Response of raspberries to treatments with Spirulina sp., Dunaliella sp. and Chlorella sp. extractions

The experiments were done at two farms in Latvia. Primocane raspberries were weekly sprayed with solutions of ethanol extractions of microalgae species of Spirulina sp., Dunaliella sp. and Chlorella sp. in different concentrations from stages of shoot growth to fruit ripening. During the season, dynamics of the shoot growth, beginning of flowering and fruit ripening were recorded. After the treatments, productive length of the shoots, number of flower trusses and leaves per shoot, number of productive shoots per plot, chlorophyll index, average fruit weight and sugar content in the fruits were measured. Certain positive effects of the treatments with one or another algae extraction were observed, increasing plant height and the proportion of the productive part of the shoot, number of leaves and flower trusses per shoot and the chlorophyll index. Moreover, no negative effects of any tested treatments were observed. However, the positive effects differed in different farms and years. That can be explained by uneven growth of the plants in the farms, weed and disease spread, changing weather conditions. Therefore, we can conclude that since the results are strongly promising, further experiments in controlled environments using preparations of varied extraction types, microalgae species and different treatment protocols should be carried out.