Effects of Shading on Anatomical Aspects and Chlorophyll and Carotenoid Contents in Paricá

Paricá (Schizolobium parahyba variety amazonicum) is an important species for reforestation programs in the Amazon; nevertheless, the anatomical and physiological parameters of the seedlings of this species under shading are not yet fully understood. This study evaluated the chlorophyll and carotenoid contents, the stomatal structure, and the stomatal position in the leaf epidermis under shading of paricá seedlings. The experiment comprised a randomized block design in a subdivided plot scheme, with two sources (Belterra and Urupá) and different shading levels (full sun, 30%, 50%, and 70%). At 100 days after sowing, we performed the analyses of photosynthetic pigment concentration and leaf anatomy. We found that the leaf is hypoestomatic with paracitic stomata and unicellular filiform trichomes on both sides. Higher levels of shading increased the contents of chlorophyll a and b and reduced the stomata density and carotenoid contents in the leaves of young paricá, showing that paricá has phenotypic plasticity to shading.