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Phosphorus supply alters the root metabolism of Chinese flowering cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsenet Lee) and the mobilization of Cd bound to lepidocrocite in soil

Author:
Yang, Ping, Chen, Hui-Jun, Fan, Han-Yun, Li, Qu-Sheng, Gao, Qiong, Wang, Dong-Sheng, Wang, Li-Li, Zhou, Chu, Zeng, Eddy Y.
Source:
Environmental and experimental botany 2019 v.167 pp. 103827
ISSN:
0098-8472
Subject:
Brassica oleracea, Brassica rapa subsp. oleifera, aluminum phosphate, amino acid metabolism, cabbage, cadmium, ferric phosphate, flowering, heavy metals, lepidocrocite, metabolites, organic acids and salts, phosphorus, phosphorus fertilizers, pot culture, rhizosphere, root exudates, sand, secretion, soil, water solubility
Abstract:
Soil P status affects plant root exudates, thereby influencing heavy metal mobilization. We analyzed the effect of soil P forms and levels on lepidocrocite-bound Cd mobilization by Chinese flowering cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee). Sand pot culture experiments were performed. Sufficient and low level water-soluble P simulated sufficient and deficient P fertilizer supply, respectively. Using FePO4 and AlPO4, we simulated sparingly soluble P species in subtropical red soil. P deficiency and sparingly soluble P reduced the volume of Chinese flowering cabbage root exudates. Organic acids were the major metabolites under all treatments. Amino acid metabolism diminished under low P and Al-P. Organic acid secretion occurred in the following order: sufficient P > Fe-P > low P > Al-P. These organic acids could release lepiodcrocite-bound Cd. However, excess PO43− could precipitate Cd under sufficient P. The total mobilized Cd in rhizosphere was Fe-P > low P > Al-P = sufficient P. P promoted root metabolite secretion in Chinese flowering cabbage, especially organic acids. P deficiency facilitated the mobilization of lepidocrocite-bound Cd by organic acids. When phosphorus was sufficient, the precipitation of phosphate on Cd was greater than the mobilization of organic acids.
Agid:
6543754