Journal article

Publication year: 1994

Pages: 1053-1065

Journal: Journal of Plant Nutrition

Volume number: 17

Issue number: 6

ISSN: 0190-4167

DOI Link: https://doi.org/10.1080/01904169409364787

Publisher: Taylor and Francis Group

Abstract: 
A hypothesis has been presented and tested that bicarbonate (HCO3) and nitrate (NO3) are the most important anions inducing iron (Fe) chlorosis because these anions increase the pH of leaf apoplast which in turn depresses ferric-iron [Fe(III]) reduction, and hence, the uptake of Fe into the symplasm. Experiments with young sunflower (Helianthus annuus) plants showed that nutrition with NO3 as the sole nitrogen (N) source induced chlorosis whereas ammonium nitrate (NH4NO3) did not. Monohydrogen carbonate (bicarbonate) also favoured the development of chlorosis. The degree of chlorosis was not related to the Fe concentration in the leaves. Both anion species, NO3 and HCO3, increased the pH of the leaf apoplast which was measured by means of the fluorescence dye 5-carboxyfluorescein. A highly significant negative correlation between leaf apoplast pH and chlorophyll concentration in the leaves (r = -0.97) was found. Ferric-Fe reduction in the apoplast-measured by means of ferrocene-provided evidence that a low leaf apoplast pH, obtained with ammonium (NH4) supply, favoured the reduction of Fe(III) as compared with a higher leaf apoplast pH obtained with NO3 supply. These results support the hypothesis tested.

Harvard Citation style: MENGEL, K., PLANKER, R. and HOFFMANN, B. (1994) RELATIONSHIP BETWEEN LEAF APOPLAST PH AND IRON CHLOROSIS OF SUNFLOWER (HELIANTHUS-ANNUUS L), Journal of Plant Nutrition, 17(6), pp. 1053-1065. https://doi.org/10.1080/01904169409364787

APA Citation style: MENGEL, K., PLANKER, R., & HOFFMANN, B. (1994). RELATIONSHIP BETWEEN LEAF APOPLAST PH AND IRON CHLOROSIS OF SUNFLOWER (HELIANTHUS-ANNUUS L). Journal of Plant Nutrition. 17(6), 1053-1065. https://doi.org/10.1080/01904169409364787