Study On The Dynamic Changes And Influencing Factors Of Sweet Potato Tissue Culture Seedling Growth

This study used the stem segments of virus-free tissue culture seedlings of Jishu 26,Luoshu 13,and Longshu 9 as explants,and MS medium as the basic medium.Two cultivation methods were used:liquid culture and solid culture.Firstly,the effects of cultivation method,medium packaging amount,length and shape of inoculated stem segments on the growth of sweet potato tissue culture seedlings were studied;under the same conditions of medium composition,packaging volume(40m L/bottle),and cultivation environment,the growth dynamics and laws of sweet potato tissue culture seedlings of two varieties,Jishu26 and Luoshu 13,were studied within a culture cycle;on this basis,further research was conducted on the effects of different sweet potato genotypes,explant inoculation density,medium morphology,medium packaging amount,and bottle capacity on the dynamic growth of sweet potato tissue culture seedlings.Through this study,the basic conditions such as suitable cultivation methods,explant size and morphology for rapid propagation of sweet potato tissue culture seedlings were determined,and the growth and development changes,patterns,and influencing factors of sweet potato tissue culture seedlings within a culture cycle were clarified to optimize the optimal conditions for rapid propagation of sweet potato tissue culture seedlings,achieve precise regulation of rapid propagation technology of sweet potato tissue culture seedlings,reduce the production cost of rapid propagation of sweet potato tissue culture seedlings,and improve the efficiency of rapid propagation of tissue culture seedlings,Furthermore,it provides theoretical basis and technical support for establishing a mature and efficient technology system for rapid propagation of sweet potato tissue culture seedlings.The main results of this study are as follows:1.Screening and optimization of methods and methods for tissue culture of sweet potato seedlings(1)In the rapid propagation culture of sweet potato tissue culture seedlings,the liquid culture tissue culture seedlings grow more vigorously,and their plant height,proliferation coefficient,etc.are significantly higher than solid culture and glass wool support culture under the same conditions.(2)When using liquid culture to expand the virus-free seedlings of sweet potatoes,retaining a half cut petiole and a stem segment with a length of 1.5-2.0cm is the most suitable explant.It not only facilitates cutting and inoculation,improves inoculation efficiency,but also has a high seedling rate and rapid growth of tissue cultured seedlings.(3)The use of liquid culture for rapid propagation of sweet potato tissue culture seedlings,with an expansion medium of 30 m L/bottle,is most conducive to the growth and proliferation of tissue culture seedlings.2.Dynamic changes and patterns of growth of sweet potato tissue cultured seedlings(1)Under specific cultural conditions,from explant inoculation to tissue culture,the stem and leaf growth of sweet potato tissue culture seedlings tends to wither and decline,and the changes in stem and leaf growth within a culture cycle follow a "slow fast slow" "S-shaped growth curve.According to the growth rate and variation characteristics of stem and leaf of tissue cultured seedlings,the growth process of tissue cultured seedlings can be divided into four stages: adaptive growth stage,rapid growth stage,slow growth stage,and stagnant growth stage.(2)Sweet potato tissue cultured seedlings at different growth stages exhibit significantly different growth characteristics.During the adaptive growth period,tissue cultured seedlings mainly undergo root differentiation and elongation,axillary bud germination,but leaf formation and plant height growth are slow;During the rapid growth period,the tissue cultured seedlings have formed a relatively developed root system,and the rate of leaf formation and plant height growth is very rapid.Within 4 days,the average number of leaves of the tissue cultured seedlings has increased by 1.85 pieces per plant,and the average plant height has increased by 1.03 cm,which is significantly higher than the stem and leaf increment in other growth stages;During the slow growth period,the formation rate of leaves in tissue cultured seedlings slows down,the elongation rate of stem nodes slows down,and the increment of leaf number and plant height significantly decreases.The plant grows slowly,with an average increase of 0.67 leaves per plant and an average increase of 0.56 cm in plant height within 4 days;During the stagnant growth period,the rate of leaf formation and plant height growth of tissue cultured seedlings tend to stagnate.Within 4days,the average increase in leaf number of tissue cultured seedlings is only 0.19 pieces per plant,and the average increase in plant height is only 0.23 cm.There are also phenomena of plant decay such as an increase in yellow withered leaves and terminal bud death.3.Factors affecting the growth and dynamic changes of sweet potato tissue cultured seedlings(1)The growth process of tissue cultured seedlings under different influencing factors(sweet potato genotype,explant inoculation density,medium morphology,medium packaging amount,and bottle capacity)is similar,and can be divided into four stages: adaptive growth stage,rapid growth stage,slow growth stage,and stagnant growth stage.(2)Although the growth process of sweet potato tissue culture seedlings under different treatments is similar,there are significant differences in the speed of plant growth,the duration of each growth period,and the timing of entering each growth stage among different treatments.Compared to Luoshu 13,Jishu 26 tissue culture seedlings have a faster growth rate during the culture cycle,and the duration of the rapid growth period is longer(4 days).At the end of cultivation,the tissue culture seedlings have more leaves,higher plant height,and more robust plants.Compared with solid culture,liquid culture of tissue culture seedlings grows faster,not only entering the rapid growth period 4 days earlier,but also lasting longer(4 days).The changes in plant height and leaf increment are significant,and they enter the stagnant growth period earlier.The effects of different explant inoculation densities,medium packaging quantities,and bottle capacities on the growth process of tissue culture seedlings are similar.This is manifested as follows: under the same conditions as other influencing factors,the treatment with lower explant inoculation densities,more medium packaging quantities,and larger bottle capacities results in longer periods of rapid growth for tissue culture seedlings,and later periods of slow or stagnant plant growth.After the cultivation is completed,the overall growth trend of the tissue culture seedlings treated with different treatments shows from excellent to poor as follows: 6 plants/bottle>10 plants/bottle>20 plants/bottle;80 m L/bottle> 60 m L/bottle>40 m L/bottle;700 m L culture bottle>300 m L culture bottle.