The Effect Of Localized Nitrate And Root Application Of 6-BA On Growth And Nitrogen Metabolism Of Malus Hupehensis Rehd.

The experiment was carried out in the solar greenhouse of Shandong Agricultural University Art Experimental Station in Tai'an City,Shandong Province from 2019 to2020.The effect of local nitrogen application and root application of 6-BA on plant phenotype and nitrogen use efficiency of Malus hupehensis Rehd.seedling was studied.The main results are as follows:1.Compared with the uniform application of nitrogen,there was no significant difference in plant height and leaf number between the local application of nitrogen,the local application of nitrogen did not affect the aboveground phenotype of Malus hupehensis Rehd.seedlings.After local application of nitrogen,the net photosynthetic rate,chlorophyll a,chlorophyll b and total chlorophyll content of leaves increased,which promoted the photosynthetic capacity of leaves.The total root length,total projection area,root volume and number of root tips of local nitrogen application plants were significantly increased compared with uniform nitrogen application plants,which made up for the reduction of root phenotype of non nitrogen application plants.Finally,there was no significant difference in total root length,total projection area,root volume and number of root tips between local nitrogen application and uniform nitrogen application plants.2.There was no significant difference between the fresh weight and dry weight of the above ground which roots of the seedlings treated with local nitrogen application and that of the seedlings treated with uniform nitrogen application.Local nitrogen application improved the biomass of the roots by promoting the growth of the roots at the place of nitrogen application,which made up for the inhibition of the growth of the roots at the place of no nitrogen application,so that the biomass of the roots at the place of uniform nitrogen application was achieved,which made the fresh weight and dry weight of the total roots at the place of underground nitrogen application There was no significant difference in weight and nitrogen application.The content of Fe,Cu and Mo in the shoot was not affected by local N application.The content of Fe,Cu and Mn increased by 25.53%,33.84% and 185.16%respectively in the roots treated with local N application compared with the roots treated with uniform N application.3.Compared with the uniform application of nitrogen,the local application of nitrogen did not affect the content of nitrate nitrogen and nitrate reductase in the upper part of the ground,the content of nitrate nitrogen and free amino acids in the upper part of the ground significantly decreased,the content of soluble protein in the upper part of the ground and nitrate reductase in the lower part increased,and the content of free amino acids and soluble protein in the root basically had no effect.The content of endogenous DHZR,GA3,GA4 and IAA increased partly.4.Root treatment with 6-BA solution for a period of time can promote the plant height and leaf number of aboveground part of Malus hupehensis Rehd.seedlings,and the recovery degree increases with the increase of 6-BA concentration.The chlorophyll content of leaves decreased with the increase of 6-BA concentration.The net photosynthetic rate,stomatal conductance and transpiration rate of leaves were significantly increased with the 0.1?M of 6-BA.In a certain range,the photosynthetic capacity of Malus hupehensis Rehd.seedlings was correspondingly increased with the increase of 6-BA concentration.Compared with the control,0.5?M and 1?M 6-BA can significantly promote the total root length,total projection area,root volume and root tip number.Compared with the above ground,to promote the root development in the underground,a slightly higher concentration of 6-BA can be used.5.Different concentrations of 6-BA treatment can significantly improve the biomass of the aboveground,underground and the whole plant of Malus hupehensis Rehd.,which shows that the plant biomass is sensitive to 6-BA,and 0.1?M of 6-BA can significantly promote the accumulation of plant biomass.With the increase of6-BA concentration,the content of iron,copper and molybdenum in the underground decreased,while the content of manganese increased first and then decreased.However,compared with the treatment of 1 Mn,the application of 6-BA can improve the content of these four elements,which is consistent with the trend of photosynthetic capacity of seedlings.6.Under the condition of nitrogen application,exogenous hormone 6-BA can significantly improve the activities of nitrogen metabolism related enzymes and nitrogen absorption efficiency of Malus hupehensis Rehd.seedlings,which is conducive to the accumulation of nitrogen in plants.Root application of 6-BA can also increase the activity of nitrate reductase and glutamine synthetase,increase the efficiency of nitrogen absorption and assimilation,reduce the content of inorganic nitrogen and free amino acids in the shoot,increase the content of soluble protein,affect the distribution of nitrogen metabolites in the seedlings,and promote the content of Nitrogen Assimilates.Root application of 6-BA changed the content of endogenous hormones,increased the content of DHZR,decreased the content of GA3,GA4 and IAA.