无菌培养条件下有机碳含量对玉米切根上刺线虫生活史的影响

Effect of Organic Carbon Level on Life Cycle of Belonolaimus longicaudatus on Excised Corn Root

在不同蔗糖浓度下培养的玉米(ZeamaysL.)切根上,观察了玉米次生根根尖中不同的碳水化合物水平对刺线虫(Belonolaimuslongicaudatus)生活史的影响.结果表明刺线虫完成生活史所需的最短时间似乎没有明显受到不同有机碳含量水平的影响.碳水化合物缺乏时,明显降低刺线虫的存活率和成虫的比率.在实验结束时,碳水化合物浓度在12g/L以上的线虫在36～39d的时间内完成生活史,线虫存活率几乎要比在4g/L处理下的高出2～3倍.同时,碳水化合物充足条件下的刺线虫性分化的J4,成熟前期和成虫数量要比在最低处理浓度下的高出3倍.在碳水化合物8g/L之下时,未见雌虫产卵.该研究结果表明玉米根组织中碳水化合物含量处于低水平时,刺线虫发育速率较慢、线虫存活率低和成虫所占的比例也低.基于观察到的上述结果,推测植物根尖组织中碳水化合物的含量是限制刺线虫发育和种群数量的因子之一.

The effect of carbon held at 5 different levels with sucrose on development and female fecundity of Belonolaimus longicaudatus was separately investigated on excised corn root (Zea mays L.) at temperature of 24 ℃. The results showed that maximum rate of development was not obviously affected by organic carbon concentration tested as nematodes approaching to adult stage. The duration for the life cycle from J2 to J2 was 36～39 days at C concentration between 12 and 20 g/L. Carbohydrate-poor nutritious sediment has an important impact on the survival rate and the adult ratio of the sting nematode. At the end of experiment, survival rate of the sting nematode at level of above12g/L was near to two or three times greater than that in 4g/L treatment. In the meantime, differentiated J4, pre-adult and adult were more than three times compared to that in the lowest treatment. Female fecundity of the sting nematode nearly decline to zero in the petri-dish amended with carbon at concentration less than 8 g/L. Based on the observed decline in number of adult and survival rate of sting nematode under carbon-poor nutrient medium, it was suggested that the carbohydrate level in tissues of corn root tip was directly responsible for the low development, low survival rate and adult ratio of the sting nematode. So, carbohydrate level in the root tissues was a limiting factor for the sting nematode population development.