Evaluation Of 18 Sweet Potato Resources In Hainan And Effects Of Nitrogen Fertilizer Treatment On Yield And Quality Of Sweet Potato

In view of the relatively backward development of the sweet potato industry in Hainan,the main varieties are single,and the application standards of nitrogen fertilizer are not clear.In this study,18 sweet potato varieties were selected for trial cultivation in Xiashui Village,Wencheng Town,Wenchang City,Hainan Province,in an attempt to screen out sweet potato varieties suitable for planting in Hainan.At the same time,Hainan’s main sweet potato variety Gaoxi 14 was used as the test material.Under field conditions,three types of nitrogen fertilizers:ammonium nitrogen fertilizer,nitrate nitrogen fertilizer and amide nitrogen fertilizer,and each shape set 4 levels of 0 kg/hm²,60 kg/hm²,120 kg/hm²,180 kg/hm²on its growth and development,yield and quality.Explore the nitrogen form and level to affect the accumulation,transport and distribution of sweet potato photosynthetic products,in order to obtain a reasonable nitrogen fertilizer application standards,and provide guidance for the cultivation of high-yield and high-quality 14 lines.The main findings are as follows:1.A comprehensive evaluation of 18 sweet potato varieties through membership function transformation and factor analysis.Finally,fivevarieties with excellent comprehensive traits were selected through comprehensive evaluation,including Fujian 1,Haikou 3,American sweet potato,Wenchang 6,and Longyan 6,which provide key cues for the further promotion and utilization.2.The nitrogen fertilizer application rate of 120 kg/hm² had the highest yield of roots,and the yield increase effects under the three nitrogen forms were 16.78%,7.12%,and12.12%,respectively.Among the three forms of nitrogen fertilizer treatment,AN treatment has the best yield increase effect,and AN₁₂₀ treatment is significantly higher than other treatments.Nitrogen application can increase the number of tubers per plant and the weight of single potato.Three forms of nitrogen fertilizer have different ways to increase yield.The AN treatment increases the yield by increasing the number of tubers per plant,the NN treatment increases the yield by increasing the weight of sweet potato,and the AMN treatment has both.3.This study showed that the initial potential,average dry matter accumulation rate and maximum dry matter accumulation rate of root expansion were the highest when the application rate of nitrogen fertilizer was 120kg/hm².Among the three forms of nitrogen fertilizer treatment,the initial potential,average accumulation rate and maximum accumulation rate of root expansion of AN₁₂₀ treatment were higher than those of NN₁₂₀ and AMN₁₂₀ treatment.4.Within a certain range,nitrogen application can increase the stem thickness,branch number,average source-sink distance,T/R ratio of the sweet potato base,and significantly increase the sucrose concentration at the base of the stem.Compared with NN and AMN treatments,AN treatment increased the stem thickness,branch number,average source-sink distance at the base of the sweet potato in the early and middle growth stages,and promoted the growth and development of aboveground.In the later stage of sweet potato growth,by increasing the number of branches,the average"source-sink"distance is reduced,and the transportation efficiency of photosynthetic products is improved.Compared with AMN₁₂₀treatment,AN₁₂₀ treatment accelerates the uninstall of sucrose to the roots by increasing the sucrose concentration difference from the base to the top of the stem during the root expansion stage.5.The study results showed that the soluble sugar,sucrose,soluble protein,and polyphenol content of roots increased first and then decreased with the increase of nitrogen application rate,which was the largest when the nitrogen application rate was 120 kg/hm²,the content of starch and flavonoids continued to decrease,and vitamin C The content gradually increased.The AN₁₂₀ treatment significantly increased the content of soluble sugar,sucrose,and soluble protein;when the nitrogen application rate was 180 kg/hm²,the starch content decreased significantly.NN and AMN treatment significantly reduced the flavonoid content,a small amount of AN treatment had no effect on the flavonoid content,excessive AN treatment significantly reduced the flavonoid content.