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Acta Prataculturae Sinica ›› 2021, Vol. 30 ›› Issue (10): 53-62.DOI: 10.11686/cyxb2020351

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Effects of phosphorus on root growth and photosynthetic physiology of alfalfa seedlings under aluminum stress

Ru-yue WANG(), Shi-li YUAN, Wu-wu WEN, Peng ZHOU, Yuan AN()   

  1. Shanghai Jiao Tong University,School of Agriculture and Biology,Shanghai 200240,China
  • Received:2020-07-21 Revised:2020-09-07 Online:2021-09-16 Published:2021-09-16
  • Contact: Yuan AN

Abstract:

In order to explore the effects of phosphorus (P) on growth and photosynthesis physiology of alfalfa seedlings under aluminum stress. Simple Ca(NO32 nutrient solution (pH=4.5) containing 200 μmol·L-1 P or 100 μmol·L-1 Al or 200 μmol·L-1 P+100 μmol·L-1 Al was used to treat ‘Wl440’ seedlings, and Ca(NO32 nutrient solution (pH=4.5) without P and Al was as control. It was found that application of P significantly decreased the Al content in roots (81.53%) and leaves (61.47%) of alfalfa under Al stress. Application of P significantly increased the root length, root activity, leaf chlorophyll content, transpiration rate, stomatal conductance, photosynthetic rate, and electron transfer rate of photosystem I and Ⅱ, and significantly decreased electrical conductivity and malondialdehyde (MDA) content. The contents of oxalic acid and malic acid in Al-stressed alfalfa roots were significantly increased by phosphorus addition. In summary, these results indicate that phosphorus addition can effectively increase organic acid contents, improve the photosynthetic system, and consequently alleviate alfalfa aluminum toxicity.

Key words: alfalfa, aluminum stress, phosphorus, photosynthetic system, organic acid