Micronutrient’s Content And Its Bioavailability In Wheat Grain During Variety Succession In Guanzhong,Shaanxi Province

Micronutrient’s deficiency can cause human health problems.Wheat,as one of the staple foods in daily life,is an important source of human intake of micronutrients.Fertilization and variety are important factors affecting wheat grain micronutrient concentration.Understanding the changes of grain micronutrient concentration and its bioavailability during the succession process of wheat variety is of great reference value for future breeding and the establishment of rational fertilization technology.In this paper,we studied the changes of grain micronutrients content and bioavailability in the process of wheat variety improvement in Guanzhong area of Shaanxi Province by using the long-term fertilization location experiment in Yangling Experimental Station of Soil Quality.The long-term fertilization test included 9treatments,they were no fertilization（CK）,low amount of N and P fertilizer（N1P1）,high amount of N and P fertilizer（N2P2）,low amount of organic fertilizer combined with low amount of N and P fertilizer（M1N1P1）,low amount of organic fertilizer combined with high amount of N and P fertilizer（M1N2P2）,high amount of organic fertilizer combined with low amount of N and P fertilizer（M2N1P1）and high amount of organic fertilizer combined with high amount of nitrogen and phosphate fertilizer（M2N2P2）,and 5 representative wheat varieties released from 1970 to 2005 in Guanzhong area of Shaanxi Province were selected.They are Aifeng No.3,Xiaoyan No.6,Shaan 229,Xiaoyan 22 and Xinong 979.The main results and conclusions are as follows:The contents of Fe,Mn,Cu,Zn and Se in wheat grains ranged from 16.1-39.2 mg kg^-1,27.3-56.7 mg kg^-1,2.7-6.9 mg kg^-1,16.3-49.8 mg kg^-1 and 0.0172-0.0833 mg kg^-1,respectively.The mean values were 28.3 mg kg^-1,40.2 mg kg^-1,4.2 mg kg^-1,26.5 mg kg^-1 and 0.044 mg kg^-1,respectively.The results showed that both fertilization and variety had significant effects on Fe concentration in wheat grains,but the interaction between fertilization and variety only had significant effects in the first year.Variety had a significant effect on grain Mn concentration,while the interaction between fertilization and variety only had a significant effect on grain Mn concentration in the second year.In addition,fertilization,variety and their interaction had significant effects on Cu and Zn concentrations in wheat grains,but had no significant effects on Se concentrations in grains.At the same time,it was found that application of organic fertilizer could significantly increase the content of Mn in wheat grains,and decrease the content of Fe,Zn and Cu in grains.Reasonable increase of nitrogen and phosphorus fertilizer could increase the contents of Fe and Cu in grains,but for the contents of Mn and Zn in grains,this increasing trend was only shown at a certain organic fertilizer level.Therefore,fertilization and breeding should be used to improve the content of trace elements in wheat grains.The mean molar ratios of P/Fe,P/Mn,P/Cu and P/Zn in wheat grains were 232,151,1774和287,respectively.The variation ranges were 139-436,104-195,925-3183 and 137-528,respectively.The results showed that fertilization treatment had a significant effect on P/Fe molar ratio of wheat grains,and variety,fertilizer and variety interaction also had a significant effect in the first year.Different fertilization treatments and different wheat varieties had significant effects on the P/Mn molar ratio of wheat grains,and the interaction between fertilization and variety had significant effects on the P/Mn molar ratio of wheat grains in the second year.The molar ratios of P/Cu and P/Zn in wheat grains were significantly affected by different fertilization treatments,different wheat varieties and their interaction.In addition,the application of organic fertilizer was not conducive to improving the bioavailability of Fe,Mn,Cu and Zn in wheat grains,while the reasonable increase of nitrogen and phosphorus fertilizer was conducive to improving the bioavailability of trace elements in wheat grains.The content of Fe and Mn in wheat grains increased at first and then decreased during the succession of varieties under the treatments of M2 and M1N1P1,respectively.Under other treatments,the content of Fe and Mn in grains had no significant change during the succession of varieties.Under all fertilization levels,the contents of Cu,Zn and Se in wheat grains did not change significantly during the succession of cultivars.According to the results of quadratic function fitting,the Fe content of wheat grains under M2 treatment increased from1970 to 1984,with an annual increase rate of 0.15 mg kg^-1,and decreased from 1984 to 2005,with an annual decrease rate of 0.22 mg kg^-1（P<0.05）.The Mn content of wheat grains under the M1N1P1 treatment increased from 1970 to 1990,with an annual increase rate of 0.22 mg kg^-1,and decreased from 1990 to 2005,with an annual decrease rate of 0.16 mg kg^-1（P<0.05）.The P/Mn molar ratio of wheat grains under N2P2 treatment was significantly increased with variety succession,increasing by 0.96 y^-1（P<0.01）,there was no significant change trend under other treatments.In addition,P/Fe,P/Zn and P/Cu molar ratios in wheat grains did not change significantly during the process of variety replacement.In summary,based on the effects of variety improvement on wheat grain micronutrient concentration and bioavailability,M1N2P2 treatment was the better fertilization regime in Guanzhong,Shaanxi.In general,there was no significant change in the concentration of micronutrient and their bioavailability during the succession of wheat varieties,indicating that the quality of micronutrient in grains was maintained,which is beneficial to human health.