| Zinc is an essential micronutrient for plant and animal growth, it enters into the food chain through plant, then it enters the diets of human being directly or indirectly, thereby it affects the balance of nutrition and the health of buman being. Wheat is the food crop with the largest planting area and total yield, while it is more sensitive to Zn. covers daily caloric and mineral nutrition requirement of our northern people. However, wheat mainly distributes in calcareous soil area which is zinc (Zn) deficient or potentially Zn-deficiency, resulting in a lower Zn concentration of wheat grain. Besides, some substances, especially phytic acid, have an inhibitory effect on the utilization (bioavailability) of Zn in the human digestive tract. Phytic acid, as the major anti-nutritional factor, is the storage compound of phosphorus in grain. Phytic acid could bind Zn, resulting in reduce in solubility of Zn in food and finally restricts its utilization in human body. Beacause the flour mainly come from endosperm of wheat grain. So it is very important to improve Zn concentration and (or) decrease phytic acid concentration in endosperm. In this study the wheat of two field experiments were analysised to research the effect of different applying methods and levels of Zn fertilization on Zn nutritional quality in different wheat pearling fractions especially endosperm. This research will provide theoretical and practical value for improving nutritional quality of wheat. The main results of this study were as follow:(1) In order to alleviate Zn deficiency in human beings whose staple food is wheat, this study was conducted to assess the effect of Zn application methods on distribution of Zn, phytate and protein in wheat pearling fractions. A field experiment of soil and foliar application methods of Zn fertilizer was conducted for 2 winter wheat cultivars (S715 and XN889) in potentially Zn-deficient calcareous soil, six pearling fractions (P1-P6) of wheat grain were obtained using JMJ3 rice polishers, and P1-P5 were bran fractions of wheat grain, P6 was mostly endosperm, the concentration of Zn, phytate, protein of every wheat pearling fractions were determined. Compared with the control treatment (no Zn application), the methods of soil + foliar application and foliar application of Zn increased Zn concentration in P1-P5 fractions by 53.3%, 42.7%, respectively; and increased Zn concentration in P6 fraction by 61.1%, 52.7%, respectively; However, soil application of Zn only did not increase. Generally, the P2 fraction (the outer 4-8% layer of wheat grain) had the highest Zn and phytate concentrations, whereas the P3 fraction (the outer 8-12% layer) ranked the highest for protein concentration. All the three components showed a diminishing trend as pearling progressed from the outer layers to the inner part of wheat grain. The effect of three treatments of applying Zn on concentration of phytate in P1-P5 was not significant; however, the application of Zn increased phytate concentration in P6 and decreased the protein content in wheat pearling fractions. The phytic acid to Zn molar ratios were significantly decreased under the soil + foliar application and foliar application treatments. Whereas, the effect of soil application of Zn on grain Zn bioavailability was not significant. The distribution of Zn, phytate, protein in wheat grain is uneven, the concentrations of three components are higher in the outer layer especially the aleurone tissue; there are lowest concentration in the starchy endosperm. Zn application methods and cultivars have not positive effect on the distribution patterns of the three components between the outer and inner parts of wheat grain. Comparing with the three Zn application methods, the foliar application of Zn fertilizer to wheat is the economical and effective method to attain high Zn concentration and bioavailability in wheat grain especially for the endosperm, with alleviating Zn deficiency in human.(2) To investigate the effect of zinc fertilizer on distribution of Zn, phytate and protein in wheat pearling fractions on potentially Zn-deficient soil. A field experiment was carried out. The experiment design consisted two varieties of wheat (Zhengmai 9023 and Xinong 889) with five levels (0, 7.5, 15, 30 and 45 kg Zn ha-1). six pearling fractions (P1-P6) of wheat grain were obtained using JMJ3 rice polishers, and P1-P5 were bran fractions of wheat grain, P6 was mostly endosperm, the concentration of Zn, phytate, protein of every wheat pearling fractions were determined. Results showed that Zn fertilization had increased partly grain Zn concentration. When apply Zn fertilizer 30 kg hm-2, Zn concentration increased by 22.3%, but no significant. The Soil application of Zn fertilizer had no significant effect on phytate concentration in different pearling fractions of ZM9023 and bran of XN889, and phytate concentration in P6(endosperm) of XN889 was increased significantly in Zn7.5, Zn30, Zn45 treatments. The phytic acid to Zn molar ratios and protein can not significantly be increased as Zn levels increased.Generally, the P2 fraction (the outer 4-8% layer of wheat grain) had the highest Zn and phytate concentrations, whereas the P3 or P3 fraction (the outer 8-12% layer) ranked the highest for protein concentration. All the three components showed a diminishing trend as pearling progressed from the outer layers to the inner part of wheat grain. In general, the methods of soil application of Zn Zn in potentially Zn deficient soil can not increase significantly grain Zn concentration and bioavailability, The distribution of Zn, phytate, protein in wheat grain is uneven, the concentrations of three components are higher in the outer layer especially the aleurone tissue; there are lowest concentration in the starchy endosperm.(3) Potential Zn-deficiency is widespread in calcareous soil in North China, and Zn concentration and its bioavailability of wheat grain could be improved by application of Zn fertilizer in this region, however, the balance of micronutrients might be changed by soil or spraying Zn. In order to investigate the effect of Zn application methods on the micronutrient accumulations and distribution of wheat grain, A field experiment of soil and foliar application methods of Zn fertilizer was conducted for 2 winter wheat cultivars (S715 and XN889), six pearling fractions (P1-P6) of wheat grain were obtained using JMJ3 rice polishers, and P1-P5 were bran fractions of wheat grain, P6 was mostly endosperm, the concentration of Fe, Mn, Cu of every wheat pearling fractions were determined. Results showed that, The effect of three treatments of applying Zn on concentration of Fe and Mn in P1-P5 was not significant; however, Fe concentration in P6 was decreased by 15.6% with the application of Zn, and the methods of foliar application and soil + foliar application of Zn increased Mn concentration in P6 fractions by 11.5%, 11.1%, respectively; the application of Zn decreased the Cu concentration in wheat pearling fractions especially P6. Soil, foliar and soil + foliar application of Zn decreased Cu concentration in P6 by 42.2%, 17.7%, 20.2%;Generally, the P2 fraction (the outer 4-8% layer of wheat grain) had the highest Fe and Cu concentrations, whereas the P1 fraction (the outer 8-12% layer) ranked the highest for Mn concentration. All the three components showed a diminishing trend as pearling progressed from the outer layers to the inner part of wheat grain.In a word, when the foliar application of Zn fertilizer to wheat increased significantly Zn concentration and bioavailability in wheat grain especially for the endosperm, Mn concentration was increased partly in P6, and Fe and Cu concentration was decreased, The distribution of Fe, Mn, Cu in wheat grain is uneven, the concentrations of three components are higher in the outer layer especially the aleurone tissue; there are lowest concentration in the starchy endosperm. |
PDF Full Text Request