Twilight
Twilight, the period between day and night. The duration of twilight influences the growth and flowering of plants. That, are Canadian and Belgian researchers now showing in Scientific Reports.
The influence of twilight on plants was up to date not really studied. For a long time it was difficult to reproduce twilight light conditions artificially. But with current techniques it is finally possible. Therefore the researchers decided to study the influence of twilight length on plants.
The first thing they analysed was of the length of twilight had any influence on the growth and flowering of tale cress plants. These plants naturally grow in regions stretching from the Mediterranean to the north of Norway. With a twilight length of 30 to 60 minutes these plants grew better than without twilight. But lengthening the twilight to 90 minutes resulted in no extra growth compared to no twilight at all. Twilight also caused the plants to flower later. How longer the twilight how later they flowered.
Twilight influences the regulation of stress mechanisms and photosynthesis
Now the question was: which circadian clock genes perceive the twilight? This turned out to be only the morning genes LHY/CCA1. Where those absent, then the plants did not react to twilight. LHY/CCA1, it turned out, got their information about the twilight conditions from the light receptors PHYE, PHYD, and CRY2. In addition, the light receptor PHYB also perceived the twilight, but sends that information directly to the flowering regulators.
The last thing the researchers studied was the effect of twilight on proteins and gene regulation. This they did through comparing plants with and without LHY/CCA1. From this they discovered that twilight influences the regulation of stress mechanisms and photosynthesis.
Twilight, thus, as long as it is not to long, enables plants to grow better. That these plants also flower later is probably due to the fact that when there is a longer twilight period, the plants are growing closer to the poles, which in turn translates into shorter summers. But an abrupt start of the night, like how traditional growth chambers treat plants, with that are probably only good for plants that grow in nature close to the equator.
Literature
Devang Mehta et al., Twilight length alters growth and flowering time in Arabidopsis via LHY/CCA1.Sci. Adv.10,eadl3199(2024).DOI:10.1126/sciadv.adl3199
Plant en Zo 