Gene effects from Bipolaris maydis incidence and severity on popcorn

Abstract

Popcorn suffers severe economic losses resulting from harmful effects caused by several diseases such as southern corn leaf blight (SCLB), which is one of the main leaf diseases able to cause considerable damages to corn crops. The realization conducting genetic studies in order to identify genotypes presenting genetic resistance to this disease it is essential. Accordingly, the aim of the current study is to estimate gene effects and combining abilities in popcorn, with emphasis on the resistance to Bipolaris maydis. Full diallel crosses were performed, including reciprocal crosses between eight lines (L76, L88, L70, L77, L55, L61, P1 and P8), in order to produce 56 hybrids (F 1 's and reciprocal hybrids). The experiment followed a randomized block design, with four replicates; in two different cultivation periods (first and second periods), in Campos dos Goytacazes, RJ. Southern corn leaf blight incidence and severity, caused by B. maydis, were assessed in each cultivation period. No reciprocal effect was observed for the evaluated characteristics, since the diallel analysis did not find significant effect from this variation source. With respect to SCLB incidence and severity in the two cultivation periods, the mean square of the effects showed that the dominance components were superior to the additivity ones. Hybrids that stood out in the two cultivation periods to the assessed features were: L88 x L61, L88 x L70, L88 x L76, L61 x L77, L61 x P1, L70 x P1, P1 x L76, L77 x L76, and P8 x L77. Efeitos gênicos da incidência e severidade de Bipolaris maydis em milho-pipocaRESUMO: O milho-pipoca sofre severas perdas econômicas devido aos efeitos danosos da incidência de doenças. A helmintosporiose é uma das principais doenças foliares e representa um considerável potencial de dano à cultura; tornando-se evidente a necessidade de estudos genéticos visando à identificação de genótipos que apresentem resistência genética para essa doença. O estudo teve por objetivo estimar os efeitos gênicos e as capacidades combinatórias em milho-pipoca, com enfoque para a resistência a Bipolaris maydis. Foram realizados cruzamentos dialélicos completos, incluindo os recíprocos entre oito linhagens (L76, L88, L70, L77, L55, L61, P1 e P8), para a obtenção de 56 híbridos (F 1 's e recíprocos). Instalouse experimento em delineamento em blocos ao acaso com quatro repetições, em duas épocas de cultivo, em Campos dos Goytacazes, RJ. Avaliaram-se a incidência e a severidade causada por B. maydis para cada época. Observou-se a ausência de efeito recíproco para as características avaliadas, uma vez que não houve efeito significativo desta fonte de variação na análise dialélica. Para a incidência e severidade de helmintosporiose, nas duas épocas de cultivo, o quadrado médio dos efeitos revelou que os componentes de dominância foram superiores aos de aditividade. Os híbridos que se destacaram, nas duas épocas de cultivo, com base no conjunto de características avaliadas, foram: L88 x L61, L88 x L70, L88 x L76, L61 x L77, L61 x P1, L70 x P1, P1 ...

Resistance to multiple leaf diseases in popcorn lines with potential for baby corn production

“…The possibility of obtaining superior hybrids can also be inferred, since there are resistant lines from different genealogies, making it possible to explore heterosis. According to Santos et al (2019), non-additive gene effects are more important for the characteristics related to NCLB resistance; therefore, hybridization is the most suitable option for obtaining productive and resistant genotypes. Similar to the findings observed for resistance to E. turcicum (NCLB), when analyzing the resistance characteristics for B. maydis (SCLB), no significant effect was observed for lines during the summer season.…”

“…When selecting a population with SCLB resistance characteristics, it may be improved by the addition of resistance and productivity genes, for later extraction of lines and hybrid production. Santos et al (2019) found the importance of the genetic effects of dominance in the control of the resistance characteristics against B. maydis. This is corroborated by studies performed by Carson, Stuber, and Senior (2004) that observed that resistance to SCLB was most influenced by non-additive effects.…”