Higher yields with less water

Alternating the irrigation between the two sides of the crop may be how we irrigate in the future. The method saves water without affecting yields.

Experiments show that plants have an effective internal communication. If the plant is short of water on one side, a warning signal is sent to the other side. The internal communication goes from the roots to the top of the plants via hormones. This knowledge can be used by the farmer to increase yields using 20-30 per cent less water.

- Each little root tip in a plant acts as a sensor that is constantly measuring the water content of the soil. If the moisture level starts falling, the root sends an alarm by way of a chemical signal to the plant top and leaves to reduce the water transpiration, explains Mathias Neumann Andersen.

The chemical involved is the plant hormone abscisic acid (ABA). The formation of ABA starts already 2-3 days after the soil has last been wetted and is related to the water deficit of the soil. It is thus a very early signal initiated before you can really start talking about a water shortage as such.

New biomolecular methods have identified the gene responsible for the formation of ABA and have shown that the gene is most strongly expressed in the root tips when the soil dries out.

The hidden potential of roots

- If we know that roots have such an important part to play in plant water use and growth, then why not use this knowledge in the production, asks Mathias Neumann Andersen.

In field experiments with potatoes, scientists have stimulated the formation of ABA in roots. The results show that this method can be used to reduce water use without affecting yields.

- Using drip irrigation in the potato ridge, we have at weekly intervals alternated the watering from one side of the ridge to the other. The dry soil on one side of the ridge induces the plant to reduce its transpiration via the ABA synthesis of the roots, explains Mathias Neumann Andersen.

The results have been surprisingly positive. The potatoes in the experiment alternatingly received 70 per cent of the ‘normal’ precipitation in the tuber growth phase. This saved about 50 mm of water with the same or even a slight increase in yield.

- This is a very important result in a global perspective, but the method is not very applicable to Danish conditions. There are other methods, however, of inducing the root production of ABA and these should be investigated with a view to their application in a climate with a relatively high level of precipitation during the summer, such as that in Denmark.

For further information please contact:

Senior scientist Mathias Neumann Andersen, Department of Agroecology, telephone: +45 8999 1742, e-mail: [email protected].