Photochemical and biochemical responses of heliconia ( Heliconia stricta ‘Iris’) to different light intensities in a humid coastal environment

A field experiment was conducted to evaluate the performance of heliconia ( Heliconia stricta ‘Iris’) grown under four levels of photosynthetically active radiation (PAR) in a randomized block design. Photochemical and biochemical parameters were recorded to assess the physiological and biochemical changes in heliconia that accompany varying light intensities. The plants grown under the lowest PAR (30 to 35% of open condition) showed enhanced growth with a higher biomass accumulation, plant height, suckering habit, emergence of flowering shoots, inflorescence yield, and light use efficiency. The leaves exposed to high PAR (open condition) recorded reduction in chlorophyll content (60.8%), chlorophyll index (43.9%), and F v /F m (21.4%) compared to values for the leaves exposed to the lowest PAR (30 to 35%). Plant soluble sugars were reduced with the increasing PAR, whereas reducing sugar content was high under fully irradiated conditions but showed a decreasing trend with a reduction in PAR. Total phenolic content and malondialdehyde were lower at 30 to 35% PAR with a reduction in magnitude of 58.4% and 34.8%, respectively, compared to the open condition. Similarly, super oxide dismutase, peroxidase, and polyphenol oxidase activities in the leaf decreased 36.2%, 28.7%, and 23.3%, respectively, from the highest PAR (or open condition) in this range. Improved photochemical and biochemical activities of plants grown under lower light intensities resulted in production of quality inflorescences. Hence, Heliconia stricta ‘Iris’ can be recommended as an intercrop on coconut plantations where the light intensity is low (30 to 35%) for improving the livelihood of farmers.