Identification of Native Trichoderma Species with High Abundance in the Rhizosphere of Pistachio Trees

Subject Areas :

Mohammad Moradi ¹ , Fatemeh Hasanzadeh Davarani ^{2 *}

1 - 2. Pistachio Research Center, Horticultural Sciences Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Rafsanjan, Iran
2 -

Received: 2025-09-05 Accepted : 2025-09-17 Published : 2025-09-21

Keywords: Antagonistic assay, Biodiversity, Rhizosphere, Adaptability, Adaptability,

Abstract :

Trichoderma fungi are among the most active microorganisms in the rhizosphere of plants, playing a crucial role in the biological control of plant pathogens and promoting plant health. In this study, native Trichoderma species were isolated, purified, and identified from soil and rhizosphere samples collected from 50 pistachio orchards across various regions in Iran. Initial isolation was performed using selective media (ELAD and SPDA) and serial dilution techniques, followed by single-spore purification on PDA and WA media. Morphological identification of isolates was based on vegetative reproductive structures, including colony shape and growth, pigmentation, sporulation, conidiophore architecture, phialide and conidium morphology, chlamydospore formation, and growth rate at different temperatures, using validated taxonomic keys. The results revealed that Trichoderma harzianum was the most frequently isolated species, likely due to its high ecological and biological adaptability to pistachio orchard soils. Other species such as T. virens, T. brevicompactum, and T. longibrachiatum were identified with lower frequencies. Comparative analysis of soil, rhizosphere, and fertilizer pit samples showed significantly higher Trichoderma abundance in the rhizosphere, highlighting its importance in plant-microbe interactions. Native isolates were screened through antifungal assays based on their antagonistic properties, and the most effective strains with high biocontrol potential were selected for the development of biological products against pistachio pathogens. These findings contribute to sustainable agriculture and integrated pest management strategies.

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