Effect of legume (Fabaceae Lindl.) seeds on selected life activities in J2 stage of Meloidogyne hapla

Meloidogyne hapla is a serious pest of many cultivated plants. In response to the economic significance of the species, efforts are being made to develop a new method to reduce its harmful effects on crops. The aim of the study was to determine the effect of diffusates from seeds of selected species of legumes on the motility of second-stage juveniles and to evaluate the effect of meal from seeds of selected species of legume on the capacity to infect the roots of tomato plants by the J2 stage. The experiment examined the effect of diffusates on the motility of the J2 stage performed in Petri dishes, at temperatures of 10 °C, 17 °C and 21 °C. The evaluation of the J2 stage infectivity was estimated in a pot experiment performed under controlled conditions of 20 ± 1 °C. The pots were filled with sterile substrate mixed with meal from the seeds of selected plants at 1%, 5% and 10% of the substrate weight. The studies carried out in the Petri dishes showed varying effects of the seed diffusates from selected legume plants on the motility of the J2 stage of Meloidogyne hapla. J2 were found to lose their motility within 24 h after immersion in water containing seed diffusates from Melilotus albus, Trifolium pratense T. repens, in the temperature ranges investigated (10 °C, 17 °C and 21 °C). However, in a mixture of seed diffusates and soil filtrate from the root zone of tomato plants, the absence of motility in the second-stage juveniles was observed after 24 h at 17 °C and 21 °C, with seed diffusates from Lotus corniculatus, Medicago sativa, Medicago × varia, Melilotus officinalis, as well as Onobrychis viciifolia, Ornithopus sativus, Vicia sativa, used in the mixture. Galega officinalis Risa (GoR) seed diffusates were found to have an inhibiting effect on the motility of the J2 stage of M. hapla 24 h following the immersion of the J2 stage in the solution of the soil filtrate containing tomato root diffusates, at 21 °C. The J2 stage were not rendered immotile in all the experiment set-ups involving the seeds of V. faba, Lupinus spp., likewise in the control set-ups. In the pots studied, a significant effect of the addition of legume seed meal on the development of M. hapla nematodes and tomato plants was found. The introduction of Lotus corniculatus, Onobrychis viciifolia and Vicia sativa seed meal into the substrate in the proportion of 1%, 5% and 10% resulted in the inhibition of the J2 stage penetration into the roots of tomato plants at temperatures of 17 °C and 21 °C. With the admixture of the M. sativa and T. repens seed meal, within the temperature range investigated, no nematode infection was observed in the roots, regardless of the seed meal content in the substrate. As regards to the fresh weight, tomato plants grown in a substrate containing 1% and 5% of the V. sativa cv. Jaga seed meal were characterised by significantly higher plant weight values as compared to those grown in the control set-up. The obtained results imply that is advisable to expand the scope of research to include other economically important crops damaged by the northern root-knot nematode.