Adaptability and stability of corn inbred lines regarding resistance to gray leaf spot and northern leaf blight

Belisa Cristina Saito,Leonardo Queiroz Silva,João Antonio Da Costa Andrade,Major M Goodman

doi:10.1590/1984-70332018v18n2a21

Belisa Cristina Saito, Leonardo Queiroz Silva + Show 2 more

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https://doi.org/10.1590/1984-70332018v18n2a21

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Abstract

Abstract The objectives of this study were to identify resistant and susceptible corn inbred lines based on their stability and adaptability for resistance to disease symptoms of gray leaf spot and northern leaf blight, suggest resistant inbred lines aimed at producing synthetics, and identify the sowing dates with higher occurrence of diseases to use these dates for identification of genetic resistance. We evaluated 41 corn inbred lines in randomized block designs with three replications and 11 sowing dates. Evaluations were performed 30 days after silking. Stability and adaptability analyses were performed by the regression method. The highest severities of disease occurred in sowing from June to September. On average, all the inbred lines were classified as resistant; however, considering adaptability and stability, five inbred lines were found suitable to produce dent synthetics resistant to both diseases. For flint synthetics resistant to both diseases, inbred lines IVF1-7, IVF1-10, 2F, 9F, and 10F are most suitable.

Highlights

A 50% reduction in capturing incident radiation caused by the decrease in green tissue 15 days before and after female flowering may lead to 40% to 50% reduction in grain yield (Fischer and Palmer 1984)
In Brazil, it was described by Chupp (1953), but the disease became common in 2000, when epidemics were reported in production fields in the central region of the country, due to the increase in inoculum promoted by crop tillage, center pivot irrigation, and the second crop season (Brito et al 2007)
The objectives of this study were to identify resistant and susceptible inbred lines based on their stability and adaptability for resistance to disease symptoms of gray leaf spot and northern leaf blight, suggest resistant inbred lines aimed at producing synthetics, and identify the sowing dates with the higher occurrence of these two diseases to use these dates for identification of genetic resistance

Summary

Introduction

Gray leaf spot (Cercospora zeae-maydis Tehon & E.Y. Daniels) and northern leaf blight (Exserohilum turcicum (Pass.) Leonard & Suggs) are among the leaf diseases that affect the corn crop in Brazil and worldwide. Daniels) and northern leaf blight (Exserohilum turcicum (Pass.) Leonard & Suggs) are among the leaf diseases that affect the corn crop in Brazil and worldwide Genotypes susceptible to these diseases are responsible for severe reduction in grain yield since the direct result of these diseases is decreased photosynthetic area from destruction of the green tissues. The symptoms of gray leaf spot first appear on lower leaves, about two or three weeks before tasseling. These leaf lesions are long, brown, rectangular, and elliptical. Under high humidity conditions (above 90%), daytime temperatures ranged from moderate to high (22 to 32 oC), and cold nights with dew, dense sporulation occurs, rendering leaves gray, the characteristic color of this disease (Casela and Ferreira 2003, Robertson et al 2008)

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