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Sulphate and ammonium in mist impair the frost hardening of red spruce seedlings

Institute of Terrestrial Ecology, Bush Estate, Penicuik EH 26 OQB, Midlothian, UK
New Phytologist (Impact Factor: 7.67). 04/2006; 118(1):119 - 126. DOI: 10.1111/j.1469-8137.1991.tb00572.x

ABSTRACT summaryTwo-year-old seedlings of red spruce [Picea rubens Sarg. syn. P. rubra (Du Roi) Link] were grown in open-top chambers supplied with charcoal-filtered air near Edinburgh, Scotland. Between May and November 1988, plants were exposed to mists containing NH4+, SO42− and NO3− ions at concentrations of 1.6 mol m−3 and H+ at 3.2 mol m−3, in pairwise combination and all together. The mists were applied twice weekly at a rate of 2 mm precipitation equivalent per application. Treatment with H2SO4 severely damaged the plants after 3 wk; the concentration for this treatment was therefore reduced from 1.6 mol m−3 to 0.5 mol m3, and new plants were substituted, in June 1988. Frost hardiness was assessed by freeze-testing detached shoots, then measuring rates of electrolyte leakage. No effects of the mist treatments were detected during the early stages of frost hardening, but on 31 October, shoots that had received sulphate and ammonium ions were less hardy than ‘control’ shoots treated with deionized water. The temperature which killed 20% of shoots was 14 °C higher, and the temperature which killed 56% of shoots was 7 °C higher than for ‘control’ shoots. Acidity per se had no effect on frost hardiness; nitrate ions had no effect and may have mitigated the effects of sulphate when applied together.The results confirm earlier data, and indicate that uptake of NH4+ and SO42− ions can disturb the frost-hardening process. There are important implications for pollution control strategies in the northeastern United States, if damaging interactions between frost hardiness of red spruce and pollutant deposition are linked to ammonium and sulphate rather than nitrate ions.

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    • "The rate constants (k) calculated from all four readings for each individual shoot were plotted to determine threshold (k) to distinguish live from dead shoots (Sheppard et al., 1993 b, 1995 a). Lethal temperatures causing 50 % shoot death (LT &! ) were calculated using probit analysis (SAS, 1985 ; Cape et al., 1991) based on this threshold leakage value. "
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    ABSTRACT: Four pot experiments are reported in which Norway spruce (Picea abies (L.) Karst) seedlings, of different nutrient status, were treated with acid mist for one growing season in open-top chambers (OTCs). Combinations of H+, SO42−, NH4+ and NO3− were applied at different frequencies of application and supplying different doses of S and N kg ha−1. Plant growth, visible injury, frost hardiness and nutrient status were observed. These experiments were undertaken to improve our understanding of the interaction of environmental factors such as nutrition and mist-exposure frequency on seedling response to N and S deposition. Both acidity (pH 2·7) and SO42− ions were necessary to induce visible injury. Mist containing SO42−, H+ and to a lesser extent NH4+ significantly reduced winter frost hardiness. Increasing the misting frequency, and to a lesser extent the overall dose, increased the likelihood of acid mist causing visible injury and reducing frost hardiness. Post-planting stress, low N status and needle juvenility increased the likelihood of acid mist causing visible injury. Increased plant vitality, adequate N status and growth rate reduced the likelihood of acid-mist-induced reductions in frost hardiness. Principles underlying the responses of spruce seedlings treated in controlled conditions to acid mist are discussed.
    New Phytologist 07/2008; 138(4):709 - 723. DOI:10.1046/j.1469-8137.1998.00139.x · 7.67 Impact Factor
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    • "In a typical acid rain or mist event the principal ions present are H+, SO$-, NH& and NO?, but it is not known which ion, or combination of ions, is responsible for the observed effects of acid precipitation. In red spruce, there is evidence that the SOj-ion is a major cause of both foliar injury (Jacobson et al. 1990) and decreased frost hardiness (Cape et al. 1991). Eamus and Fowler (1990) showed that acid mist increased stomata1 conductance at low light flux densities and that the usual decline in stomata1 conductance associated with increased intercellular CO2 concentration was not observed. "
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    ABSTRACT: Red spruce (Picea rubens Sarg.) seedlings growing outside in open-top chambers were sprayed twice weekly with artificial mists at either pH 2.5 or 5.6, for five months during the 1988 growing season. The mists contained one of the following: water, pH 5.6 (control); (NH(4))(2)SO(4), pH 5.6; NH(4)NO(3), pH 5.6; HNO(3), pH 2.5; H(2)SO(4), pH 2.5; or (NH(4))(2)SO(4) + NH(4)NO(3), pH 2.5. During January 1989, the light responses of assimilation and stomatal conductance were assessed in the laboratory following a 4-day equilibration at 12 degrees C. The aerial portions of the intact trees were then subjected to a mild (-10 degrees C) frost for three hours during the night and the rate of recovery of light-saturated assimilation (A(max)) was determined the following day using the same branches as were used for the assimilation studies before the frost treatment. The same trees were then subjected to a second frost of -18 degrees C for three hours during the following night and the recovery of A(max) of the same branches was measured the next day. All of the acid mist treatments increased A(max) and apparent quantum yield relative to the control treatment when measured before the frost treatments. Frosts of -10 and -18 degrees C resulted in a significant decline in A(max) of seedlings in all treatments except the control. Stomatal conductance increased with increasing irradiance in seedlings in the acid mist treatments that did not contain SO(4) (2-) ion. Stomatal conductance of seedlings in acid mist treatments containing SO(4) (2-) ion was insensitive to changes in irradiance over the range 50-1500 micro mol m(-2) s(-1). It is concluded that acid precipitation increased the sensitivity of the assimilation response to midwinter frosts that follow a brief warm period. The SO(4) (2-) ion appears to be significant in causing increased sensitivity to frost and in causing stomatal insensitivity to light flux density.
    Tree Physiology 10/1993; 13(2):145-55. DOI:10.1093/treephys/13.2.145 · 3.41 Impact Factor
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