Morpho-physiological and anatomical responses to shade avoidance are exhibited in Surinam cherry seedlings

Abstract

We aimed to evaluate the acclimation of Eugenia uniflora seedlings in response to irradiance gradient employing several morphological and photosynthetic traits. Seedlings were grown for 21 months under full sunlight (S0) and three artificial shade levels: 30% (S30), 50% (S50), and 80% (S80). Growth, biochemistry( pigments), photosynthetic, and anatomic parameters were assessed. Seedlings under S0 and S30 displayed the most significant growth, biomass accumulation, photosynthetic rate, and increased leaf thickness. S0 seedlings also had leaf anatomical traits associated with protection against total sunlight conditions, confirming irradiance tolerance. Nonetheless, the main attributes of shade acclimation in E. uniflora were revealed in S50 seedlings, where the increase in leaf area and the maintenance of gas exchange in this treatment achieved similar levels to seedlings under S0 and S30. Under S80, photosynthetic capacity, growth, and biomass accumulation were critically reduced. The plasticity index portrayed growth and photosynthetic traits as the most important variables that aid the adaptation of E. uniflora under different irradiance intensities. Conditions under S0 and S30 optimize the growth of Surinam cherry seedlings. Therefore, these conditions suit cultivating E. uniflora seedlings in nurseries and orchards. This study represents the first experimental approach to determining the optimal light intensity in E. uniflora seedlings.