Differential Iron Chlorosis of Oat Cultivars1

Iron chlorosis symptoms of varied severity were observed among oat (Avena byzantina C. Koch) cultivars in field trials at Beeville, Tex., during the 1975 and 1976 seasons. A cultivar exhibiting severe iron chlorosis and one having no apparent chlorosis symptoms in the field were grown in the greenhouse in two different soils known to have low levels of available iron. Growth of the "resistant" cultivar was relatively normal in both soils, whereas leaves of the "susceptible" cultivar were chlorotic, and plant growth was severely retarded. The addition of iron to either soil corrected the chlorosis symptoms of the susceptible cultivar. Plants of the susceptible cultivar grown in iron‐treated soil produced more than three times as much aboveground dry matter and more than twice as much crown and root weight as plants grown in untreated soil. Shoot and root yields of the resistant cultivar were influenced only slightly by iron treatment. Knowledge of the sensitivity of oat cultivars to iron chlorosis should be useful in developing new cultivars for areas where iron chlorosis is a problem.