Functional leaf traits of maize landraces with low and high susceptibility to damage by Spodoptera frugiperda (Lepidoptera: Noctuidae)

In the search for environmentally friendly options to manage plant pests and enhance productivity with fewer external inputs in agriculture, the screening of landraces has gained importance. The aims of this study were to characterize functional leaf traits in maize landraces, including morphological traits such as leaf toughness, thickness, specific leaf area (SLA), and number of trichomes, as well as physiological leaf traits such as photosynthesis, transpiration rate, and stomatal conductance. We aimed to determine the association of these traits with leaf damage caused by Spodoptera frugiperda across 24 maize landraces. Relationships of dependence among leaf traits and leaf damage were determined using principal component analysis, multiple regression analysis and sequential path analyses. All morphological leaf traits showed differences among maize landraces mainly at 20 and 30 days after emerge (DAE) whereas at 40 DAE the differences decreased. By the contrast, physiological leaf traits had high variation at 40 DAE among maize landraces. We found a negative dependency of principal component conformed by photosynthesis, transpiration rate, and stomatal conductance over leaf damage. Based on the level of leaf damage, we categorized maize landraces into two groups with low and high susceptibility. Surprisingly, we observed that in the former group, physiological leaf traits affected the number of trichomes, whereas in the latter group, they influenced leaf thickness. This finding highlights the necessity of detailed assessments of foliage properties to understand the impact of S. frugiperda infestations. Such an analytical approach is crucial in scientific research, providing deeper insights into the underlying mechanisms of interaction between the pest and its host plants.