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Phytosiderophore Release Related to Susceptibility of Wheat to Iron Deficiency

Hansen, N. C., Jolley, V. D., Berg, W. A., Hodges, M. E., Krenzer, E. G.
Crop science 1996 v.36 no.6 pp. 1473-1476
Triticum aestivum, cultivars, chlorosis, iron, roots, leaves, cutting, grazing, calcareous soils, screening, genotype, nutrient deficiencies, siderophores, varietal resistance, Oklahoma
Some wheat (L. emend. Thell.) genotypes when grazed by livestock and subsequently used for grain production develop Fe deficiency chlorosis and decline in grain yield. Wheat is known to release phytosiderophores (compounds involved in Fe mobilization and uptake) in response to Fe deficiency stress. These studies conducted in environmental growth chambers correlated the release of phytosiderophore from the roots of eight wheat genotypes with field chlorosis scores from Oklahoma grazing trials. Plants were grown hydroponically in low Fe nutrient solutions and phytosiderophore release was measured with an Fe-binding assay. Since grazing exacerbates Fe deficiency chlorosis development, the eight genotypes were tested both with and without clipping. Phytosiderophore release with time was summed to improve correlation compared with individual daily measurements. The field chlorosis scores and the sum of the first six phytosiderophore release measurements (Days 6 to 11 after imposition of low Fe treatment) from unclipped wheat were not correlated (= −0.17, = 0.70), but the sum of the last five days (13 to 17) was highly correlated with field chlorosis scores (= −0.82, = 0.01). Clipping did not greatly improve the relationship (= −0.83, = 0.008). Correlation coefficients were more consistent for individual days when plants were clipped. Three-day sums of phytosiderophore release provided good correlations when data were collected in the latter stages of Fe deficiency development (Day 11). Identification of chlorosis resistant lines by monitoring phytosiderophore release will by-pass years of field trials and should be implemented by plant breeders where wheat is managed concurrently for forage and grain production on calcareous soils.