Perennial grain - AbsoluteAstronomy.com

While many fruit, nut and forage crops are long-lived perennial plant

Perennial plant

A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...

s, all major grain crops

Food grain

thumb|150px|Barleythumb|150px|LentilGrains are small, hard, dry seeds harvested for human food or animal feed Agronomists also call the plants producing such seeds grains or grain crops....

are annuals

Annual plant

An annual plant is a plant that usually germinates, flowers, and dies in a year or season. True annuals will only live longer than a year if they are prevented from setting seed...

or short-lived perennials grown as annuals. Scientists from several nations have argued that perennial versions of today's grain crops

Food grain

thumb|150px|Barleythumb|150px|LentilGrains are small, hard, dry seeds harvested for human food or animal feed Agronomists also call the plants producing such seeds grains or grain crops....

could be developed and that these perennial grains could make grain agriculture more sustainable.

Rationale

The 2005 Synthesis Report of the United Nations’ Millennium Ecosystem Assessment program labeled agriculture the “largest threat to biodiversity and ecosystem function of any single human activity.” Perennial grains could reduce this threat, according to the following logic:

Most agricultural land is devoted to the production of grain crops: cereal, oilseed, and legume crops occupy 75% of US and 69% of global croplands. These grains include such crops as wheat, rice, and maize; together they provide over 70% of human food calories.
All these grain crops are currently annual plants which are generally planted into cultivated soil.
Frequent cultivation puts soil at risk of loss and degradation.
This "central dilemma" of agriculture in which current food production undermines the potential for future food production could be escaped by developing perennial grain crops that do not require tilling the soil each year. No-till
No-till farming
No-till farming is a way of growing crops from year to year without disturbing the soil through tillage. No-till is an agricultural technique which increases the amount of water and organic matter in the soil and decreases erosion...

technology enables short-lived (annual) crops to be grown with less intense tillage, but perennial plants provide the most protection for the soil.

Methods for developing perennial grains

Three ways of developing perennial grain crops have been proposed:

The primary gene pool
Gene pool
In population genetics, a gene pool is the complete set of unique alleles in a species or population.- Description :A large gene pool indicates extensive genetic diversity, which is associated with robust populations that can survive bouts of intense selection...

s of several domesticated grain crops include perennial types, even though these crops are generally grown as annuals. Pigeon pea
Pigeon pea
The pigeon pea , also known as tropical green pea, toor dāl or arhar dāl , ತೊಗರಿ ಬೇಳೆ kadios , or Congo pea or gungo pea , pois Congo , gandul , gunga pea, or no-eye pea, [Cajanus...

is a large-seeded grain legume (pulse
Pulse
In medicine, one's pulse represents the tactile arterial palpation of the heartbeat by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed against a bone, such as at the neck , at the wrist , behind the knee , on the inside of the elbow , and near the...

) with both short-season (annual) and long-season (perennial) varieties. If the highest-yielding annual varieties were hybridized with the longest-living varieties, robustly perennial, high-yielding varieties could be developed.
The secondary or tertiary gene pools of most domesticated grain crops include perennial species. Gene exchange between such species is possible, though sometimes difficult. Genes enhancing the agronomic traits of wild perennials, increased seed size, for example, could be brought in from domestic grain relatives. Alternately, genes increasing the lifespan of domesticated grains could be obtained by crossing with wild perennial relatives. For example, domestic Asian rice can be crossed with wild perennial rice species to exchange genes for many traits.
Wild perennial plants with oil-, carbohydrate- or protein-rich seeds could be domesticated
Domestication
Domestication or taming is the process whereby a population of animals or plants, through a process of selection, becomes accustomed to human provision and control. In the Convention on Biological Diversity a domesticated species is defined as a 'species in which the evolutionary process has been...

without any wide hybridization. Although our grain crops were all domesticated thousands of years ago, modern genetic theory and molecular genetic techniques may greatly accelerate the process compared with the original process of domestication. The Rodale Institute and The Land Institute have each had plant breeding projects in which a wild, perennial grass, Thinopyrum intermedium
Thinopyrum intermedium
Thinopyrum intermedium is a sod-forming perennial grass. It is part of a group of plants commonly called wheatgrass because of the similarity of their seed heads or 'ears' to common wheat...

was subjected to recurrent cycles of selection for improved grain traits.

Potential disadvantages of perennial crops

Does not address food security today. Perennial grain crops are in the early stages of development and may take many years before achieving yields equivalent to annual grains.
Makes crop rotation more difficult. Crop rotation
Crop rotation
Crop rotation is the practice of growing a series of dissimilar types of crops in the same area in sequential seasons.Crop rotation confers various benefits to the soil. A traditional element of crop rotation is the replenishment of nitrogen through the use of green manure in sequence with cereals...

s with perennial systems are possible, but the full rotation will necessarily take longer. For example, a perennial hay crop. like alfalfa
Alfalfa
Alfalfa is a flowering plant in the pea family Fabaceae cultivated as an important forage crop in the US, Canada, Argentina, France, Australia, the Middle East, South Africa, and many other countries. It is known as lucerne in the UK, France, Australia, South Africa and New Zealand, and known as...

is commonly rotated with annual crops or other perennial hay crops after 3–5 years. The slower pace of rotation—compared with annual crops—could allow a greater buildup of pathogens, pests or weeds in the perennial phase of the rotation.
Builds soil organic matter at the expense of plant productivity. In the absence of tillage, and in soils with depleted organic matter, crops with large root systems may build up organic matter to the point that nearly all of the soil nitrogen and phophorus is immobilized. When this happens, productivity may decline until either the organic matter builds up to a level where equilibrium is reached between nutrient mineralization and nutrient immobilization or fertilizer is added to the system.
Hydrological impacts. Perennial plants may intercept and utilize more of the incoming rainfall. than annual plants each year. This may result in water tables dropping and/or reduced surface flow to rivers.
Reduced nutrient delivery to downstream farms. Wide replacement of annual with perennial plants on agricultural landscapes could stabilize soils and reduce nitrate leaching to the point that the delivery of sediment and dissolved nitrogen to downstream landscapes could be reduced. Farmers in these areas may currently rely on these nutrient inputs. On the other hand, other sectors might benefit from improved water quality.
Improved habitat for pests. If fields are not left bare for a portion of the year, rodents and insects populations may increase. Burning of the stubble of perennial grains could reduce these populations, but burning may not be permitted in some areas. Furthermore, rodents and insects living underground would survive burning, whereas tillage disrupts their habitat.

Advantages of perennial crops

Several claims have been published::

Greater access to resources through a longer season.Perennial plants typically emerge earlier than annuals in the spring and go dormant in the autumn well after annual plants have died. The longer growing season allows greater interception of sunlight and rainfall. For example, In Minnesota, annual soybean seedlings emerge from the soil in early June. By this time perennial alfalfa has grown so much that it is ready for the first harvest. Therefore, by the time a soybean crop has just begun to photosynthesize, a field of alfalfa has already produced about 40% of the season’s production.
Greater access to resources through a deeper rooting zone. Most long—lived plants construct larger, deeper root systems than short-lived plants adapted to the same region . Deeper roots enable perennials to "mine" a larger volume of soil each year. A larger volume of soil also available for exploitation per unit of cropland also means a larger volume of soil water serves as a reservoir for periods without rainfall.
More efficient use of soil nutrients. Leaching of nitrogen from fertilizer has been found to be much lower under perennial crops such as alfalfa (lucerne) than annual crops such as maize. A similar phenomenon is seen in unfertilized fields harvested for wild hay. While adjacent wheat fields required annual inputs of fertilizer, the wild perennial grasses continued to produce nitrogen-rich hay for 75 to 100 years with no appreciable decline in productivity or soil fertility. Presumably, the larger root systems of the perennial plants and the microbial community they support intercept and cycle nutrients passing through the system much more efficiently than do the ephemeral root systems of crop plants.
Sustainable production on marginal lands. Cassman et al. (2003) wrote that for large areas in poor regions of the world, “annual cereal cropping …is not likely to be sustainable over the longer term because of severe erosion risk. Perennial crops and agroforestry systems are better suited to these environments.” Current perennial crops and agroforestry systems do not produce grain. Grain
GRAIN
GRAIN is a small international non-profit organisation that works to support small farmers and social movements in their struggles for community-controlled and biodiversity-based food systems. Our support takes the form of independent research and analysis, networking at local, regional and...

provides greater food security than forage
Forage
Forage is plant material eaten by grazing livestock.Historically the term forage has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used more loosely to include similar plants cut for fodder and carried to the animals, especially...

or fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

because it can be eaten directly by humans (unlike forage) and it can be stored (unlike fruit) for consumption during the winter or dry season.

External links

Perennial upland rice takes root An article by Paul Cox in the New Agriculturalist.
The Land Institute A scientific institute in Kansas, U.S.A. with several perennial grain breeding programs.
Resilent crops A short story from Canadian television news.

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

Rationale

Methods for developing perennial grains

Potential disadvantages of perennial crops

Advantages of perennial crops

See also

External links