ISHS Acta Horticulturae 450: International Symposium Growing Media and Plant Nutrition in Horticulture
TOLERANCE OF ORNAMENTAL PLANTS TO SALT, SODIUM AND CHLORIDE IN POTTING SUBSTRATES CONTAINING COMPOST MADE OF SEPARATELY COLLECTED ORGANIC RESIDUES |
| Authors: | F. Weinhold, H.-C. Scharpf |
| Keywords: | Threshold values for Cl, Na, salt, Begonia, Impatiens, Pelargonium, Petunia, Primula, Saintpaulia, yard-waste, bio-waste, Cl-, Na-, salt-contents in composts |
| Abstract:
In this study, some ornamental crops were tested for their tolerance to increasing Na, Cl and salt concentrations following addition of compost to peat substrates. The results show considerable differences in Cl tolerance among tested plant species. Strong growth inhibition was observed with Primula as well as Saintpaulia, at concentrations above 450 to 500 mg Cl/l substrate. Pelargonium showed growth reduction when Cl concentrations exceeded 880 mg/l while Petunia growth remained unaffected up to 1000 mg Cl/l. The critical values for Na were as follows: Pelargonium: 780 mg Na/l, Begonia: 550 mg Na/l, Petunia: 540 mg Na/l, Primula : 140 mg Na/l substrate. Assuming that 40 % compost will be used and that the critical Na and Cl values should be determined by the most sensitive species, composts used in production of potting substrates may contain up to 1000 mg Cl/l and 225 mg Na/l. Under these conditions 2,5 g salt/l in the mature compost could be tolerated by all tested plant species. These limits are valid for compost: peat mixtures only. Other salt, Na or Cl sources such as high concentrations in irrigation water or other substrate components e.g. coconut fiber have to be taken into account for the determination of quality criteria of composts used in substrates. | |
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