Arbuscular mycorrhizal (AM) fungi form symbiotic associations with most terrestrial plants
and play an important role in nutrient and water uptake, as well as in plant tolerance to abiotic
and biotic stresses. They also improve soil structure and reduce nutrient leaching. Their
presence and effectiveness in soils are strongly affected by agricultural practices, particularly
tillage intensity and fertilization regime.
In this study, we investigated the effects of tillage intensity and different fertilization regimes
on AM fungal root colonization in barnyard grass (Echinochloa crus-galli) and guizotia
abyssinica (Guizotia abyssinica). We examined the effects of conventional and conservation
tillage and of no fertilization, mineral fertilization, and organic fertilization on AM fungal root
colonization and arbuscule occurrence. We also assessed the role of barnyard grass as a weed
species and Guizotia abyssinica as a cover crop in maintaining soil mycorrhizal potential.
Plant sampling was conducted in a long-term field experiment at the Biotechnical Faculty,
University of Ljubljana. Mycorrhizal colonization was assessed microscopically using the
Trouvelot et al. (1986) method. The presence of hyphae and arbuscules was assessed, and the
following parameters were calculated: mycorrhizal intensity (M%), intensity of mycorrhizal
colonization in colonized root segments (m%), arbuscule abundance in the root system (A%),
and arbuscule abundance in the mycorrhizal portion of the cortex (a%).
Results showed that both tillage and fertilization influenced AM fungal colonization, with
stronger effects in barnyard grass than in guizotia. In barnyard grass, the lowest mycorrhizal
intensity was observed under conventional tillage combined with mineral fertilization (T-NPK),
while higher values occurred under conservation tillage with no fertilization or organic
fertilization. Mineral fertilization significantly reduced mycorrhizal intensity compared to
organic and unfertilized treatments. In both species, colonization was generally higher under
conservation tillage, although most differences were not statistically significant. Guizotia
showed overall low colonization of roots with AM fungi, with no significant treatment effects.
Overall, conventional tillage combined with mineral fertilization negatively affected arbuscular
mycorrhiza, while conservation tillage and organic fertilization supported higher mycorrhizal
potential in soil. The barnyard grass, despite its weedy nature, can serve as an important host
for AM fungi, which may enhance the mycorrhizal potential in agricultural soils and potentially
increase the mycorrhization of cultivated plants with the local community of AM fungi.
|
