Diallel analysis for resistance to northern leaf blight in popcorn under contrasting nitrogen availability

Abstract

AbstractNitrogen‐use efficient and leaf‐disease resistant corn (Zea mays L.) cultivars are important to reduce costs and increase sustainability in farming. Studies have shown that non‐additive genes may enhance nutrient‐use efficiency and disease resistance in corn crops. This work aimed to analyze the responses of popcorn hybrids to northern leaf blight (NLB) under contrasting nitrogen availability. We evaluated NLB incidence and severity in 28 diallel hybrids and their parental lines. Competition trials were set in a randomized block design and arranged in a 6 × 6 lattice. The trials were conducted in four environments: two sites and two nitrogen availability conditions per site (ideal [IN] and low [LN]). The area under the progress curve of NLB incidence and severity was estimated for each genotype. To reduce the disease in multiple environments, general combining ability (GCA) of parentals is more important than specific combining ability (SCA) of hybrid combinations. The interactions between SCA and environment were significant for the disease resistance. Therefore, the best combinations should be identified for each environment so that NLB resistance could be enhanced. Low nitrogen availability enhanced the ability of parents to reduce NLB incidence and severity. Hybrid development is an efficient strategy to attain genetic gains in NLB resistance in multiple environments, regardless of N availability. The exploitation of additive gene effects may assist plant breeders in obtaining promising parents for the development of resistant hybrids in multiple locations.