According to the necessity to find new control strategies at low environmental impact against plants parasitic nematodes, a pot experiment on tomato (cv. Super Marmande) was carried out to verify the efficacy of soil ozonated water treatments against the root-knot nematode Meloidogyne incognita. Treatments were applied at transplant and for 15, 30 and 60 days and compared with: a) untreated control and b) fenamiphos treatment (synthetic nematicide) at 62.5 L/Ha used as controls. Pots were arranged, according to a randomised block design, in a glasshouse (25 + 2°C) on benches with ten replications for each treatment. Ozonated water for watering was produced in situ by an ozone generator dissolving ozone gas into the water until an ORP of 800 mV. At the end of the experiment, 60 days after transplant, plants were uprooted from each pot to estimate root gall index (RGI), caused by nematode attack, according to a 0-10 scale. Nematodes extracted from roots by the sodium hypochlorite's method and those extracted from 500 mL soil with the Coolen's method were used to calculate for each pot the final nematode population density and the reproduction rate (r=Pf/Pi). All data from the experiment were subjected to analysis of the variance (ANOVA) and means compared by the Least Significant Difference's Test using the software PlotIT. Root gall index was significantly reduced in all treatments with ozonated water in comparison to the untreated control, although it was significantly higher than those observed in the chemical control. Final nematode population density and reproduction rate were significantly lower in soil ozonated water treatments for 30 and 60 days compared with the untreated control. No significant difference was observed between these two last treatments and fenamiphos. Histological observations on M. incognita galled tomato roots, treated with ozonated water for different application times, were made to compare the anatomical changes induced by the nematode among the different treatments. In the roots of the untreated control and in those treated only for a limited time (15 days) were observed well developed polinucleate giant cells (feeding sites) associated with fully developed females able to deposit a large number of eggs. Undersized giant cell feeding sites associated with immature females, with reduced ability to produce large number of eggs, were noted in tomato roots treated with ozonated water for a longer exposure time (30 and 60 days). In the chemical control was observed well developed giant cells and mature female with limited egg production. No statistical difference was noted in the percentage of hatch from egg-masses produced in the different treatments, including the controls, subjected to an hatching test.
Ozonated water treatments: Control of the root-knot nematode Meloidogyne incognita and histological observations
SASANELLI N;LAQUALE S;VOVLAS N;
2014
Abstract
According to the necessity to find new control strategies at low environmental impact against plants parasitic nematodes, a pot experiment on tomato (cv. Super Marmande) was carried out to verify the efficacy of soil ozonated water treatments against the root-knot nematode Meloidogyne incognita. Treatments were applied at transplant and for 15, 30 and 60 days and compared with: a) untreated control and b) fenamiphos treatment (synthetic nematicide) at 62.5 L/Ha used as controls. Pots were arranged, according to a randomised block design, in a glasshouse (25 + 2°C) on benches with ten replications for each treatment. Ozonated water for watering was produced in situ by an ozone generator dissolving ozone gas into the water until an ORP of 800 mV. At the end of the experiment, 60 days after transplant, plants were uprooted from each pot to estimate root gall index (RGI), caused by nematode attack, according to a 0-10 scale. Nematodes extracted from roots by the sodium hypochlorite's method and those extracted from 500 mL soil with the Coolen's method were used to calculate for each pot the final nematode population density and the reproduction rate (r=Pf/Pi). All data from the experiment were subjected to analysis of the variance (ANOVA) and means compared by the Least Significant Difference's Test using the software PlotIT. Root gall index was significantly reduced in all treatments with ozonated water in comparison to the untreated control, although it was significantly higher than those observed in the chemical control. Final nematode population density and reproduction rate were significantly lower in soil ozonated water treatments for 30 and 60 days compared with the untreated control. No significant difference was observed between these two last treatments and fenamiphos. Histological observations on M. incognita galled tomato roots, treated with ozonated water for different application times, were made to compare the anatomical changes induced by the nematode among the different treatments. In the roots of the untreated control and in those treated only for a limited time (15 days) were observed well developed polinucleate giant cells (feeding sites) associated with fully developed females able to deposit a large number of eggs. Undersized giant cell feeding sites associated with immature females, with reduced ability to produce large number of eggs, were noted in tomato roots treated with ozonated water for a longer exposure time (30 and 60 days). In the chemical control was observed well developed giant cells and mature female with limited egg production. No statistical difference was noted in the percentage of hatch from egg-masses produced in the different treatments, including the controls, subjected to an hatching test.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
