Application of a flowing solution culture technique to study the parasitic fitness of the nematode Radopholus similis on banana plantlets under two different nitrogen nutrient regimes

A flowing solution culture technique was used to study the effects of N nutrition on banana root infestation by the burrowing nematode Radopholus similis . Paired groups of banana plants were grown in separate compartments containing coarse sand (2–5 mm diameter). Input nutrient solutions had fixed compositions and identical total N concentrations. The two compartments differed in their NH₄⁺/total N concentrations, one receiving 0% NH₄⁺/total N (100% NO₃^?/total N) and the other 60% NH₄⁺/total N (40% NO₃^?/total N). The compartments were connected by a inverted T-shaped tube containing fine sand (200–250  μ m diameter) through which nematodes were inoculated. The pH and N concentrations of the output solution were determined at regular intervals. The pH of the output solution differed markedly between the two compartments, with values of 6.8 and 3.6 in the 0% and 60% NH₄⁺ compartments, respectively. In the compartment receiving 0% NH₄⁺, the number of nematodes in the roots and the growth of banana plants was significantly higher than in the compartment receiving 60% NH₄⁺. Even though they were more infested by nematodes, banana plants receiving 100% NO₃^? developed better than the less infested plants grown in the medium containing 40% NO₃^?.