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

Abstract

Nitrogen-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. INTRODUCTIONOverusing mineral fertilizers and agrochemicals harm natural resources essential for farming sustainability (Fagard et al.,Abbreviations: AUDPC, area under the disease progress curve; AUDPC/I, area under the disease progress curve for leaf blight incidence; AUDPC/S, area under the disease progress curve for leaf blight severity; GCA, general combining ability; IN, ideal nitrogen availability; GCA, general combining ability; LN, low nitrogen availability; NLB, northern leaf blight; SCA, specific combining ability.

Additive and Non-Additive Effects on the Control of Key Agronomic Traits in Popcorn Lines under Contrasting Phosphorus Conditions

“…In environments with adequate water and nutrient supply [15][16][17] and under water-deficit conditions [18,19] as well as P and N stress [10,20,21], additive genetic action prevails for grain popping expansion, while non-additive action has been the most important in the expression of grain yield under water stress [14,18,19]. These results are also consistent with studies conducted with biotic stressors [22][23][24][25][26].…”

Driving Sustainable Popcorn Breeding for Drought Tolerance in Brazil

“…Genetic effects controlling popcorn traits under well-watered conditions (Larish and Brewbaker, 1999 ; Pereira and Amaral Júnior, 2001 ; Silva et al, 2010 ; Jele et al, 2014 ; Dar et al, 2018 ; Coan et al, 2019 ; Schwantes et al, 2020 ), biotic stresses (Schwantes et al, 2017 ; Mafra et al, 2018 ; Amaral Júnior et al, 2019 ; Kurosawa et al, 2020 , 2021 ), and nutritional deficiencies (Gerhardt et al, 2019 ; Santos et al, 2019 , 2020 ) have revealed that the additive genetic action is prevalent for PE, whereas the non-additive action has been the most important for GY expression and its components. In addition, non-additive genetic effects were the most prevalent controlling GY under water limitations in tropical maize (Betrán et al, 2003 ).…”

UENF P01, UENF P02 and UENF P03: popcorn hybrids with high phosphorus use efficiency

“…Particularly for popcorn production, which generates an annual turnover of about 1 billion dollars in the USA, to date all improved seed planted in Brazil must be imported, due to its higher grain yield and popping expansion, which AT Amaral Jr et al has motivated the development of research at the State University of Northern Rio de Janeiro (UENF), whose focus is the development of productive cultivars, with high expansion capacity, resistant to the main pathogens and pests and with better use of P. Genotypes are being developed with tolerance or resistance to biotic stresses (Schwantes et al 2018, Schmitt et al 2019, Kurosawa et al 2021; to abiotic stresses, in particular drought (Lima et al 2021, to low nitrogen , Khan et al 2021, Khan et al 2022) and to low P availability (Gerhardt et al 2017). In addition, genome wide selection (GWS) in a recurrent intrapopulation selection program was used to accelerate the breeding of superior segregating generations (Mafra et al 2019, Albino-Schwantes et al 2020.…”