Effects of southern root knot nematode population densities and plant age on growth and yield parameters of cucumber

Southern root-knot nematode (Meloidogyne incognita) is one of the major constraints to cucumber production throughout the world. The effects of M. incognita on growth and yield of cucumber have not been studied. In the present studies, the effects of five initial population densities (500, 1000, 2000, 4000 and 8000 freshly hatched second stage juveniles) of M. incognita were investigated on growth and yield parameters of cucumber. The relationships between inoculum levels and growth and yield parameters at three plant ages were also determined. Cucumber plants of 2-, 3- and 4-week ages were inoculated with different nematode densities and observations were recorded 9 weeks after inoculation. Reductions in growth and yield parameters by nematode densities were calculated over control. All inoculum densities and ages of plants at the time of inoculation influenced growth and yield of cucumber. A positive correlation was found between inoculum levels and percent reductions in growth and yield parameters. On the other hand, ages of plants at inoculation had negative correlations with percent reductions in these parameters at each inoculum level. It is concluded that M. incognita has the potential to severely impair the growth of cucumber and delaying exposure of cucumber to nematodes can significantly abate yield losses.