Population Dynamics and Damage Potential of Meloidogyne hapla to Rose Rootstock Species

摘要

The relationship between initial population densities (Pi) of Meloidogyne hapla on growth of three rose rootstocks (Rosa corymbifera Laxa', R.multiflora and R.canina Inermis') and nematode population development was studied. Each plant species was inoculated with ranges of nematode densities of 0, 0.062, 0.125, 0.25, 0.50, 1, 2, 4, 8, 16, 32, 64 and 128 second-stage juvenile/g soil and were allowed to grow for 9weeks. Seinhorst yield model y=m+(1-m)Z(Pi-T) was fitted to total fresh biomass data of the rootstocks. The tolerance limits (T) were 0.04, 0.09 and 0.01J2/g soil and the minimum yield (m) 0.65, 0.47 and 0.43 for R.corymbifera Laxa', R.multiflora and R.canina Inermis', respectively. The reproductive factor (Pf/Pi) was highest at low initial nematode densities for all rootstocks and then decreased to below maintenance level with increasing initial population densities. Root gall severity consistently increased with initial nematode population density. Furthermore, number of root galling showed a strong positive relationship with final nematode population per gram root fresh weight. The relation between Pi and Pf was also fitted to the Seinhorst population model (Pf=(M*Pi)/Pi+M/a). Rosa multiflora supported the population of M.hapla to a maximum population density (M) of 27.53J2/g soil with an estimated average maximum multiplication rate (a) of 24.39. For R.corymbifera Laxa' and R.canina, the maximum multiplication rate was 4.34 and 3.62 and the maximum population density 6.08 and 4.78J2/g dry soil, respectively. Hence, it was demonstrated that all three rootstocks were susceptible to even low initial nematode densities and therefore are considered good hosts for M.hapla.