Alfalfa – the botany behind a feed-boosting forage crop
If you are thinking of introducing alfalfa to your forage mixtures, it is helpful to know the basics of the plant's botany.
Development
A germinating alfalfa seed produces a radicle followed by two cotyledons. The first true leaf is mono-foliate; the next is normally trifoliate. The presence in fully developed plants of multi-foliate leaves is a variety characteristic often associated with enhanced forage quality simply because the leaves provide better nutrition than the stems.
Inoculation
Alfalfa is like other leguminous crops in that it is self-sufficient in nitrogen. The nitrogen is drawn in through the symbiotic work of Rhizobium bacteria. If you are planting in soils that lack Rhizobium bacteria, you have to inoculate the seed at the time of sowing or use a pre-inoculated seed such as Nitrigin Gold®.
Shoots and roots
New shoots emerge from the crown buds of older plants. The growth is rather upright. Alfalfa has deep-growing taproots that provide drought-tolerance and rapid regrowth from stored carbohydrates.
Dormancy
Alfalfa varieties are traditionally divided into ten fall dormancy (FD) groups. Each group corresponds to the stage during autumn when growth declines. The earlier the onset of dormancy, the lower the group number. The most dormant varieties (FD 1) cease growing very early; the least dormant (>=FD10) barely stop growing, which makes them more vulnerable to low-temperature / frost damage. As a rule of thumb, you can use the dormancy group number as a guide to the number of cuts you can take during the season: 3 cuts for FD3, 8 for FD8 etc.
Lodging / standability
Varieties that exhibit high standability (= no lodging) are much appreciated by those who want to dry their alfalfa. Harvesters can finish their harvest under good conditions, even in the last field within a cutting cycle.
For breeders, the challenge is to develop thin-stemmed varieties for their better feed quality without compromising standability.
Seed production
Alfalfa is an insect-pollinated plant, sown in the spring under a cover crop or, during summer and autumn, on bare land. Seeds can be harvested during the following two years.