A new study suggests that surrounding blueberry plants with grass helps them absorb more iron and increases their antioxidant content. While soils are rich in iron, most of it is insoluble. Study senior study author Dr. José Covarrubias: “Most plants get enough iron by secreting chemicals that make it more soluble. These iron ‘chelators’ can be released directly from the roots, or from microbes that grow among them, and allow the iron to be absorbed. Blueberries, however, lack these adaptations because they evolved in uncommonly wet, acid conditions which dissolve the iron for them.”
“Iron is essential for the formation and function of plant molecules like chlorophyll that allow them to use energy. That’s why iron deficiency shows up as yellowing leaves – and drastically reduces plant growth and yield.”
Covarrubias said that in blueberries, iron-dependent enzymes produce the antioxidants that make them a “superfruit.” To correct iron deficiency in blueberries, the soil must be acidified or synthetic iron chelators must be added. According to Covarrubias, each of these techniques has its drawbacks.
“The commonest industrial approach is soil acidification using sulfur, which is gradually converted by soil bacteria into sulfuric acid. The effects are slow and difficult to adjust – and in waterlogged soils, hydrogen sulfide might accumulate and inhibit root growth.”
“Grasses – which are well-adapted to poor soils – can provide a sustainable, natural source of iron chelators via their roots when grown alongside fruiting plants. Intercropping with grass species has been shown to improve plant growth and fruit yield in olives, grapes, citrus varieties – and most recently, in blueberries.”
Dr. Covarrubias concluded: “Our findings validate intercropping with grasses as a simple, effective, sustainable alternative to standard iron correction strategies in blueberries. Both commercial and private growers can put this strategy to use right away to boost their blueberry crop and antioxidant content.”