O papel dos cotilédones e dos eófilos durante o estabelecimento inicial em Cedrela fissilis Vell. (Meliaceae)

Abstract

The seedling stage is seen as crucial in the survival of the most diverse plant species, due to the remarkable vulnerability of individuals during this stage of development to biotic and abiotic environmental factors, such as herbivory injuries and light variability. In general, cotyledons and eophiles perform functions of great importance in the establishment and development of seedlings, such as nutrient supply and photosynthesis. Thus, it is extremely important to elucidate the impacts caused by the loss of such structures in the early stages of seedling establishment and how these impacts can reflect on the survival and development of the plant in the long term. The objective of the present study was to understand the role of cotyledons and eophiles during initial establishment in Cedrela fissilis Vell. (Meliaceae), a plant commonly found in forest phytophysiognomies and with photosynthesizing cotyledons, also known as “cedro rosa”. To this end, the morphophysiological responses of C. fissilis to partial (-1) or total (-2) losses of cotyledons and eophiles in 30-day-old seedlings were analyzed. The experiments were carried out between July and October 2024, in a shaded nursery located at the Federal University of Uberlândia – Umuarama Campus (Uberlândia-MG). Growth parameters (height, root length, stem diameter, number of leaves and total leaf area), physiological parameters (electron transport rate - ETR) and effective quantum yield - ∆F/Fm') and biomass partitioning ratios (leaf area ratio, and root, steam and leaf dry mass ratios) were analyzed. The results showed that, although the removals did not cause significant impacts on the growth and partitioning of biomass in C. fissilis, there was an increase in photosynthetic functions in cotyledons in the absence of one or two eophiles. In addition, it was also observed that this mechanism of compensatory photosynthesis is not carried out efficiently in the eophiles of seedlings with one or two missing cotyledons. It is also evidenced by the high survival rate of C. fissilis at the end of the experimental tests a certain resilience of the species to late injury in the long term.