Effects Of Different Density And Nitrogen Application On Yield Formation And Lodging Resistance Of Gaoyou 2018 With High Gluten

It is an eternal theme of wheat production technology to obtain stable production,high yield and high resource efficiency.In this paper,we studied the effects of different density and nitrogen application on yield formation andlodging resistance of strong gluten wheat Gaoyou 2018 for two consecutive years from 2016 to 2018.The field experiment was arranged with split plot design with density as the main plot and N application as the sub plots in 2016 2018.The planting density were D240,2.4 million;D300,3 million;D360,3.6 million;D420,4.2 million;D480,4.8 million;D540,5.4 million plants per hectare.six main area density and the levels of N application were N120,20 kg·hm^-2;N180,180 kg·hm^-2;N240,240 kg·hm^-2;N300,300 kg·hm^-2 for sub plots.The results were as follows:1.With the increase of density,the total number of stem（spike）and dry matter accumulation of wheat increased first and then decreased.The total stem（spike）number and dry matter accumulation amount（except the mature period）both reached the maximum value at D480 in Xinji experimental station from 2016 to 2017.The variation range of final spike number between different densities was 659.2⁷71.1 million ·hm^-2,and the difference between D480 and D360 and D420 was not significant.The total stem number of D480 in all growth periods was the highest except the jointing and maturation periods in Gaocheng experimental station from 2017 to 2018.There were no significant difference in mature period of spikelets and accumulation of dry matter between different density.2.Wheat LAI reached the maximum in booting stage and showed an unimodal curve changes with the development of growth period.From 2016 to 2017,the LAI of wheat（except the rising period）increased first and then decreased with the increase of density.The D480 treatment got the highest IAI（24 days after flowering）,and D480 was significantly greater than D240 in each period.From 2017 to 2018,the LAI of wheat in the rising and jointing stages reached the highest in D480 and is significantly greater than D240 and D300.The D420 treatment got the highest IAI in booting and flowering stages and there was no significant difference between the densities at the flowering stage.At 24 days after flowering,the LAI of D360 treatment was the highest and was significantly greater than D480,but there was no significant difference from other density treatments.3.SPAD of wheat flag leaf decreased rapidly on the 21 st day after flowering and the highest value was D360 from the 7th day to the 21 st day after flowering with the highest value of D480 in the flowering period from 2016 to 2017.The D240 treatment got the highest SPAD and D420 got the highest value from 7 d to 21 d after flowering during flowering period from 2017 to 2018.There was no significant difference between D240 and D300 with D420 treatment.The changes of light transmittance of wheat are different in two years.From 2016 to 2017,the light transmittance of flag leaves decreased with the increase of density.D360 and D300 got the minimum light transmittance of the inverted double leaf layer and the inverted triple leaf layer in the flowering stage and the middle grouting stagerespectively.From 2017 to 2018,the light transmittance of each leaf layer increases first and then decreases with the increase of density at the flowering and grouting stage,among which D480 and D540 had lower light transmittance.4.The grouting rate of each treatment increased first and then decreased with the growth period.It got the highest grouting rate at 18 days after flowering and 24 days in these two different grow period respectively.It was the highest rate at D240 and D300 from 6 d to 18 d and 24 d after flowering,and was significantly greater than D480 from 2016 to 2017,While,from 2017 to 2018,the highest rate was at D540 at 6 d after flowering,but no significant difference with D240 treatment.The highest grouting rate was D240 from 18 d to 24 d after flowering.Therefore,low density maintained a high grouting rate after flowering all times.5.There was a small difference of 1000-grain weight under different densities comparing the yield and yield composition of Xinji test station from 2016 to 2017.Grain number per ear decreased with the increase of density,and D300 was significantly greater than other density while there were no obvious difference of grain number per ear between D300 and D240.It was 3.48 of the largest spike grain number difference between density.The number of spikes increased first and then decreased with the increase of density,and the number of spikes of D300,D360,D480 and D540 was higher.In the Yucheng test station,there were not significant different in the 1000-grain weight and the number of panicles at each density from 2017 to 2018.The number of spikes treated by D240 and D300 was significantly greater than other densities.6.The response of plant height and barycenter height to density was different in two years.The first section length and the second section length of wheat base increased with the increase of density.From 2016 to 2017,plant height and center of gravity increased first and then decreased,with the highest value at D480.From 2017 to 2018,the height of the plant and the height of the center of gravity at 30 d after flowering were highest at D540.The length of the first internode and the length of the second internode in two years（the highest was D480 on 20 days after flowering）were the highest at D540.From 2017 to 2018,the length of the first and second internodes D540 was significantly higher than that of D240 on the 20 th day after flowering.The first and second internode rod wall thickness,roughness,fullness and mechanical strength were all treated with the density of D240（except that the thickness of one rod wall at 20 d after flowering from 2016 to 2017 was the highest with the density of D300）.From 2016 to 2017,there was no significant difference in the thickness of rod wall treated with different densities and the mechanical strength of D240 was significantly higher than that of D540.From 2017 to 2018,the thickness of the rod wall of D240 on the 20 th day after flowering was significantly higher than that of D540 and the difference was not significant on the 30 th day after flowering.In the two-year experiment,D240 got a higher thickness and fullness of internode bar wall than that of D540.7.It was D540 that has the the highest accumulation in total nitrogen accumulation,leaf,ear and grain compared with different densities in mature stage from 2016 to 2017,than that of D240.The nitrogen accumulation of stem sheath ranged from 8 kg·hm^-2 to 17 kg·hm^-2,and that of grain ranged from 120 kg·hm^-2 to 170 kg·hm^-2.While the total nitrogen accumulation,leaves and panicles were the highest with D420 from 2017 to 2018.Nitrogen accumulation in stem sheath decreased with increasing density,ranging from 29⁵0 kg·hm^-2 and from 100¹30 kg·hm^-2 in grain.N240 and N300 had the largest nitrogen accumulation in two years,but the difference with other densities was not significant.In a word,it was D300 and D360 that had a relatively high yield considering the effects of comprehensive density and nitrogen application on winter wheat yield,yield formation and anti-knock ability.Although high density（D480 and D540）were better than D300 and D360 in total stem（spike）number,dry matter accumulation,nitrogen accumulation and LAI.However,the high-density flag leaf had a low transmittance,a thousand-grain weight,and a small number of kernels which would cause group obscuration,yield decline,and increase the risk of lodging.There were no significant difference in total stem（ear）number,LAI,dry matter accumulation,light transmittance,yield and lodging resistance by different nitrogen application,indicating that lower nitrogen application rate could also meet crop nitrogen requirements.Considering the cost-saving and high-yield aspects,the suitable density is between 3 million and 3.6 million in different years in Hebei Province,and the suitable nitrogen application rate is 120 kg·hm^-2.