Abstract
To study the influence of light on growth and yield of Vanilla plants, 3 plots were marked in a vanillary, receiving sunlight with intensities varying between 300-1500 µE m-2 s-1. Our results showed that photosynthesis was effective in Vanilla plants growing at sunlight of 300-800 µE m-2 s-1 whereas only plants receiving 600-800 µE m-2 s-1 sunlight were able to effectively partition the accumulated carbon into fruiting structures. Therefore, concerning productivity, light conditions of 600-800 µE m-2 s-1 were most favoured while 300-600 µE m-2 s-1 sunlight conditions were found to favour vegetative growth. Sunlight above 800 µE m-2 s-1 affected productivity negatively. It was observed that proline as well as carotenoids accumulated in Vanilla plants with increasing light intensities. However, the protective mechanisms against the photodestructive high light were not sufficient to protect Vanilla plants from the photoinhibitory damage. This was clearly manifested by the high levels of lipid peroxidation as judged by the malondialdehyde (MDA) levels, low chlorophyll content, low oxygen evolution rate and low productivity in plants exposed to sunlight above 800 µE m-2 s-1. These results confirm that shade plants do not have a well-developed mechanism to counteract the after-effects of photo inhibition.
Study Snapshot
Vanilla plants thrive in 600-800 E m-2 s-1 sunlight, with higher light intensities negatively impacting productivity, while protective mechanisms are insufficient to counteract photo-inhibition damage.
Population: Vanilla plants
Methods: Controlled experimental study
Outcomes: Growth, yield, proline and carotenoid levels, lipid peroxidation, chlorophyll content, oxygen evolution rate
Results: Sunlight at 600-800 µE m-2 s-1 maximised vanilla plant productivity; higher light reduced yield.