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Effect of magnesium‐deficiency on antioxidative systems in needles of Norway spruce [ Picea abies (L.) Karst.] grown with different ratios of nitrate and ammonium as nitrogen sources
Author(s) -
POLLE ANDREA,
OTTER TILMAN,
MEHNEJAKOBS BEATE
Publication year - 1994
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1994.tb04026.x
Subject(s) - picea abies , chemistry , ammonium , superoxide dismutase , nitrate reductase , peroxidase , horticulture , chlorophyll , kjeldahl method , botany , chlorosis , nutrient , nitrogen , antioxidant , biochemistry , enzyme , biology , organic chemistry
summary The effect of magnesium deficiency and variations of the ammonium to nitrate ratio on chlorophyll, soluble protein and antioxidative systems was investigated in current year's needles of clonal spruce trees [ Picea abies (L.) Karst.]. The trees were grown for 1 yr in sand culture with circulating nutrient solutions containing sufficient (0.2 mM) or limiting (0.041 mM) concentrations of Mg. The nitrogen concentration of the nutrient solutions was not varied (5 mM) but the NO 3 − /NH 4 + ‐ratio was adjusted TO 0.76 in Mg‐sufficient and to 1.86, 0.76 and 0.035 in Mg‐limited plants, Under Mg‐limitation, the chlorophyll, soluble protein and Mg‐contem were lowest in needles of trees supplied with NH 4 + and highest in trees supplied with NO 4 − as major N‐source. Apoplastic peroxidase activities were not affected by changes in nutrition. In total needle extracts, NADH oxidase, ascorbate peroxidase, mimodehydroascorbate reductase, glutatkione reductase and asoorbate content were not, or only little, affected by changes in nutrition, except for trees grown with the highest N 4 + ‐concentrations. Glutathtone content and guaiacol peroxidase were increased in Mg‐deficient needles. Superoxide dismutase activity was decreased in Mg‐limited needles of trees grown with N 4 + and increased in needles of trees grown with NO 3 − as a major N‐source, Except for superoxide dismutase, the activities of antioxidant enzymes and substrates were not correlated with the decree of needle chlorosis. Superoxide dismurase activity was low compared to enzymatic activities involved in H 2 O 2 detoxification. Supposing that the needles suffered from enhanced oxidative stress, these results suggest that scavenging of O 2 − was a limiting factor in stress compensation rather than the detoxification of H 2 O 2 .