| Wheat grain Zinc(Zn) and Selenium(Se) concentration is generally low in China, and foliar application of Zn and Se fertilizer is significant to increase the grain Zn and Se concentration. Therefore, researches on the responses of wheat grain Zn and Se concentration to foliar-Zn and foliar-Se application are attached great importance to reasonable application of Zn and Se and to the improvement of wheat grain Zn and Se nutrition in China. Thirty field trials were conducted in 14 different provinces in major wheat production areas in china, studying the effects of foliar-Zn and foliar-Se application on the wheat grain Zn and Se concentration, the difference between acid and alkaline soil regions, and the relation concerning grain Zn and Se concentration to main soil properties and the wheat shoot Zn and Se concentration before jointing stage. Main results were as follows:1. Results from the thirty field trials showed that foliar Zn application had no effect on the grain yield, biomass and harvest index of wheat, but significantly increased the grain Zn concentration by an average of 5.2 mg/kg(17.5%), with a 5.3 mg/kg(16.4%) increase in acid soil region and a 5.2 mg/kg(18.4%) increase in alkaline soil region. There was no significant difference between acid and alkaline soil regions for Zn uptake and distribution in wheat. Compared with the control the foliar Zn application increased Zn uptake of wheat grains, glumes, and stems by 19.4%, 28.7%, and 99.2%, and up to 26.0 g/ha, 117.5 g/ha and 255.5 g/ha respectively. The Zn harvest index of wheat under foliar Zn application was 64.1%, 12.2% lower than control. Grain Zn recovery and grain Zn biofortification index were nearly the same between acid and alkaline regions, with an average of 3.0% and 3.8 mg/kg respectively. A significant positive correlation(P<0.05) was found between soil DTPA-Zn and the grain Zn concentration, with the grain Zn concentration increased by 4.0 mg/kg for each 1.0 mg/kg increase of DTPA-Zn, but a significant negative correlation(P<0.001) was found between top 0-20 cm soil p H and grain Zn concentration, with the grain Zn concentration decreased by 3.8 mg/kg for one unit topsoil p H rise. Grain Zn concentration was also significantly(P<0.001) correlated with the shoot Zn concentration before jointing stage, with each 1.0 mg/kg increase of the shoot Zn concentration resulting in 0.4 mg/kg grain Zn concentration increase. The foliar Zn application had no effect on the relationships mentioned above. There was no significant correlation between topsoil organic matter contents and grain Zn concentrations.2. Results from the thirty field trials showed that foliar Se application had no significant effect on the grain yield, biomass and harvest index of wheat, but significantly increased the grain Se concentration to 647.8μg/kg( by 20.9 times), compared to 31.0 μg/kg without foliar Se application. There was a significant increase in Se uptake in wheat. Compared with the control, the foliar Se application increased Se uptake of wheat grains, glumes and stems by 21.8, 8.3, and 14.40 times, up to 4.37 g/ha,0.50 g/ha and 3.46 g/ha, respectively. Grain Se recovery and the shoot Se recovery were averaged to be 3.7% and 6.9%, respectively. Grain Se biofortification index was 5.3 μg/kg. The Se harvest index of wheat under foliar Se application was 5.3mg/kg averagely, significantly increased by 51.6%. A significant positive correlation(P<0.01) was found between the 0-20 cm soil available Se and the grain Se concentration in the control treatment, with the grain Se concentration increased by 1.03 μg/kg for each 1.0 mg/kg increase of the soil available Se; but no significant correlation was found in the foliar Se application treatment. There was no significant correlation between topsoil p H and organic matter content to grain Se concentrations. A significant negative correlation(P<0.05) was found between top 0-20 cm soil available P and grain Se concentration without foliar Se application, with the grain Se concentration decreased by 1.0 μg/kg for 1mg/kg soil available P rise. Grain Se concentration was also significantly(P<0.05) correlated with the shoot Se concentration before jointing stage, with each 1.0 μg/kg increase of the shoot Se concentration resulting in 5.3 μg/kg and 0.68 μg/kg grain Se concentration increase in the control and the foliar Se application, respectively. |
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