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Clipping Foliage Differentially Affects Phytosiderophore Release by Two Wheat Cultivars

Hansen, Neil C., Jolley, Von D., Brown, John C.
Agronomy journal 1995 v.87 no.6 pp. 1060-1063
Triticum aestivum, cultivars, forage crops, grain crops, plant nutrition, iron, chlorosis, grazing, defoliation, adverse effects, nutrient availability, nutrient uptake, calcareous soils, nutrient deficiencies, siderophores, varietal resistance
Recent observations of grazing-induced Fe-deficiency chlorosis in wheat (L.) grown on calcareous soil indicates that Fe deficiency should be considered one of the factors associated with decreased grain yield in grazed wheat. Quantity of phytosiderophore release by roots of Fe-deficient grasses has been closely linked to resistance to Fe-deficiency chlorosis in numerous species and could potentially explain these observations. Phytosiderophore release following clipping was determined for two wheat cultivars (‘Abilene’ and ‘2157’) widely divergent in field chlorosis resistance. Plants were grown hydroponically in a complete nutrient solution containing 0.2 mg L Fe as Fe-HEDTA (-hydroxyethylethylenediaminetriacetic acid). Phytosiderophore release was measured using an Fe-binding assay under nonaxenic conditions. Abilene and 2157 wheat responded differently to clipping of foliage. Initial response in both was reduced release of phytosiderophore, but the Fe-chlorosis resistant cultivar (Abilene) responded to clipping by quick and complete restoration of the initially suppressed phytosiderophore, whereas the susceptible cultivar (2157) did not. Clipped Abilene released more phytosiderophore per gram of root than control plants on some days, but 2157 did not. Root growth was equally suppressed by clipping in both cultivars, compared with uncut control plants. Differential effect of defoliation on phytosiderophore release by these two cultivars helps explain some of the differences in Fe-deficiency chlorosis resistance ohserved in the field. These results indicate that Fe-chlorosis resistant wheat cultivars should be selected when managing wheat for both forage and grain production on calcareous soils.