Characteristics of absorption, distribution and utilization of ¹⁵N in Red Globle Grape under fertilizer application in different depths

【Objectives】 This study was conducted to investigate the characteristics of absorption, distribution and utilization of 15N in Globle grape under fertilizer application in different depths, whichprovided a theoretical basis for guiding the reasonable nitrogen fertilizer application for grape under field conditions. 【Methods】 The experimental material was theRed Globlegrape which was grown for 15 years in grape main producing regions of Hebei Huailai to analyze the rule of 15N uptake, distribution and use in grape trees by 15N-urea fertilizer application at different depths(0, 20, 40 cm) in spring. 【Results】The results showed that Globle grape yield and Vc content with intermediate fertilization in 20 cm depth were optimal, respectively up to 22.77 t/hm2 and 117.2 mg/kg, which had the significant differences with surface (16.22 t/hm2 and 103.8 mg/kg) and 40 cm (19.32 t/hm2 and 102.3 mg/kg) fertilizer application. The Ndff of rootlets and other organs in each growth stage with 20 cm fertilizer application was significantly higher than surface and deep fertilization application. There were no significant differences with the 15N distribution rate in different organs of grape plant during the same period in three fertilizer application depth treatments, and the rate of 15N distribution in different organs showed the same trend during the whole growth period, so the fertilization depth had little influences on migration and distribution of 15N between organs. With the process of growth, the utilization ratio of 15N-urea of grape plants in different treatments was increased gradually, which was minimum in flowering, the nitrogen uptake and use efficiencies with 20 cm fertilization were highest, which were 7.36%, 14.70%, 20.24% and 24.54% separately in four growth periods, and were larger than those with the surface fertilization (7.05%, 10.74%, 12.70% and 16.54%) and the 40 cm fertilization treatment (5.39%, 7.31%, 10.93% and 13.62%). In fruit enlargement period, the whole plant 15N distribution rates were showed as rear central front, and were as leaf fruit branches in aboveground plants, and were as rootlets coarse main in grape underground part, which were consistent with different fertilization depth treatments. From three different fertilization depth, the 15N utilization rates of the fruit, leaves, branch, stem and root of the plant in the same parts, were the highest with 20 cm fertilization by flow, which were significantly higher than that with surface and 40 cm fertilization. 【Conclusions】The abilities of nitrogen absorption and nitrogen use efficiencies in grape trees were the best with 20 cm fertilizer application, fertilizer application depth had a significant impact on nitrogen absorption and utilization of Globle grape trees, had few influences on nitrogen distribution in whole tree. Therefore, 20 cm fertilizer application treatment was the best fertization program in grape main production areas of Hebei.