Effect of nitrogen supply on frost resistance, nitrogen metabolism and carbohydrate content in white clover (Trifolium repens)

Abstract

Effects of mineral nitrogen (2, 4, 6 and 8 mM NH NO ) and nodulation with Rhizobium on frost hardiness in seedlings of white clover (Trifolium repens) have been studied. Seedlings of a population from Bodø (67°N lat.) were grown in Leonard jars under controlled conditions in a phytotron. For induction of frost hardening, plants were first exposed to 12 h photoperiod conditions for 2 weeks at 18°C, then for 2 weeks at 6°C and finally for 2 weeks at 0.5°C. Frost hardiness after treatments at 6 and 0.5°C was significantly enhanced by increasing nitrogen supply and was positively correlated with total nitrogen content of the stolons. Frost hardiness of nodulated plants correlated to the tissue nitrogen concentration. Content of soluble proteins in stolons decreased during hardening at 6°C but did not change during treatment at 0.5°C. There were minor changes in total amount of free amino acids during hardening. Both absolute and relative amounts of proline and arginine increased, and those of asparagine decreased during hardening. Absolute amounts of all free amino acids increased with increasing nitrogen supply, but the changes during hardening were similar in all treatments. There was a significant increase in the content of soluble carbohydrates during hardening. However, this increase was inversely related to nitrogen supply.

Stolon characteristics related to winter survival in white clover

“…High levels of sugars (equivalent in this study to WSC), however, without correspondingly high levels of total polysaccharides (TNC) in stolons have been found to be negatively related to freezing tolerance in white clover (Wood & Sprague 1952). Sandli et al (1993) observed a significant increase in soluble carbohydrates and in starch levels during frost hardening in white clover, but noted that starch increased to a lesser extent. However, in that study, patterns of soluble carbohydrate and starch accumulation during hardening were greatly affected by the various nitrogen supply treatments imposed (Sandli et al 1993).…”

“…Sandli et al (1993) observed a significant increase in soluble carbohydrates and in starch levels during frost hardening in white clover, but noted that starch increased to a lesser extent. However, in that study, patterns of soluble carbohydrate and starch accumulation during hardening were greatly affected by the various nitrogen supply treatments imposed (Sandli et al 1993). A high level of sugars in stolons is an indication of starch hydrolysis (Ruelke & Smith 1956), so successful overwintering of white clover stolons appears to require the correct balance between starch storage and breakdown.…”

Reducing the acrylamide‐forming potential of wheat

“…The use of nitrogen fertilizer increases the free asparagine and total free amino acid concentrations in wheat causing a concomitant increase in the acrylamide‐forming potential (Sandli et al. ; Kingston‐Smith et al. ; Hoegy et al.…”

“…The use of nitrogen fertilizer increases the free asparagine and total free amino acid concentrations in wheat causing a concomitant increase in the acrylamide-forming potential (Sandli et al 1993;Kingston-Smith et al 2006;Hoegy et al 2013). This, however, is only the case when nitrogen fertilization is in much greater proportion than sulfur.…”

Acceleration of frost hardening in Vaccinium vitis-idaea by nitrogen fertilization

“…A hypothesis that nitrogen impairs the frost hardiness of plants has been in circulation for a long time, and many results support it (Christersson 1975;Puempel et al 1975;Aronsson 1980;Hellergren 1981;Friedland et al 1984;Nihlgård 1985;Dueck et al 1990;Pietilä et al 1990;Cape et al 1991) although some reports contradict the hypothesis (Thompson 1982;DeHayes et al 1989;Klein et al 1989;Sandli et al 1993). In addition, a recent review concluded that the idea that increasing levels of tissue N predispose plants to a greater risk of frost injury is far from justified (Barnes et al 1996).…”