Nematode community composition and ecological indicators in cabbage, Brassica oleracea L. rhizosphere soils of Eastern Fergana Valley, Uzbekistan

This study examines the species composition, trophic structure, and ecological functioning of soil nematode communities in the rhizosphere of cabbage, Brassica oleracea L. (Brassicales: Brassicaceae) agroecosystems across six districts of the Eastern Fergana Valley, Uzbekistan. To investigate the nematode fauna associated with cabbage plants, field studies were conducted in six districts located in the southeastern part of the Fergana Valley. The research was carried out during the spring and autumn seasons of 2024-2025. A total of 38 nematode species belonging to five orders were identified, reflecting considerable variation in faunal structure among sampling sites. Ecological indices, including the Maturity Index (MI), Enrichment Index (EI), Structure Index (SI), Plant-Parasitic Index (PPI), and Channel Index (CI), were used to assess soil food web status and ecosystem stability. Enrichment-dominated systems, particularly in Marhamat, were characterized by high EI values and the dominance of bacterivorous nematodes, whereas more mature and structured food webs were evident in districts such as Khojaobod and Buloqboshi, where higher MI and SI values were recorded. These findings highlight the diagnostic value of nematode-based indicators for evaluating soil health and emphasize the need for district-specific management strategies to support sustainable agricultural productivity in the region.