Effect of population densities of Meloidogyne incognita on common bean.

The effect of initial population densities of an Italian population of Meloidogyne incognita host race 1 on the growth of common bean was investigated in 800 cm3 pots. Each pot was inoculated with 0, 0.0625, 0.125, 0.25, 0.5, 1, 2, 4, 8, 16, 32, 64, 128, 256 or 512 eggs and second stage juveniles/cm3 soil and sown with one pregerminated seed of the dwarf common bean cv. Talento. Data of height, internode length and fresh top and root weight of the plants fitted the Seinhorst model y=m+(1-m)zP-T. The tolerance limits of fresh top and root weight, height and internode length of plants were 0.25, 2, 0.3 and 0.5 eggs and juveniles/cm3 soil, respectively. Minimum relative yields of fresh top and root weights, height and internode length of plants were 0, 0, 0.15 and 0.14 at =128 eggs and second stage juveniles/cm3 soil, respectively. The maximum reproduction rate of the nematode was 888-fold at the lowest initial population densities. The root gall index was lowest at low initial populations and highest maggiore/uguale 16 eggs and second stage juveniles/cm3 soil.