Understanding maize genotype behavior under stunt complex pressure

Entendendo o comportamento de genótipos de milho sob pressão do complexo dos enfezamentos

ABSTRACT

The stunt complex, transmitted by Dalbulus maidis, has become one of the main maize diseases in recent years in Brazil and Latin America. Genetic resistance is one of the best ways to control and prevent plant diseases due to its efficiency, low environmental impact, and reduced need for phytosanitary products. We sought to identify maize genotypes tolerant to the stunt complex and quantify the levels of damage caused by the disease in commercial hybrids and native varieties. A two-year field experiment was conducted to evaluate the maize stunting. We used an augmented block design with 60 genotypes and 3 test hybrids, arranged in 4 blocks. We assessed the incidence and severity of stunting between stages R2 and R3. We evaluated the agronomic characteristics of the different genotypes to compare them with the effects caused by the stunt complex and each genotype’s tolerance. We found more than 1,000 kg ha^-1 of losses for commercial and native hybrids due to the stunt complex. Regression and multivariate analyses showed results that prove the effect of the maize stunt complex in reducing productivity, which allowed the classification of the evaluated genotypes into tolerance and resistance levels. The genotypes GNZ 7788 VIP3, Sempre 10A40 VIP3, DKB 360 PRO3, FS 575 PWU, NK Defender VIP3, and MG 540 PWU proved to be the best genotypes to serve as resistance sources to the stunt complex. The results emphasized the importance of genetic improvement in adding resistance/tolerance traits to breeding programs and increasing maize productivity and global sustainability.

Index terms:
Mollicutes; spiroplasma; phytoplasma; Dalbulus maidis; tolerance; breeding.