Source–Sink Manipulation Affects Accumulation of Zinc and Other Nutrient Elements in Wheat Grains

To better understand the source–sink flow and its relationships with zinc (Zn) other nutrients in wheat (Triticum aestivum L.) plants for biofortification improving grain nutritional quality, effects of reducing photoassimilate source (through flag leaf removal spike shading) or sink all spikelets from one side spike, i.e., 50% removal) field accumulation Zn grains two cultivars (Jimai 22 Jimai 44) were investigated at soil application levels. The kernel number per (KNPS), single panicle weight (SPW), thousand (TKW), total (TGW) sampled, concentrations yields various nutrient elements including Zn, iron (Fe), manganese (Mn), copper (Cu), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) magnesium (Mg), phytate (phytate-P), phytic acid (PA) phytohormones (ABA: abscisic acid, ethylene precursor ACC: 1-aminocylopropane-1-carboxylic acid), carbon/N ratios determined. Soil significantly increased N K. Cultivars showing higher had lower protein micronutrient quality. SPW, KNPS, TKW (with exception half spikelets), TGW, most severely reduced by spikelet removal, secondly shading, slightly removal. Grain Mg consistently showed negative correlations KNPS but positive TKW. There general among Fe, Mn, Cu, Mg, bioavailability Fe (estimated molar PA/Zn, PA/Fe, PA × Ca/Zn, Ca/Fe). Although Ca was decreased treatments simultaneously limited increase Fe. In general, different interact each are affected to degrees manipulation. Elevated endogenous ABA levels ABA/ACC associated grain-filling inhibited K grains. However, ACC diametrically opposite. These results provide a basis alleviate human malnutrition.