Effects of deficit irrigation on tomato and eggplant and their infection with the root-knot nematode under controlled environmental conditions

Deficit irrigation has been widely investigated as a valuable strategy for dry regions where water is the limiting factor in crop cultivation. Soil moisture can be one of the important factors that influence root-knot nematode (RKN) disease development. To determine how different levels of irrigation can affect disease development, irrigation regimes ranging from 20% to full field capacity (FC) were applied to tomato and eggplant plants inoculated with Meloidogyne javanica (M. javanica) under controlled conditions. In addition, in vitro bioassays were done to evaluate the effect of water potential and soil moisture content on M. javanica viability in the soil and reproduction on plant hosts. The relative egg hatching percentage decreased significantly with decreasing water potential from -0.1 to -1 MPa. The use of 80% irrigation level caused minor reductions in growth but significantly reduced nematode infection load. Nematode infection was reduced even further at lower levels of irrigation, however this also led to marked reductions in fresh and dry weights of the tomato and eggplants. Therefore, deficit irrigation could be used at a rate of 80% or 60% of FC to increase water use efficiency and reduce the level of RKN (M. javanica) infection without greatly reducing the growth performance of tomato and eggplant crops. © 2013 © 2013 Taylor & Francis.