Effect of spraying with chelated iron and tryptophan on some vegetative characteristics of two mint(Mentha spicata L.) varieties

• Taghreed Fakher Jaber1*, Zainab Hussein Alawi1

  Author

Modern agricultural trends have focused on reducing fertilization rates and improving fertilizer efficiency and environmental safety. Therefore, a field experiment was conducted during the 2024-2025 growing season in the fields of the Horticulture and Forestry Department of the Najaf Governorate Agriculture Directorate. The aim was to study the effect of foliar spraying of the  chelated iron and amino acid tryptophanon some vegetative characteristics of two mint (Mentha spicata L.) varieties: common mint and peppermint. The experiment was implemented using a 3:3 factorial design with a split-plot design and a randomized complete block design (RCBD) with three replications. The experiment included two treatments: foliar spraying of the amino acid tryptophan at three levels (0, 50, and 100 mg.l^-1) and foliar spraying of chelated iron at three levels as well (0, 40, and 80 mg.l^-1). These treatments were applied as foliar sprays twice during the growing season.

The results showed a significant positive effect of both single and double foliar spray treatments on all studied vegetative traits. The interaction between high levels of chelated iron and tryptophan resulted in the highest standard indicators for plant height, total number of leaves, and number of lateral branches, as well as a significant increase in photosynthetic efficiency through increased chlorophyll content (SPAD units) in the leaves. The current study demonstrates that the complementary use of amino acids and increased physiological availability of iron by spraying chelated iron, is a vital and effective strategy for stimulating vegetative growth and improving the quantitative and qualitative yield of mint plants under the conditions of central Iraq.

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