NEMATODES IN THE SOIL AND ROOTS OF SPRING BARLEY GROWN IN CROP ROTATION AND LONG-TERM MONOCULTURE
Background. Species structure of plant parasitic nematode populations from the rhizosphere of spring barley grown in an 18-year-old crop rotation and in a 48-year-old monoculture were analyzed and compared.
Material and methods. Plots were established in fields of spring barley grown in an 18-year-old crop rotation and in a 48-year-old monoculture. Four 1 m2 plots were located in each corner of each field. Four soil samples from each 1 m2 plot were taken by a pedestrian cane of a 3 cm section at a depth of 40 cm in the vicinity of the barley roots at start (BBCH 09) and a day after harvest (BBCH 99). Each soil sample weighed 1 kg and contained 50 g of fresh roots and spikes. The sample from each of the four 1 m2 plots was a replicate (and at the same time, the combination of the soil + roots + stems), hence the isolated nematode from each part of the sample was a set of nematodes associated with the host on 1 m2.
Results. Populations of dominating species such as Bitylenchus dubius, Merlinius microdorus, Pratylenchus neglectus and Heterodera avenae became higher in the monoculture than in the crop rotation. H. avenae eggs and larvae were infected by pathogenic fungi in 50% of samples from the monoculture (vs. 60% of the cysts from the crop rotation), and 18–35% of Pratylenchus specimens were colonized by bacteria, mainly by Bacillus penetrans.
Conclusion. The results illustrated nematological changes occurring in long-term cropping systems and provided additional information necessary to fight dangerous viral vectors for the examined cereal.