Híbridos de milho (Zea mays L.) e intensidade de danos, a campo, ao complexo de enfezamento

Abstract

Corn is an important cereal, which has the largest production volume in the world. In Brazil it is cultivated throughout the national territory and in the last decades it has undergone profound transformations, leaving a subsistence scenario for a highly technified agriculture, which allows production of corn throughout the year, as well as the maintenance of most phytosanitary problems. Among these, the pest-insects stand out and, in recent years, those related to corn leafhopper, mainly due to the fact that this is the vector of Corn Stunt Disease. Due to the problems caused by the transmission of the pathogen by the leafhopper and the use of resistant hybrids as the main damage reduction strategy, the present study aimed to evaluate in the field the behavior of corn hybrids to Corn Stunt Disease transmitted by the corn leafhopper. The study was carried out at the Agricultural Research Center of Copacol, located in the municipality of Cafelândia, in the western region of Paraná. Fifty commercial corn hybrids were evaluated, with evaluation of Stunt severity, phytotechnical parameters and productivity. Leaf damage, ear and size scores were assigned to assess the damage caused by stunting ranging from 0 to 10, being zero when there were no symptoms. The data were subjected to analysis of variance and the means compared by the Scott-Knott test at 5% probability, using the Sisvar Statistical Software, while the Cluster analysis and Spearman correlation were performed using the Statistica 7.0 Software. The hierarchical groupings of the dissimilarity matrix were obtained by the method of Unweighted Pair Group with Arithmetic Mean (Upgma). Results showed that some hybrids express the symptoms, but remain among the most productive, while others express the symptoms and their productivity is strongly influenced. FORMULA VIP2 and NS 45 VIP3 hybrids had a higher incidence of leaf, ear and size stunting . Hybrids NTX 454 PRO2, P 3707 VYH, P 3282 VYH, NTX 468, B 2730 VYH, K 9500 PRO2, B 2620 PWU, NTX 790, NK 422 VIP3, NS 45 VIP3, FS 512 PWU, MG 618 PW, K 9300 PRO3, K 9606 VIP3 and DEFENDER VIP3 showed higher symptoms of stunting and were among the hybrids with lower grain yield. DKB 255 PRO3, DKB 360 PRO3, MG 593 PW, FS 564 PWU, MG 580 PWU, AG 8065 PRO3, MG 545 PWU, P 3380 HR, P 3858 PWU, and AG 9000 PRO3 hybrids showed lower rates of stunting and lodging and remained in the group of hybrids with higher yields.