| As a major wheat producing area in China,the Huanghuai wheat production region has long been faced these two major problems,improper application of nitrogen fertilizer and shortage of water resources,which bring great challenges for wheat yield and food security.Reasonable water and fertilizer application,which helps to build a good root system,is an important way to improve water and fertilizer utilization efficiency and achieve high and efficient wheat yield.In our study,the pot experiment was conducted during the wheat growing period of 2020-2022 at the Science and Education Park of Henan Agricultural University,with two wheat cultivars,Bainong207 and Xinmai 35,as the test materials.Two factors,moisture and N application,were set,with moisture as the main zone,well-watered(WW),75 % ± 5 % relative water content of soil and drought stress(DS),50 % ± 5 % relative water content of soil,N application was set as the secondary zone,with three N application levels of 0,120 and240 kg hm-2,which translates into pot doses of 0(N0),1.16(N1)and 2.32 g(N2)of urea per pot.The changes of root growth,photosynthetic material production,nitrogen translocation and yield of wheat under different water and nitrogen treatments were systematically studied to provide theoretical basis and technical support for reasonable water and nitrogen management in wheat production.The main results were obtained as follows.1.Effects of different water and nitrogen treatments on wheat yield and its componentsBoth N application and moisture had a significant effect on wheat yield and its components.Maintaining appropriate soil moisture conditions and reasonable N application both significantly increased spike number,spike grain number and yield of wheat.Compared with DS,the yield of Bainong 207 and Xinmai 35 increased by 51.15 %and 57.08 %(2020-2021),27.43 % and 31.39 %(2021-2022)under WW treatment,respectively.Compared to N0,N1 and N2 treatments increased yield of Bainong 207 by 24.02 % and 42.84 %(2020-2021),13.34 % and 43.86 %(2021-2022),respectively;Xinmai 35 increased by 21.21 % and 36.08 %(2020-2021),36.19 %and 46.74 %(2021-2022),respectively.In terms of yield components,irrigation and N application significantly increased the spikes and kernels in both cultivars,1000-Kernel mass slightly decreased with increasing N application,but the difference between treatments was not significant.The highest yield was obtained in both cultivars with WWN2 treatment.2.Effects of different water and nitrogen treatments on photosynthetic material production and accumulation and translocation of nitrogen in wheatBoth irrigation and nitrogen application significantly increased photosynthetic capacity,accumulation and translocation of dry matter and nitrogen in wheat.Under well-watered conditions,the chlorophyll content,net photosynthetic rate and stomatal conductance of wheat were significantly higher than that under drought stress conditions,and showed N2 > N1 > N0 under different N treatments.Compared to DS treatment,the WW treatment increased the above-ground dry matter accumulation of Bainong 207 and Xinmai 35 by 24.00 % and 36.17 %(two-year average),respectively.Compared with N0,NI and N2 treatments increased the aboveground dry matter accumulation by 23.62 % and 40.46 % for Bainong 207 and 28.44 % and 56.19 % for Xinmai 35,respectively.Under different water and nitrogen treatments,the aboveground nitrogen accumulation increased with the advancement of growth period and showed the maximum performance at maturity,while root nitrogen accumulation reached the maximum at flowering.Compared with DS treatment,post-anthesis nutrient organ nitrogen translocation of Bainong 207 and Xinmai 35 increased by 10.79 %and 27.70 %,respectively,under WW treatment.Compared with N0,the N1 and N2 treatments increased the post-anthesis nutrient organ nitrogen translocation of Bainong207 was by 46.75 % and 82.67 %,respectively,and Xinmai 35 increased by 64.14 %and 94.61 %,respectively.Reasonable water and nitrogen are beneficial to promote accumulation and translocation of dry matter and nitrogen to improve wheat yield.3.Effects of different water and nitrogen treatments on root morphologyComparing to the DS treatment,root length and root surface area of Bainong 207 increased by 36.40 % and 31.83 %,17.18 % and 15.11 % for Xinmai 35(two-year average)under WW treatment.The root-to-shoot ratio showed a decreasing trend with the increase of N application,which of Bainong 207 and Xinmai 35 decreased by 18.32 %and 21.12 % for N1 and 28.08 % and 32.35 % for N2,respectively,compared with N0.Adequate water and appropriate N application both promoted root growth,and a reasonable root-to-shoot ratio was beneficial to root absorb water and nutrients from the soil.The ANOVA analysis showed that the single factors of moisture and N application had significant or greatly significant effects on root length,root surface area,root weight,root volume and root-to-shoot ratio of wheat,while the interaction between them did not have significant effects on root-to-shoot ratio.4.The correlation analysis between root morphology and yieldBy analyzing the relationship between root morphology and yield of wheat,it was found that the yield of both cultivars showed significant positive correlations with root length,root surface area,root volume and root dry weight,while negative correlation with root-to-shoot ratio,and the number of spikes was significantly correlated with root indexes at all sampling times(wintering,jointing,flowering and maturity).We have considered the main and mutual effects of moisture and N application on photosynthetic capacity,accumulation and translocation of dry matter and nitrogen,root morphology and yield of wheat.Under this test condition,75 % ± 5 % relative soil water content and 240 kg hm-2 N application(WWN2 treatment)were conducive to the coordinated development of the three elements of wheat yield,and the accumulation and translocation of aboveground dry matter and nitrogen and root morphology all showed high levels,indicating that maintaining 75 % ± 5 % relative soil water content and 240 kg hm-2 N application is a suitable water and N combination for wheat cultivation. |
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