Abstract:【Objective】Nematodes are one of the classic indicators of soil health. This study aimed to clarify the composition of soil nematode community and its response characteristics to soil physicochemical properties in ‘Shushanggan’ apricots plantations in Yili River Valley, so as to provide a theoretical basis for sustainable management of ‘Shushanggan’ apricots plantations.【Methods】In this experiment, soil samples of ‘Shushanggan’ apricots from plantations aged 4, 8, 10, 14 and nearly barren land were collected in Sango-ng Township, Huocheng County in September, 2023.The geographical location and elevation of the sampling site were determined by GPS. Five undertree forestlands of ‘Shushanggan’ apricots plantations in different planting years were selected as the quadrates (20 m´20 m), and the soil layers were selected by 0-10 cm and 10-20 cm. Five small samples (10 cm´10 cm) were selected from the plantation land under each tree 0.5 m from the base of trunk and mixed into one soil sample by five-point sampling method. A total of 50 soil samples were collected from the five plots. An appropriate amount of soil sample was taken from each layer of each quadrate, mixed evenly and air-dried to determine the physicochemical properties of soil. Soil nematodes were isolated by sucrose density gradient centrifugation and identified by morphological method. To investigate the number, composition and ecological function index of soil nematode community of ‘Shushanggan’ apricots plantations. Then, this research analyzed the relationship between soil nematode groups and soil physicochemical properties. 【Results】The results showed that a total of 7066 nematodes were isolated from all plots, and 52 genera of nematodes were identified, belonging to 2 classes, 6 orders and 23 families, with an average density of 373 nematodes per 100 g of dry soil. The density of soil nematodes in ‘Shushanggan’ apricots plantations decreased first, reaching the highest in 10 years (752 nematodes per 100 g dry soil), and then increased. The dominant genera of the ‘Shushanggan’ apricots plantations at different ages were Acrobeloides, Paratylenchus, and Microdorylaimus. Among them, the dominant genera of the 4- and 10-year-old trees in the ‘Shushanggan’ apricots plantations are Acrobeloides, Chiloplacus, Aphelenchus and Microdorylaimus. The dominant genera of the 8- and 14-year-old trees are Pararotylenchus, Rotylenchus and Helicotylenchus. According to the c-p value, c-p2 and c-p3 were the main groups. The density of soil nematode in the 8-, 10- and 14-year-old trees was higher in the 10~20 cm soil layer, and higher in the 0~10 cm soil layer on the 4 years old trees. There were significant differences in diversity index(H′) between10 years old ‘Shushanggan’ apricots plantations and barren land(p<0.05). Soil nematodes diversity index(H′) in ‘Shushanggan’ apricots plantations decreased first, reaching the lowest in 10-years, and then increased. The plant parasitic index(PPI) in barren land was significantly lower than that in ‘Shushanggan’ apricots plantations of different ages. The maturity index(MI) of the 4-year-old ‘Shushanggan’ apricots plantations were significantly lower than those of other plots, while the Wasselska index(WI) was significantly higher than that of other plots. The nematode channel ratio(NCR) of the 8-year-old were significantly lower than those of the 10-year-old ‘Shushanggan’ apricots plantations, while the MI and PPI of the 8-year-old were the highest. Soil total kalium(TK), pH and calcium (Ca) were the main environment factors affecting the composition of soil community in ‘Shushanggan’ apricots plantations(p<0.05). Correlation analysis showed that TK was negatively correlated with c-p1 and bacterivores nematodes (Ba). Soil moisture content (SM) was positively correlated with all nematode trophic groups and c-p groups. pH and Ca were strongly positively correlated with Fu and negatively correlated with c-p3 and Pp.【Conclusion】After the conversion of barren land to ‘Shushanggan’ apricots, the tolerance nematodes c-p2 and c-p3 increased and the sensitivity nematodes c-p4 decreased, indicating that ‘Shushanggan’ apricots plantations was disturbed to varying degrees on trees of different ages, and ‘Shushanggan’ apricots plantations was disturbed the most on trees of 4 years old, followed by 10 years old. Although the density of nematode in the 10-year-old ‘Shushanggan’ apricots plantations was higher than that in other plots, the stability and diversity of nematode community were poor due to human interference, while the diversity and stability of barren land were higher than those in other plots, indicating that the soil nematode diversity was higher in undisturbed ecosystems. In general, the disturbance of 4- and 10-year-old trees was larger, and the disturbance of 8- and 10-year-old trees was smaller. However, the soil enrichment degree of ‘Shushanggan’ apricots plantations in 4- and 10-year-old was higher, and the food web structure was more mature. Instead, the soil food chain of 8- and 14-year-old trees was shorter, and the soil organic matter conversion ability was poor. In conclusion, the main trophic groups of 4- and 10- year-old trees were Bacterivores, and the soil health was good. The main trophic groups of 8- and 14-year-old trees were Fungivores, and the soil health was poor. The results provided theoretical basis for rational planting of ‘Shushanggan’ apricots plantations.
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