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Role for Potassium in the Iron‐Stress Response Mechanism of Iron‐Efficient Oat
Author(s) -
Hughes D. F.,
Jolley V. D.,
Brown J. C.
Publication year - 1992
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1992.03615995005600030026x
Subject(s) - chlorosis , avena , potassium , chelation , chemistry , iron deficiency , horticulture , ethylene , cultivar , agronomy , biology , biochemistry , inorganic chemistry , organic chemistry , medicine , anemia , catalysis
Adequate soil K enhances the ability of certain Fe‐deficiency‐stressed monocotyledonous and dicotyledonous plants to obtain Fe. In dicotyledonous plants, this increased capacity to obtain Fe where adequate K is present is associated with specific Fe‐stress response mechanisms including H + ion efflux, reductant release, and reduction of Fe 3+ to Fe 2+ at the root (Strategy I). A different Fe‐stress response mechanism recently identified in Fe‐efficient grasses is the release of phytosiderophore (a plant‐produced Fe 3+ chelator; Strategy II). Our objective was to determine if varied K additions affect either the production and release of phytosiderophores or the uptake of Fe in oat ( Avena sativa L.; a Strategy II plant). A series of hydroponic experiments was conducted imposing varying solution K concentrations on Fe‐deficiency‐stressed ‘Coker 227’ oat, an Fe‐efficient cultivar. Significantly more phytosiderophore was released by roots of oat plants grown with adequate K (84 mg K L −1 ) than by roots of plants grown at low concentrations of solution K (0 and 7 mg K L −1 ). The diminished phytosiderophore production in the absence of K corresponded significantly with greater Fe‐deficiency chlorosis and lower leaf Fe contents. Oat plants grown in adequate K successfully competed with equimolar concentrations of Fe and EDDHA [ethylene‐diamine di (O‐hydroxyphenylacetic acid)], but did not compete for Fe where excess EDDHA was added, further substantiation of a role for K in the production and release of phytosiderophore.