[Soil conditioners affect rhizospheric bacterial communities of Cabernet Sauvignon]

Three soil conditioners were prepared from granulated food waste and decomposed cattle manure combined with desulfurization gypsum, coal gangue, and maifanite, respectively. Field trials were conducted in the saline field growing Cabernet Sauvignon. The effects of soil conditioners on rhizospheric bacterial communities were studied, with the aim of providing a scientific basis for soil amelioration and restoration. Five treatments were designed, including the control (T1), conventional fertilization (T2), reduced chemical fertilization+organic matter-based soil conditioner with calcium additives (T3), reduced chemical fertilization+organic matter-based soil conditioner with silica additives (T4), and reduced chemical fertilization+organic matter-based soil conditioner with magnesium additives (T5), each with three replications. The results indicated that soil conditioners improved the rhizospheric nutrients, yield, and quality of grape (P<0.05), increased relative abundance of Proteobacteria by 17.32%-23.37%, decreased relative abundance of unidentified_Bacteria and Acidobacteriota by 4.22%-28.42% and 20.88%-35.81%, respectively. The bacterial community composition and diversity were different between treatments. Function analysis showed that the expression levels of the genes involved in chromosome and protein synthesis, mRNA biosynthesis, and glyoxylate and dicarboxylate metabolism were up-regulated in the treatments with soil conditioners. The correlation analysis revealed that multiple environmental factors affected the alpha diversity of rhizospheric bacterial communities, and some bacterial taxa were closely related to the grape yield and quality. It is concluded that soil conditioners can effectively alter rhizosphere nutrient levels and bacterial community structures and functions. T5 treatment outperforms other treatments in improving the physico-chemical and biological characteristics of rhizosphere, and the yield, and quality of grape. It has potential for application, and provides an important basis for development of new-type soil conditioners.