Growth and photosynthesis of a shade tolerant palm tree species under different light conditions

GATTI, MARÍA GENOVEVA; CAMPANELLO, PAULA INÉS; GOLDSTEIN, GUILLERMO

Miami, Estados Unidos

Congreso; Reunión Anual de Biología Tropical; 2004

Association of Tropical Biology and Conservation

The shade tolerant palm tree species Euterpe edulis is an important component of the sub canopy in the Atlantic Forests of Northeastern Argentina. This palm species produces one of the best edible palm hearts in the Americas. Due to its great demand, it has been relentless harvested resulting in a substantial decrease of its population size. This palm is considered a keystone species because of its synchronized production of fleshy fruits consumed by native mammals and birds. In spite of its importance, the physiological and ecological characteristics of this species are poorly understood which makes difficult the design of management and restoration programs to increase its abundance. With the purpose of determining the optimal light levels conditions for E. edulis seedlings growth, a greenhouse experiment was conducted. Seedlings of E. edulis were grown under four light treatments: 10, 30, 40 and 65% of total solar radiation. We measured diameter increment of the stem at ground level to estimate growth rate and used a pulse-amplitude modulated yield analyzer to measure photosynthetic capacity in response to light. Daily courses of the electron transport rate were also obtained. The diameter increment of the stem differed between treatments and it was correlated to the average daily electron transport rate, but it was not related to the maximum photosynthetic capacity observed in each light treatments. The electron transport rate can be considered a proxy for carbon assimilation under current environmental conditions. We recorded the highest photosynthetic capacity at intermediate light conditions (30%), because light levels higher than 30% cause photoinhibition of the photosynthetic system in this shade tolerant species.