O objetivo deste trabalho foi verificar o efeito do sombreamento de Ocimum selloi com telas coloridas do tipo Cromatinet® (50%) vermelha, azul e a condição natural de pleno sol (sem tela) sobre as características biométricas, fisiológicas, anatômicas e ultraestruturais da planta após 90 dias. As plantas nas telas coloridas tiveram maior crescimento em altura, mas o maior acúmulo de biomassa seca total e particionada e relação raiz: parte aérea (R:PA) ocorreram na condição de pleno sol. A espécie proporcionou plasticidade fenotípica, verificada pelos ajustes das variáveis área foliar total (AFT), área foliar específica (AFE), razão de área foliar (RAF) e razão de massa foliar (RPF) em função dos tratamentos. Ocorreu maior espessamento foliar na condição de pleno sol pelo somatório do maior espessamento da epiderme abaxial e do parênquima esponjoso. A densidade estomática foi maior nas plantas a pleno sol. O número de cloroplastos e seu tamanho foi maior nas telas coloridas, enquanto o maior acúmulo de amido ocorreu a pleno sol e tela vermelha.
The objective of this work was to investigate the effects of shading on the growth and development of the medicinal plant Ocimum selloi after 90 days. Seedlings were maintained under three different light treatments, namely, full sunlight vs coloured shade treatments provided by red and blue ChromatiNet® 50% coloured netting. After 90 days of cultivation, height, stem diameter, petiole length, total leaf area (TLA), specific leaf area (SLA), leaf area ratio (LAR) and leaf weight ratio (LWR) of each plant hare measured. Microscopic examination of leaf sections were conducted in order to determine the leaf blade thicknesses, together with the size and density of the stomata, the number and area of chloroplasts, and chloroplast starch grains present in the palisade parenchyma cells. Although coloured shade-grown plants were taller in comparison with those grown in full sunlight, total dry biomass together with root, stem and leaf tissue biomasses were lower. Plants exhibited phenotypic plasticity, as demonstrated by the different TLA, SLA, LAR and LWR values that were recorded under the various light treatments. Stomatal density and leaf thickness was increased in plants maintained in full sunlight owing to the expansion of the abaxial epidermis and the spongy parenchyma. Chloroplasts were more numerous and larger in plants grown under shading, whilst the accumulation of chloroplastic starch grains was greater in plants grown under red shading or in full sunlight.
