The harvest moon and the plants in the picture mark two traditional festivals that coincide this weekend. The four plants from the left (willow, palm, myrtle and citron) symbolise the Jewish festival of Sukkot (Tabernacles, Leviticus 23:40). The flower on the right is Osmanthus, the fragrant tea olive, associated with the moon and the Chinese Mid-Autumn Festival. Both festivals fall on the fifteenth day of anautumn lunar month and usually coincide, but they can be a month apart due to differences in when the Chinese and Hebrew calendars insert leap months (7 times in 19years) to align with the solar year.
The five plants in the picture are there as festive representatives, but this post is about the effects of the moon on plants in general. The moon exerts a gravitation pull that is probably imperceptible to most plants except, obviously, coastal species affected by the tides. However, light from the moon has direct biological effects; we this with our own eyes using our own visual photoreceptors.
Plants are clearly affected by light, primarily the sunlight that drives photosynthesis. Moonlight is more than 300,000-fold weaker and of no photosynthetic relevance. However, plants also have photo responses that are unrelated to photosynthesis. In Leaf 38(https://lnkd.in/eJUyhrFS)I discussed control of flowering by daylength and how the 1947 rice crop in aTrinidad field was rescued by extinguishing the nightly flare of an adjacent oil-refinerywhose light was breaking the continuityof dark hours needed for the rice to flower. The full moon is definitely brightenough to have similar effects. This is well documented in the scientific literature,the citation below being just one example of many.
Breitler et al (2020) conducted a comprehensive study of how moonlight alters expression of thousands of genes in coffee plants, and found “massive transcriptional modification” (direct quote) including effects on some genes that function as part of the endogenous circadian clock to control how the physiology runs through the day and night.
If the above is too scientific and your local weather allows, Isuggest that you step outside tonight and enjoy the full moon. Festivegreetings.
Further reading
▶ Breitler JC et al (2020). Full moonlight-induced circadian clock entrainment in Coffea arabica. BMC plant biology, 20(1), 24. https://doi.org/10.1186/s12870-020-2238-4
