Wild strawberries have been used by man since pre-Roman times. The strawberries we know from commercial cultivation today originate from the structured crossing of European and American strawberries that started in the 1800s.

The taste of summer

The strawberry season begins when the temperature starts to rise and lasts the whole summer. Strawberries are widely used in ice cream, lemonade, and jam production, but most people probably associate the taste with eating fresh berries in the summer. As most of the strawberries sold in Norway are bought fresh in grocery stores, it’s important that the Norwegian varieties can withstand handling all the way from the field to the store shelf.

Breeding goals

Graminor is responsible for breeding new strawberry varieties that are adapted to the Norwegian climate and market needs. Strawberry breeding takes place at Njøs fruit and berry centre in Leikanger.

Njøs fruit- and berry centre

Graminor’s goal is to present farmers with varieties that produce a large crop, with good taste, winter hardiness, early ripening and that can withstand shipping and handling from harvesting until it is placed on the store shelf. It is also important that the varieties are strong against fungi, disease and are resistant to insects. Growers can reduce the use of chemical pesticides if new varieties have greater resistance to pests and diseases than the currently available varieties.

Important traits:

  • Yield
  • Taste
  • Early maturation
  • Winter hardiness
  • Storage capabilities
  • Resistance to disease and pests
  • Withstands physical handling

Our strawberry varieties

Crossing a new variety

Our strawberry breeding is based upon systemic registrations from previous crossings and measurement of the offspring’s results and characteristics. Strawberries are crossed with the goal of creating varieties that have good taste, good yield, suitable firmness and strong disease resistance.

Pollination of a crossing plant

Marker assisted selection (MAS) has become a part of European and Norwegian plant breeding. The molecular biological method is based on finding the genes that give a variety strong resistance, for example, to a disease. If these genes, and genetic markers for them, can be found, then the least resistant varieties can be selected out at an early stage. Instead of several years out in the field, it is possible to find out whether a variety is strong or weak against a pest with leaf samples.

The strawberry crossings are done in a section of our greenhouse that can be isolated from the other sections so that we avoid interferance. There, the crossing plants are first treated for a short day and later they get a long day with more light that makes them bloom.

After the plants bloom, we harvest the pollen from them and collect it in glasses. The pollen carriers on the mother plant are removed and the pollination with the desired father is carried out. Pollinated flowers are covered to avoid foreign pollination.

Our greenhouse consists of several sections that can be isolated from each other

The seeds sit on the outside of the strawberries. To harvest the seeds, we cut off the skin on the berry and leave it to dry before harvesting. The seeds are placed in an acid bath to ease germination. About 3,000 seeds are sown each year and every single seed is a potential new variety.

Strawberry plants develop runners that are genetically similar to the mother plant, and propagation takes place via these small plants. Thus, strawberries can reproduce themselves both by vegetative propagation – to get an identical plant, and by seed propagation – to get a new and genetically unique plant.

In the field, 6 strawberry plants of the mother and 6 strawberry plants of the father are planted in succession. Then 30 offspring are planted. This gives us a good overview of which traits come from the mother and which from the father, and whether the crossing is a good or bad combination.

Registering how strong the varieties are against various pests and diseases is an important part of the fieldwork. How do the berries sit on the plant? Are they easy to pick or are they hidden?

After the berries have been picked, the crop yield, berry size, firmness, colour, and perhaps most importantly for the person who buys the berry in the store, taste, are all registered.

Graminor’s strawberry breeder Muath Alsheikh registering the colour and taste of new berries

At Graminor, we’re always working to increase resistance to pests and diseases in all the species we develop new varieties of. In strawberries, for example, it is important that the plants have strong resistance to mildew and grey mould since there are diseases that often cause great losses to strawberry producers.

Meet the strawberry team