Effect of foliar iron application on regreening and chloroplast development in iron-chlorotic soybean

Abstract

Abstract Several iron‐containing fertilizers such as FeSO4 Fe‐EDTA, Fe‐EDTA + urea, Fe‐EDTA + superphosphate and a “commercial product”; (SD 807) containing N, Fe, Zn and Mn were applied to iron‐chlorotic soybean leaves and the effects on regreening and reorganization of iron‐chlorotic chloroplasts were studied. Fe‐EDTA + urea seemed most effective, but was in higher concentrations most likely to cause foliar injury. SD 807 had caused a lighter green than the other fertilizers. Reduction of grana‐stacking is characteristic of iron‐deficient chloroplasts. Concomitant with regreening, grana‐stacking of chloroplasts increased. Six days after foliar application the recovered chloroplasts resembled chloroplasts of control plants, although they contained fewer thylakoids per granum than control chloroplasts. Iron resupply to the nutrient solution, however, resulted in well‐developed chloroplasts, comparable with control chloroplasts. In more pronounced iron deficiency, when leaf colour appeared to be yellow‐white, chloroplasts displayed severe disintegration. In such cases it was not possible to achieve regreening by foliar fertilization. Key words: Iron deficiencyFoliar applicationSoybeanChloroplast ultrastructure