Comparative analysis of leaf micromorphology and anatomy in cultivated and weedy sunflower (Helianthus annuus)

Abstract

There are various opinions in the literature on the importance of morpho-anatomical leaf features, such as the number of stomata, the presence of trichomes, cuticle thickness, cell size, leaf thickness, etc. for the susceptibility of plants to foliar herbicides. Knowing that differences in the plant's sensitivity to herbicides may be due to differences in leaf sufrace and inner structure of leaves, a detailed micromorphological and anatomical analysis was performed on the leaves of tolerant and susceptible sunflower forms, both in cultivated hybrids and populations of weedy sunflower. It is interesting that while no significant differences in the number of trichomes and stomata between the resistant and susceptible weedy sunflower populations were observed, in comercial sunflower genotypes these numbers were significantly different. Namely, the number of stomata in the sensitive comercial sunflower hybrid was significantly higher than in the tolerant ones, but the tolerant hybrids had significantly more leaf trichomes than the sensitive one. Consequently, it is possible that the higher density of trichomes makes it impossible for the herbicides to reach the surface of the leaf epidermis, resulting in a reduced uptake. It has also been shown that plants with different levels of herbicide susceptibility also differ in various anatomical parameters.