Global warming poses a threat to food security, particularly for essential crops like cowpea, which exhibits sensitivity to heat stress. This study aimed to evaluate the morpho-agronomic diversity of cowpea genotypes under different daily temperature regimes. The experiment was conducted in growth chambers, and biometric and productive traits were measured to quantify genetic divergence using Mahalanobis distance and UPGMA clustering. Temperature increases markedly altered trait expression. Under the 20–26–33 °C regime, 100-grain weight, leaf dry weight, pod weight, and stem dry weight accounted for 54.44% of the total variation. Under the higher temperature regime (24.8–30.8–37.8 °C), number of pods, plant height, stem fresh weight, and leaf dry weight explained 67.27% of the diversity, evidencing the impact of heat stress on vegetative and productive traits. Cluster analysis identified five distinct groups, confirming genetic variability and temperature-dependent dissimilarity patterns. Genotypes Bico de Ouro 17-53, Bico de Ouro 17-33 and BRS Tumucumaque maintained higher grain number and grain weight under elevated temperatures, whereas others showed yield reductions of up to 65%. These findings demonstrate exploitable genetic variability for heat tolerance in cowpea and support the use of morpho-agronomic traits as effective criteria for selecting genotypes adapted to warmer environments.

Cowpea production can be severely affected by powdery mildew, a disease whose epidemiology is highly influenced by environmental conditions. In the context of climate change, understanding the effects of increasing temperatures on disease development is essential. In this study, 12 cowpea cultivars were evaluated under two daily temperature regimes: 20°C min–26°C average–33°C max (current condition) and 24.8°C min–30.8°C average–37.8°C max (warming scenario, +4.8°C). The experiment was conducted in growth chambers under a completely randomized design, with standardized inoculation. Evaluations were conducted on disease severity, area under the disease progress curve (AUDPC), number of lesions per leaf, number of conidia per counting field and conidial germination. Increased temperature prolonged the incubation period (i.e., from 7 to 9 days) and significantly reduced disease severity, AUDPC, lesion number, number of conidia per counting field and germination. Multivariate analysis indicated that temperature was the primary factor structuring disease response patterns, with limited differentiation among cultivars under the warming scenario. No cultivar showed resistance to the powdery mildew. The reduction in disease development is primarily attributed to the direct inhibitory effect of high temperature on pathogen development rather than to plant host resistance mechanisms. These results highlight the importance of temperature as a key driver of powdery mildew epidemiology under climate change conditions.

Cowpea ( Vigna unguiculata (L.) Walp.) is a crop of major importance in semiarid regions, where powdery mildew can significantly reduce productivity. This study evaluated powdery mildew severity in four cowpea cultivars grown under monocropping and intercropping with two biomass sorghum ( Sorghum bicolor (L.) Moench) across two planting seasons (June and December 2021) under semiarid conditions. The experiment was conducted in a randomized complete block design arranged in a 12 × 2 factorial scheme with three replications, and disease severity was assessed at the R9 stage by means of the percentage of leaf area affected. Planting season significantly affected disease severity, and a significant season × treatment interaction was detected, indicating that the effects of cultivar and cropping system depended on planting season. Disease severity was higher in the June planting, whereas December planting reduced severity by 69.60%. Intercropping reduced disease severity for most cultivars during the June planting. Monocropping systems showed higher grain yield due to greater plant density, averaging 2.11 and 2.29 t ha ^{− 1} in June and December planting, respectively, while intercropping averaged 1.15 and 1.22 t ha ^{− 1} . However, intercropped cowpea maintained stable productivity per plant despite a 50% reduction in plant density. These results demonstrate that adjusting planting date and adopting intercropping with adapted cultivars can simultaneously reduce powdery mildew severity and maintain productive stability in semiarid cowpea systems.