) expected genetic gain in the F3 over the F2 means suggested that although expected progress from selection could be lowered by non-additive gene effects, this trait could be transmitted to the offsprings of hybridization program with huge success, through backcrossing. Although, available soil P (6.03 –8.09mg/kg) was observed to be below the critical level, phosphorus uptake in the F1 and the segregating generations was observed to be higher than what obtained in the parents to suggest that the progenies of a P-efficient x P-inefficient cross would be efficient in P utilization

Combining ability of earlymaturing white maize inbreds under stress and nonstress environments

Maize (Zea mays L.) hybrids resistant to Striga hermonthica (Del) Benth and tolerant to drought are vital to the sustainability of productivity of the maize-based farming systems of West and Central Africa (WCA). Thirty-six diallel crosses derived from nine early maturing white maize inbreds were evaluated under drought, well-watered, striga-infested, and striga-free conditions at five locations in Nigeria between 2007 and 2009. The objective was to examine the combining ability, performance and stability of the inbreds, and to identify the heterotic groups. Additive and nonadditive gene actions were important in the control of the inheritance of drought tolerance and striga resistance in the inbreds. General combining ability (GCA) mean squares of grain yield and other traits were larger than those of specific combining ability (SCA), indicating that additive gene action was more important in the inheritance of drought tolerance. The GCA mean squares for striga damage rating at 8 and 10 weeks after planting (WAP) were about six and five times greater than those of the SCA, indicating that additive gene action played a major role in the inheritance of the striga traits. The GGE biplot analysis revealed that TZEI 4 and TZEI 5 were the most promising inbreds in yield performance and stability across the test environments. Two heterotic groups were identified; [TZEI 7, TZEI 19, TZEI 2, TZEI 4] and [TZEI 5, TZEI 3]. Tester TZEI 3 was the closest to the ideal tester. Entry TZEI 7 had the highest GCA effects and TZEI 2 the lowest

Improvement of yield and other traits of extra early maize under stress and nonstress environments

Striga, drought, and low soil fertility constrain maize (Zea mays L.) productivity in West and Central Africa. Two Striga-resistant extra-early populations, TZEE-W Pop STR C0 (white) and TZEE-Y Pop STR C0 (yellow) were evaluated in field trials in Nigeria, from 2005 to 2007 to assess progress in improvements for grain yield, Striga resistance, and other traits when Striga-free, Striga-infested, and under low- and high-N. Under Striga infestation, yield gain from C0 to C4 was 136 kg ha−1 for the yellow population and 71 kg ha−1 cycle−1 for the white. The yield gain in advanced cycles of selection in the yellow was associated with decreases in Striga emergence at 8 and 10 weeks after planting (WAP) and Striga damage at 8 WAP while that of the white was accompanied by increased days to silking and ears per plant as well as a decrease in Striga emergence at 8 WAP. Under Striga-free conditions, yield gain from C0 to C4 was 164 kg ha−1cycle−1 for the white and 221 kg ha−1 cycle−1 for the yellow. The yield gain in advanced cycles of selection was more pronounced under high-N (157 kg ha−1 cycle−1) than low-N (144 kg ha−1cycle−1) in the yellow, and higher under low-N than high-N in the white. Selection in the yellow was accompanied by increased days to anthesis and silking, plant and ear heights under low-N and increased days to silking under high-N. In the white, selection induced increased days to anthesis, ear height, and decreased anthesis-silking interval

Factors contributing to the duration of postpartum abstinence among Nigerian women: semi-parametric survival analysis

Background: The duration of postpartum abstinence is on the decrease but has not been met with increased uptake of contraceptive in Nigeria. This imbalanced transition could result in shorter birth intervals and worsen maternal and child health outcomes. There is a paucity of information on the duration and predictors of time to end of postpartum abstinence in Nigeria. This study was aimed at understanding the time to end of postpartum abstinence and factors predicting the duration in Nigeria. Methods: The NDHS 2013 data was used. Data of all women who had ever given birth were included. The time to end of postpartum abstinence was censored among currently breastfeeding mothers. The Kaplan Meier Product Limit method was used to estimate the survival and hazard function while the Cox regression was used to fit a model for time to end of postpartum abstinence at 5% significance level. Data were weighed and provisions were made for multicollinearity. Results: The overall average duration of postpartum abstinence in Nigeria is 3 month. In all, 58% ended postpartum abstinence within the first three months while 18%, 10%, and 14% ended it within 4–6 months, 7–12 months and after one year respectively. Postpartum abstinence did not last beyond 3 months among 83% of the women in the North-West region, compared with 23% in the North Central region, and 34% in the South East. The Muslims had the highest proportion of women who ended postpartum abstinence within the first three months after delivery at 72% compared with Catholic women (31%). The median time to end of postpartum abstinence was lowest (2 months) among women from North West, Muslims, in poorest wealth quintiles and those with no education. The “hazard” of earlier resumption of sexual activity after birth was over 3 times more likely among women in the North West than those in the North Central (aHR = 3.09, 95% CI: 2.95–3.24). Women using contraceptives had a 40% hazard of ending postpartum abstinence earlier. Rural women were 7.6% times less likely to end postpartum abstinence compared to their urban counterpart. Women from rich households have an excess risk of 14% to end postpartum abstinence early compared to women from poor households. Conclusion: Women of reproductive age in the North West, who are Muslims and with no education are at higher risk of ending postpartum abstinence early. Hence, policymakers and reproductive health stakeholders should design effective intervention targeted at this group of women as a means of controlling fertility