Response of Blueberry Species to Excessive Manganese

Abstract

Abstract The response of blueberries (Vaccinium spp.) to added Mn was studied in soil, solution, and sand cultures. Weekly additions of up to 0.8 mg Mn to Berryland sand soil (4.3 kg/pot) for 7 months produced the most growth in highbush blueberries, and additions of 6.4 mg Mn/week resulted in growth reductions but no visual toxicity symptoms. Solution culture- (800 ml/bottle) grown ‘Blueray’ highbush blueberries tolerated Mn additions up to 96 μg·ml−1 without significant growth reductions. Under similar conditions, a lowbush clone grew best at high added Mn and had higher foliar Mn concentrations than did ‘Blueray’, the rabbiteye cultivar ‘Tifblue’, or a selection of Vaccinium elliotti Chapman. Lowering solution Ca, Mg, and NO3 levels sharply increased foliar or stem Mn concentrations of all species. Growth of three genetically diverse hybrid blueberry progenies were not signficiantly affected by relatively high levels of applied Mn or Al when grown in sand culture. Increasing Al had a greater effect on increasing root Mn concentrations than did an increase in Mn levels. There were no visual Mn toxicity symptoms expressed in any of the three media from excessive Mn levels.