| Zinc?Zn?plays animprotant role in normal life activities such as human growth and development.Zn deficiency is a widespread global health problem,nearly half of the world population suffers from Zn deficiency,and approximately 100 million people were affected in China.The major cause for Zn deficiency in humans is inadequate dietary intake of Zn.Wheat is one of the most important staple food crops.Loess Plateau is the main dryland wheat production area in China,where the wheat is a major source of staple food crop and human Zn nutrition.Therefore,It is of great significance to study grain Zn concentration variation and its relationship to yield formation,Zn uptake and utilization of high-yielding wheat cultivars under dryland conditions,and clarify the reason of grain Zn concentration variation,for the purpose to improve wheat yield and grain Zn concentration and improve people's Zn status through breeding new cultivars with high yield and high Zn or regulating fertilizer application.This study was a 3-year field experiment which was conducted in the dryland area of the Loess Plateau from 2013 to 2016,the main experimental factor was no fertilization?CK?and fertilization?NP?,and the sub factor was the 123 wheat cultivars,which were collected from the main wheat production areas in China.At harvest,plant samples were collected,yield formation andthe contents and uptakes of N,P,K and Zn in the samples were analyzed.Main results were as follows:1.Significant differences existed in grain Zn concentration among high-yielding wheat cultivars under fertilization treatment.Grain Zn concentration of high-Zn cultivars was 20.1mg·kg-1,low-Zn cultivars was 13.0 mg·kg-1.By fertilization,grain Zn concentration of high-Zn cultivars was increased by 7%,but that of low-Zn cultivars was decreased by 22%.2.The high-yielding and high-Zn cultivars had lower spike number.The spike number of high-Zn cultivars was 7%lower than those of low-Zn cultivars.High-Zn cultivars had no difference from low-Zn cultivars in grain yield,biomass,harvest index,thousand grain weight and grains number per spike.Meanwhile,high-Zn cultivars had greater fertilizer effects than low-Zn cultivars on grain yield,biomass,spike number,and grains number per spike.3.The high-yielding and high-Zn cultivars had higher Zn uptake,Zn harvest index,and grain Zn formation efficiency.The grain Zn uptake,shoot Zn uptake,Zn harvest index,and grain Zn formation efficiency of high-Zn cultivars were respectively 52%,38%,10%and 10%higher than those of low-Zn cultivars.Meanwhile,high-Zn cultivars had greater fertilizer effects than low-Zn cultivars on grain Zn uptake and shoot Zn uptake.4.The high-yielding and high-Zn cultivars had higher grain N and P concentrations,and had higher straw N and K concentrations.Grain N and P concentrations of high-Zn cultivars were respectively 9%and 7%higher than those of low-Zn cultivars,and straw N and K concentrations were respectively 11%and 17%higher.By fertilization,grain N,straw N,P and K concentrations were increased,grain P and K concentrations were decreased for two group cultivars.5.The high-yielding and high-Zn cultivars had higher grain N and P uptake,but had lower K harvest index.The N and P uptake of high-Zn cultivars were higher than those of low-Zn cultivars,and were no difference in N and P harvest index;the K uptake of high-Zn cultivars was no difference from low-Zn cultivars,and was lower than those of low-Zn cultivars.By fertilization the increase of N,P and K uptake in high-Zn cultivars were significantly more than those of low-Zn cultivars,and the decrease of N,P and K harvest indices of high-Zn cultivars were similar to low-Zn cultivars.In low-Zn soils in the typical dryland area of the Loess Plateau,the high-yielding and high-Zn cultivars had higher grain N and P concentrations,the key to increasing wheat grain zinc concentration is to promote zinc uptake and its allocation to grains.Meanwhile,considering high P concentrations may decrease grain Zn bioavailability,fertilization practice should rationally control P use,while increasing N supply to increase grain N,Zn concentrations and Zn bioavailability. |
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