南方根结线虫不同密度对番茄生长的影响

南方根结线虫病(Meloidogyne incognita)是番茄生产上的主要病害。为明确土壤中南方根结线虫初始密度与番茄产量损失的关系，在温室条件下，通过盆栽试验，测试土壤中根结线虫不同初始密度对番茄不同生长期株高和生物量等方面的影响。结果显示，番茄植株的长势随接种密度的增加而减弱，即随着接种密度的增加，植株高度降低，叶片数和花穗数减少，鲜重与干重显著减轻，番茄的发病程度则逐渐加重。利用Seinhorst模型，分别以株高、鲜重、干重为指标确定了番茄对根结线虫的最低忍耐值T；综合本研究结果，确定番茄对根结线虫的最低忍耐值为4.4头/(mL·土)，低于该密度线虫虽对番茄根部造成一定危害，但对植株地上部的生长影响不明显。

Effect of Initial Population Densities of Meloidogyne incognita to the Growth of Tomato

Root knot nematode (RKN, Meloidogyne incognita) is a serious disease in tomato production. The effect of RKN initial population densities on the tomato height, the number of leaves, the number of flower spikes, the fresh and the dry weight of plant were evaluated in pot experiments under the greenhouse condition to understand the effect of population density on the pathogenic potential of M. incognita in tomato. 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. incognita, but the disease index was increased. The T value (tolerance limit) was calculated based on the plant height, fresh weight, dry weight with the Seinhorst model. The final tolerance limit of tomato to RKN was determined as 4.4 nematodes per milliliter soil. There was some damage to the root, but no obvious influence on the growth of tomato was observed when the nematode densities were lower than tolerance limit.