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Acta Prataculturae Sinica ›› 2021, Vol. 30 ›› Issue (5): 186-199.DOI: 10.11686/cyxb2020453

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Screening of phosphite-tolerant alfalfa varieties and identification of phosphite tolerance indicators

Ji-xiang WANG(), Huan-yu GONG(), Xiang-jian TU, Zhen-xing GUO, Jia-nan ZHAO, Jian SHEN, Zhen-yi LI(), Juan SUN()   

  1. College of Grassland Science,Qingdao Agricultural University,Qingdao 266109,China
  • Received:2020-10-13 Revised:2020-12-21 Online:2021-05-20 Published:2021-04-16
  • Contact: Zhen-yi LI,Juan SUN

Abstract:

Phosphite, a reduced form of orthophosphate, is characterized by its high solubility, high transport efficiency, and low reactivity in soil. The aim of this study was to screen for phosphite-tolerant alfalfa varieties and provide information for the development of phosphite fertilizers by exploring differences in phosphite tolerance among different varieties of alfalfa at the seedling stage. Thirty-seven alfalfa varieties were cultured in Hoagland’s nutrient solution with orthophosphate (0.5 mmol·L-1 KH2PO4) or phosphate (0.5 mmol·L-1 KH2PO3) as the sole phosphorus resource. We analyzed 12 morphological and physiological characters: Plant height (PH), stem diameter(SD), shoot phosphorus content (SPC), shoot dry weight (DWS), root dry weight (DWR), root∶shoot, total root length (RL), root surface area (RSA), root phosphorus content (RPC), chlorophyll content (Chl), leaf area (LA), and net photosynthetic rate (Pn). Based on the phosphite-tolerance coefficient (PTC) of each individual index, we used principal component analysis, membership function analysis, cluster analysis, and stepwise regression to comprehensively evaluate phosphite tolerance characteristics and establish a mathematical model. The results showed that phosphite stress resulted in increased root total phosphorus content, increased chlorophyll content, and decreased values of other indexes in different varieties. The 12 indicators were divided into five composite indicator groups in a principal component analysis. The 37 alfalfa varieties were classified into four categories in terms of phosphite resistance: highly resistant (two varieties; WL903 and Kehan); Moderately resistant (12 varieties); Low resistance (17 varieties), and sensitive (six varieties). The following regression model was developed for evaluating phosphite tolerance: Y=-0.174+0.102PH+0.189DWR+0.168RL+0.187RSA-0.061PnR2=0.9908). The precision of the regression equation was higher than 93.22% for each alfalfa variety. The results show that the highly phosphite-resistant alfalfa varieties were Kehan and WL903. Under phosphite stress, the tolerance of alfalfa varieties to phosphite can be quickly identified and predicted by measuring PH, DWR, RL, RSA, and Pn.

Key words: alfalfa, phosphite, principal component analysis, cluster analysis, stepwise regression analysis