We researched the effect of different levels of shade and seasonality on the photosynthetic
characteristics and growth in juvenile Aniba rosaeodora trees that were cultivated in a
plantation in Santarém, Pará, Brazil. The trees were between two and three years old and
were submitted to four treatments: (T1) = 70% shade; (T2) = 50% shade; (T3) = 30%
shade; (T4) = full sun. Variables analyzed were height and diameter growth, chloroplast
pigment concentrations, chlorophyll a florescence, concentrations of essential oil, and dry
mass of stem, branches, leaves and roots. The 50% and 70% shade treatments showed the
highest height and diameter growth, demonstrating physiologic elasticity, and lowest
growth was found for the full sun treatment. The values for chloroplast pigment
concentrations were nearly equal between treatments, with small seasonal variation. Only
the T4 treatment altered the photosystem II efficiency, thus inhibiting photosynthesis and
growth, and the T4 and T3 treatments cause the development of photoprotection
mechanisms. The largest amount of essential oil was collected from the T2 treatment, and
the lowest from the T1 treatment. The T1 treatment yielded the largest amount of dry
biomass and T4 the lowest. These results indicate that 50% and 70% shade strongly
influenced the development of the juvenile trees and also the yield of essential oil,
especially for the T2 treatment. The T4 treatment negatively influenced these variables
due to the high incidence of solar radiation that directly inhibited photosynthesis.
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