Abstract Bhendi Yellow Vein Mosaic Virus (BYVMV) is an emerging threat to okra ( Abelmoschus esculentus L.) production, causing severe yield losses. To develop high-yielding BYVMV-resistant okra cultivars, a full hybridization experiment was conducted using two local varieties Selection-21 (S-21) and Sobuj-Sathi (SS) and five BYVMV-resistant lines (M 6 L 3 , M 6 L 4 , M 6 L 5 , M 6 L 6 and M 6 L 7 ). Six hybrids – M 6 L 3 (M) × S-21 (F), M 6 L 6 (M) × S-21 (F), M 6 L 3 (M) × M 6 L 6 (F), M 6 L 4 (M) × SS (F), M 6 L 3 (F) × M 6 L 4 (M) and M 6 L 4 (F) × M 6 L 3 (M) – were found to be largely free from BYVMV infection. Additionally, data were recorded for plant height (cm), number of flowers per plant, number of fruits per plant, average fruit weight (g), number of seeds per fruit, 100-seed weight (g), disease incidence, disease severity index and yield (g/plant). The results revealed that, five of the six hybrid combinations – M 6 L 6 × S-21, M 6 L 3 × M 6 L 6 , M 6 L 4 × SS, M 6 L 3 × M 6 L 4 and M 6 L 4 × M 6 L 3 – were resistant to BYVMV, each showing 0% disease incidence. The hybrid M 6 L 3 × S-21 exhibited moderate resistance with a disease incidence of 13%. The highest yields were obtained from M 6 L 6 × S-21 and M 6 L 3 × M 6 L 6 , both significantly outperforming their parental lines. An examination of the disease severity index of begomoviruses and whitefly ( Bemisia tabaci ) population dynamics revealed that first whitefly incidence on parental lines was observed in early March, peaking in May and disappearing by June. The lines M 6 L 7 and M 6 L 6 had the highest (6.82) and lowest (1.61) whiteflies observed on leaves, respectively, which corresponds to a contrasting disease incidence in M 6 L 7 (PDI = 73.3%) and M 6 L 6 (PDI = 13%), respectively. Collectively, these findings demonstrate that hybridization is an effective approach for developing BYVMV-resistant okra varieties with enhanced productivity. Significance of the study What is already known regarding this topic? Bhendi Yellow Vein Mosaic Virus (BYVMV) of okra is transmitted by a small insect vector known as the whitefly ( Bemisia tabaci ). This virus causes a significant yield loss in okra production in Bangladesh. Infected plants may exhibit varying degrees of stunting, leaf curling and yellowing of leaf veins. The fruit skin is leathery, rough and yellowish. A hybridization programme aimed at developing disease-resistant okra lines could be an effective strategy for producing BYVMV-free okra cultivars. An important method for developing a BYVMV-free okra is to create F 1 hybrids. What are these new findings? Desirable traits from both parents can produce superior F 1 hybrid offspring. In this study, the hybrid offspring were resistant to BYVMV and exhibited superior yields and other morphological characteristics compared with their parents. What were the expected effects of horticulture? These findings are expected to significantly affect the production of BYVMV-free okra, a disease causing significant threat to okra production. Moreover, hybridization is anticipated to provide a viable strategy for improving both okra pod yield and quality. Farmers can grow high-yielding better-quality okra without using chemical control (health hazards). This approach also offers economic benefits for growers by promoting sustainable, eco-friendly farming practices and greater profitability through using BYVMV-resistant germplasm. The ultimate goal of the okra breeding programme is to release new varieties that possess elite combinations of desirable horticultural characteristics, including BYVMV disease resistance.
Piuli et al. (Fri,) studied this question.