Researchers have found a way to grow better blackcurrants using probiotics
November 13, 2021
F.EW FRUITS contain more health-promoting antioxidants than black currants. Often grown in cooler parts of Europe, they are in great demand with consumers looking for pesticide-free juices made from the berries. However, farmers can struggle to increase their yields without relying on chemicals. That could change not only with black currants, but also with other fruits through the careful use of probiotics.
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Probiotics are primarily known to use microorganisms, including certain bacteria, to restore or improve the intestinal flora in humans and animals. But plants can also benefit from working with bacteria. Bacteria help plants, among other things, in the production of antibiotics that keep pathogenic microbes away from their leaves, help them to collect nitrogen from the environment and help them dissolve minerals from the soil.
Knowing this, Virgilija Gaveliene and Sigita Jurkoniene from the Institute of Botany Natural Research Center in Lithuania set out to find a way to use probiotics to increase the yield of the black currant bushes grown in that country. The researchers also knew from other work that strawberry and raspberry production could be increased by exposing plants to a carefully selected mix of bacteria from families such as Bacillus, Acinetobacter and Pseudomonas. And they were aware of preliminary evidence that probiotics have the potential to increase the production of certain antioxidants like anthocyanins and flavonoids.
Together with colleagues, they set up an experiment. Four black currant fields, each one hectare in size, were exposed to different probiotic treatments. These were applied first when the shoots were just beginning to grow and then again when the buds were beginning to bloom. A field was sprayed with a mixture of bacteria that the team suspected would improve growth and yield. Another field was sprayed with a mixture of organic fertilizers and bacteria that the researchers expected would improve the berries' chemical makeup and nutritional content. The third field was sprayed with both mixtures, while the fourth was left as a control and sprayed with water only. After the harvest, the team measured the biomass of the freshly picked berries and examined their chemistry.
As they report in Agricultural Science and Technology, the results were impressive. While a thousand blackcurrants randomly collected from the control plot weighed just over 538 grams, the same number from the field exposed to both treatments weighed almost 783 grams, and a similar increase was seen for those sprayed with the yield-enhancing bacteria Field.
However, the team was concerned that improved berry growth could come at the expense of fewer antioxidants. To this end, their analysis showed that exposure to one of the probiotic mixtures alone significantly reduced the antioxidant activity of black currant from the control level of 73% to 65% and 60%. Only exposure to both probiotic mixtures made it possible to increase black currant growth while maintaining a statistically identical level of antioxidant activity of 72.7%.
All in all, Drs. Jurkoniene and Dr. Gaveliene believes that the right mix of bacteria can help blackcurrant farmers meet demand without the use of chemicals. And it could help other breeders. What works for berries should theoretically also work for other fruits like apples, pears and oranges. Further experimentation is required to be sure. ■
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This article appeared in the Science & Technology section of the print edition under the heading "Probiotic Berries"
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