Iron and zinc fertilization with reference to the grain quality of triticum aestivum L.

Abstract

Iron + Zinc (applied to the soil as ferrous sulphate and zinc sulphate) were found to significantly increase the number ear heads per tiller, length of ear heads, number of grains per ear, grain yield per plant and the weight 1000 grains in proportion to its concentration used both in pot and field experiments. This was coupled with the increase in total carbohydrate, starch and crude protein contents of wheat grains. All these activities were found optimum at the identical concentration of Fe + Zn (@ 7.5 mg kg^‐1 soil). A further increase in the exogenous iron and zinc concentrations (up to 12.5 mg kg^‐1 soil) led to the sharp decline of all these activities near the control level. Yield characters were observed to be better supported in the field condition than in pot cultures. Since natural availability of iron and zinc in the soil are only 2–4 mg kg^‐1 soil and 0.60 mg kg^‐1 soil, respectively, it is apparently suggested that the threshold level of iron and zinc (@ 7.5 mg kg^‐1 soil) has a definite role in the synthesis of carbohydrates, starch and protein contents in the wheat grains. It is further suggested that normal metabolism might be reasonably hindered due to an increased uptakability of Fe and Zn at their higher concentrations (@ 10 mg kg^‐1 soil and 12.5 mg kg^‐1 soil, respectively). This causes a reduction in the synthesis of chlorophyll and indole‐3‐acetic acid, leading to an inhibition of photosynthesis at grain filling stage and ultimately reduced total carbohydrate, starch and protein contents of grains, which might be a good reason for the production of inferior quality of wheat grains. The positive role of the threshold concentration (@ 7.5 mg kg^‐1 soil) of exogenous iron and zinc in the growth and yield potentiality of wheat crop is, therefore, emphasized.

Key words:

• Indole‐3‐acetic acid
• Chlorophyll
• Yield attributes
• Carbohydrates
• Protein
• Wheat grains