Taxonomic profiling of nematode community using morphological and metabarcoding approaches under diverse irrigation...

Accurate identification of nematode communities is essential for understanding their ecological roles and functions in soil. However, the comparative analysis of morphology-based (MBI) and high-throughput sequencing (HTS) nematode community under contrasting irrigation regimes remains poorly understood. In this study, we investigated nematode community response in long-term mandarin and pomegranate orchard ecosystems managed under drip and surface irrigation using both identification approaches. Genera richness was consistently higher in HTS approach with 40 and 43 genera in mandarin and pomegranate orchards, respectively, compared with 29 genera each under MBI. This represents an improvement of 27.5-32.5% increase in genus detection. The Sorensen similarity index between approaches ranged from 0.37 to 0.53, indicating only low to moderate agreement. Identification approach showed a stronger effect on perceived nematode community composition than irrigation system (PERMANOVA, R² = 0.61, p < 0.01). HTS yielded higher Shannon diversity, evenness, structure index (SI), enrichment index (EI), and MI_2-5 values, while MBI returned higher basal index and nematode channel ratio values, revealing that methodological choice could influence ecological interpretation of soil food web condition. Surface irrigation supported significantly greater bacterivorous nematode abundance, consistent with enhanced bacterial decomposition pathways under fluctuating soil moisture. In contrast, drip irrigation was associated with significantly higher MI, ∑MI, and plant-parasitic index, collectively indicating a more structured, K-strategist-dominated community with greater plant-parasitic pressure. Soil food web assessment further revealed that MBI-based communities clustered predominantly in the structured quadrant, while HTS shifted communities toward the enrichment-structure transition zone, underscoring how detection capacity governs food web interpretation. These findings demonstrate that HTS and MBI provide complementary rather than interchangeable assessments of nematode biodiversity, and that irrigation management carries measurable, ecologically interpretable consequences for soil food web dynamics in orchard systems.