Computers keep asparagus plants vital

By contrast, when asparagus plants are cut too long, the sugar level is depleted and the quality declines. Wageningen UR researchers are working on a computer programme to advise asparagus growers on the best possible moment to stop harvesting.

Starting asparagus harvesting as early as possible is one thing, but it is quite another to reliably stop harvesting at the most opportune moment.

Asparagus are basically stems that are still under the soil, without any leaves above. This is why growing asparagus stems costs the plant such an enormous amount of energy. Plants have to store that energy in their roots during the previous year, which is why growers cannot just continue harvesting the stems. Cutting too long means that there will be insufficient energy left in the roots to obtain enough stems above the ground. These stems grow needles (the leaves) that the asparagus plant uses to create sugars, which are then stored in the roots to be used during the next season.

The traditional saying that asparagus should not be cut after 24 June, Saint John’s Day, no longer applies. Growers are able to start harvesting much earlier in the year than was previously the case. This is made possible, for example, by using the residual heat of an energy unit to heat the soil. What has not changed, however, is the need to stop cutting at the right time. Farmers aim to stop at the optimal moment: not too late and not too soon.

The sugar level of the roots is therefore a key factor in the vitality of these plants. Unfortunately, the sugar level as an absolute value is an insufficient indicator of when to stop cutting. The main indicator is the reduction in sugar levels, which is why Wageningen UR is partnering with the Geisenheim Research Station in Germany to develop a computer programme that will assist Dutch asparagus growers in determining the precise moment to stop cutting. The growers regularly measure the sugar level of the roots with a simple device, which does not take much time. Based on the results, the computer programme gives advice on when to stop cutting asparagus.

The computer programme is called Aspire and will be tested on ten Dutch asparagus farms during the 2008 season. The researchers expect that this pilot will offer a sufficient basis for widespread use in the 2009 season.