Norwegian wheat tolerant to water-saturated soil

Norwegian and Nordic wheat varieties appear to have quite high water tolerance and are well suited to tolerate periods of rain compared to many foreign varieties.

Tove Sundgren has conducted drastic water saturation tolerance tests on Norwegian and foreign wheat varieties by flooding them. The results show that the Norwegian varieties survived the attempt to “drown” them. In particular, the varieties Bjarne, Mirakel and Zebra have so far shown good survival capability in water-saturated soil.

“The Nordic wheat varieties have been bred in a domestic climate where wet summers are not uncommon and are therefore well-suited to our growth conditions.  The results I have so far confirm how important it is to carry out cereal breeding and variety testing under Nordic growing conditions,” explains Tove Sundgren. She is carrying out research for a doctorate at the University of Life Sciences, NMBU.

Flooded at 3-leaf stage

Climate change in the Nordic region has led to increased quantities of rainfall, which has meant that water may remain in plant cultivation soil and restrict the provision of oxygen to cereal plants. How wheat varieties tackle this lack of oxygen, is the question Tove Sundgren wishes to have answered through her doctorate research project “Water saturation tolerance in cereal varieties”.

Normally cereal varieties are tested outdoors in favourable growth conditions, but on this occasion the worst conditions conceivable are created. Water is pumped into the basin-like trial field, surrounded by deep moats, at the third leaf stage. The wheat plants then stood in something that could be described as a rice paddy for three weeks. A similar test has also been carried out with barley at NMBU.

Spectral images from a drone

Tove has used many hours to observe and register stress responses, including straw length, the number of ears and yellowing of leaves in the trial field. This is actually the fourth year running that such saturation tests have taken place at Vollebekk trials farm at NMBU. In 2015 the plants were photographed from above with a hyperspectral camera from a lift in order to register the stress level after three days under water. This year a drone has been used to take the photographs.

“Pictures from the camera can give very good information and in a much shorter time than I can manage with my observations. Even though we generally get the same answers, the drone can save a lot of time,” comments the doctorate researcher. Developing quick, reliable and cheap methods to characterise tolerance properties is important if we are to improve tolerance characteristics in cereal breeding.

Compensates with crown roots

At present it is not only the development of the wheat plants above ground that is being studied. The roots are also being analysed. Tove has a theory that when the seed roots are standing in water-saturated soil and do not receive oxygen, the higher crown roots take over the job from the seed roots of obtaining oxygen for the plants. It is this ability to compensate for lack of oxygen acquisition that may be part of the reason why some varieties have a greater survival capability than other varieties in years of heavy rainfall, believes Tove, who is careful to emphasise that at present she does not have enough evidence to be certain of this.

Mapping important genes

Previously more than 400 varieties and lines of wheat, barley and oats have been tested in the saturation trial. Of these, 177 have been wheat lines. This year the number of wheat varieties has been reduced to 16. This means that larger squares of the same variety can be included in the trial – which can also give yield data that previously was not possible.

Tove has chosen this year’s 16 wheat varieties and lines based on very special criteria:

“I have deliberately taken the weakest and strongest wheat varieties with regard to water tolerance, so it will be easier to obtain more certain differences between the varieties. Several of the strongest varieties are Norwegian. This may mean that we have a wetter climate here than in other countries, and that unconsciously we have concentrated on varieties and lines that have better genes for such conditions,” concludes the doctorate researcher.