Sunflower broomrape (Orobanche cumana Wallr.) has severely restricted the development of the sunflower industry in China, and more efficient and convenient control methods are urgently needed. In this experiment, we investigated the effects of N, P and silica fertilizers on the parasitism rate of O. cumana, as well as on the yield of sunflower and native microbial communities in the field. Firstly, pot experiments were conducted to select the most effective fertilization method and to determine the physiological and biochemical indexes of sunflowers. Subsequently, field application studies were carried out to determine the physiological indexes, yield, O. cumana parasitism on sunflower, and the effect on the indigenous microbial community. The results demonstrate that compared with the CNP treatment (Control), the number of parasites under the N1P5 treatment significantly decreased by 66.15%. The exogenous application of silica can significantly reduce the number of O. cumana parasites. The treatments with N1P5 (N/P = 1:5) and available SiO₂ content higher than 40 mg/kg (NS2, NS3, SF2 and SF3) significantly increased superoxide dismutase (SOD) activity and decreased malondialdehyde (MDA) content in sunflower leaves. In the field, fertilization significantly decreased the number of O. cumana parasites. The S treatment improved the native microbial community structure and enriched beneficial microorganisms, including Vicinamibacteria and Pyrinomonadaceae. Additionally, applying the S treatment significantly increased sunflower yield by 23.82% and crude protein content by 20.20%. In summary, the application of silicon fertilizer can effectively improve the host microbial community, reduce O. cumana parasitism and improve the yield and quality of sunflower.

Forests store carbon in downed logs, whose decomposition is driven by bacterial and fungal communities. Yet most studies treat individual logs as homogeneous units, obscuring internal–external gradients in wood chemistry as fine-scale habitat filters. To address this gap, we combined ALDEx2, SpiecEasi networks, Mantel tests and PLS-SEM on 24 samples from Larix principis-rupprechtii logs spanning three decay stages (I, III, and V) and two radial positions. Chemical heterogeneity between positions peaked at Stage III (5.9-fold difference in total nitrogen), with severe internal nitrogen and phosphorus depletion. Bacterial alpha diversity converged between positions by Stage V, whereas fungal communities maintained persistent divergence, and differentially abundant taxa showed stage- and position-associated enrichment patterns. Network topology did not differ detectably between internal and external wood. Path modelling showed contrasting associations: fungal composition tracked primarily the decay-stage axis, whereas bacterial composition was associated more weakly and mainly through an indirect nutrient channel. These results provide a fine-scale, descriptive account of divergent bacterial and fungal responses to within-log heterogeneity during downed-log decomposition in a temperate coniferous forest.