Comparative Study On Nitrogen Absorption Characteristics Of Different Ttypes(Varieties)of Wheat Seedlings

In order to further explain the differences of nitrogen absorption and utilization efficiency of different ecological types of Wheat Seedlings under the same nitrogen application level,29 semi winter wheat varieties and 29 spring wheat varieties were selected to study the differences of nitrogen absorption efficiency of different types of wheat seedlings by solution culture method;On this basis,8 spring wheat varieties and 8 semi Winter Wheat Varieties with different nitrogen efficiency were selected.The nitrate absorption curve of root system and nitrate ion flow velocity of root tip of different wheat varieties with different nitrogen efficiency were compared,and the correlation between them and nitrogen efficiency was analyzed.The results and conclusions are as follows:1.Under the condition of conventional nitrogen concentration,nitrate nitrogen accumulation,root shoot ratio,stem leaf dry weight coefficient of variation in wheat stem,leaf and root were the largest,which could better reflect the differences among different wheat varieties,while total nitrogen content coefficient of variation was the smallest,which could not reflect the differences among different wheat varieties.2.The dry matter accumulation in stems,leaves and roots of semi winter wheat varieties were higher than that of spring wheat varieties,while the contents of organic nitrogen,nitrate nitrogen and total nitrogen were lower than that of spring wheat varieties.The trend of nitrogen accumulation(absorption)was consistent with that of nitrogen content,that is,the accumulation of organic nitrogen,nitrate nitrogen and total nitrogen in stems,leaves and roots of semi winter wheat varieties were lower than that of spring wheat varieties.The dry matter production efficiency of stem,leaf,root and whole plant of semi winter wheat was significantly higher than that of spring wheat.3.The results showed that the root shoot ratio could not reflect the difference of nitrogen uptake among different wheat varieties.The dry matter accumulation in stem,leaf and root of spring wheat was higher than that of semi winter wheat,while the content and accumulation(absorption)of organic nitrogen,nitrate nitrogen and total nitrogen were lower than that of semi winter wheat.Correlation analysis showed that there was a significant positive correlation between total dry weight and whole plant dry matter productivity;There was no significant correlation between root shoot ratio and whole plant dry matter productivity;There was a significant negative correlation between the total nitrogen content of stem and leaf and the dry matter yield of the whole plant;There was no significant correlation between root total nitrogen accumulation and nitrogen dry matter productivity of whole plant4.The results of nitrate nitrogen absorption curve showed that the NO3-absorption rate of different wheat varieties increased with the increase of NO3-concentration,but there was significant difference among the varieties.Among the eight spring wheat varieties,Sumai 11 maintained a higher absorption rate,with higher Vmax and Km values,and Sumai 188 had the largest Vmax and Km values,Yangmai 25 has the smallest Vmax and km;Among the eight semi winter wheat varieties,Xinmai 26 and Ruihua 520 had higher Vmax and Km values,xumai 33 had higher Vmax and Km values,and Baomai 5 had lower Vmax and Km values.The nitrogen efficiency of spring wheat varieties with high Vmax value was also high,while that of wheat varieties with low Vmax value was low,indicating that the nitrate nitrogen absorption rate of spring wheat varieties was consistent with nitrogen efficiency;However,Vmax and nitrogen efficiency of semi winter wheat varieties were not consistent.Correlation analysis showed that there was a correlation between Km value and nitrogen efficiency of spring or semi winter wheat varieties,but it was not significant.5.The results of ion flow velocity measurement showed that the nitrate ion flow velocity of all varieties had the largest velocity in the range about 400μm～600μm away from the top of root tip,different varieties are different.The results showed that the nitrate ion flow velocity of 8 spring and 8 semi winter varieties showed an inward flow trend,but there were significant differences among different varieties.Among the spring varieties,Sumai 11 had the largest nitrate ion flow velocity(48.2 pmol·cm-2·s-1),Ningmai 21 took the second place,and Huamai 7 had the smallest nitrate ion flow velocity(48.2 pmol·cm-2·s-1);Among the semi winter varieties,xumai 33 was the largest(48.2 pmol·cm-2·s-1)and Xinmai 26 was the smallest(48.2 pmol cm-2·s-1)Correlation analysis showed that there was a positive correlation between the maximum nitrate ion flow velocity and Vmax of the eight spring wheat varieties,but there was no significant correlation between the maximum nitrate ion flow velocity and Vmax of the eight semi winter wheat varieties.6.The results showed that Ningmai 21,Sumai 11,Ningmai 22,Sumai 188,Huaimai 35,Baomai 5,xumai 33 and Annong 0711 were nitrogen efficient varieties.Yangmai 22,Huamai 7,Shengxuan 6,Yangmai 25,Xinmai 26,Baomai 2,Lianmai 7 and Ruihua 520 were low nitrogen efficiency varieties.