The Impact of Abiotic Factors on Soil-borne Pathogenic Fungi in Orchards

Abstract

We examined fine roots and soil samples from different trees across 20 sites of orchards. Fungal frequency of occurrence (%) were calculated in fine roots and soil per location and across locations. Fusarium spp. was the most frequent fungi in fine roots in both Al Za’franiya (100%) and Tarmiyah (100%); and the most frequent fungi across locations with (84.2%). While Aspergillus spp. was the most frequent fungi in soil dilution in both Al Za’franiya (75.0%) and Abu Ghraib (50.0%); and the most frequent fungi across locations with (50.0%). Further, we examined five abiotic factors, irrigation, geographical locations, type of plant, type of soil, and type of water to identify their effect on fungal community of fine roots and soil in terms of least squares means and standard error (LS means±SE) across 20 orchard sites. Al-Za'franiya fine roots revealed abundance of fungal community (5.0±1.14), followed by Dora (1.0±0.93), Abu Ghraib (0.6±0.72), and Tarmiyah (0.3±0.51); while Lythraceae revealed a significant effect on fungal community (5.5±1.15). Similarly, Al-Za'franiya soil recorded  a significant effect on fungal community (4.0±1.17); while Lythraceae had a significant effect on fungal community (5.0±1.10). Whereas irrigation, type of soil, and type of water showed no influence (p > 0.05) on fungal community in both fine roots and soil. These findings highlight the predominant of Fusarium spp. reflects the importance of this fungus as a potential pathogen in the agricultural environment of Iraq. Further, the variation in the effects of tested abiotic factors on the fungal community of soil-borne pathogenic fungi of both fine roots and soil emphasizes the epidemic risk on agricultural ecosystem in Iraq.