Anaerobic stimulation of root exudates and disease of peas

Summary The relationships between root exudation, root disease and anaerobic root stresses were investigated. Sand culture and mist chamber studies demonstrated that low O₂ and high CO₂ reduced plant growth and increased the exudation of ethanol, amino acids, and sugars by pea roots. The relative loss of ethanol by roots was much greater in treatments with atmospheres of N₂ containing 30% CO₂ than in treatments of air containing 30% CO₂ or N₂. Ethanol was not detected in the nutrient solution of aerated plant roots. Atmospheres of N₂ plus 30% CO₂ caused 500% greater mycelial growth ofFusarium solani f. sp.pisi and 400% more disease of inoculated pea roots. Relative losses of four amino acids and four sugars were much greater in atmospheres of N₂ plus 30% CO₂ than in N₂ or air.