| In this study,a field experiment was carried out at Yigang Farm in Shangshui County,Zhoukou City,Henan Province,during two consecutive winter wheat growing seasons from 2018 to 2020.The experiment was designed as a three-factor split plot arrangement.Treatments included two varieties(Xinhua 818 with medium tiller ability and high heading rate and Bainong 207 with high tiller ability and medium heading rate),three nitrogen rates(N0,0 kg·hm-2;N240,240 kg·hm-2;N360,360 kg·hm-2)and three plant densities(M1,225 ten thousand plant·hm-2;M2,375 ten thousand plant·hm-2;M3,525 ten thousand plant·hm-2).The differences of carbon-nitrogen metabolism in flag leaf,vascular bundle structure in stem,endogenous hormone content in grain and yield of winter wheat under three-factor treatments were analyzed.The internal relationships between different physiological index parameters and grain yield were explored.The suitable combination of nitrogen-density treatment in the moist clayey soil area of southeast Henan province was revealed and its physiological mechanism of increasing production and efficiency was clarified.The objective of this study was to provide technical support and reference basis for the high-yield,high-efficiency and sustainable cultivation of winter wheat.The main results were summarized as follows:1.Effects of nitrogen-density regulation on the yield of winter wheat with two tillering and panicle type.The interaction effects of nitrogen-density significantly affected the grain per spike of winter wheat with two tillering and panicle type,which in turn affected the grain yield.The nitrogen fertilizer was the main effect.In 2018―2019,the yield of the two varieties in M2N240 treatment was the highest,while in 2019―2020,the yield in M1N360 treatment was the highest,followed by the M2N240 treatment.And there was no significant difference in the yield between the two treatments.Compared with the M1N0 treatment with the lowest yield,the average yield increase of the two varieties in M1N360 and M2N240 treatments were56.48%、55.81%(Xinhua 818)and 136.26%、137.17%(Bainong 207),respectively.2.Effects of nitrogen-density regulation on the carbon and nitrogen metabolism of winter wheat with two tillering and panicle type.Variety,nitrogen fertilizer and density and their interactions significantly affected the carbon and nitrogen metabolism of winter wheat.The effects of nitrogen application amount and plant density on carbon and nitrogen metabolism of the two winter wheat varieties in different growth stage were different.On the whole,the advantages of nitrogen-density regulation on carbon and nitrogen metabolism of the two winter wheat were mainly in the late and middle filling stage,respectively.And the physiological parameters of each carbon and nitrogen metabolism in M2N240 treatment were the largest.The carbon metabolism physiological parameter in M2N240 treatment had an average increase of 88.66%―261.22%compared with the minimum treatment M3N0.The average increase of the nitrogen metabolism physiological parameter in M2N240 treatment was 75.89%―688.58%,compared with the minimum treatment M1N0 or M3N0.With the development of the growth period,the correlation between the carbon metabolism physiological indexes and the yield of the two cultivars changed from negative to positive,and all the nitrogen metabolism physiological indexes(except nitrate nitrogen)were significantly positively correlated with the yield.The balance of carbon and nitrogen metabolism had a greater impact on the yield formation of winter wheat varieties with different tiller-heading rate,especially in the late growth stage,which may be the main physiological reason that the yield of Xinhua 818 was higher than that of Bainong 207 as a whole.3.Effects of nitrogen-density regulation on the vascular bundle structure of winter wheat with two tillering and panicle type.Nitrogen fertilizer and density could significantly regulate the vascular bundle structure of winter wheat,enhance the efficiency of nutrient transport,and then increase the yield.The number of vascular bundles and the xylem vessel area of large vascular bundles were positively correlated with the yield.Compared with Xinhua 818,the regulation effect of M2 treatment in Bainong 207 on the vascular bundle structure was higher.In Bainong 207,medium density was beneficial to the increase of stem wall thickness,vascular bundle area and phloem area,but its correlation with yield was weak.The regulation effect of nitrogen application amount on the vascular bundle structure in Xinhua 818 was significant.Compared with N0 treatment,the number of small vascular bundles,total number of vascular bundles,protoxylem and metaxylem vessel area of large vascular bundle in N240 treatment increased by 36.32%,33.69%,43.71% and 35.43%,respectively.The effect of nitrogen-density regulation on the vascular bundle structure of the two winter wheat cultivars was mainly reflected in the level of nitrogen application amount.Under proper nitrogen application,the vascular bundle structure in Xinhua 818 could promote the efficient nutrient transport,and then achieve yield increase.4.Effects of nitrogen-density regulation on the endogenous hormone content in grain of winter wheat with two tillering and panicle type.The interannual trend of the effect of nitrogen application rate on the endogenous hormone contents in grains of the two winter wheat varieties was basically the same,and the hormones content in 2018―2019 years was higher than that in 2019―2020 years.On the whole,the content of endogenous hormone in Xinhua 818 was higher than that in Bailong 207,and the difference of endogenous hormone content between the two varieties was mainly reflected in the superior grains.The increase of nitrogen application could increase the auxin,gibberellin and abscisic acid contents in superior and inferior grains,but the endogenous hormone content between N240 and N360 treatments varied with variety,grain position,and filling stage.Under different nitrogen application treatments,the trends of auxin and gibberellin contents in superior grains of the two winter wheat were the same.In Xinhua 818,the changing trends of the auxin and gibberellin contents were N240>N360>N0 in the middle filling stages and N360>N240>N0 in the late filling stages,respectively,while those in Bainong 207 were N360>N240>N0 and N240>N360>N0,respectively.In the middle and late filling stage,the abscisic acid contents of superior and inferior grains in Xinhua 818 were highest in N240 treatment.However,under different nitrogen application,those in Bainong207 were different in superior and inferior grains.In conclusion,compared with Bainong 207,the grain filling of Xinhua 818 in M2N240 treatment started earlier and lasted longer,and the content of endogenous hormone in superior and inferior grains was more coordinated,which may be one of the physiological reasons for the high seed setting rate of Xinhua 818.Considering the yield,carbon-nitrogen metabolism in flag leaf,vascular bundle structure in stem and endogenous hormone content in grain of winter wheat with two tillering and panicle type,the single factor or two-factor interaction of M2N240 treatment significantly regulated the physiological function of carbon-nitrogen metabolism in the middle and late filling stage,the grain filling rate in the superior grains and the transport efficiency of vascular bundle,thereby promoting the formation of its grain yield.The M2N240 combination treatment could be used as a suitable nitrogen-density cultivation mode for winter wheat in the moist clayey soil area of southeast Henan province. |
PDF Full Text Request