Phosphorus application, nutrient absorption, and endophytic root bacterial communities in maize grown in phosphorus-deficient rocky arid soils, China

Phosphorus deficiency is one of the major constraints for crop growth in Karst rocky desertification regions. Different phosphorus treatments have become important strategies for enhancing agricultural productivity; however, the effects of phosphorus fertilization on nutrient allocation and root endophytic microbiome at different growth stages under field conditions remain inadequately explored. Therefore, this study implemented four phosphorus application treatments in a field-based maize cultivation system: P0 (0 kg ha⁻¹), P1 (75 kg ha⁻¹), P2 (150 kg ha⁻¹), and P3 (225 kg ha⁻¹). Nutrient distribution and root endophytic microbial community dynamics were analyzed at the jointing and milk-ripening stages. The results demonstrated that: (1) With increasing phosphorus application, the total nitrogen (TN) and total phosphorus (TP) in roots and leaves at the jointing, silking, and milk-ripening stages exhibited a pattern of “low phosphorus treatment enhancing TP content, while high phosphorus treatment suppressing TP uptake.” Total potassium (TK) content showed a decreasing trend, with the highest nutrient uptake observed at the phosphorus application rate of 150 kg ha⁻¹. (2) Analysis of the root bacterial community revealed a decline in bacterial diversity with increasing phosphorus levels, but the abundance of Proteobacteria and Actinobacteria were significantly enhanced. (3) Correlation analysis indicated that low phosphorus treatment (P0) induced microbial community restructuring, high phosphorus treatment (P3) promoted the proliferation of functional taxa such as Pseudomonadaceae, while medium phosphorus treatment (P2) showed the most significant correlation between microbial community structure and phosphorus availability. This study provides valuable scientific insights for optimizing phosphorus fertilization in maize production in karst regions.