Morphological adaptations of maize accessions in response to natural field pathogen pressure

Abstract

This study evaluated the morphological response of ten maize accessions obtained from the International Institute of Tropical Agriculture (IITA), Ibadan, to field pathogens. The field experiment was conducted using a completely randomized design with four replicates. The maize accessions were planted in unsterilized soil under natural field conditions. Data on morphological traits were collected over ten consecutive weeks, and disease severity was rated on a scale of 1 to 5. The findings reveal that Tropical Zea mays (TZM) 115 and TZM 105 accessions outperformed others in most morphological traits. TZM 115 had significantly higher values for the number of leaves (NOL: 10.41) and tassel length (TL: 52.73 cm) while TZM 1422 had the lowest values (NOL: 6.81, TL: 12.44 cm). This is further supported by hierarchical clustering analysis, which indicates that TZM 115 shares some similarity with accessions in the other two clusters. Regarding disease resistance, TZM 105 exhibited the highest resistance to field pathogens, with a disease severity rating of 2.90, whereas TZM 45 had the highest recorded severity rating of 3.38. Thus, this research elucidates the considerable genetic diversity present among maize accessions, revealing notable variations in growth patterns, agronomic characteristics and disease susceptibility. These results also enhance our comprehension of how morphological traits influence disease resistance and highlight the capability of certain maize accessions to thrive in the presence of field pathogens. Therefore, accessions TZM 115 and TZM 105 are recommended for adoption in maize breeding and improvement programs due to their high disease resistance potential and favorable morphological traits for sustainable and cost-effective resistance strategies.