EFFECT OF PRATYLENCHUS NEGLECTUS AND P. THORNEI ON THE GROWTH OF FABA BEAN

Abstract

An experiment was undertaken to investigate the effect of a range of inoculum densities of Italian populations of Pratylenchus neglectus and P. thornei on the growth of faba bean (Vicia faba) in pots. Clay pots of 1 l capacity were filled with steam sterilized sandy soil and sown with a single pregerminated seed of faba bean cv. Aguadulce. At plant emergence a suspension of either nematode species, juveniles and adults, was poured into six holes around the seedling roots to give initial population densities of 0, 0.03, 0.06, 0.125, 0.25, 0.5, 1, 2, 4, 8, 16, 32, 64, 128 or 256 nematodes/cm3 soil. Data of fresh top weight of plants fitted the Seinhorst model y= m+ (1-m)z[supPû[supT] According to this model, tolerance limits (T) of faba bean to P. neglectus and P. thornei were 2 and 2.2 nematodes/cm³ soil, respectively. Minimum relative yields (m) of faba bean were 0.4 and 0.6 for fresh top plant weight for P. neglectus and P. thornei, respectively, and occurred at Pi = 128 specimens/cm³ soil. Maximum reproduction rates (Pf/Pi) were 18.3 and 3.3-fold, at lowest Pi, for P. neglectus and P. thornei, respectively.