Respostas morfofisiológicas de mudas de Eugenia uniflora em condições de sombreamento

Abstract

Plants have a remarkable ability to change their phenotype in response to highly heterogeneous light conditions, normally found in the natural environments. Eugenia uniflora has been considered as very demanding in relation to light. To test the acclimation. Hypothesis of species in shaded environments were analyzed the growth of the plant, accumulation of dry mass, biomass allocation, leaf morphology, content of chlorophyll and carotenoids, gas exchange parameters of photosynthetic (assimilation of CO2, stomatal conductance, rate of transpiration, internal carbon dioxide concentrations). The chlorophyll a fluorescence parameters (minimum fluorescence, maximum fluorescence, effective quantum yield of PSII and electron transport rate), along a gradient of luminous intensity in seedlings of E. uniflora. The seedlings were cultivated for 21 months at under different levels of shading: 0% (full sun), 30%, 50% and 80% of solar radiation interception. Seedlings grown under full sun and 30% shade accumulated significantly more dry mass than the seedlings grown in 50% and 80% shade, during the study period. The largest leaf size and specific leaf area were obtained in seedlings grown under 50% shade, while cultivated plants under full sun presented more number of leavesThe chlorophyll a and total chlorophyl were higher in the leaves under shading, while the concentration of chlorophyll b and carotenoid content were not affected by different shading. The level of 80% shading limited the net assimilation of CO2 and the rate of electron transport. The stomatal conductance and transpiration rate were higher under 50% shading, and the intercellular CO2 concentration did not differ between treatments. E. uniflora presents some adaptation to different intensity of solar radiation, mainly through modifications in physiological, morphological, leaves and photosynthetic properties. In conclusion, the conditions of full sun and 30% of shading were the best light intensities for the cultivation of E. uniflora. Based on our results E. uniflora can be classified as an optional sol plant.