Journal Article

Responses of Scots pine (<i>Pinus sylvestris</i>) seedlings grown in different nutrient regimes to changing root zone temperature in spring

S. Iivonen, R. Rikala, A. Ryyppö and E. Vapaavuori

in Tree Physiology

Volume 19, issue 14, pages 951-958
Published in print December 1999 | ISSN: 0829-318X
Published online December 1999 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/19.14.951
Responses of Scots pine (Pinus sylvestris) seedlings grown in different nutrient regimes to changing root zone temperature in spring

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We examined effects of nutrient availability and changing root zone temperature (RZT) on growth, gas exchange and plasma membrane H+-ATPase (PM-ATPase) activity of roots of 1-year-old Scots pine (Pinus sylvestris L.) seedlings during spring flushing. The 6-week growth-chamber experiment was carried out in hydroponic cultures that supplied the seedlings with low (0.5 mM N) or high (3 mM N) nutrient concentration and two rates of increase in RZT were simulated: slow warming (SW-treatment) and fast warming (FW-treatment). Air temperature, humidity, and light conditions were similar in all treatments. Growth of roots and shoots was retarded at low RZT, and fresh mass increment of roots was closely correlated with RZT sum. High nutrient availability increased nitrogen concentrations of needles and stems, but only at RZTs >13 °C. Low RZT and low availability of nutrients suppressed gas exchange of the seedlings. Real PM-ATPase activity was highly dependent on RZT. At high RZTs, real PM-ATPase activity was affected by nutrient availability but this effect was related to root growth. We conclude that, under conditions of high nutrient availability, Scots pine seedlings can compensate for the suppressive effects of long-term exposure to low RZT by rapidly accelerating growth, gas exchange and root metabolism, but only when RZT has increased above a threshold value, which was 13 °C in this study.

Keywords: gas exchange; growth; H+-ATPase; nitrogen; nutrient availability; plasma membrane; roots

Journal Article.  0 words. 

Subjects: Plant Sciences and Forestry

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