科研进展

【论文题目】Response of alfalfa growth and rhizosphere properties to soil phosphorus levels and mowing（盐碱地紫花苜蓿生长和根际过程对土壤磷水平和刈割的响应）

【作者】unjie Tian（田俊杰）, Weifan Wan（万伟帆）, Qian Liu（刘茜）Bayinnamula Zhao（赵巴音那木拉）and Haigang Li （李海港）

摘要

Introduction:Phosphorus (P) deficiency is a key limiting factor for alfalfa growth, and root exudates are considered as a strategy for alfalfa P acquisition under P stress, which requires the supply of photosynthetic products. However, mowing may affect the concentration of root exudates of alfalfa in salt-affected soil by reducing the supply of photosynthetic products through reduced photosynthesis. This study aimed to investigate the possible mechanism of increasing P utilization rate with different P application rates after mowing.

Methods: Field and pot experiments were conducted with alfalfa grown under five P application rates (0, 60, 120, 180 and 240 kg ha^-1). Plant growth, shoot P concentration, rhizosphere carboxylates concentration, rhizosphere acid phosphatase (APase) activity and rhizosphere pH were measured.

Results and discussion:P application significantly improved plant height and branch number, with the highest levels observed when P application rate was 180 kg ha^-1. Crude protein content was also improved (13.3%-23.3%) with increasing P application rates and reached the maximum when P application rate was 240 kg ha^-1. The yield of alfalfa increased with higher shoot P concentration. Furthermore, mowing significantly reduced rhizosphere carboxylates concentration (30.4%-100%) and APase activity (39.8%-75.0%) across all P treatments. However, these reductions were less pronounced when the P application rate exceeded 120 kg ha^-1. In contrast, rhizosphere pH was unaffected by mowing across different application rates. Overall, this study demonstrates that P fertilization not only promotes alfalfa growth and quality in salt-affected soil but also mitigates the adverse effects of mowing on rhizosphere carboxylates concentration and APase activity. This highlights the potential of P fertilization to reduce P fixation and enhance P uptake by regulating rhizosphere-activated soil P dynamics after mowing. This study provides a basis for enhancing the P utilization rate after mowing.

【关键词】Alfalfa; Phosphorus; Mowing; Carboxylate exudation; rhizosphere pH