Can spraying wheat with zinc and iron increase both its yield and its nutritional content?

Details

Zinc (Zn) and iron (Fe) are important micronutrients for plant growth. The abstract describes their deficiency in plants, especially cereal crops, as a major nutritional problem worldwide.

To study how spraying zinc and iron onto leaves affects grain quality traits and yield, researchers conducted an experiment on Aseman dryland wheat at Gonbad Kavous Agricultural Researches Center during 2019–2020. It was a factorial experiment based on a Randomized Complete Block design with 4 replications.

The experiment combined four foliar treatments—zinc at 2 g/L, iron at 3 g/L, zinc and iron together, and pure water as the control—with three spraying stages: tillering, shoot elongation, and seed filling. Measurements included grain yield, grain zinc and iron concentrations, grain protein content, and leaf photosynthetic pigment content.

Foliar treatment significantly affected all studied traits except the chlorophyll a/b ratio. Spraying time also produced significant differences in grain protein content, grain iron and zinc concentrations, chlorophyll a content, and carotenoid content.

Compared with the pure-water control, all three nutrient-spray treatments—zinc, iron, and zinc plus iron—significantly increased grain zinc and iron concentrations, grain protein content, and grain yield. Overall, zinc spraying increased grain zinc concentration by 39.85%, and iron spraying increased grain iron concentration by 89.43%, compared with the control. Grain protein content was highest with the combined zinc-and-iron treatment at 11.45% and lowest in the control at 7.87%. The combined treatment increased grain yield by 42.48% compared with the control.

The interaction between foliar treatment and spraying time showed that the highest grain yields occurred with zinc and iron applied together at grain filling and shoot elongation: averages of 8625 and 8600 kg/ha, respectively.

The researchers concluded that zinc and iron fertilizer applications can increase grain nutrient concentrations and yield in dryland wheat under the climatic conditions of this region.