Growth Cycle of Asparagus
Asparagus is a perennial crop with an annual growth cycle that includes a sequence of depletion and accumulation of soluble carbohydrate (CHO) in a large storage root system (see CHO Graph). The order and timing of events in the sequence depend on the climate and crop management system. In temperate climates, there are usually three phases in each annual cycle:
- a dormant phase during winter when the soil temperature is low; stored CHO is usually at maximum during this phase.
- a spring-summer spear harvest period during which spear growth starts and increases as soil temperature increases; spear growth depletes stored CHO.
- a phase during summer-autumn when the spears are allowed to grow and form a fern canopy which senesces when the crop enters dormancy again; stored CHO is depleted further during initial fern establishment and is then replenished before winter by assimilate production by the established fern canopy.
Although the general features of this cycle are well known, growers have
seldom known the CHO status of the root system during the annual cycle
or, if they did, how to interpret such information. Therefore, traditionally
the focus has been on management of above-ground growth, assuming that
production of healthy, vigorous fern will lead to high spear yield and
quality in the following season.
AspireNZ is based on the proposition that management of the crop’s storage root system is just as important for achieving high production. Good management of the annual cycle leads to high spear yield resulting from a high level of soluble CHO in the roots during harvest, in the current season as well as in following years.
