温度和初始接种量对南方根结线虫侵染力的影响

Effects of temperature and initial inoculation density on root-knot nematode (Meloidogyne incognita) infection ability

在棚室盆栽条件下,研究了南方根结线虫在不同温度、不同蔬菜寄主及不同初始接种密度下的症状表现。结果表明,5—9月,气温在22.17~27.61℃之间,南方根结线虫在黄瓜上最短3 d出现明显症状;1—4月和10—12月,气温在15.38~18.67℃之间,15 d出现明显症状,显症时间延迟,发病程度受到抑制。15种感病蔬菜寄主中,以西瓜、甜瓜、苦瓜、黄瓜、南瓜、西葫芦和小青菜症状表现时间比较短,10 d以内表现症状;番茄、豇豆、茄子和甘蓝症状表现时间比较长,15 d出现症状;而韭菜和葱30 d仍未出现明显症状。南方根结线虫对6种蔬菜（黄瓜、番茄、茄子、小青菜、辣椒、韭菜）的侵染能力存在显著差异,黄瓜和番茄的根结百分率、根际二龄幼虫数、雌成虫数和卵块数显著高于茄子、小青菜、辣椒和韭菜。随着二龄幼虫接种密度的增加,番茄感病症状表现时间缩短,相应的病情指数也在增加,在接种量为80头·100g-1（土）时,4 d出现明显症状。接种量为160头·100g-1（土）时超过其饱和数量,发病率和病情指数增加不明显。

The effects of temperature,host vegetables and initial inoculation density of root-knot nematode（Meloidogyne incognita） on root-knot nematode driven vegetable symptoms were investigated under greenhouse conditions.The results showed that the optimum temperature for root-knot nematode incidence from May to September was 22.17~27.61 ℃,with obvious symptom detection in cucumber plants after three days.When temperature was 15.38~18.67 ℃ during January to April and October to December,obvious symptom detection in cucumber plants was after 15 days.Symptom appearance time was delayed and disease incidence inhibited.15 different host plants were infected by the second-stage juveniles of M.incognita.Symptoms appeared in 10 days for watermelon,melon,bitter-gourd,cucumber,pumpkin,squash and green grocery.There were 5 days later for tomato,cowpea,eggplant cabbage and celery.Symptom appearance time in leek and welsh onion was the longest,without becoming obvious after 30 days.The infection ability of M.incognita varied significantly among the six vegetables（cucumber,tomato,eggplant,green grocery,leek and pepper）.The numbers of second-stage M.incognita juveniles in rhizosphere soil and adult females and egg-masses in cucumber and tomato roots were more than those in eggplant,green grocery,leek and pepper.With initial inoculation density enhancement of second-stage juveniles,obvious symptoms appeared earlier in tomatoes with a more severe disease index.When inoculation density of second-stage M.incognita juveniles was 80.100 g-1（soil）,obvious symptoms appeared in tomatoes after four days.At second-stage M.incognita juvenile inoculation rate of 160.100 g-1（soil）,it exceed saturation density thereby suppressing disease rate and index.