Water use efficiencies of maize cultivars grown under rain-fed conditions

Enhancing water use efficiencies of rain-fed maize is a requirement for sustainable maize production, particularly in areas prone to low/ drought and erratic rainfall patterns. This study was conducted to assess the relationship be-tween total biomass/grain yield and water use efficiencies of three maize cultivars (Golden Crystal, Mamaba and Obatanpa) grown under rain-fed conditions in a coastal savannah agro- ecological environment of Ghana. Results of the study showed that a unified linear model, WUETDM = 0.03 TDM with R2 = 0.765 and P ≤ 0.001, described adequately the relation be-tween water use efficiency and total biomass (dry matter), which is applicable for the three maize cultivars for both the major and minor cropping seasons. A linear model could only, however, describe adequately well the relation between WUEGY and GY for the major (WUEGY = 0.001 GY – 0.67; R2 = 0.996; P ≤ 0.001) and minor (WUEGY = 0.002 GY + 0.289; R2 = 0.992; P ≤ 0.001) cropping seasons for all the maize cultivars. The linear models developed for the maize cul-tivars, relating WUEGY to GY, are specific to each of the crop growing seasons, indicating that seasonal rainfall impacts significantly on harvest index of the maize cultivars but diffe-rently in each of the crop growing seasons as a results of differences in seasonal rainfall. How- ever, the models could be used to estimate wa-ter use efficiencies of each of the three maize cultivars given the appropriate TDM and GY as inputs for the environment under which the study was conducted.Daniel Kwasi Asare, Justice Okona Frimpong, Emmanuel Ofori Ayeh, Harry Mensah Amoate

Combined effects of shade and drought on physiology, growth, and yield of mature cocoa trees

Open Access ArticleClimate models predict decreasing precipitation and increasing air temperature, causing concern for the future of cocoa in the major producing regions worldwide. It has been suggested that shade could alleviate stress by reducing radiation intensity and conserving soil moisture, but few on-farm cocoa studies are testing this hypothesis. Here, for 33 months, we subjected twelve-year cocoa plants in Ghana to three levels of rainwater suppression (full rainwater, 1/3 rainwater suppression and 2/3 rainwater suppression) under full sun or 40 % uniform shade in a split plot design, monitoring soil moisture, physiological parameters, growth, and yield. Volumetric soil moisture (ϴw) contents in the treatments ranged between 0.20 and 0.45 m3m−3 and increased under shade. Rainwater suppression decreased leaf water potentials (ѱw), reaching −1.5 MPa in full sun conditions indicating severe drought. Stomatal conductance (gs) was decreased under the full sun but was not affected by rainwater suppression, illustrating the limited control of water loss in cocoa plants. Although pre-dawn chlorophyll fluorescence (Fv/Fm) indicated photoinhibition, rates of photosynthesis (Pn) were highest in full sun. On the other hand, litter fall was highest in the full sun and under water stress, while diameter growth and carbon accumulation increased in the shade but was negatively affected by rainwater suppression. Abortion of fruits and damage to pods were high under shade, but dry bean yield was higher compared to under the full sun. The absence of interactions between shade treatments and rainwater suppression suggests that shade may improve the performance of cocoa, but not sufficiently to counteract the negative effects of water stress under field conditions

Influences of climate variability on cocoa health and productivity in agroforestry systems in Ghana

Open Access Article; Published online: 14 Oct 2022The susceptibility of cocoa to harsh climatic conditions is evident in cocoa growing areas in Ghana, and climate distribution models show reduced cocoa suitability to climate change. We assessed how cocoa health and productivity were affected by varying climate conditions for 4 years in 23 cocoa farms along a gradient of low rainfall/high temperature in the north to high rainfall/low temperature in the south of Ghana's cocoa belts. Twenty cocoa trees per farm (in total 460) were observed and scored for their canopy condition, flower intensity, and damaged pods due to mirids, cocoa shield bugs, and black pod disease (BPD). Harvested pods and extracted dried cocoa beans were evaluated to ascertain yield/productivity. Insect pest damages to pods were on average 2.3 ± 0.8, 2.2 ± 1.0, and 3.0 ± 0.7 pods tree−1 year−1 in the south, middle and north, respectively. The healthiest and highest yielding trees were in the rainy south at 0.99 ± 0.02 kg dry beans tree−1 followed by the middle (0.84 ± 0.02 kg) and the north (0.60 ± 0.01 kg). BPD infection was highest in the south at 1.1 ± 1.1 pods tree−1 year−1, followed by the middle (0.7 ± 0.8), and the north (0.4 ± 0.6). Within sites variability in rainfall and temperature was not found to affect yields significantly. The variability in cocoa performance and occurrence of pests and diseases observed within sites may thus be caused by farm management practices that are key to the enhancement of productivity at site level. We recommend regular pruning of cocoa and shade trees to increase aeration and prevent BPD in high rainfall areas, and an increase in shade tree components in dry regions for insect pest management in cocoa systems

Selected shade tree species improved cocoa yields in low-input agroforestry systems in Ghana

Open Access Article; Published online: 13 Aug 2022CONTEXT Cocoa agroforestry systems differ in the diversity of shade tree species composition. Though cocoa benefits from shade, there is a lack of species-specific information on shade trees that enhance soil fertility and yield. OBJECTIVE We examined how soil characteristics and cocoa yield were affected by eight commonly retained forest tree species, compared with unshaded control plots over a 3-year period. METHODS Using 74 circular plots from 10 cocoa farms in the Western region of Ghana, we sampled soils from two random points within each plot. Soil nutrients at the beginning and end of the study were analyzed, and yield was expressed as number of harvested pods and dry weight of beans per hectare. RESULTS AND CONCLUSIONS Levels of soil K and Ca were below recommended values. Although soil available phosphorus (P) was higher in control plots than under shade trees, yield around shade trees were higher than on unshaded plots. Cocoa yield differences between shade tree species and control plots were significant only in the major crop season, but not in the minor crop season. Cocoa yields under Cedrela odorata, Khaya ivorensis, Terminalia superba and Milicia excelsa were significantly higher than on control plots. Hence, the inclusion of specific shade tree species in cocoa agroforestry systems is important to maintain high yields in cocoa systems with low inputs. SIGNIFICANCE To our knowledge, this study presents one of the first attempt to assess the impacts of specific shade tree species on soil characteristics and cocoa yield

Limited effects of shade on physiological performances of cocoa (Theobroma cacao L.) under elevated temperature

Open Access Article; Published online: 08 Jul 2022Shade is one of the recommended management solutions to mitigate the effects of heat stress, which is a major challenge for cocoa production globally. Nevertheless, there are limited studies to verify this hypothesis. Here, we evaluate the effects of heat and shade on cocoa physiology using experimental plots with six-month old potted seedlings in a randomized complete block design. Infrared heaters were applied for one month to increase leaf temperatures by an average of 5–7 ºC (heat treatment) compared with no heat (unheated treatments), and shaded plants were placed under a shade net removing 60% of the light compared with no shade (sun treatments). Plants under heat treatments in sun and in shade showed severe reduction in photosynthesis. Measurements of chlorophyll fluorescence and photosynthetic light response curves indicated that heat caused damages at photosystem II and additionally resulted in lower rates of maximal photosynthesis. Temperature optima for photosynthesis were at 31–33 ºC with only small differences between treatments, and as light saturation was reached at low PAR levels of 325 – 380 µmol m−2 s−1 in shade and 427 – 521 µmol m−2 s−1 in sun, ambient rates of photosynthesis were comparable between sun and shade treatments. Heat treatments resulted in decreased concentrations of chlorophyll and changed pigment composition, reduced specific leaf areas, and plant biomass. While shade may benefit cocoa seedlings, our results indicate that the positive effects may not be sufficient to counteract the negative effects of increased temperatures on cocoa physiology

Notes on village systems of small ruminant production in Ghana and a bibliography of Ghanian small ruminant research

Reports partial results of a study of small ruminant production in nine villages in the Kumasi area of Ghana. Describes the management systems and outlines flock demography

Monitoring of the cocoa Swollen shoot virus disease control project, Ghana. Report on the final mission from May 14th to June 11th 1997

Cette mission est la quatrième et la dernière du projet d'expertise au Ghana pour le suivi des opérations de lutte contre la maladie virale du "Cocoa Swollen Shoot Disease" (CSSVD). A l'issue de 34 mois de campagne (de juillet 1994 à avril 1997) un total de 13 712 476 cacaoyers virosés ont été abattus, ce qui représente 137% de l'objectif fixé. Néanmoins, il reste 67,1 % des foyers dans l'est et 47,3 % dans le centre du Ghana. Le projet a apporté les finances et l'aide technique nécessaire au remplacement des surfaces traitées avec des cacaoyers tolérants au CSSVD. Cependant à cause de l'opposition de nombreux fermiers quant aux primes à l'abattage considérées comme trop faibles et un délai de paiement trop long, de nombreux foyers de l'épidémie n'ont été que partiellement éradiqués. Seul 13,5 % des surfaces traitées ont été replantés en 1995-96. Dans la plupart des champs visités, les agriculteurs continuent à replanter le cacaoyer de manière traditionnelle, il en résulte une faible croissance des semences et une forte mortalité. Un ensemble de recommandations sont données pour parvenir à résoudre les problème

Support for ban on smoking in public places among adults in Sub-Saharan Africa

Background Secondhand smoke (SHS) exposure continues to be a major problem across Sub-Saharan Africa (SSA). Studies have called for immediate steps to address SHS exposure in SSA. Although several SSA countries are implementing smoke-free policies (SFPs), public support of these policies can affect their success. While support for SFPs has been studied in other countries, there is limited literature on SFPs in SSA. This study estimated the prevalence and factors associated with support for SPFs in four SSA countries. Methods Data from 27,952 participants of the Global Adult Tobacco Survey conducted in Nigeria (2012), Cameroon (2013), Uganda (2013) and Kenya (2014) were analyzed. Supports for smoking ban in eight public places were assessed. Descriptive analysis was conducted to estimate prevalence of support for SPF for the eight places and any support (defined as a support for SFP in at least one public place) for each country and pooled data. A multivariable logistic regression was used to examine factors associated with any support for SFPs. We report odds ratios and 95% confidence intervals (CI). Results Support for any SFP was 99.3% ,99.4%, 99.8%, and 99.8% in Kenya, Uganda, Cameroon and Nigeria, respectively. In the pooled data, support for SFPs ranged from 64.4% in restaurants to 98.8% in worship places. Adjusting for covariates, support for SFPs was significantly increased in participants who were aware of SHS harm, believed smoking causes serious illness, lived in homes where smoking is restricted, lived in smoke-free homes, resided in countries where three to five public places were completely smoke-free, and those aged 15-44 years. Conclusions The results suggest that support for SFPs increases as the number of smoke-free public places in a country increases. Implementing complete SFPs as described in the WHO FCTC in the SSA countries will likely succeed due to the prevailing high support for these policies