Juha Heiskanen

Kaksiosaisten turvepohjaisten kasvualustojen vaikutus männyn paakkutaimien kasvuun

Heiskanen J. Kaksiosaisten turvepohjaisten kasvualustojen vaikutus männyn paakkutaimien kasvuun.

English title: Effect of peat-based two-component growth media on the growth of containerized scots pine seedlings

Abstract

One-year-old containerized scots pine seedlings (Pinus sylvestris L.) were grown in two-component growth media mixtures containing 75% (by volume) light, low humified Sphagnum peat and under an irrigation regime where the seedlings were abundantly reirrigated after -10 to -15 kPa matric potential was achieved in the growth media. The greatest seedling growth was in pure peat and in peat to which coarse perlite had been added. The poorest growth was in mixtures of peat and hydrogel and of peat and water repellent rockwool. Intermediate growth was found in peat to which fine perlite or water absorbent rockwool had been added. During drying in the range -2 to -90 kPa matric potential of the growth medium, the decrease in the net photosynthesis of seedlings at the bud formation phase was linear when aeration was not a restricting factor. During drying, the net photosynthesis was relatively large and was of a similar magnitude in pure peat and in peat to which coarse or fine perlite had been added. Significantly smaller net photosynthesis was observed in peat to which water repellent rockwool or water absorbent rockwool or hydrogel had been added. During drying under wet conditions (-1 to -4 kPa matric potential) when limited aeration was a restricting factor, the net photosynthesis increased linearly. Due to better aeration, the, net photosynthesis was higher in the mixture of peat and coarse perlite than in pure peat. Keywords: aeration, nutrients, photosynthesis, physical properties of soil, substrate, water retention J. Heiskanen, The Finnish Forest Research lnstitute, Suonenjoki Research Station, FIN-77600 Suonenjoki, Finland

Received 31 October 2017 Published 1 January 1994

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