To prepare a novel cassava starch-based phosphorus releasing super-absorbent polymer (CST-PRP-SAP), the single factor and orthogonal experiment were applied to analyze the effects of different reaction conditions on the absorption and phosphorus release capacities of CST-PRP-SAP samples. The structural and morphological characteristics of the cassava starch (CST), powdered rock phosphate (PRP), cassava starch-based super-absorbent polymer (CST-SAP) and CST-PRP-SAP samples were all compared with various technologies, such as the Fourier transform infrared spectroscopy and X-ray diffraction pattern, etc. The results showed that the CST-PRP-SAP samples had good performances of water retention and phosphorus release which were synthesized, such as the reaction temperature, starch content, P₂O₅ content, crosslinking agent, initiator, neutralization degree, and acrylamide content, which were 60 °C, 20% w/w, 10% w/w, 0.02% w/w, 0.6% w/w, 70% w/w, and 15% w/w, respectively. The water absorbency of CST-PRP-SAP was almost larger than that of the CST-SAP sample with a P₂O₅ content of 5.0% and 7.5%, and they all gradually decreased after three consecutive water absorption cycles. The CST-PRP-SAP sample could maintain about 50% of the initial water content after 24 h, even at the temperature of 40 °C. The swelling process of CST-PRP-SAP conformed to the non-Fickian diffusion, which was determined by the diffusion of water molecules and the relaxation process of polymer chain segments. The cumulative phosphorus release amount and release rate of the CST-PRP-SAP samples were increased with the increasing PRP content and the decreasing neutralization degree. After a 216 h immersion, the cumulative phosphorus release amount and release rate of the CST-PRP-SAP samples with different PRP contents were increased by 17.4 and 3.7 times, respectively. The rough surface of the CST-PRP-SAP sample after swelling was beneficial to the performance of water absorption and phosphorus release. The crystallization degree of PRP in the CST-PRP-SAP system was decreased and most of the PRP existed in the form of physical filling, and the available phosphorus content was increased to a certain extent. It was concluded that the CST-PRP-SAP synthesized in this study has excellent properties of continuous water absorption and retention with functions of promotion and the slow-release phosphorus.

This study was carried out to investigate effects of subsoiling on the diversity and composition of the bacterial community in a wheat–maize rotation field in the Guanzhong area of Shaanxi Province, China. After the wheat harvest, surface soil samples were collected under two tillage methods (single rotary tillage (RT) and subsoiling + rotary tillage (ST)) to perform high-throughput sequencing and bioinformatics analysis. Soil properties and root length density (RLD) of winter wheat at booting and flowering stages were also studied. Results showed that ST treatment significantly raised the water storage, organic carbon and total nitrogen contents of deep soil (>40 cm), and notably increased the total soil pH, ammonium nitrogen content and RLD in the tillage layer from 0–70 cm at booting stage and 0~100 cm at flowering stage, but the residual nitrate nitrogen significantly decreased by 17.74%. Compared with RT, soil bacterial richness and diversity in the 10~20 cm layer of ST treatment showed a significantly decreased trend. The relative abundances of GAL15, Actinobacteria, Nitrospirae, Rhizobiales, Burkholderiales, Pseudomonas and Serratia in the 10–20 cm layer were remarkably increased in ST. Principal Component Analysis (PCA) and Redundancy Analysis (RDA) results showed that surface soil pH, ammonium nitrogen and nitrate nitrogen contents have the strongest effect on the bacterial structure. In addition, there were positive correlations between the RLD and the relative abundances of Rhizobiales, Burkholderiales, Pseudomonas and the ammonium nitrogen content. In conclusion, although subsoiling was not conducive to improving soil bacterial community richness and diversity, it significantly increased soil beneficial bacteria (biological nitrogen-fixing bacteria, ammonifying bacteria, nitrobacteria) abundances, reduced the nitrogen loss caused by denitrifying bacteria, promoted earlier root development and improved the plant utilization ratio of soil nutrients.

Salinity and alkalinity stresses severely suppress rice seedling growth and substantially reduce rice yield; whereas the application of oligosaccharides as plant growth regulators has been demonstrated to remarkably enhance crop tolerance to abiotic stresses. To investigate the potential growth-promoting effects of KP-priming (mixed-oligosaccharides, 1.12 mg mL⁻¹) on rice seedlings under salinity (100 mmol L⁻¹ NaCl) and alkalinity (10 mmol L⁻¹ Na₂CO₃) stresses, plant morphology and physiology assessments, and transcriptome analyses were performed. The KP-priming significantly improved rice seedling tolerance to salinity and alkalinity stresses, evidenced by increases in plant height, dry matter weight, and fresh weight, and improved root morphology (root length, surface area) and vitality by 10.27–89.06%. Leaf cell membrane stability was improved in KP-priming by increasing the soluble sugar content and superoxide dismutase, peroxidase, and catalase activities by 2.74–97.32%, and reducing accumulation of malondialdehyde and hydrogen peroxide by 17.67–49.70%. KP-priming treatment significantly enhanced leaf photosynthetic capacity through promoting photosynthetic pigments and maximum photochemical efficiency by 2.34–135.76%, and enhancing leaf stomatal aperture by 21.58–75.84%. Transcriptomic analysis revealed that differentially expressed genes in response to KP-priming under salt and alkaline stresses were predominantly associated with photosynthetic pathways. Total 4125 (salinity) and 1971 (alkalinity) DEGs were identified under stresses compared to KP-priming. Transcriptional profiling of KP-priming-treated leaves demonstrated significant up-regulation of key photosynthetic genes, including OsRBCS5, PGR5, Se5, OsPORA, GRA78, OsLhcb7, and OsPS1-F. This coordinated gene expression was functionally associated with enhanced leaf photosynthesis capacity and mitigated oxidative damage through improved electron transport and reactive oxygen species scavenging mechanisms. Our findings demonstrated that KP-priming initiated a self-regulatory mechanism in plants, orchestrating a dual protective response that simultaneously mitigated oxidative damage while enhancing photosynthetic efficiency and stress resilience. This study provided initial insights into using KP-priming to alleviate salinity and alkalinity stresses and its underlying molecular mechanisms, which is valuable for both field management practices and understanding rice tolerance to abiotic stresses.