While root exudates play a crucial role in maintaining ecosystem balance and promoting plant growth, existing research primarily focuses on single ecosystems (e.g., field crops), with systematic investigations of their ecological functions in compound cropping systems, particularly nitrogen (N) cycling mechanisms in orchard multi-cropping systems, remaining limited. This review focuses on the N impact mechanisms mediated by plant root exudates in orchard ecosystems, emphasizing how root exudates optimize soil N activation, absorption, and utilization efficiency by modulating rhizosphere processes (e.g., nitrogen mineralization, root architecture remodeling). Studies indicate that the changes in orchard ecosystem function mediated by organic acids and flavonoids root exudates can significantly reduce nitrogen loss risks and increase the soil nitrogen turnover rate by lowering pH-activated nutrients, balancing the C:N ratio, and immobilizing microbial communities. This process also involves the coordinated regulation of nitrification, denitrification, and microbial fixation. Future research should prioritize investigating the interaction networks and regulatory mechanisms between root exudates of associated orchard crops and N-fixing microorganisms. This research direction will provide a scientific basis for improving the N use efficiency in orchard crops, optimizing fertilizer reduction techniques, and reducing chemical fertilizer usage, providing significant implications for achieving sustainable agricultural development. The theoretical support offers important scientific and practical value for advancing green and sustainable agriculture.

Peach is one of the most economically valuable fruit trees. Haploid peach trees occur spontaneously at very low frequencies and they are usually highly sterile. Therefore, the haploid with partial fertility is extremely rare germplasm, which is highly valuable to genetic research and breeding programmes. In this study, we investigated the cytological mechanism underlying the fertility of a peach haploid mutant ‘9-D’ derived from a spontaneous mutation. Cytologic evaluation and flow cytometry analysis demonstrated that ‘9-D’ is a pure haploid. Scanning electron microscope analysis revealed a considerable proportion of abnormal pollen grains in ‘9-D’. Pollen viability assay by Alexander staining showed that 50.4% of pollen grains from ‘9-D’ were viable. However, the pollen germination assay showed that only 7.6% of the pollen grains could germinate normally. Investigation of the chromosomal behavior of pollen mother cells at different stages of meiosis showed that pollen mother cells of ‘9-D’ lacked the process between anaphase I and prophase II of meiosis. Various types of sporophyte morphology were observed in haploid pollen mother cells at the tetrad stage. Measurement of the diameter of pollen grains indicated the presence of pollen with 2x ploidy in ‘9-D’. The offspring of ‘9-D’ were predominantly triploid or triploid aneuploid. The triploid offspring were more likely derived from the 2x male gametophyte combined with the haploid female gametophyte, which may explain the reason why ‘9-D’ has fertility. This study not only expands our understanding of haploid fertility mechanisms, but is also useful for ploid breeding programs in peach.

Organic phosphorus (OP) transformation in perennial vineyards is strongly influenced by long-term cultivation, fertilization, and associated changes in soil properties. However, the relationships among soil OP speciation, phosphatase activities, and phoC- and phoD-harboring bacterial communities remain poorly understood. In this study, soils from 20-year-old vineyards (Y20) and adjacent uncultivated reference sites (CK) in Penglai, China, were compared. Soil available P was significantly higher in Y20 than in CK, increasing from 15.83 to 40.50 mg kg⁻¹, whereas total P, OP, and microbial biomass P did not differ significantly between treatments. The contents of soil orthophosphate and corrected monoesters (cMonoesters) were in the range of 15.34–97.45 and 6.90–24.49 mg kg⁻¹, respectively, and were significantly higher in Y20 than in CK. Among the identified monoesters, the mean concentrations of myo-inositol hexakisphosphate (myo-IHP), scyllo-IHP, and choline phosphate in Y20 were 4.12, 0.69 and 0.69 mg kg⁻¹, respectively, significantly higher than those observed in CK. The Y20 soils also exhibited 17.94% higher acid phosphomonoesterase (ACP) activity and 28.05% lower alkaline phosphomonoesterase (ALP) activity than the CK soils. Furthermore, the α-diversity of phoC-harboring bacteria was lower in Y20, whereas the composition of phoD-harboring communities differed significantly between the two land-use types. Correlation analyses showed that soil OP forms correlated positively with ACP activity and phoD community composition, but negatively with ALP activity. Overall, the differences between Y20 and CK suggest that long-term vineyard cultivation was associated with increased P availability through redistribution among soil P forms and with the accumulation of relatively stable cMonoesters. These patterns were closely related to phosphomonoesterase activities and the composition of phoD-harboring bacterial communities. These findings highlight the potential interactions among P speciation, phosphatase activities, and functional microbial communities in vineyard soils and provide hypotheses for further investigation of P transformation processes.