Two greenhouse experiments were conducted to evaluate the nematicidal
activity of certain alkaloid plants namely, periwinkle (Catharanthus roseus), datura
(Datura stramonium), lupin (Lupinus albus), pomegranate (Punica granatum) and
fenugreek (Trigonella foenum-graecum) against root-knot nematode Meloidogyne
incognita infecting cucumber (Cucumis sativus) and reniform nematode
(Rotylenchulus reniformis) infecting cantaloupe (Cucumis melo var.cantaloupensis).
Dried powdered parts of such plants were screened at three rates (1, 3 and 5g /
plant). In most treatments data indicated a positive correlation between tested rates
and plant biomass. Dried leaf powder of C. roseus (62.5%) as well as dried seed
powder of L. albus ( 52.8%), and T. foenum-graecum ( 43.2 %) induced remarkable
improvement in total plant fresh weight of cucumber at the rate of 5g/plant.
However, dried leaf powder of D. stramonium (41.4%) recorded a significant
increase in total plant fresh weight at the rate of 3g/plant. By all treatments of
alkaloid plants root-knot nematode population whether in soil and roots, root galling
and number of egg masses were significantly suppressed. Dried leaf powder of C.
roseus at three tested rates (71.8, 71.6 and 72.6%) performed the best and
suppressed total nematode population of M. incognita followed by T. foenumgraceum
at 5g/plant (70.1%). On the other hand, a slight to moderate improvement
in plant growth parameters of cantaloupe infected with R. reniformis was indicated
in pots receiving alkaloids plants. The highest percentage of increase in total plant
fresh weight was noticed with dried leaf powder of C. roseus at three tested rates
(28.5, 31.4 and 32.6%) respectively. The best protection of cantaloupe against R.
reniformis was recorded with dried seed powder of T. foenum-graecum (57.9, 65.2
and 75.0%) and P. granatum (55.4, 55.9 and 61.7%) at three tested rates,
respectively which ultimately suppressed R. reniformis population.