| The experiment was conducted in two consecutive winter wheat growing seasons in 2018-2020 in Henan Province to address the common production problems of"excessive nitrogen application,high sowing,and poor matching between the agronomic control combination and the biological characteristics of varieties,making it difficult to shape a good production group structure,resulting in low and unstable yield".The experiment was conducted under field conditions in Yigang farm,Shangshui County,Zhoukou City,Henan Province,China.The experiment was conducted in a split-zone design,with variety as the main zone and two different tiller types,Xinhua wheat 818 and Bainong 207;planting density as the secondary zone and three levels,2.25 million plants/hm2(M1),3.75 million plants/hm2(M2)and 5.25 million plants/hm2(M3);nitrogen application as the secondary zone and no nitrogen application(N0),180 kg/hm2(N1),240 kg/hm2(N2),300 kg/hm2(N3),360 kg/hm2(N4).The analysis focused on the effects of variety,planting density and nitrogen application on tiller formation,dry matter and nitrogen accumulation and translocation,nitrogen utilization efficiency,spatial and temporal distribution of root morphology,yield and its constituent factors of winter wheat,and explored the relationship between dry matter production,nitrogen uptake and utilization,root morphology and seed yield of winter wheat.The aim was to screen the nitrogen density combinations suitable for high-yielding and high-efficiency production of winter wheat in the tidal soils of southeast Henan,with the aim of providing technical support for high-yielding and high-efficiency cultivation of winter wheat in this region.The main results of the study are as follows:1.Effects of nitrogen application rate and planting density on tillering and panicle formation of two winter wheat varietiesNitrogen application and planting density had significant effects on the number of spikelets per plant and tiller spike rate of both winter wheat varieties.The trends of the number of spikelets per plant and tiller spike rate with N application and planting density were basically the same in both winter wheat growing seasons.Xinhua wheat 818 had stronger tillering power than Bainong 207,while the tiller-to-shoot ratio was the opposite.Nitrogen application significantly increased the number of spikelets per plant,and the number of spikelets per plant of both winter wheat varieties tended to increase first and then decrease with the increase of N application,and the number of spikelets per plant of both winter wheat varieties was greatest under N2 or N3 treatment at all densities,and there was no significant difference between N2 and N3 treatments.With the increase of planting density,the number of spikelets of both winter wheat varieties decreased significantly,and the decrease of N treatment was greater than that of no N treatment.The number of adult spikelets per plant was reduced by 34.86%,50.94%(Xinhua wheat 818)and 35.61%,51.86%(Bainong 207)for medium and high densities of the two varieties,respectively,compared with the low density;the average number of adult spikelets per plant was increased by 20.92%,24.01 and 22.95%for the M1,M2 and M3 treatments without nitrogen application,respectively,compared with the nitrogen application treatment.2.Effects of nitrogen application rate and planting density on dry matter accumulation and transport in two winter wheat varietiesThe dry matter accumulation of the two winter wheat varieties differed in different fertility periods,and the dry matter accumulation of Xinhua wheat 818 at overwintering,nodulation,flowering and maturity was higher than that of Bainong 207,with an average increase of 4.76%,3.73%,10.83%and 15.58%,respectively.The preflower dry matter translocation,translocation rate and its contribution to seeds of the two winter wheat varieties differed in response to nitrogen application and planting density.Under low and medium densities,N application in the range of 0～300 kg/hm2 was not conducive to the preflower dry matter transfer of Xinhua wheat 818,but was beneficial to increasing the contribution of postflower dry matter to the seeds;under high N(N3,N4)treatments,the dry matter transfer amount,rate and contribution to the seeds of Bignon 207 were higher under all three planting densities,indicating that increased N application was beneficial to accelerating the preflower dry matter accumulation and transfer of Bignon 207.The dry matter accumulation and transfer rate of Bignon 207 under N3 and N4 treatments were higher at all planting densities.3.Effects of nitrogen application rate and planting density on nitrogen absorption and utilization of two winter wheat varietiesThe pre-flowering nitrogen transfer rate and pre-flowering nitrogen contribution rate of both winter wheat varieties showed a trend of "increasing then decreasing" with the increase of nitrogen application,while their pre-flowering nitrogen transfer rate showed different performance.The pre-flowering nitrogen translocation of Xinhua wheat 818 showed an increasing trend with the increase of N application under the treatment of M1 and M2,and an increasing trend followed by a decreasing trend under the treatment of M3 at high density;the pre-flowering nitrogen translocation of Bignon 207 showed an increasing trend followed by a decreasing trend with the increase of N application regardless of the planting density.Under the same level of nitrogen application,increasing planting density was beneficial to improve pre-flowering nitrogen accumulation and its nitrogen contribution;with the increase of planting density,the nitrogen fertilizer utilization rate,nitrogen fertilizer bias productivity and nitrogen harvest index of the two winter wheat varieties showed the same trend,with the overall change of increasing and then decreasing.The nitrogen uptake efficiency of Xinhua wheat 818 decreased with increasing planting density,while that of Bainong 207 increased with increasing planting density.Under the same planting density,increasing nitrogen application was beneficial to promote the accumulation of nitrogen in nutrient organs of winter wheat,and the pre-flowering nutrient organ nitrogen accumulation was the largest in the combination of M2N2 nitrogen density treatment.4.Effects of nitrogen application rate and planting density on the spatial and temporal distribution characteristics of roots of two winter wheat varietiesThe total root length(TRL),total root surface area(TRSA),and total root volume(TRV)of wheat per unit volume of 1 m soil layer showed a trend of increasing and then decreasing throughout the reproductive period,but there were differences in the reproductive period when the peak of each root morphological parameter occurred under different N-density combinations.At the same planting density level,TRL,TRSA and TRV of winter wheat showed a trend of increasing and then decreasing with the increase of N application;at the same N application level,TRL,TRSA and TRV of winter wheat also showed a trend of increasing and then decreasing with the increase of planting density,and the peak of TRL,TRSA and TRV of M2N2 treatment was the largest.Root length density(RLD),root surface area(RSA)and root volume(RV)of different soil layers in the same fertility period showed similar trends in the vertical direction,and all decreased gradually with the depth of soil layer.5.Effects of nitrogen application rate and planting density on the yield and its constituent factors of two winter wheat varietiesThe average yield,number of spikes per unit area and thousand grain weight of Xinhua wheat 818 were significantly higher than those of Bainong 207,with an average increase of 13.76%,19.70%and 10.08%respectively in both years,while the number of spikes was Under the same planting density,the increase of nitrogen fertilizer was beneficial to increase the yield,number of spikes per unit area and number of grains per spike,but not to increase the grain weight of winter wheat.In the range of 0～300 kg/hm2 of N application under low density,the increase of N fertilizer was beneficial to increase the number of spikes and grains per unit area,thus increasing the yield,and the effect of Xinhua wheat 818 was better when it exceeded 240 kg/hm2;in the range of 0-240 kg/hm2 of N application under medium and high density,the increase of N fertilizer could increase the number of spikes and grains per unit area and coordinate the relationship with the thousand grain weight,thus achieving the yield increase.The relationship between the number of spikes and grains per unit area and their relationship with the thousand grain weight could be reconciled to achieve yield increase.6.The relationship between root morphological parameters,nitrogen accumulation and yield of winter wheatThe regression analysis of plant N accumulation and seed yield with N application,and root length density,root surface area density and root volume density with N application at three planting densities of two winter wheats showed that the suitable N application rate for Xinhua wheat 818 to achieve high yield was 223.16 kg/hm2 to 258.91 kg/hm2 at medium and high density planting,while that for Bignon 207 was 274.35 kg/hm2 to 305.75 kg/hm2.The N fertilizer utilization efficiency of Xinhua wheat 818 was higher than that of Bainong 207,and this variety could achieve higher yields under lower N application conditions.Considering the peak N application levels of the three root morphological parameters of the two wheat varieties at different planting densities,the N application rates of 209.24 kg/hm2 to 226.76 kg/hm2 were beneficial to the root growth of winter wheat,increasing its root volume,root surface area and root length density,and enhancing the plant’s water and fertilizer uptake and utilization.Under the ecological production conditions of this experiment,the M2N2 nitrogen-density treatment combination with a total nitrogen application of 240 kg/hm2 and a planting density of 3.75 million plants/hm2 was beneficial to the coordinated development of the three factors of dry matter accumulation,nitrogen utilization,root morphological distribution characteristics and grain yield regulation of Xinhua wheat and Bainong 207.Under the ecological production conditions of this experiment,the combination of M2N2 N-density treatment with a total N application of 240 kg/hm2 and a planting density of 3.75 million plants/hm2 was favorable to the coordinated development of the three factors of Xinhua wheat 818 and Bainong 207 yield.240 kg/hm2)can be used as a suitable combination of nitrogen density control for winter wheat cultivation in the tidal soil area of south Henan. |
PDF Full Text Request