Plant Diversity ›› 2014, Vol. 36 ›› Issue (01): 56-64.

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Effects of Nitrogen and Phosphorus Supply on Root Morphology of Two Pedicularis Species

 CHEN  Yan-1、3, GUAN  Kai-Yun-1、2, LI  Ai-Rong-1   

  1. 1 Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Sciences,
    Kunming 650201, China; 2 Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences,
    Urumqi 830011, China; 3 University of Chinese Academy of Sciences, Beijing 100049, China  
  • Online:2014-01-25 Published:2014-12-01


In this study, we used hydroponics to cultivate the root hemiparasites, Pedicularis tricolor and P. rex,  in the absence of their host plants. The direct effects of nitrogen (N) and phosphorus (P) levels and different nitrogen forms on root architecture of the two species were tested in two experiments using nutrient solutions modified from the standard Long Ashton formula. In Experiment 1, solutions were used which either lacked N or P, or contained double the standard concentrations of N  or  P. In Experiment 2, different forms of N (NO3-N and NH4+N) were supplied. Obvious changes were observed in root morphology of both Pedicularis species in response to different levels of N and P supplied. However, the two Pedicularis species showed different responses to N and P deficiency. In P. tricolor, both N and P deficiency promoted elongation of the main and lateral roots, as well as the formation of haustoria. In contrast, root development in P. rex was significantly inhibited by a lack of either N or P. No haustoria were observed in roots of P. rex in any of these treatments. Varying the nitrogen source had a strong effect on root morphology and growth of both Pedicularis species, with NO3-N promoting better root development and biomass accumulation, relative to NH4+N. In addition, we observed that P. tricolor produced many haustoria without the need of mechanical stimulus. In light of these findings, we propose that mechanisms of haustorium formation may be significantly different between these two species, and that N and P may be involved in the regulation of haustorium formation in both species.

Key words: Pedicularis L., Hydroponics, Mineral element, Root morphology, Haustoria

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