Effect of Barium on Growth and Macronutrient Nutrition in Tanzania Guineagrass Grown in Nutrient Solution

Barium has been identified as a toxic element to most plants, although for grasses the toxicity has not been determined. A greenhouse experiment was performed to evaluate the effect of barium on growth parameters, barium accumulation, and macronutrient concentration in Tanzania guineagrass (Panicum maximum Jacq.), cultivated in nutrient solution. Five barium rates and a control were set in a complete randomized block design, with four replications. Forage yield, leaf area, barium, and macronutrient concentrations and accumulation were measured. Leaf area and yield sharply decreased with increase of barium concentration in the nutrient solution. The greatest barium concentration and accumulation were found in culms and sheaths. Toxic barium concentrations were estimated to be 1.24 mmol L-1 (170 mg L-1) in nutrient solution and 225 mg kg(-1) in the diagnostic leaf, and the main symptoms of toxicity were interveinal chlorosis followed by necrotic spots in the leaf laminae of the grass.