Accumulation Mechanism Of Antioxidant And Regulation Effect Of Nitrogen And Phosphorus Fertilizer Application On Wheat Grain With Different Grain Color

The experiment was conducted at Henan Agricultural University Experimental Station during 2013-2014 and 2014-2015 cropping years with spilt-plot design.Fertilizer treatment was the main plot and wheat varieties was assigned as the subplot.Six wheat cultivars were used as experiment materials: two white wheat cultivars(Yumai 49-198 and Zhengmai 366);two red wheat cultivars(Yangmai 15 and Yangmai 22);two black wheat cultivars(Zhenzhouhei 1 and Shandongzimai 1).Four fertilizer treatments were applied with N1P1(N90kg/hm2,P2O560kg/hm2),N2P1(N240kg/hm2,P2O560kg/hm2),N1P2(N90kg/hm2,P2O5209kg/hm2),N2P2(N240kg/hm2,P2O5209kg/hm2).The aim of this study was to investigate the influence of nitrogen and phosphorus fertilization application on the wheat yield,grain antioxidant content,antioxidant ability.At the same time,the accumulation trend and its mechanism of the phenolic acid during the grain filling stage were also studied.The main results are as follow:1.ANOVA of the grain yield,yield components and antioxidant contentWheat variety,planting year,fertilization treatment and their interactions all show significant influence on grain yield,yield components and antioxidant content.Among them,variety and fertilization treatment have significant influence on most of the tested traits.2.Effects of nitrogen and phosphorus fertilizer application on grain yield of wheat withdifferent grain colorsConsidering the yield data of two planting years,it can be found that the grain yield is significantly improved at N2P1 treatment.Compared with others fertilizer treatment,the yield is increased by 8.7-14.3%,6.7-27.1% under the N2P1 treatment in 2015 and 2014,respectively.Correspondingly,the spike number is increaseed by 7.1-40.0%.However,no significant differences is observed among different varieties in 2014 for grain yield.In 2015,the yield of black wheat is significantly lower than that of others wheat varieties.These results indicate that high nitrogen and low phosphorus application would benefit wheat grain yield under this experimental condition;red wheat and white wheat have significantly higher yield than black wheat.3.Effect of nitrogen and phosphorus fertilizer application on total flavonoids,totalphenols and antioxidant activity of wheat with different grain colorsThe total phenol content of black wheat is significantly higher than that of red wheat and white wheat.The total flavonoids content of black wheat(Shandongzimai 1)is significantly higher than those of other varieties;its antioxidant activity(FRAP,ABTS)is also significantly higher than others.The DPPH value of red wheat is significantly higher than that of others.These results indicate that black wheat and red wheat have higher antioxidant ability and white wheat has the relative lower antioxidant ability.4.Effect of nitrogen and phosphorus fertilizer application on bound and solublephenolic acids content of wheat with different grain colorsThe main types of phenolic acids in wheat grain is not affected by fertilizer treatments.Five main phenolic acids were tested in wheat grain,including ferulic acid,p-coumaric acid,caffeic acid,vanillic acid,and syringic acid.The content of bound phenolic acids is about 1-5 folds higher than that of soluble phenolic acids.Ferulic acid is the main bound phenolic acids,accounted for about 86-95% of total bound phenolic acids.Under the high phosphorus fertilizer conditions(N1P2 and N2P2),the content of bound ferulic acid are significantly higher than those at low phosphorus fertilizer conditions.The amount of bound ferulic acid in black wheat is significantly higher than that of red wheat and white wheat.The bound ferulic acid,vanillic acid,syringic acid content of red wheat are significantly higher than that of other varieties.5.Accumulation of total phenols and flavonoids of different wheat during grain fillingstageThe accumulation of total phenolic in different wheat varieties during grain filling stage show a trend with two-peak curve.The first peak appeares at the 14 day after anthesis(DAA),while the second one is observed at 28 DAA.Under different fertilizer treatments,the changes of total phenols gave the same trend.The content of total phenols under low nitrogen treatments is higher than that of under other fertilizer treatment.During grain developing,the accumulation of total flavonoids in wheat with different grain color showes a trend of increasing-decreasing-increasing.The content of total flavonoids peaks at the 14 day after anthesis,then decline slowly.However,there is a increase between 28 DAA to 35 DAA.Also the content of total flavonoids of the same varieties shows the same trends under different fertilizer treatments.The trend of phenolic acids compounds of wheat with different grain color varies during grain filling stage.The contents of both ferulic acid and syringic acid peaks at 14 DAA.On the other hand,the content of p-comaric acid and the coffeic acid represent the highest value at 7 DAA.The contents of phenolic acid of white and red cultivars are relatively higher at the early stage of grain filling,while black wheat has relative higher content at the later stage.6.Expression profile of genes related to phenolic acid synthesis during grain filling indifferent grain color wheatThe expression of genes related to phenolic acid synthesis for wheat with different grain colors during grain filling stage are divided into three patterns.The first set of genes exhibit higher expression levels both at early and later grain development;these genes include Ta PAL1,Ta PAL2,Ta COM1,Ta4CL2 and Ta C4 H in black and red wheat,and Ta C4 H in white wheat.The second set of genes only exhibite higher expression levels during early development,including Ta COM2,Ta C3H2 and Ta4CL1 in black and red wheat,and Ta PAL1,Ta PAL2,Ta4CL1,Ta4CL2,Ta COMT1,Ta COMT2,Ta C3H2 in white wheat.The third pattern is only one gene,Ta C3H1,which is highly expressed at the later grain filling stage.Most of genes in white wheat belong to the second group,and most of genes in red and black wheat is included in group one.These results suggest that different wheat variety should be cultivated by suitable ways according to their unique end-use.For black wheat varieties,it should be focused on improving the antioxidant content;Whereas,for white wheat and red wheat,the high yield and high effective should be a priority.