Aphis gossypii Glover (Hemiptera: Aphididae) is among major arthropods causing significant damage to okra in the tropics. Resistant varieties could reduce aphid infestation and increase productivity. This study was carried out to identify aphid-resistant and high yielding okra accessions for management of the pest. Eleven farmers’ varieties and four aphid-resistant accessions from AVRDC were evaluated at its Nkolbisson station in Yaounde, Cameroon. Field screening was done to determine resistance to aphids, days to 50% anthesis and days to 50% commercial maturity. Aphid data was expressed as the area under infestation pressure curve and subjected to statistical analysis based on mean (m) and standard deviation (S.D.). Crop cycle and yield data were subjected to analysis of variance. Accession ‘VI033824’ was the most resistant to aphids (474 ± 41.9 per leaf) with yield 0.76 ± 0.26 t/ ha whereas the yield of the highly susceptible Babungo (1519.8 ± 0.0 aphids) was 1.33 ± 0.07 t/ha, 75.5% higher that the yield of the only resistant variety. Abelmoschus esculatus was less attacked (601.4 ± 60.0 aphids) by aphids than Abelmoschus caillei (826.0 ± 71.6 aphids; df = 1, 41; Pr {>Chi} = 0.037). The yield of A. caillei species were higher (1.26 ± 0.14 t/ha) than A. esculentus species (0.43 ± 0.08 t/ha; df = 1, 41; Pr {>Chi} = 0.0002). Hence, varieties with resistance, tolerance to aphids and earliness could be incorporated into integrated pest management of aphids and enhance productivity of okra.

Genotype by environment interaction remains a substantial issue in all breeding programs. Crop genotypes are generally developed in a central breeding location, but always require the evaluation of breeding products in different environments. This is particularly relevant in countries that have a wide range of climates. Eighteen cassava genotypes were evaluated in Cameroon in eight environments—varying in seasonal rainfall and temperature patterns and soil characteristics—over two cropping seasons. Soil nutrient content was analyzed and trials were established in a randomized complete block design in three replications. Response of genotypes to major cassava pests and diseases, yield and carotenoids content was evaluated. It was observed that four genotypes did not show cassava mosaic disease (CMD) symptoms irrespective of the environments. The local check had highest CMD incidence and severity across all environments. Average number of whitefly per plant across all environments was highest on TMS 96/0023. Average cassava green mite (CGM) infestation was low on all the genotypes. Fresh root yield of five genotypes ranged between 25 and 30 tons per ha for both years. Significant and positive correlation was found across locations between fresh root yield and soil K, P and Mg. AMMI analysis revealed highly significant differences among genotypes and environments and significant genotype × environment interaction for most of the estimated traits, indicating variability in genotypes performance with environment.

Cassava is a key food security crop in Central Africa, but its production depends largely on the use of local farmers' varieties characterized by inherently low yield which is compounded by generally high susceptibility to various growth and yield-limiting pests and diseases. Improved cassava genotypes have demonstrated the potential to substantially improve cassava's contribution to food security and the development of the cassava industry and the improvement of nutrition status elsewhere in Western Africa. Eleven improved cassava genotypes were compared with a local landrace (LMR) used as a check under field conditions over two years in eight locations, grouped in four agro-ecologies in Cameroon. Pest and disease abundance/incidence and damage severity were evaluated. At harvest, root yield and carotenoid content were measured. Best linear unbiased predictors showed the lowest breeding value for LMR with the cassava mosaic virus disease (+ 66.40 ± 2.42) compared with 1.00 ± 0.02% for the most susceptible improved genotype. Two genotypes (I010040-27 and I011797) stood out for having higher predicted fresh root yield means which were at least 16 times greater compared with LMR. Predicted total carotenoid content was the highest (+ 5.04 ± 0.17) for improved genotype I070593 compared with LMR which showed the lowest (- 3.90 ± 0.06%) and could contribute to the alleviation of vitamin A deficiency from cassava-based food systems. Diffusion of high-yielding and nutritious genotypes could alleviate food and nutritional security in Central Africa.