Comportamento de genótipos de milho as doenças transmitidas pelo inseto vetor Dalbulus maidis (DeLong & Wolcott) (Hemiptera: Cicadellidae)

Abstract

Maize (Zea mays L.) is one of the most important agricultural crops in Brazil, with great economic, social, and strategic relevance for national agribusiness. The present study aimed to evaluate the performance of twelve maize genotypes under natural infection by the etiological agents of the stunt complex, under continuous vector infestation ensured by the “green bridge” technique. This strategy consisted of the staggered planting of the susceptible hybrid NS 75 VIP³ in the borders and corridors of the experimental area, ensuring the maintenance of Dalbulus maidis populations throughout the crop cycle. The field experiment was carried out in Entre Rios do Oeste, Paraná State, at the Experimental Station Professor Alcebiades Luiz Orlando (UNIOESTE), in a randomized complete block design (RCBD), with twelve treatments and three replications, totaling 36 plots. Climatic conditions during the trial were marked by a gradual increase in average temperatures and irregular rainfall distribution, factors that favored vector multiplication and symptom expression. Analysis of variance revealed significant differences only for plant height, indicating the expression of genetic variability among hybrids for this trait. Hybrids such as DEFENDER VIP³ and NS 71 VIP³ achieved greater heights, whereas SUPREMO VIP³ exhibited shorter plants, associated with higher vector colonization. Although no significant statistical differences were observed for grain yield, degree of stunting, or vector population, mean values revealed consistent patterns. The hybrid AG 9035 PRO³ stood out with the highest yield and the lowest degree of stunting, representing a promising material for environments with high vector pressure. P3310 VYHR also performed satisfactorily, combining high productivity with a low degree of stunting. FS 575 PWU, although not the most productive, showed the lowest vector infestation and reduced stunting, suggesting antixenosis or partial resistance mechanisms. In contrast, SUPREMO VIP³ exhibited the poorest performance, combining the lowest yield, the highest degree of stunting, and the largest vector population. The results confirmed that resistance to the stunt complex is partial and quantitative, depending on the interaction among genotype, environment, and vector population dynamics. The identification of hybrids such as AG 9035 PRO³, P3310 VYHR, FS 575 PWU, and DEFENDER VIP³, which combined yield stability with reduced symptom severity, represents an advance for breeding programs and integrated crop management in regions with high pressure of Dalbulus maidis.