engleski

Effect of genotype, nitrogen and Zn form on agronomic bio-fortification of wheat (Triticum aestivum L.) with zinc

The biofortification strategies include plant breeding strategy as long-term process and application of Zn-containing fertilizer as a short-term solution and both made synergistic approaches for accumulation additional Zn in grains. Plant breeding often includes varieties screening as a first step, and therefore 343 winter wheat varieties were analyzed in Zn, Fe and phytate content. Zn concentrations (13, 30 – 38, 93, average 21, 35 mg/kg) varied less than phytate (PA) concentrations (3, 62 – 23, 68, in average 11, 37 g/kg, ), and PA/Zn ratio was 55 in average (16, 5-140). Cluster analysis isolated 4 varieties with concentrations of Fe and Zn higher and PA/Fe & PA/Zn ratios lower than average. Lower PA/Fe and PA/Zn ratios were determined in another 49 varieties, but Fe and Zn concentrations were slightly lower, and 13 other varieties have some characteristic that point to bioavailability higher than average. There was more than half varieties (175) with average Fe, Zn and PA concentrations. Remaining 102 varieties would result in low Fe and Zn bioavailability. Based on previous screening of wheat varieties, 11 parental genotypes were selected for crossings and 19 crossing combination were produced. In 10 crossing combinations grain Zn concentration was 2.37 % to 118 % higher than parental average. Also, one crossing combination was singled out having lower Cd concentration than parental average. Based on this results promising breeding lines were selected sown for further testing, that will potentially lead to selection towards bio- fortification for high Zn and low Cd grain concentration. Within fertilization approach few different field experiments were conducted with no effect of Zn application on grain yield. First one includes foliar or soil application of Zn on four wheat genotypes on calcareous and on acid soil. Acid soil resulted in generally 20 % higher concentrations of Zn in wheat grain comparing to calcareous soil (44 vs. 37 mg/kg), but relative higher increment was achieved on calcareous than acid soils (22 % vs. 10 %) comparing to control treatments. Foliar application was more efficient than application in soil. Cultivars differ very significantly, the highest concentration (60 mg/kg Zn) was determined after foliar Zn application on high- quality cultivar, and lower (34-41 mg/kg) on high-yielding cultivars. Second experiment compared Zn foliar application in sulfate or EDTA form on calcareous soils. Zn- EDTA increased Zn in grain for 7 mg/kg reaching maximum 40 mg/kg, and Zn-sulfate increased Zn in average for 17 mg/kg (maximum 57 mg/kg). All Cd concentrations were very low, but Zn-EDTA further decreased Cd in grain for 49 %. The distribution of total Cd without Zn fertilizer in aboveground plant was 1/3 in straw, 1/3 in grain and 1/3 in rest of plant, but after Zn- EDTA half of Cd remain in straw, and only 1/5 accumulated in grain. Zn application significantly decreased PA/Zn ratio from high to moderate level. Third experiment with two varieties, 4 levels of nitrogen fertilization and foliar Zn application resulted in 46 % increased Zn concentration (21.6 to 31.6 mg/kg). Nitrogen fertilization significantly affected the Zn concentration, and biofortification at all levels of fertilization resulted in increased Zn (40- 52%). The conclusion was that the variety and nitrogen fertilization significantly affected the concentration of Zn in the grain.

zinc ; bioavailability ; biofortification ; nitrogen ; wheat ; iron ; cadmium

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