ABSTRACT

Phosphorus (P) use efficiency (FPUE) is very low due to fixation of P with the hydrous oxides of iron and aluminum in acid soils and calcium in neutral to calcareous soil. The roots of wheat (Triticum aestivum) excrete low molecular weight organic acids (LMWOAs) to increase P bioavailability in P-deficient soil through acidification, chelation, and exchange mechanisms. However, the amount of LMWOAs excreted in the rhizosphere is small, and they undergo rapid microbial degradation. The present study was undertaken by applying different levels of LMWOAs and phosphorus to the soil followed by sowing of wheat seeds to learn the impact of applying LMWOAs, especially oxalic (OA) and citric acid (CA), on the yield and FPUE of wheat. The results showed that application of P fertilizer along with OA and CA significantly increased the Olsen P concentration in soil and in turn increased P uptake, FPUE, and yields of wheat. Application of OA @ 15 mg kg⁻¹ recorded 20% (±0.22%) and 30% (±0.55%) higher grain and straw yield, respectively, over control and was more effective than CA. Among LMWOAs, application of OA @ 15 mg kg⁻¹ was more effective than CA. Therefore, the application of OA has the potential to reduce the excess application of phosphorus and its buildup in soils and cause eutrophication of water bodies.

摘要

由于酸性土壤中的铁和铝的水合氧化物以及中性至钙质土壤中的钙固定磷（P）的使用效率（FPUE）非常低。小麦的根（Triticum aestivum) 排泄低分子量有机酸 (LMWOA)，通过酸化、螯合和交换机制提高缺磷土壤中的磷生物有效性。然而，根际中排泄的 LMWOA 数量很少，它们会经历快速的微生物降解。本研究通过在土壤中施用不同水平的 LMWOA 和磷，然后播种小麦种子来了解施用 LMWOA，尤其是草酸 (OA) 和柠檬酸 (CA) 对小麦产量和 FPUE 的影响。结果表明，磷肥与OA和CA的施用显着增加了土壤中Olsen P的浓度，进而增加了P的吸收、FPUE和小麦的产量。OA @ 15 mg kg ^-1的应用记录的谷物和稻草产量分别比对照高出 20% (±0.22%) 和 30% (±0.55%)，并且比 CA 更有效。在LMWOA 中，OA @ 15 mg kg ^-1的应用比CA 更有效。因此，OA的应用有可能减少磷的过量施用及其在土壤中的积累，并导致水体富营养化。