Evaluation of tri-linear corn hybrids (Zea mays L.), due to their reaction to the asphalt stain complex caused by pathogens (Phyllachora maydis, Monographella maydis and Coniothyrium phyllacorae)

Abstract

During the year 2013, a trial was installed with the objective to identify corn hybrids by its reaction to the foliar illness called Tar Spot Complex. The trial was conducted in thirteen places in different cities of El Salvador, and nine of them had antecedents with this illness. The evaluation was developed from May to November.

The experimental design Alpha-latice 4*5 was used, with three repetitions and 20 treatments. The treatments where made of 17 experimental tri-lineal hybrids and three commercial hybrids as witnesses. An analysis of variance was carried out by each place and combined, especially because of the percentage of cobs with bad coverage; percentage of rotting of the total of cobs and percentage of rotten cobs affected by the complex and performance. The AMMI Biplot GGE-SREG model was used to determine the genotype-environment interaction, finding significance for such interac­tion; as well as the individual factors that led to the 1% of probability. Ten out of the thirteen places where the study was carried out did not show the illness. But the other ones happened drastically upon the performance. The hybrid with higher advantage in the places with no presence of the illness was DK-357 with 8.35 ha-1, followed by HES-3 and HES-1 with 7.75 and 7.1 ha-1 respectively. In the places where there was presence of the illness, the best hybrids were HES-3, HES-17 and DK-357, with performances of 4.04, 4.01 and 4t ha-1 respectively.

The percentages of cobs affected by the illness for these hybrids were 50.3%, 46.8% and 60.7% respectively. The less affected hybrid by the illness was HES-1, with 42.9% of the infected cobs and performance of 3.85 t ha-1. The analysis of stability reported the more stable hybrids to HES-27 and HES-13. The results gathered show HES-1 as the tolerant hybrid and HES-3 as resistant.