| Root-knot Nematode is a plant pathogenic nematode in most species, the most widelydistributed and harm the most serious category of parasitic nematodes, mainly harmMeloidogyne incognita, M. javanica, M. arenaria and M. hapla, of which the most seriousharm to M. incognita. This paper studies the M. incognita under different temperatureconditions dynamics, larval infestation protective enzymes and their impact on the growth ofcucumber seedlings of different tomato varieties, made the following main results.1.Effects of temperature on the survival of Meloidogyne inicognitaThe effect of temperature on the survival of Meloidogyne incognita was studied inlaboratory and field experiments. The results showed that the large number of M. incognitawas occurred in soil in late December and mid-November, and the numbers were437.6per100g soil and427.6per100g soil. In addition, the number of nematodes decreased graduallyin soil with the temperature decreased in late December, and significantly decreased inmid-January, even died in mid-February. In laboratory experiments, the number of secondstage of juveniles (J2) hatched from the single egg was0, and the survival rate was0%at-20℃and-12℃; The number of J2hatched from the single egg was0, and the survival rateof J2gradually decreased after4days, even the survival rate was0%on22th day at2℃; Thenumber of J2hatched from the single egg was150.6, and the survival rate of J2graduallydecreased after10days, even the survival rate was0%on30th day at13℃. The number of J2hatched from the single egg was696.4, and the survival rate of J2gradually decreased after8days, even the survival rate was0%on28th day at25℃. Meanwhile, the survival rate was0%at25℃, which were treated at2℃at first. Therefore,Meloidogyne incognita was notsurvived with soil to overwinter in the field of Lanzhou.2.Effects of initial population of Second Juvenile of Meloidogyne incognita on Growth OfCucumiMeloidogyne incognita is a serious disease in cucumis production． The effect ofMeloidogyne incognita initial population densities on the cucumis height，the number ofleaves，the numberof flower spikes，the flesh and the dry weight of plant were evaluated in potexperiments under the greenhouse condition to understand the effect of population density onthe pathogenic potential of M.incognita in cucumis．The results showed that the plant height，the number of leaves，the number of flower spikes，and the fresh and the dry weight of plant were decreased with increasing densities of M.ineognita,but the disease index wasincreased.The T value (tolerance limit) was calculated based on the plant height，freshweight，dry weight with the Seinhorst model．The final tolerance limit of cucumis toMeloidogyne incognita was determined as410.There was some damage to the root，but noobvious influence on the growth of cucumis was observed when the nematode densities werelower than tolerance limit．3.To six varieties of tomato seedlings were used to study the effects of infection byMeloidogyne incognita15days and25days to six varieties of tomato seedlings protectiveenzymes. The results showed that:15days after inoculation of M. incognita, SOD activityincreased varieties of red tyrant relative minimum of14.6%, PPO activity relative increase ofup to55.6%, the number of root knot104.2; SOD activity increased relative species Diorminimum54.7%, PPO activity increased up to175.3%relative to root knot count is0;incognita25days after inoculation, SOD activity of red tyrant relatively reduced by13%thenumber of root knot237.4; fronts One of SOD and PPO activity relative increase65.6%and172.8%, respectively, root knot count is0. After a comprehensive analysis, the varieties ofChristian Dior and fronts One of the strongest resistance to M. incognita, resistant varieties ofred tyrant weakest southern root-knot nematode infestation SOD activity after a minimum,PPO activity of the biggest changes. |
