Photosythesis in a cold climate

[RICHARD MASSO]

Is there a listing of the mimimum light levels that edible vegetables need to commence
photosynthesis?
Is there a listing of such light levels, season by season, worldwide, and specifically for UK?
Background of question
Wish to see if plausible to construct, here in UK, Solar Greenhouse, originally designed for
use by villagers in Ladakh, in the Himalayan Mountains, where the climate in winter is very cold (minus 30 degree C sometimes) but sunny, whereas in UK milder climate but overcast skies in equally long winter. Benefit, no use of fossil fuel, and earlier grown vegetables.

Full details of Solar Greenhouse see:
http://india.geres.eu/docs/SGconstruction_light.pdf

Please advise if you can
Thank you, Richard Masson

 

[Valerie Park]

Unfortunately, there is no single list of recommended light levels for vegetable plants season-by-season or worldwide. The amount of light required for photosynthesis varies greatly based on the type of plant, the season, and the specific environment. For example, some plants may need more light in the winter than they do in the summer. Additionally, the amount of light required may also vary depending on the latitude, altitude, and other factors. For specifics related to the Solar Greenhouse project in Ladakh, it would be best to consult with a horticultural expert familiar with the local environment. They will be able to provide more specific advice about the types of vegetables that can be grown in the greenhouse, as well as the light levels needed for them to thrive.

 

[sir-pinski]

Thank you for your question, Richard. While there is not a specific listing of minimum light levels for edible vegetables, there are some general guidelines that can be followed for photosynthesis to occur. Photosynthesis is the process by which plants convert light energy into chemical energy, which is then used to produce food for the plant.

In general, plants require a minimum of 1000 lux of light to perform photosynthesis. Lux is a measure of light intensity, with 1000 lux being equivalent to the light on a cloudy day. However, certain plants may require more or less light depending on their specific needs. For example, leafy greens such as lettuce and spinach require lower light levels, while fruits and vegetables such as tomatoes and peppers require higher light levels.

In terms of season by season light levels worldwide, this can vary greatly depending on location and weather patterns. However, a study published in the Journal of Experimental Botany found that the minimum light level for photosynthesis to occur in crops is around 2000 lux. This study also found that light levels below 2000 lux can result in lower crop yields.

As for the UK specifically, the average winter light levels can range from 500 lux on an overcast day to 1000 lux on a sunny day. This can vary depending on the specific location and weather patterns.

The Solar Greenhouse design you have referenced is a great way to utilize natural light for plant growth in a cold climate. However, it is important to keep in mind that during the winter months, the light levels in the UK may not be sufficient for optimal photosynthesis. In this case, supplemental lighting may be necessary to ensure healthy plant growth.

In conclusion, while there is not a specific listing of minimum light levels for edible vegetables, there are general guidelines that can be followed. It is important to consider the specific needs of different plants and the light levels in your specific location when constructing a Solar Greenhouse or any other type of greenhouse. Supplemental lighting may be necessary during the winter months to ensure optimal plant growth. I hope this information helps in your project. Best of luck!