Cocoa (Theobroma cacao L.) is an important cash crop in many tropical countries, particularly in West Africa. Heat and drought are both known to affect the physiology of cocoa plants through reduced rates of photosynthesis and transpiration, as well as changed physiological processes such as the functions of photosystems, chlorophyll synthesis, stomatal conductance and expression of heat-shock proteins. This in turn leads to decreased yields and increased risks of mortality under severe heat and drought. To help cocoa plants adapt to climate change, the literature suggests agroforestry as a potential farm management practice. It has been argued that the lack of tree cover in cocoa cultivation systems exposes the crop to heat and direct solar radiation, thus increasing evapotranspiration and the risk of drought. Drawing on data generated from two on-field studies, this chapter assesses the shade effect on cocoa’s physiological responses to drought and heat stress to determine whether shade would be beneficial under climate change scenarios. We conclude that shade improves the physiology of cocoa, but that this may not be sufficient to compensate for the negative effects of high temperatures and severe drought exacerbated by climate change in sub-optimal conditions.

Shade trees are important components of cocoa-agroforestry systems because they influence yields, soil fertility and the occurrence of pests and diseases and may support adaptation to climate change. Based on a review of the existing literature and on primary data from field experiments, this chapter reports on the species-specific effects of shade trees in relation to the management of insect pests, black pod diseases and their impacts on cocoa yield. Shade tree species in cocoa systems impact soil available phosphorus differently and shade tree species such as Spanish cedar (Cedrela odorata), limba (Terminalia superba) and mahogany (Khaya ivorensis) increase cocoa yield compared with cocoa systems without shade trees. The architecture of shade tree species may influence below-canopy temperatures and relative humidity, which potentially affect pests such as mirids and black pod disease infections and ultimately cocoa yield. As farmers have local knowledge of and preferences for certain shade tree species, strengthening the combination of scientific and local knowledge can prove a powerful tool for the improved management of shade tree species, as well as cocoa pests and diseases.

Due to the vulnerability of pepper (Capsicum spp.) and the virulence of tomato spotted wilt virus (TSWV), seasonal shortages and surges of prices are a challenge and thus threaten household income. Traditional bioassays for detecting TSWV, such as observation for symptoms and reverse transcription-PCR, are time-consuming, labor-intensive, and sometimes lack precision, highlighting the need for a faster and more reliable approach to plant disease assessment. Here, two imaging techniques—Red–Green–Blue (RGB) and hyperspectral imaging (using NDVI and wavelength intensities)—were compared with a bioassay method to study the incidence and severity of TSWV in different pepper accessions. The bioassay results gave TSWV an incidence from 0 to 100% among the accessions, while severity ranged from 0 to 5.68% based on RGB analysis. The normalized difference vegetative index (NDVI) scored from 0.21 to 0.23 for healthy spots on the leaf but from 0.14 to 0.19 for disease spots, depending on the severity of the damage. The peak reflectance of the disease spots on the leaves was identified in the visible light spectrum (430–470 nm) when spectral bands were studied in the broad spectrum (400.93–1004.5 nm). For the selected wavelength in the visible light spectrum, a high reflectance intensity of 340 to 430 was identified for disease areas, but between 270 and 290 for healthy leaves. RGB and hyperspectral imaging techniques can be recommended for precise and accurate detection and quantification of TSWV infection.

Conventional propagation of yam (Dioscorea spp.) is constrained by low multiplication rates, pathogen accumulation, and vulnerability of field-maintained germplasm to biotic and abiotic losses. However, most studies emphasize survival, whereas fewer evaluate accession-specific growth performance alongside water-extractable phenolic content and antioxidant responses under the same conservation conditions. This study integrated morphological, biochemical, and post-conservation regrowth assessments to evaluate eight Ghanaian yam accessions maintained for 24 weeks on hormone-free complete Murashige and Skoog medium. The experiment followed a completely randomized design with three biological replications. All accessions maintained 100% survival without contamination throughout conservation, although substantial accession-dependent differences occurred in vegetative performance. At week 24, UWR produced 5.5 shoots/plant, 14 leaves/plant, and reached 8.5 cm height, while NKURAKAU produced 4.5 shoots plant⁻¹ and reached 8.2 cm. In contrast, SO showed weaker growth, producing 2.8 shoots plant⁻¹, 6 leaves plant⁻¹, and 4.5 cm height. During four weeks of post-conservation recovery, NKURAKAU exhibited the strongest regrowth, producing 1.8 shoots plant⁻¹, 4.2 leaves plant⁻¹, and 5.0 cm high plantlets. Biochemical responses were also accession-specific. AMO exhibited the highest water-extractable TPC after 24 weeks of conservation (4.1 mg GAE/100 g dry weight), whereas UWR showed the lowest response (1.7 mg GAE/100 g dry weight). Conversely, SO and NKURAKAU exhibited comparatively strong DPPH radical-scavenging activity despite lower phenolic contents. No statistically detectable linear association between endpoint TPC and DPPH radical-scavenging activity was observed among the eight accessions (r = −0.24, p > 0.05). Exploratory hierarchical clustering of biochemical trait distinguished AMO as higher-TPC phenotype and SO/NKURAKAU as higher-DPPH phenotype. Overall, combining morphological traits, biochemical indicators, and post-conservation regrowth provides a more informative basis for accession-specific germplasm management than survival alone. NKURAKAU and UWR showed the most balanced performance, while AMO was notable for shoot multiplication and higher TPC.