Perennial Crops: New Hardware for Agriculture
Annual Crops and the Cycle of Disturbance
Almost all grains, dry legumes (pulses), and oilseed crops are annual crops, or “annuals”. Annuals are planted from seed, grow to maturity, produce seed or fruit and then die, all in one year. Today, annual crops account for roughly 85% of the human population’s food calories and the vast majority of planted croplands worldwide.
To successfully grow annuals, farmers have to suppress or kill the vegetation (weeds) that compete with crops for sunlight, nutrients, and water, especially when the crops are seedlings. Over millennia, farmers traditionally used implements such as hoes and plows to eliminate vegetation from the landscape before sowing annuals. This soil disturbance has caused significant amounts of soil carbon loss (which ends up in the atmosphere as CO2), soil erosion, nutrient leakage, and changes in soil organisms. Recently some farmers in the developed world have replaced reliance on tillage with chemical herbicides. This shift to “no till” cropping reduces erosion and tends to improve soil organic matter, but can still result in nutrient leakage, low soil organic carbon levels, and reliance on fossil fuel based inputs that carry possible health risks.
Perennial Crop Solutions to Annual Agricultural Challenges
Perennial plants do not have to be reseeded or replanted every year, so they do not require annual plowing or herbicide applications to establish.
Perennial crops are robust; they protect soil from erosion and improve soil structure. They increase ecosystem nutrient retention, carbon sequestration, and water infiltration, and can contribute to climate change adaptation and mitigation. Overall, they help ensure food and water security over the long term.
Many fruit, forage and some vegetable crops, including fruit trees, alfalfa, grapes, asparagus, and olive trees, are perennials that have been grown for thousands of years. The Land Institute is working to add perennial grains, legumes, and oilseed crops to the list.
Perennial grains, legumes and oilseed varieties represent a paradigm shift in modern agriculture and hold great potential for truly sustainable production systems. In addition to identifying and developing perennial food crops, The Land Institute also conducts ecological intensification research in order to put those crop plants into diverse mixtures called polycultures that mimic the benefits found in native and natural ecosystems.
We are using two approaches to breed perennial grain, pulse, and oilseed crops:
- Domestication of wild perennial plants
- Perennialization of existing annual crops
Domesticating Wild Perennials
Farmers have been domesticating wild perennial plants for the last 10,000 years. This is the approach that resulted in many of our current crops.
Domestication starts with identification of perennial species that have one or more desirable attributes such as high and consistent seed yield, synchronous flowering and seed maturation, and seed retention, also called non-shattering (a feature of non-shattering plants that hold onto their seeds like an ear of corn rather than disperse them over the landscape like a dandelion).
Large, diverse populations of the crop are grown out at The Land Institute, and plant breeders select the best individuals for the traits of interest. These individual plants are then cross-pollinated, and the resulting seeds are planted to produce the next improved breeding population.
The Global Inventory Project is an ambitious, large-scale, global collaboration between The Land Institute, the Missouri Botanical Garden (one of the world’s largest research botanical gardens), and Saint Louis University to identify perennial species candidates for domestication and use in perennial polycultures in temperate and tropical climates.
Perennializing Annual Crops
The second method of breeding new perennial crop species is to cross an existing annual grain crop with a wild perennial cousin. When successful, these “wide hybrid crosses” produce plants that maintain seed yield and quality similar to the annual parent while inheriting the perennial lifestyle from the other parent.
Sorghum is a tropical grass originally domesticated as a crop in sub-Saharan Africa. Like annual sorghum, the perennial hybrids maintain good seed yield, but seed size and flavor require further breeding attention. Land Institute perennial hybrids are being trialed in several sub-Saharan African countries to determine if they can persist through dry seasons.
Helping Grow Perennial Agriculture
The Land Institute is breeding new perennial grain and seed crops adapted to ecologically intensified polycultures that mimic natural systems in order to produce ample food and reduce or eliminate impacts from the disruptions and dependencies of industrial agriculture.
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