Today’s plants won’t survive forever. Here’s how we’re growing plans for the future.
Eight billion people make for a lot of mouths to feed — a lot of rice, corn, and wheat. Which are the most cultivated and consumed crops around the globe.
For these crops to produce enough food for our growing appetite, it is necessary to always improve their yield, make sure they survive our changing climate and resist pests and diseases.
While you are having French fries for lunch, enjoying your cup of coffee, or shopping for new cotton t-shirts, hardworking agronomists, are constantly testing new plant varieties around the globe to secure tomorrow’s supply of plant-derived products.
We can think of an agronomist as a matchmaker of plants. One chooses two plants with desirable traits — for example, a coffee plant resistant to the deadly leaf rust and one that is very productive — and assists their pollination. To do this, an agronomist takes the pollen of the first plant, usually with a small paintbrush, and puts it on the second flower’s female reproductive part, or pistil.
The agronomist, whose name comes from the Greek words for ‘field’ and ‘arrange’, spends a lot of their time watching plants. They not only measure the growth and yield of plants to know which ones do best in each condition, but also tickle flowers with a brush to ensure better seed production. For example, in an irrigated trial, they check whether increasing the amount of water available to a plant speeds up its growth or slows it down. They also try to understand what characteristics give a plant its advantage in certain conditions, such as if a warmer or drier environment increases the plant’s productivity.
After a few months of gestation, the flower of the hand-pollinated plant grows into a shiny fruit (i.e coffee cherry, banana, corn cob). The analogy to remember here is that fruit is the equivalent of a human uterus protecting an embryo, which can be equated with seeds.
The seed from the fruit can be planted to initiate the first generation of hybrids — or F1-hybrids. For example, 30 years ago, a few hand-pollinated, wild, and highly productive coffee plants generated thousands of unique new F1-hybrids. But, only a handful of these seedlings showed the characteristics desired by the plant breeder. Once those promising F1-hybrids were identified, the plant breeder multiplied them, but couldn’t reproduce these F1-hybrids by hand-pollination, as was done for their parents.
F1-hybrids are very unstable, meaning that their offspring is unlikely to show many desired characteristics. The only solution is to clone the F1-hybrid. Potatoes and tubers can be replanted, and coffee seedlings can be micro-cut. When cloning is not possible, or when the plant breeder wants to stabilize the hybrid, the F1-hybrid must be self-pollinated: where the pollen of an F1-hybrid is collected and put in its own pistil. After six to seven generations of artificial self-pollination and selection, the new hybrid is finally stabilized, and its seeds can be used successfully by farmers.
Before being released to farmers, new hybrids must undergo a crucial on-field test to ascertain where they grow best. Ideally, a plant variety would grow very well and produce high yield everywhere. In practice, it is not the case — just like certain genres of books aren’t universally popular, plants often have specific niches too. And so, the agronomist must check where each new plant variety is best suited.
Once the plant breeder has created new plant hybrids or varieties, they can establish trial plots to observe how the plant behaves in real conditions. In the best-case scenario, trials are established in heterogeneous environments. This could be along a gradient of temperature, altitude or rainfall conditions. For perennial crops like cacao or coffee, trials must be monitored for several years to have enough harvest data. On the other hand, annual crops only need one or two years of monitoring.
Then, the agronomist’s job is to understand what conditions make a plant variety produce high yields, so they can provide advice to private companies or agricultural extension offices about the right varieties to give to farmers.
An ideal plant hybrid — one that outcompetes others in most environments — would be high-yielding and stable over a range of habitats. But, given the fact that plant genetics interacts with the environment around, this is a rare case. Therefore, most high-yielding plants give low harvests in other environments.
Many environmental factors can cause a decrease in the yield of a variety. For example, mean temperature changes along an altitudinal gradient can cool down plants and decrease their production. Similarly, low rainfall in one place can make a plant too thirsty to be productive. Pests and diseases are more abundant and aggressive in warmer climates. Farmers’ management, like fertilizer and pesticide inputs and irrigation, also play an important role in making an environment suitable or not suitable for a given crop variety.
For coffee, management under shade in an agroforestry system can completely change the shape of the plant. Coffee plants in an agroforestry system have a very different environment compared to those not in one: agroforestry allows the area to be fresher and darker. Darkness makes the coffee plant grow longer branches and larger branches. Freshness makes the coffee tree produce bigger cherries, and therefore, higher quality beans.
After a few years of collecting data on a handful of carefully selected varieties planted in various locations, the agronomist can finally report which variety performs best — in what conditions and with what farming management.
All this selection and testing takes several years. Climate change is accelerating environmental changes, while rain patterns and mean temperature, are changing quicker than breeding programs. As forests and other ecosystems are destroyed to make space for agriculture and industry, wild species disappear every day. All these challenges hinder our wellbeing since the plants we use today may not grow well in future environments.
Of course, plant breeders are equipped with new technology to make the breeding process quicker and more efficient; for instance, genetically modified organisms have changed the way we see plants.
At an individual level, all we can do is to consume sustainably, avoid deforestation and greenhouse gas emissions, and reduce the impact we have on the environment of our beloved plants.