Nanotechnology is one of the most important fields of research in today's world. The production of this new technology is witnessing a significant increase due to its diverse range of applications across various disciplines. Graphene oxide nanoparticles (GO) and zinc oxide/graphene oxide nanocomposite (ZnO/GO) have garnered considerable attention from researchers because of their unique properties such as high electrical, thermal and mechanical conductivities and significant water retention capacity. These nanoparticles are used in in various fields such as medicine, pharmaceuticals, agriculture, electric and chemistry. Therefore, given the extensive utilization of GO and ZnO/GO nanoparticles, it is essential to comprehensively explore the environmental implications associated with the presence of these nanoparticles. This research has eva‎luated the influence of different concentrations of GO and ZnO/GO nanoparticles on seed germination, seedling growth, and rhizosphere soil properties of wheat. In a seed germination test, wheat seeds were subjected to varying concentrations of GO and ZnO/GO nanoparticles ranging from zero to 1000 mg/L, in petri dishes. In a greenhouse experiment, GO and ZnO/GO nanoparticles were added to the wheat pots at seven concentration levels of zero, 10, 50, 100, 250, 500 and 1000 mg/kg in three replicates. The height and greenness index (SPAD) were recorded before harvesting the plants. After 40 days, the plants were harvested and subsequently dried in an oven to determine the dry mass of both the shoots and roots. To examine the impacts of nanoparticles and the influence of roots on soil health indicators, the rhizosphere soil was carefully separated from the non-rhizosphere soil in each pot, and dried separately in dedicated containers for further analysis. The soil without addition of the nanoparticles was considered as the control treatment. The following parameters were measured in the soil samples: pH values, electrical conductivity, cation exchange capacity, available concentrations of iron, zinc, copper, manganese and absorbable nickel, percentage of organic carbon, basal respiration, microbial biomass carbon, metabolic quotient, soil water repellency, percent of water-stable aggregates, water content at matric suctions 10 kPa (FC) and 1500 kPa (PWP) and plant available water (PAW). The results revealed that application of both GO and ZnO/GO nanoparticles, across all concentrations, led to an enhancement in the germination percentage and rate of wheat seeds. The greenness of wheat seedling leaves demonstrated an increase up to a concentration of 250 mg/kg of GO nanoparticles. Moreover, it was observed that ZnO/GO nanoparticles, across all concentration levels, significantly enhanced leaf greenness compared to the control group. The organic carbon contents of soil underwent an increase as the concentration of GO and ZnO/GO nanoparticles rose. GO and ZnO/GO nanoparticles also increased the soil water repellency and percent of water-stable aggregates in soil. Furthermore, the application of GO and ZnO/GO nanoparticles led to an increase in the plant available water of the soil. In general, by increasing concentration of GO and ZnO/GO nanoparticles, soil basal respiration and microbial biomass carbon increased. In conclusion, the findings suggest that low concentrations (10 to 100 mg/kg) of GO and ZnO/GO nanoparticles have the potential to positively impact the growth of wheat seedlings, improve the living conditions for the soil microbial community, and enhance physical characteristics of the soil. However, it is important to note that high concentrations of these nanoparticles may have detrimental effects on microorganisms, soil health, and plant growth.

مهران شيرواني جوزداني

مهدي بازرگاني پور , محمدرضا مصدقي

حسين خادمي موغاري , حميدرضا عشقي زاده