Biological Control of Root-Knot Nematodes Using Some Antagonistic Microorganisms on Tomato

Abstract

Tomato (Lycopersicon esculentum Mill.) is considered a main contributor to food of humans. It is mainly grown in all countries whether in fields or protected cultures. Tomato is considered one of the most essential vegetable crops. It is grown in Egypt in different seasons throughout the year basically in newly reclaimed desert lands. Root-knot nematodes, Meloidogyne spp. are considered is one of the most economically important pest because its damage, infection level , wide host range and minimize the quality and quantity of the crop . This study can be summarized as follows : 1-Experimentally, the culture broth of four bacterial isolates i.e. P. fluorescens, A. brasilense, A. chroococcum & B. megaterium were used to test their effect on egg hatching and juveniles mortality of Meloidogyne spp. under room temperature after 24,48,72 & 168h of exposure. 2-The present results exhibited that all bacterial isolates affected nematode eggs and juveniles especially B.megaterium where fulfilled the least percentage of egg hatching and the highest percentage of juveniles mortality after 168 h of exposure by 17.3 & 92%, respectively compared to control. 3-This has been inferred through doing an experimentally test for this bacterium on King's B medium in petri dishes and incubated it for 48 h at 27ċ where the results exhibited that this bacterium had the ability to analyze the protein existed in this medium by exhibiting a clear halo zone around the bacterial colony. 4-The same four bacterial isolates were used as a culture broth at three application times (one week before, at the same time and one week after) of nematode inoculation to study their effect on Meloidogyne spp. on tomato plants under greenhouse conditions. 5-These results exhibited that all bacterial isolates significantly affected the nematode and vegetative parameters especially during adding them at one week before of ,nematode inoculation where B.megaterium fulfilled the highest reduction percentages of nematode parameters and highest increase in vegetative parameters , antioxidant enzymes and pigments concentrations due to secrete natural compounds which act against the nematode and promoting the plant growth. 6-Other experiment was done under greenhouse conditions by applying B.megateriumin two forms i.e. liquid and capsules contained and uncontained humic acid at the rate of 3,5,10 ml or capsules /plant to know which two forms are the most effect . 7-These present results exhibited that both forms fulfilled a significant effect in inhibiting the nematode parameters and increasing the vegetative parameters of plant, but using the capsules is better than a liquid form because it supplies with the permanent protection for bacteria from adverse conditions as well as slowly release of the bacteria which had a longer effect in soil.