Identification And Biological Characteristics Of Root-knot Nematodes From Greenhouse Vegetables

Root-knot nematode is a kind of important pathogen, which widely distributes all over the world. Because of this strongly pathogenic pathogen is small, easily disguise, widely parasitize, and easily and rapidly propagate, it is difficult to forecast, prevent and cure. Especially, it seriously endangers vegetables. In recent years, with the improvement of cultivation techniques, extension of vegetable cultivation area, the environmental conditions of greenhouse become more and more suitable for the propagation of root-knot nematode. The occurrence of root-knot nematodes in greenhouse vegetables increased year by year, seriously influencing the quality and output of vegetable. The type of greenhouse vegetable root-knot nematodes in Yangling was surveyed and identified by morphological method in this paper. Biological characteristics of dominant species were studied. The main results were as follows:1. According to the morphological identification, the type of root-knot nematodes damaging the greenhouse vegetable in Yangling was determined as Meloidogyne incognita Chitwood.2. Meloidogyne incognita in Yangling overwintered as eggs, 2nd, 3rd and 4th instar larvae and female adult in root and soil. Its life history of parasitic stage accomplished in 35 days at the accumulated temperature 759.5D℃and average temperature 21.3℃, while its total embryonic development required 9.90 days at 27℃.3. Temperature could affect the hatch and survival of 2nd instar larvae of Meloidogyne incognita seriously. In the range of 15~30℃, at 25℃and 20℃, the hatching rates were much higher. At 10℃and 35℃, the hatching rates were lower. In the range of 15~30℃, the hatching time was significantly shortened with the temperature rising. The optimum temperature was 10~25℃for survival of 2nd instar larvae.4. Humidity could significantly affect the hatch and survival of 2nd instar larvae of Meloidogyne incognita. When soil moisture was 25%, the number of hatched larvae and survival of 2nd instar larvae were the highest. When the water content of 30%, they were the lowest.5. pH value was also an important factor which influenced the growth and development of Meloidogyne incognita. The effect of different pH values on the hatch and survival of 2nd instar larvae of Meloidogyne incognita were almost consistent. When the pH value was 5 to 8, the hatching rate and survival rate of 2nd instar larvae were respectively over 80% and 86%. When the pH value was below 5 or over 8, the hatching and survival rate gradually decreased.