Study On Virus-Free Seedling And Propagation System Of Sweet Potato Varieties Planted In Hongan

China is the world’s largest producer of sweet potatoes(Ipomoea batatas(L.)Lam.).The sweet potato industry in Hongan County,Hubei Province holds a significant position and receives strong support from the local government.However,the spread of sweet potato viruses poses a threat to the development of the sweet potato industry.Plant virus diseases are a major problem in modern agriculture,causing substantial economic losses to important crops.Therefore,early detection of these pathogens and treatment of infected crops to make them virus-free is still one of the primary methods of controlling viral outbreaks.The aim of this study is to establish a virus-free environment for the primary sweet potato varieties grown in Hongan,Hubei Province,and to create a supportive virus-free seedling propagation system to control the spread of sweet potato virus disease.The research results are as follows:1.A universal sweet potato virus-free tissue culture system has been established.Stem tip culture was carried out at 20-22 ℃.Combining the progress of previous research,MS medium was used with the addition of 0.2 mg/L 1-Naphthaleneacetic acid(NAA)and 1.0 mg/L 6-Benzylaminopurine(6-BA)for the virus-free treatment of 13 main sweet potato varieties.The regeneration rate of sweet potatoes reached 84.62%,and the plant rate of different sweet potato varieties ranged from 5% to 100%.The two varieties that were more difficult to regenerate were both purple sweet potatoes,indicating that the tissue culture system still needs optimization.2.A sweet potato virus detection system has been established.The meristem is cultured and differentiated into plants,then the plants are tested for the presence of viruses through serological testing and PCR molecular testing methods.After confirming that the plant does not contain viruses,the identification and screening of superior lines is then carried out.3.A comparative trial was conducted to screen superior lines.The trial adopted a completely randomized block design with three repetitions in each experimental plot.The observation indicators were the tuber yields under various grading standards,which were <100g,100g-250 g,250g-500 g,>500g respectively.Under the standard of 100g-250g(fresh-cooked type),Gan-12 of the Zitanhong was identified as a superior line.Under the >500g standard(starch processing type),Fenshu 2-2 of the Fenshu was identified as a superior line.4.A preliminary sweet potato virus-free seed(seedling)propagation system has been established.The selected excellent lines were propagated by tissue culture seedlings(first-level seedlings),matrix seedlings(second-level seedlings)in the warm net room,and field seedlings(third-level seedlings)in the net shed for breeding production seeds.After 7 days of tissue culture cutting,the survival rate is about 96.70%.After 14 days,the survival rate is about 95%.The virus-free seedlings were easy to grow too vigorously after cutting.Seedling pruning and drug control were used to control the growth.As a result,the yield of the control treatment(without control measures)was the highest.The control did not have a yield-increasing effect.In order to increase the yield,the control treatment still needs to be optimized;The harvested tissue culture seedling micro tubers are small and shriveled.The tissue culture seedlings can be appropriately densely planted when cutting to increase the space for matrix cutting seedling expansion.