Growth and survival of the freshwater clam,Galatea paradoxa (Born 1778) cultured on different substrata at the Volta estuary,Ghana

This study was conducted to assess the optimum clam size and substratum type for the culture of Galatea paradoxa. The experiment was conducted over a 90‐day period at the Volta Estuary, Ghana. Three size classes of G. paradoxa categorized as small (27.6 ± 0.4 mm), medium (36.8 ± 0.4 mm) and large (50.0 ± 0.6 mm), were used to ascertain the effect of a sandy and muddy substratum on growth performance and survival. Growth increased from the small‐sized clams to the large‐sized clams at 2.54, 3.03 and 3.43 g, respectively, over the experimental period. Growth was higher (P < 0.05) in the muddy substratum (3.58 g) compared with sandy (2.41 g). Similarly, the specific growth rate increased from 0.99% day^?1 in the small‐sized clams to 1.36% day^?1 in the large‐sized clams. Survival rates were significantly higher (99.4%) for the large‐sized clams compared with the medium (78.8%) and the small‐size clams (74.1%). There was significant interaction between the size class and the substratum type with a trend towards increasing survival rate from the small to the large size clams in both substrata. The survival rate was lower in the muddy substratum (71.4%) compared with the sandy substratum (96.7%). The yield was significantly higher in the muddy (2.01 kg m^?2 90 day^?1) compared with sandy substratum (1.87 kg m^?2 90 day^?1). The results of this study indicate that the culture of small‐sized clams is best practiced on sandy substratum due to their elevated survival rates, whereas the muddy substratum appears most suitable for the culture of larger clams (>40 mm) because of their relatively higher survivorship and better growth performance.     

A strategy for tree-perennial crop productivity: nursery phase nutrient additions in cocoa-shade agroforestry systems

Shade tolerant species response to nutrient additions and light regulation by canopy trees in perennial agroforestry systems has been well documented. However, accelerated early growth, particularly in cocoa-shade systems, may be offset by competition for limited resources on nutrient poor sites. To date, few agroforestry management strategies focus on nutrient manipulation of the shade tree component or strategies for precision nutrient application. Our research objective was to diagnose interactions between nutrient supplied shade trees intercropped with cocoa. We established greenhouse trials in Kwadaso, Ghana cultivating Terminalia superba seedlings with four fertility treatment levels: conventional rate (current practices) under linear additions, and half, full and double conventional rate under exponential additions (steady-state nutrition) to determine maximal growth and nutrient uptake. After 4 months of additions in the nursery, pre-fertilized T. superba seedlings were then out-planted into field trials with cocoa seedlings. After 4 months of intercropping, cocoa associated with half rate exponentially supplied T. superba had significantly larger leaf area, greater leaf number, and higher nutrition (N and P uptake) than cocoa associated with full rate conventionally supplied T. superba. This may be attributed to (1) more favorable light conditions under these taller shade seedlings and (2) the internal use of nutrients associated with exponentially supplied T. superba seedlings, which lowered stress on native soil resources. The latter is corroborated with our findings on soil fertility status. This strategy focused on reducing fertilizer inputs and developing precise plant nutrition technology for on-farm use. Our findings suggest that shade seedlings under steady state nutrition can mitigate early growth competition in the field.     

Effect of sandy and muddy substrates on the growth and survival of the freshwater clam Galatea paradoxa (Born 1778)

This study was conducted to determine the effect of a sandy and muddy substrate on the growth and survival of three size‐classes of Galatea paradoxa (Born 1778). The experiment was conducted over a 6‐month period in a 1000 m² pond at the research farm of the Faculty of Renewable Natural Resources. Three size classes (shell length) of G. paradoxa categorized as small (20–30 mm), medium (31–40 mm) and large (>40 mm) were used to ascertain the effect of a sandy and muddy substrate on growth performance. Growth in general was very slow, between 1.4 and 2.4 mm over the 6‐month experimental period. The lengths measured at the end of the experiment were also significantly different. However, the mean length gained and the specific growth rate for the three size classes in the two substrates (sandy and muddy) were not significantly different (P>0.05). The results of this study indicate that the pond environment is not suitable for the culture G. paradoxa as the species is adapted to life in a river with its filter‐feeding activity dependent on the water current. The effect of the substrate type on growth was not significant. However, the substrate type did affect survival, with sandy substrates yielding in better survival than muddy ones.     

Factors that affect the adoption and maintenance of weekly vitamin A supplementation among women in Ghana

OBJECTIVE: To identify regimen, individual, community and cultural factors that affect adoption and adherence to weekly vitamin A supplementation in Ghana. DESIGN: Fifty semi-structured interviews were conducted with women who would be eligible for vitamin A supplementation, 30 with husbands, and 13 with drug sellers, birth attendants and health workers. Six focus group discussions were also conducted with women. These interviews were followed by a 4-month capsule trial with 60 women. Data from a previously conducted communication channel survey of 332 women were also reviewed. SETTING: The study was conducted in Kintampo District in central Ghana. SUBJECTS: Participants for the semi-structured interviews and focus groups were selected from four villages and the district capital, and women in the capsule trial were selected at random from two villages. RESULTS: Knowledge of vitamins was low and taking 'medicines' for long periods and when healthy is a new concept. In spite of this, long-term supplementation will be accepted if motives are explained, specific questions answered and clear instructions are given. Potential barriers included the idea of 'doctor' medicines as curative, false expectations of the supplement, forgetting to take the supplement, losing the supplement, travelling, lack of motivation, perceived side-effects, concerns that the supplement is really family planning or will make delivery difficult, and concerns about taking the supplement with other 'doctor' or herbal medicine, or when pregnant or breast-feeding, or if childless. CONCLUSION: Successful supplementation programmes require appropriately designed information, education and communication strategies. Designing such strategies requires pre-programme formative research to uncover barriers and facilitators for supplementation.     

Evaluation of winter wheat cultivars for drought resistance

Summary Cultivars of winter wheat (Triticum aestivum L. em. Thell.), considered by wheat breeders to be drought sensitive or drought resistant, were grown under two irrigation regimes (daily or weekly waterings) to determine physiological responses to drought and to evaluate methods to use in screening for drought resistance. Leaf water potential, stomatal resistance, plant resistance to water flow, and soil water potential were measured for three weeks on vernalized plants in a growth chamber. When water was lacking, drought-sensitive plants had a lower leaf water potential than did drought-resistant plants. With both daily and weekly waterings, stomatal resistance was higher in drought-resistant plants than in drought-sensitive plants. Plant resistance to water flow, calculated as the difference between the soil water potential and leaf water potential divided by the amount of water used by the plant, was usually higher in drought-resistant plants than in the drought-sensitive plants. The results showed that, when screening for drought resistance, stomatal resistance was a better method to use than determinations of leaf water potential or plant resistance to water flow.Journal article 3578 of the Agricultural Experiment Station, Oklahoma State University. Work was partially supported by a Grant-in-Aid of Research from Sigma Xi, The Scientific Research Society of North America, to the senior author.     

Leaf nutrients content of tomato and incidence of insect pests and diseases following two foliar applications

The leaf plays key roles in plant functions. In this study, we evaluated major nutrients (Nitrogen (N), phosphorous (P), and potassium (K)) contents of the leaves of tomato (Solanum lycopersicum) following applications of two foliar nutrients sources. Pest population dynamics as well as disease incidence and severity of the crop were also evaluated. The study was conducted at the Plantation Crops Section of the Kwame Nkrumah University of Science and Technology, Ghana in two consecutive cropping seasons. Two tomato varieties were treated with two foliar nutrients sources viz. Herbagreen and Sidalco liquid fertilizer in a split-plot layout. A conventional (granular) NPK fertilizer and a control (no application) were also evaluated. The foliar applications generally increased leaf N concentration of tomato more than the conventional NPK fertilizer and the control. Sidalco liquid fertilizer significantly (p < 0.05) increased foliar K concentration in the major season while Herbagreen increased K concentration by 108% over the NPK fertilizer in the minor season. However, leaf P concentrations were similar (p > 0.05) among the foliar and soil applications. The foliar applications (p < 0.05) reduced the densities of Bemisia tabaci (Gennadius) than the NPK fertilizer and the control in both seasons of cropping. In the minor season, Herbagreen (p < 0.05) reduced both incidence and severity of late blight. Herbagreen treated plants produced fruit yield comparable to the conventional NPK fertilizer and registered lower disease incidence and severity as well as lower insect pest populations possibly due to its silicon content.     

Bio-insecticidal effectiveness of three formulations of diatomaceous earths against Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) in stored cowpea

Journal of Plant Diseases and Protection - Three diatomaceous earths (DEs), InsectoSec®, Diatomeenerde Probe-A and Fossil Shield® 90.0, were tested in the laboratory against...     

Urea and(or) feather meal supplementation for yearling steers grazing limpograss (Hemarthria altissima var. 'Floralta') pasture.

The unique relationship between TDN and CP concentration (low CP relative to TDN) in the whole-plant of 'Floralta' limpograss (Hemarthria altissima) may provide an opportunity for improving cattle performance through protein supplementation. In each of three consecutive years, yearling Brahman x British crossbred steers (initial weight approximately 270 kg) grazed limpograss during the summer and fall (five steers per ha, three pasture replications per treatment) and were fed liquid cane molasses-based supplements (1.4 kg DM daily) alone, or containing urea and(or) hydrolyzed poultry feather meal. In yr 1 and 2, protein supplementation did not influence ADG. In these years, pasture availability was in excess at all times, and visual observations indicated that the upper canopy contained abundant leaf. Pasture samples collected in a manner to simulate grazing had in vitro organic matter disappearance (IVOMD):CP ratios ranging from 6.5 to 8.1, and plasma urea nitrogen concentration in the blood of steers fed no supplemental protein was high (10.6 to 15.9 mg/dL), both not suggestive of a situation where providing a protein supplement might improve animal performance. In yr 3, ADG was improved (P < 0.05) by protein supplementation. Forage availability was in excess at the beginning of the trial but declined significantly as the trial progressed. At the end of the trial, forage IVOMD:CP ratio (11.1) and plasma urea nitrogen values of steers fed no protein supplement (6.6 mg/dL) were both suggestive of a situation where providing supplemental protein might improve animal performance. Grazing management of limpograss pasture can affect canopy composition, thereby influencing cattle response to protein supplementation. In cases where limpograss is moderately grazed resulting in abundant leaf in the grazed horizon, dietary energy:protein ratio can be balanced, and positive responses to protein supplementation may not be observed. Where limpograss is grazed more intensively resulting in greater quantities of stem in the upper pasture canopy, an imbalance of dietary protein (low) relative to energy can develop, increasing the opportunity for enhancing cattle performance through protein supplementation.     

Responses of small mammals to land restoration after mining

Context

Land degradation from mining influences biodiversity and ecosystem functioning. However, comparative studies using small mammal functional groups within rehabilitated mining sites are missing, despite their significant ecological contributions.

Objectives

We investigated the recovery of small mammals according to their trophic guild and terrestriality in restored mining sites and analyzed whether they were influenced by restoration scheme (active or passive), restoration time, mineral type, body mass and invasive species. We were especially interested in whether functional groups showed different recovery patterns across time.

Methods

We classified small mammals into functional groups according to trophic levels distinguishing carnivores, herbivores and omnivores, and according to their terrestriality categorized as above ground-dwelling (AGD) and fossorial and/or ground-dwelling individuals (FGD). We studied small mammal recovery globally following restoration of mining sites based on a meta-analysis using effect sizes. Influences of environmental variables were investigated with linear mixed models using effect sizes as response variable.

Results

We did not find significant differences for restoration scheme and time but we did for mineral type, body mass and invasive species in terms of population (abundance) recovery. Trajectories of functional group recoveries differed: FGD and herbivores quickly recovered after mining activities stopped, but declined later, whereas AGD, carnivores and omnivores recovered within the first few years or decades.

Conclusions

Our results highlight the different vulnerability of functional groups, and the importance of considering this in conservation interventions.