Effect of paclobutrazol on the development of iron chlorosis in soybeans

Abstract

Iron‐efficient (A7) and ‐inefficient (T203) soybean cultivars were grown in nutrient solution culture both with and without the plant growth regulator paclobutrazol at low levels of Fe. Paclobutrazol affected root morphology, greatly reduced shoot growth, and delayed the onset of chlorosis in the penultimate leaf of both cultivars by several days at all Fe levels as compared to untreated controls. The chemical delayed, but did not hinder, the iron stress response mechanism (proton and reductant extrusion). Paclobutrazol did not delay the onset of chlorosis by mobilizing Fe to the leaves because foliar Fe content in paclobutrazol treated plants was similar to that of untreated ones. These results suggest that paclobutrazol may be a useful tool in studying the interactions between growth, chlorophyll synthesis, the development of Fe chlorosis, and the Fe stress response mechanism.

Key words:

• Chlorophyll
• Glycine max (L.) Merr
• Growth regulator
• Iron stress response

Notes

Permanent address: Botany Department, University of Jodhpur, India