Effects Of Nitrogen Supply On Growth Of Plantlets In Vitro And Microtuberization Of Three New Potato Varieties

Nitrogen is particularly important for the growth and development of plants.Different plan ts or varieties have different absorption of nitrogen.Because potato is directly planted by tuber as seed in agricultural production,it is easy to be infected with virus es,which leads to potato degradation.Potato virus is a living parasite,so it is difficult to develop chemicals to control it.Breeding resistant varieties is a simple,economic and effective way to solve the degradation problem.However,there are about 40 viruses to infect potatoes,so it is difficult to develop varieties resistant to all of them.Therefore,the application of virus-free seed potato is an effective way to solve the problem of potato degradation.In the production process of virus-free seed potato,planlets in vitro and microtubers are the source,and the production of plantlets in vitro and microtubers mostly uses MS medium.MS medium is designed for tobacco pith callus culture,which is not necessarily suitable for the production of plantlets in vitro and microtubers.Nitrogen content may be too high for potato.In this experiment,three new potato varieties,’Dongnong 310’,’Dongnong 321’ and ’Dongnong 322’,were used as experimental materials.Based on MS medium,seven nitrogen levels(30,36,42,48,54,60(CK)and 66 mmol/L)were set to study the effects of different nitrogen levels on the growth indexes(plant height,root length,root number,stem node number,stem and leaf fresh weight,stem and leaf dry weight,root fresh weight,root dry weight,and stem diameter),physiological indexes(chlorophyll,proline,superoxide dismutase,soluble protein,and malondialdehyde)of plantlets in vitro,and microtuber traits(total microtuber weight,total microtuber number,large microtuber(diameter more than 5 mm)weight,large microtuber number,and microtuber dry weight).The results are as follows:(1)Except for stem diameter,root number,chlorophyll,malondialdehyde and superoxide dismutase,the effects of variety × nitrogen interaction on other traits studied were significant or highly significant.(2)The nitrogen level had a highly significant effect on the trats of plantlets in vitro and microtubers,indicating that changing the nitrogen level of MS medium has an effect on the growth of plantlets in vitro and microtubers.(3)When the nitrogen concentration was set at 36 mmol/L,the number of stem nodes of the three varieties was the highest,but when the nitrogen concentration was 42 mmol/L,the stem diameter of the three varieties was the highest.When the nitrogen concentration was set at 42mmol/L,’Dongnong 310’ and ’Dongnong 322’ had the highest fresh weight and dry weight of stems and leaves,but for ’Dongnong 321’,when the nitrogen concentration was 48 mmol/L,the fresh weight of stems and leaves was the highest,and when the nitrogen was 54 mmol/L,the dry weight of stems and leaves was the heaviest.(4)When the nitrogen was set at 42 mmol/L,’Dongnong 310’ and ’Dongnong 322’ had the highest number of total microtubers and large microtuber;when the nitrogen was 48 mmol/L,the number of total mictotuber and large microtuber of ’Dongnong 321’ were the most.The growth and development of plantlets in vitro was better,and the yield of induced microtubers was also improved when the nitrogen level in MS medium was reduced.These results could be used for reference in the study and production of plantlets in vitro and microtubers of potatoes.