Nitrogen is essential for sustaining life on the planet, and it is the most important nutrient for obtaining high agricultural production. However, their use leads to the release of nitrous oxide with a global warming potential 296 times higher than the CO 2 molecule, making it a challenge to reduce their use in agriculture. The objective of this research was to identify efficient popcorn inbred lines and responsive nitrogen use and exhibit a good expansion volume. For this, 29 inbred lines from the Germplasm Collection of Darcy Ribeiro North Fluminense State University (UENF) were evaluated at two contrasting levels of nitrogen availability (low and ideal) at two representative locations in the north and northwest of the state of Rio de Janeiro, Brazil, arranged in a randomized block design with three replicates. These inbred lines were discriminated against efficient use of nitrogen by multivariate GGE Biplot. Selective accuracy was close to 1, showing that the genotypes were enough to provide contrasting success in selection procedures. The first two main components (PC) retained 93.82% of the total variation, and PC1 furnished an information ratio (IR) that was unaffected by noise. L77 was the most unstable line, while P7, P2, P6, P3, P5, P4, P9, P10, P8, P9, L70, L74, and L55 were efficient and responsive. The GGE biplot method is recommended for the reliable identification of popcorn lines that are efficient and responsive to the use of nitrogen.Index terms: Zea mays; multivariate analysis; abiotic stress; G x E interaction. RESUMOO nitrogênio é indispensável à manutenção da vida no planeta, sendo o mais importante nutriente para a obtenção de elevadas produções agrícolas. No entanto, a sua utilização ocasiona a liberação de óxido nitroso, com potencial de aquecimento global 296 vezes maior que a molécula de CO 2 , tornando-se um grande desafio a redução de seu uso na agricultura. O objetivo desta pesquisa foi identificar linhagens de milho-pipoca eficientes e responsivas no uso de nitrogênio e que apresentem um elevada capacidade de expansão. Para isto, avaliaram-se 29 linhagens da Coleção de Germoplasma da Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF) em dois níveis contrastantes de nitrogênio (baixo e ideal) em dois locais representativos do Norte e Noroeste do Estado do Rio de Janeiro, Brasil, arranjadas no delineamento em blocos casualizados com três repetições. Estas linhagens foram discriminadas em relação a eficiência no uso do nitrogênio pela técnica multivariada GGE Biplot. A acurácia seletiva foi próxima de 1, revelando que os genótipos foram suficientes contrastantes para proporcionar sucesso em procedimentos seletivos. Os dois primeiros componentes principais (CP) retiveram 93,82% da variação total, sendo que o CP1 expressou relação de informação (IR) não impactada por ruídos. L77 foi a linhagem mais instável, enquanto P7, P2, P6, P3, P5, P4, P9, P10, P8, P9, L70, L74 e L55 foram eficientes e responsivas. Recomenda-se o método GGE Biplot na identificação fidedigna de l...

No abstract

No abstract

No abstract

The antifungal activity of fungi with biocontrol potentials should be studied. Therefore, this study aimed at establishing alternative agent to replace the chemical control of papaya black spot. We investigated the antagonistic activity of the fungi Hansfordia pulvinata (H-611), Acremonium sp (A-602, A-617 and A-598), Simplicillium lanosoniveum (S-599), Lecanicillium lecanii (L-622), and Sarocladium implicatum (I-609) on the phytopathogenic fungus A. caricae, by evaluating the mycoparasitism, the enzymatic activity and the production of volatile and non-volatile compounds. For the evaluation of mycoparasitism, each antagonic fungi isolate was microcultured along with conidia of A. caricae. Then, events of mycoparasitism were evaluated at 24h, 48h, 72h, and 96h after inoculation under an optical microscope. We estimated the enzymatic activity (protease and lipase) of the fungi in a particular culture medium for each enzyme. The activity of the protease was reflected in the mean diameter of the halo. The lipase activity was measured by the halo/colony relation. In order to detect volatile compounds in the antibiosis test, A. caricae was cultured under a medium along with the isolates described. For the test of non-volatile compounds, we evaluated the germination of A. caricae in culture medium by diffusion under cellophane paper. As a result, the mycoparasitism of the H-611, A-602, A-617, A-598, S-599, and L-622 isolates was confirmed on the microcultures. We observed higher activities of protease in the I-609, S-599, A-602, and A-598 isolates. The H-611 and A-602 isolates presented higher activities for lipase. We did not observe effect of volatile compounds in any of the tested isolates. In the non-volatile compound test, there was production of antifungal metabolite highlighting the A-617 isolate, which inhibited the germination of the conidia of A. cariae by 100%.

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.