Regulating Effects Of N And Zn Application On Accumulation And Distribution Of Mineral Elements And Grain Quality In Winter Wheat

Pot and field experiments were conducted with two factors of N and Zn applications,using high-yielding wheat cultivar Yumai 49-198.In pot experiment,there were two levels of Zn rates（0 and 0.18 g ZnSO₄·7H₂O per pot）and two levels of N applications（0 and 2.32 g N per pot）.In field experiment,there were two levels of Zn rates（0 and 9.60 kg ZnSO₄·7H₂O/hm²）and four levels of N applications（0,180,240 and 300 kg N/hm²,respectively）.The aims of study were,（1）to evaluate the effect of different Zn and N application on plant physical characteristics,grain yield,and the translocation,assimilation and distribution of N and Zn in the organs of wheat plant;（2）to understand the concentration and bioavailable of elements,and flour quality properties in the grain milling and its mixed fractions under different N and Zn conditions.The study would provide us with academic bases for improving yield and quality simultaneously.The main results were as follows:The results indicated that Zn application significantly increased CA activity in leaf,especially at anthesis and middle grain-filling stage,whereas no significant improvement was observed in GDH activity,photosynthesis characters and grain yield.N application significantly increased GDH activity in both leaf and grain,and photosynthesis characters such as Pn,gs and Tr,and improved grain yield by 75.6%,mainly by higher spikes and grain number.HI was significantly increased under the nitrogen application conditions.However,with the increase of N rate,PFP decreased by 22.7% but NUE had no siginificant variation.The results showed that Zn application did not affect N translocation and its efficiency,and the contribution of plant organs such as stem,leaf and spike.Under the N application conditions,the translocation of N in most organs of wheat plant was significantly improved by 2.48-2.90 times,and it increased while N translocation efficiency in spike decreased with increasing N rates.Zn application significantly decreased N concentration of spike by 13.6% in spike,while increased Zn in each organ,for example,grain by 42.8%.N application increased N concentration by 65.4%-112.1% in most organs of wheat plant（highest vaules of N concentration were found in treatment of N application 180 kg/hm²）and improved Zn concentration in wheat grain by 8.9%.To a certain extent,N and Zn application could increase Zn concentration in the grain in the potential Zn deficient soil.Additionally,N contribution in stem and spike was significantly decreased with N and Zn application.N application also improved N contribution in leaf and grain,whereas it decreased in grain with the increasing of N rates.Zn contribution in organs,especially in spike,was improved but it in grain declined by 18.0% and 28.2% under the N and Zn application,respectively.This result implied that more N was translocated to leaf and grain,more Zn to spike under N and Zn application conditions.Correlation analysis indicated that N translocation and concentration in different organs were positively correlated with grain yield.The whole grain was pealed into 7 fractions（F1-F7）to evaluate the concentration and distribution of N and Zn in the grain.The results showed that the highest values of N concentration were obtained in F2 and F3（28.64 g/kg and 28.23 g/kg）,and the lowest in F7（16.25 g/kg）.And the highest values of Zn concentration were found in F1 and F2（69.01 g/kg and 67.72 g/kg）.Zn application did not affect the N concentration in each fraction,while increased Zn concentration in each fraction by 45.0%-59.3%.N application significantly improved N concentration in each part（highest values were obtained in treatment of 180 kg N /hm²）and only significantly affected Zn concentration in fractions of F1,F5 and F7.For the distribution,Zn application significantly increased N distribution in F1 by 4.9% but did not affect Zn distribution in each fraction.N application increased N distribution in F2,F3 and F4 but decreased in F1 and F7,and increased Zn distribution in F7 by 14.3% but decreased in other fractions by 4.6%-6.3%.This implied that more N increased in grain was translocated to aleurone layer,and more Zn to inner parts under N application condition.Correlation analysis indicated that linear relationship existed between N concentration in each organ and grain yield.No correlations were found between Zn concentration and yield,N concentration.Most elements were concentrated in the DF,XF and B1 among the milling and mixed fractions.Zn application improved Zn concentration in each fraction by 32.7%-67.7%,and Cu in XF by 8.5%,but decreased N in DF,P,K,Ca,Cu,Mn,and Fe in DF,XF and B2.However,P,K,Mg,Cu and Fe in mixed fractions did not change with Zn application.Under the N application,N concentration in each fraction was increased by 31.9%-52.9%,and Ca,Mg,Cu,Mn and Fe in XF,B1,R2,R3 were increased,but P in the bran and reduction flour decreased.Correlation analysis indicated that N concentration was negatively correlated with P in the whole grain.Significant positive correlation existed among K,Ca,Mg,Cu,Mn and Fe（R2 was 0.330-0.740）,as well as between Zn and Cu.Although no effect on the distribution of N,K,Ca,Mg,Fe and Zn,Zn application significantly increased the bioavailibility of Zn,but decreased that of Ca,Mg,Cu and Fe in the milling and its mixed fractions.N applicaton increased the distribution of N in DF,P and Mg in XF,Mn and Fe in R1 and bioavailibility of Cu and Fe in the reduction and Mg and Zn in mixed fractions,but decreased P in R1,Mg and Zn in DF.Moreover,TAZ in the patent flour,flour,general flour and wholegrain were 0.22,0.36,0.57 and 0.98 mg/d,respectively,and significantly increased by 27.8%-61.0% under the N and Zn application.Variation of protein and starch content was found among the milling and its mixed fractions.The highest value of protein content was obtained in DF,XF and B3,and the highest value of total starch was in R1 and R2.The contents of protein and starch in the milling and mixed fractions were signigicantly increased with N application,but no difference was found under the condition of Zn application.N application increased protein distribution in DF to 21.1%,and decreased the content of total starch and amylopectin in the flour,especially in B1,R1 and R2,thus increased the ratio of amylose to amylopectin by 13.8%.B1,B2 and R1 had a greater influence on starch viscostiy characteristics of flour fractions.N application significantly decreased viscosity value of flour and increased swelling power of B3.Breakdown in R1 and R2 was higher in the treatment of 180 kg N/hm²,while setback in reduction flour was the lowest in the treatment of 240 kg N/hm².Furthermore,content of total starch and amylospectin was significantly positively correlated with each viscosity characteristics.Correlation analysis indicated that the concentrations of N,Ca,Mg,Cu and Fe in wheat grain were positively correlated with grain yield and protein content in the mixed fractions（R² was 0.395-0.997）,but negatively correlated with P concentration.The concentrations of N,Ca and Cu were negatively correlated with starch content in the patent flour,flour and grain.Regression analysis showed that linear relationship existed between the contents of protein,starch in the mixed fractions with yield and N translocation and concentration of plant organ.The correlations above implied the existed possibility of synergy improvement for mineral nutrition,grain quality and yield.That is,with the increase of the concentration of mineral elments,both the quality and yield could be simultaneously improved.