Effects Of Root Characteristics On Nitrogen Use Efficiency Of Triticum Aestivum L.

Triticum aestivum L.is the main food crop for mankind,and its output directly affects people’s living standards,economic development,and social stability.Increasing wheat output can effectively solve the above problems.The application of nitrogen fertilizer is necessary to ensure the yield.Unreasonable application of nitrogen fertilizer not only leads to low nitrogen fertilizer utilization efficiency,but also brings harm to the ecological environment,economic development and human health.Improving nitrogen fertilizer utilization efficiency is crucial to the solution of the above problems.important.In this study,20 wheat varieties with different nitrogen efficiency were used as materials,and the method of hydroponics + sand culture was used to combine nitrogen and no nitrogen to determine the nitrogen efficiency,root morphological characteristics,root anatomical characteristics,root physiological characteristics and nitrogen metabolism of wheat at the seedling stage.The determination of the inheritance and expression of related genes,establishes the relationship between root characteristics and nitrogen efficiency,and hopes to provide theoretical support for the selection and breeding of nitrogen-efficient wheat varieties.The results of the study are as follows:(1)The grain nitrogen content and nitrogen accumulation of different genotype wheat varieties have significant differences.According to the amount of grain nitrogen accumulation,20 varieties are divided into high,medium and low grain nitrogen accumulation varieties.The high grain nitrogen accumulation varieties include Xinong 583,Ximai 203,Zhongxinmai 28,Fugao 2,Xinong 529,Huagao 55 The varieties with medium-grain nitrogen accumulation include Shaanmai 139,Zhongmai 170,Zhongmai 175,Xinong 627,Xinong 3517,Xiaoyan 22,Zhengmai 366,and Xinong 389.The low-grain nitrogen accumulation varieties are Changfeng 2112.Qin Xin 271,Zhisheng No.5,Xinong1018,Xi’an 240,Xinong 538.The highest nitrogen accumulation was 1.007 mg/seed,the lowest was 0.732 mg/seed,and the average was 0.889 mg/seed.Under different treatment conditions,the order of nitrogen absorption efficiency,nitrogen accumulation in each part,and total nitrogen accumulation of plants among varieties was consistent with the accumulation of grain nitrogen.(2)Root morphology is significantly affected by the presence or absence of nitrogen,and root morphology also affects nitrogen efficiency.The root dry weight,leaf dry weight,total root length,total root surface area,and total root volume of the nitrogen treatment were significantly greater than those of the non-nitrogen treatment,but the average root diameter was smaller than that of the non-nitrogen treatment.The root dry weight,leaf dry weight,total root length,total root surface area,and total root volume were 1.28%～40.27%,1.58%～33.33%,15.21%～80.56%,6.35～67.24,3.17 higher than those without nitrogen.%～51.11%.Varieties with high grain nitrogen accumulation have higher root dry weight,leaf dry weight,total root length,total root volume and total root surface area than those with low grain nitrogen accumulation.Root morphology characteristics are significantly related to nitrogen absorption efficiency and nitrogen accumulation,indicating that better root morphology can promote the absorption and accumulation of nitrogen by roots.(3)Root anatomical characteristics affect the nitrogen efficiency of wheat,but different characteristics have different effects.The stem diameter,cortex thickness,epidermal thickness,number of cortex layers and epidermal cells of nitrogen-treated wheat varieties were higher than those of non-nitrogen treatment,the highest were 10.53%,24.72%,9.81%,14.58%,12.84% higher,respectively,but the cortex The number of parenchyma cells is less than that of nitrogen-free treatment.Under nitrogen treatment,the number of cortex layers was significantly negatively correlated with the aboveground nitrogen distribution ratio(-0.44),and was significantly positively correlated with the root distribution ratio(0.44),indicating that the more cortex layers,the lower the aboveground nitrogen distribution ratio,The higher the root distribution ratio;the skin thickness and the root distribution ratio are significantly negatively correlated(-0.54),indicating that the thinner the skin thickness,the higher the root distribution ratio.(4)Different root physiological indexes have different effects on nitrogen efficiency.Compared with the nitrogen-free treatment,the nitrate reductase activity of wheat roots and leaves of different varieties of wheat under the nitrogen-containing treatment increased,and the overall performance was nitrogenous root> nitrogen-free root> nitrogenous leaf>nitrogen-free leaf,two treatments Under the conditions,the nitrate reductase activity in roots and leaves had no significant relationship with nitrogen absorption,accumulation and distribution.The root respiration rate under nitrogen treatment was 18.46-65.47% higher than that under nitrogen-free treatment,and S13 and S19 were higher under both treatments.Root respiration rate and nitrogen absorption efficiency,shoot nitrogen accumulation,root nitrogen accumulation,and whole plant nitrogen accumulation were significantly positively correlated under nitrogen treatment,and the correlation coefficients were 0.59,0.53,0.47,0.46,respectively.It shows that the increase of root respiration rate promotes the increase of nitrogen absorption efficiency and nitrogen accumulation.(5)The expression of NRT1.1 in the roots and leaves of the wheat treated with nitrogen was greater than the expression of NRT1.1 in the roots and leaves of the nitrogen-free treatment,respectively,and the overall performance was nitrogenous roots> nitrogen-free roots> nitrogenous leaves> nitrogen-free leaves.S19,a variety with high grain nitrogen content,had the highest expression of NRT1.1(in leaves)under the two conditions,indicating that the high expression of NRT1.1 in leaves may promote nitrogen absorption and accumulation in plants.(6)Root morphology has the greatest influence on nitrogen absorption,accumulation and distribution of wheat.Root respiration rate also has an impact on nitrogen absorption and accumulation.In addition,the thinner the epidermis and the thicker the cortical layer,the nitrogen of wheat varieties Absorption,accumulation and distribution are higher.