Effect of nitrogen fertilization on zinc and iron uptake and yield components of wheat

This study was performed to assess the role of nitrogen (N) rate and application time in combination with zinc (Zn) and iron (Fe) supplement in soil and foliage at booting stage of wheat (Triticum aestivum var. Krabat) for augmentation of protein, Zn and Fe in grain. Eighty four plastic pots of wheat containing 8 plants in each pot were grown in a climatically controlled growth room. The rates of N supply were 28.57, 42.86 and 57.14 mg N kg-1 soil, equivalent to 80, 120 and 160 kg N ha-1, respectively and for Zn and Fe, the rate was 10 mg kg-1 soil and additional 30% through foliar spray at the designated N treatments, a total of 21 treatments. Plants missed tillering reducing overall grain and straw yields. Grain and straw yield pot-1, 1000 grains weight, number of grains pot-1, whole grain protein content, concentration and total uptake of Zn and Fe in grains were determined. Analysis of variance demonstrated that soil applied N at sowing interacted often with Zn-Fe- treatments resulting differences in number of grains pot-1, straw yield, grain Fe- concentration and uptake of Zn and Fe in grain. A tendency of higher yield was seen when increasing N rate at sowing was applied but the tendency was reduced at higher dose (160 kg N ha-1 in this study). Relatively higher grain yield, protein content and the uptake of Zn and Fe in grain were obtained at split N equivalent to 160 kg N ha-1 (applying 70% of allocated N at sowing and 30% at stem elongation). But lower N rates at sowing resulted in reduced grain yield with higher concentrations of Zn and Fe in grain. At soil plus foliar supply of zinc sulfate (ZnSO4) and ferric ethylenediamine tetraacetic acid (Fe-EDTA) together enhanced grain protein content, concentration of Zn and Fe up to 46% and 64% and their total uptake in grain by 35% and 42%. For the localization of Zn and Fe in grain, LA-ICPMS and MA-XRF were used. Scanning of half grain along the crease pointed co-localization of Zn and Fe at germ, crease and aleurone. Split application of N with sufficient dose at sowing and stem elongation or beyond in combination with soil plus foliar application of Zn and Fe can be a good agricultural practice to enhance protein, Zn and Fe content in wheat. Key words: Zinc and iron uptake, nitrogen fertilization, foliar spray of zinc and iron, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICPMS), wheat, wheat grain protein, grain components. 2014-12-15