| Wheat is one of the most important staple food cereals in China, especially as the mostmain resources of energy and mineral nutrients of the northern Chinese residents, which is ofgreat significance for their Zn nutrition level. Unfortunately, wheat in north China is mostlygrown in calcareous soil with low available Zn, and grain Zn concentration is consequentlylow and hardly meet with the nutritional demands of Zn from local people. Therefore,improving Zn concentration of wheat grain is very important for solving the problem of Zndeficiency of local people, and some two-year long field experiments were conducted to studyeffects of Zn fertilizer application rates, Zn fertilizer application methods and soil moisturecondition on wheat yield, and Zn fertilizer uptake and utilize, and provide reliable theoreticalbasis for optimizing Zn fertilizer management in low-Zn dry land region in our country.Obtained results are as follows:1. By a two year long location-fixed field experiment, the effectiveness of Zn applicationto a Zn-deficient calcareous soil was measured using six Zn fertilizer rates (0,10,25,50,100,150kg ZnSO4·7H2O ha-1). The results showed that soil DTPA-Zn was increased significantlywith the increase of Zn fertilizer, but the grain yield was not affected by soil application of Zn.Zn application increased grain Zn concentration by32%and44%, respectively in the first andsecond cropping season, and with the maximum of grain Zn concentration correspondingly upto19.8and32.1mg kg-1, but they were still lower than the recommended level of40-60mgkg-1. Total Zn utilization efficiency less than1%. Application of Zn fertilizer increased Feconcentration of grain, but showed no obvious influences on its N, P and K concentrations.Increased precipitation promoted wheat Zn absorption and allocation to grain on dryland.Therefore, the current recommended Zn application (ZnSO4·7H2O15-45kg ha-1) is not ableto improve the Zn nutrition of wheat grain and its yeild in dryland area of northwestern China.2. Field experiments were conducted in two locations in the middle part of Loess Plateau,to study the effectiveness of soil application, foliar application and soil+foliar application ofZn by winter wheat grown at two N rates. Results showed that little effect of Zn applicationwas found on grain yield of winter wheat.The grain Zn contents were increased by Znapplication, but the increasing degree was varied with the Zn application methods. The grain Zn contents were increased by about40%and up to40mg kg-1by foliar application andsoil+foliar application of Zn. Whereas, the effect of soil application on grain Zn contents wasnot significant, although it triply increased soil DTPA-Zn. Zinc utilization efficiency of foliarapplied Zn was higher than that of soil and soil+foliar applied Zn. Each one kg ha-1foliarapplied Zn was observed to be able to increase the grain Zn content by6.70-13.04mg kg-1.Grain Zn utilization and total Zn utilization efficiency were respectively6.02%-9.40%and19.78%-30.91%for foliar applied Zn, which were correspondingly80and132-221timesmore than those for soil applied Zn. Nitrogen rates had no effect on yeild and Zn utilization.Therefore, foliar application of Zn is more cost-effective and environmental friendly than soilapplication, and is one of the important practices to improve grain Zn concentration onZn-deficient soils in dryland area of northwestern China.3. Results of two-year long field experiments showed that the supplemental irrigation of20to30mm water at jointing and booting stage had no significant effect on grain yield andsoil DTPA-Zn, obviously tended to increase grain Zn concentration and Total Zn utilizationefficiency. |
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