70 



MINERAL SALTS ABSORPTION IN PLANTS 



form mycorrhiza. There is scattered evidence in the hterature that 

 infected plants grow more actively and have a higher ash content 

 than those not infected. Routien and Dawson (1943) suggested 

 that mycorrhizal roots of Pinus echinata absorb salts rapidly because 

 the fungus causes stimulation of respiration and additional release of 

 hydrogen ions from the host root for use in exchange reactions with 



32 



M 16 



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 a 



c 



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o 



\- 

 0) 

 Q. 



4 - 



o 

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'5 

 cr 



0) 



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 _o 



o 

 o 



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-1 — I — I — I — I — I — I — I — 5" 



Plant species 



14 



1 — I — I — r 



8 10 12 14 16 18 ^0 

 T — I — I — I 





X-X' 



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/ 



X— X 



/x X No* 



X- ""* 



/ 



ol/ 



y— X 



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Fig. 25. Amounts of sodium, potassium and rubidium (expressed as 

 percentage of total cation content), in 21 angiosperms, all supplied with the 

 same nutrient medium, containing these elements. Plants: 1. Fagopyrum, 

 2. Zea, 3. Helianthus, 4. Chenopodiiim, 5. Salsol, 6. Pisum, 7. Nicotiana, 

 8. Solatium, 9. Spinacia, 10. Avena, 11. Aster, 12. Papaver, 13. Lactuca, 14. 

 Plantago lanceolata, 15. Melilotus, 16. Vicia, 17. Atriplex littoralis, 18. Sinapsis 

 {Brassica), 19. Salicornia, 20. Plantago maritima, 21. Atriplex hortensis 

 (redrawn from CoUander, 1941). 



the soil (see Chapter 8, pp. 141-2). Another suggestion is that the 

 mycorrhizal fungi produce organic substances which form chelates 

 with inorganic ions in the soil. These complexes may be absorbed 

 by the host root more readily than are free ions (Schatz et al. 1954). 



6. Heredity 



Plants differ markedly in the extent to which they absorb 

 particular ions from the same solution as was shown by Newton 

 (1928) and by Collander (1941) (Fig. 25). It is extremely improbable 



