%A WU Chun-Hong,LIU Qing,KONG Fan-Mei,LI Huan,SHI Yan-Xi %T Effects of Nitrogen Application Rates on Root Yield and Nitrogen Utilization in Different Purple Sweetpotato Varieties %0 Journal Article %D 2016 %J Acta Agronomica Sinica %R 10.3724/SP.J.1006.2016.00113 %P 113-122 %V 42 %N 01 %U {https://zwxb.chinacrops.org/CN/abstract/article_6029.shtml} %8 2016-01-12 %X

A two-year field experiment was conducted in the Modern Agricultural Science and Technology Demonstration Garden of Qingdao Agricultural University in 2013 and 2014. Three varieties of purple sweetpotato (Zhezi 1, Ningzi 2, and Zijing 2) were grown with three nitrogen rates (0, 75, and 150 kg·ha–1 as N0, N1, N2 treatment, respectively). The storage root yield, dry matter accumulation rate, nitrogen accumulation amount and N use efficiency of the purple sweetpotato were investigated under the three N levels. The results showed that the storage root yields of Zhezi 1 and Zijing 2 in N1 and N2 treatments reduced to a varying degree compared with N0 treatment, with the decrease of 12.64% and 13.32% for Zhezi 1 and 3.94% and 29.06% for Zijing 2, respectively. Meanwhile, the storage root yield of Ningzi 2 in N1 treatment slightly increased by 8.5% and 3.4% in 2013 and 2014, respectively, compared with N0 treatment, but significantly decreased in N2 treatment compared with both N0 and N1 treatments. Compared with N0 treatment, the shoot biomass increased from 2.7% to 20% in N1 and from 12.3% to 36.4% in N2, in 2013, as well as from 12.6% to 51.9% in N1 and from 28.7% to 85.5% in N2, in 2014. However, the harvest index, N harvest index and nitrogen use efficiency gradually reduced with the increase N application. The correlation analysis showed that the root yield positively correlated with all the nitrogen efficiency parameters, however the shoot biomass negatively correlated with the harvest index, nitrogen harvest index and nitrogen utilization efficiency (r = 0.615**, 0.704**, 0.663**). The shoot biomass of Zhezi 1 and Zijing 2 increased with the increase of N application, showing the decrease of photosynthate from shoots to roots. The nitrogen demand of Ningzi 2 was higher than other two varieties, and the moderate nitrogen application could increase the root yield in fertile soil. In conclusion, the coordinated growth of shoots and roots is important for improving storage root yield and N use efficiency.