Ready, set, grow!

NASA-pioneered research accelerates chili breeding

Andrew Zhang joined the WorldVeg pepper breeding team as an intern through the World Food Prize Foundation’s Borlaug-Ruan International Internship Program.

A modified shipping container is an unlikely setting for cutting-edge crop research inspired by the demands of space exploration.

But what’s happening inside is helping WorldVeg scientists accelerate the development of productive, profitable, climate-smart crops.

“Plants constantly respond to their environment,” says Andrew Zhang, as we edge down the narrow gangway lined with racks of potted chili seedlings. “But with challenges like climate change, many can’t respond fast enough.”

That’s where speed breeding can help, offering a way to shorten a crop improvement process that would otherwise take years.

It’s a challenge familiar to WorldVeg: for years it has worked to improve vegetables like tomato, pepper, eggplant, okra, and mung bean. This research – built on field trials and greenhouse selection – has helped boost nutrition, climate resilience, and incomes across Asia and Africa, with more recent forays in Latin America and the Caribbean too.

But as any vegetable breeder will tell you, nature doesn’t like to be rushed. They need to cross and select plants over multiple generations to lock in traits like disease resistance and heat tolerance, sometimes taking up to a decade to develop a single improved variety. The fact that WorldVeg has developed and disseminated around 1,000 improved chili pepper lines is remarkable in itself.

But what if it could be faster?

The levers of light

The speed-breeding work in the WorldVeg container derives from research by the National Aeronautics and Space Administration (NASA) in the 1980s and 90s. The agency’s experiments demonstrated how continuous LED light could speed up plant growth in low-gravity environments. The aim was to see whether astronauts could grow food in space.

LED light could speed up plant growth

LED light could speed up plant growth

The approach was soon applied more widely in crop science on terra firma, with researchers experimenting with three “levers of light” to influence plant growth: the photoperiod (the amount of time that the plants receive light), the wavelength (which determines the color of the light), and the intensity. By adjusting these, wheat scientists were able to double the number of generations of the crop in a year from three to six.

So what can this do for vegetables?

Andrew working in the Speed breeding facility

That’s what 17-year-old Andrew has been figuring out for the last two months. As part of the World Food Prize Foundation’s Borlaug-Ruan International Internship Program, he’s been testing early, mid-season, and late maturing chili pepper types, to see how they respond to variations of light duration, color, and intensity. The aim is to see whether the benefits of speed breeding are consistent across all three, and to develop protocols so that the results can be meaningfully compared to field- and greenhouse-grown chilies.

Dark side of the bloom

Any Pink Floyd fan will be able to tell you that “white light” (like sunlight) comprises a spectrum of colors, from red through to violet. What they might not know is that red is very important in plant growth, triggering processes like germination and photosynthesis. But white light also contains far-red light. Invisible to humans, it triggers plant reactions like shade avoidance, stem elongation and – in chilies – flowering.

So after exposing the chili seedlings to 20-hours of daylight-equivalent, full-spectrum LED-generated light every day for 30 days in the speed-breeding container, Andrew then switched the lights to red, which includes far-red light.

This induced flowering in just five days for the mid-season chili – 35 days from sowing instead of the usual 45–50, making it about 30% faster in the speed-breeding container. The early- and late-maturing chilies flowered a few days later. Earlier flowering means earlier fruiting, and the possibility of getting seeds to breeders sooner. This in turn can accelerate the development of improved varieties, ultimately providing farmers with more stable and profitable crops.

Andrew working in the Speed breeding facility

But – yes, there’s a but.

While more plants flowered sooner in the container, a greater number of plants overall flowered in the greenhouse. Andrew puts this down to the fact that summer conditions make the greenhouses much warmer. As a result, the chili-breeding team is working to improve the summer season speed-breeding protocols. These will raise the temperature in the container and switch the lights to high-red much sooner, to see if these bring faster results.

For Andrew, the real test will come in the cooler winter months, when the chilies in the climate-controlled container are expected to significantly outperform those outside. It could result in one-to-three extra generations of plants in a single year. While it means he’ll be back at school in Oklahoma by the time his work to lay the foundations for speed-breeding chili at WorldVeg really start to bear fruit, it should be worth the wait.