Effects of different nitrogen levels on seedling growth and root primary vascular system of the Loquat trees

The effects of nitrogen levels(0,30,60,90,120 mmol/L) of NH4NO3 on growth,some physiological characteristics and root tissue structure of Loquat seedling were studied.The results showed that plant growth,leaf length,leaf width,leaf area,biological weight,contents of chlorophyll a and chlorophyll b,content of soluble sugar,root diameter,root stele diameter and number of vascular bundle showed the trend of increasing firstly and reducing again with increasing nitrogen levels,and there were the highest at 60 mmol/L level,while content of starch was contrary to those of above indexes.Content of total nitrogen had a trend of increasing with increasing nitrogen levels.There was a correlation between the root as correlation and number of primary xylem.