Plants need light to make food, but too much heat kills them.
But the world is getting hotter, putting harvests at risk.
Enter some clever Singapore researchers, who have created a coating which can block about 90 per cent of the heat while allowing light to pass through materials such as glass and acrylic.
This makes the material ideal in keeping things cool but bright in greenhouses - making it the perfect environment for plants.
The researchers who have made this possible are from Nanyang Technological University (NTU), and their coating is made of heat-absorbing nano particles and inorganic oxides that can be applied on different surfaces.
Dr Goh Chin Foo, who is a member of the team who developed the coating, said: "When it comes to coatings, a lot of people have the perception that removing the heat also means that light cannot pass through, but this isn't the case." He is senior scientist and cluster director at the Energy Research Institute at NTU.
The idea came after university staff asked if there was a way to make the school atrium cooler.
That was when Dr Goh and his team at the Energy Research Institute and School of Materials Science and Engineering at NTU started the project .
The material has been applied on the atrium roof and gives students and staff members respite from the heat. It helped to reduce the temperature by about 8 deg C.
To take the project a step further, the team will be testing the coating at Kok Fah Technology Farm in Sungei Tengah Road.
If all goes well, the coating could be commercialised and made available to other farmers in three months.
There are now 56 vegetable farms here contributing 13 per cent of Singapore's annual vegetable supply, amounting to about 11,400 tonnes of leafy greens last year.
Mr Wong Kok Fah, managing director of Kok Fah Technology Farm, said that he is keen to test the technology. "Anything that helps to bring down temperature."
Every year, his 9ha farm produces about 1,000 tonnes of leafy vegetables, such as caixin and kailan, which are supplied to supermarkets such as FairPrice.
He added that the warm weather has become increasingly long- drawn in recent years, affecting the growth of his crops and causing leaves to turn yellow. He now uses a net over his greenhouse, which helps to block out heat and reduce the temperature in the greenhouse by about 4 deg C. Unfortunately, the net also blocks out light, which is essential for the vegetables to grow.
Mr Wong came to know of the coating after he met Adjunct Associate Professor Matthew Tan from NTU's School of Chemical and Biomedical Engineering during a technology-sourcing trip organised by the Agri-Food and Veterinary Authority (AVA) in Japan last month.
Prof Tan, who is helping to commercialise the coating, said that while there are other films in the market which can help to block out heat, the nano coating is expected to cost less than half the price, and can be applied to a wider variety of structures, not just flat surfaces.
A film in the market could cost anywhere between $100 per sq m and $150 per sq m.
The NTU coating could also be useful in the aquaculture industry, added Prof Tan, who is also the chief technology officer of abalone producer Oceanus Group.
"It takes away the heat but allows some light to pass through. This is important for hatchery use, especially for newly hatched fish larvae to find their fish food."
The AVA has also requested a sample of the coating, which will be applied to its greenhouse at Sembawang Research Station.
The impact on vegetable growth will be measured, said an AVA spokesman.