Photosynthetic activity and growth analysis of the plant Costus spicatus cultivated under different light conditions

Abstract

The aim of the present work was to evaluate the effect of different radiance levels (25%, 50% and 100% of full sunlight) in growth (height, leaf area, number of leaves) and photosynthetic activity of the plant Costus spicatus, popularly known in Brazil as Caninha do Brejo. Photoacoustic (PA) measurements were performed in order to evaluate comparatively the photosynthetic activity rate of plants submitted to different light intensity regimes. The results obtained show that plants maintained under low light intensity levels (25% of sunlight) presented higher height, leaf area and number of leaves, while plants grown under full sunlight presented higher radicular length. PA measurements indicated higher photosynthetic rate for plants grown under 50% of full sunlight, but plants developed under 25% of full sunlight (75% shading) presented the fastest response to light incidence (photosynthetic induction).