Tissue Culture And Plantlets Regeneration Of Hemarthria Compressa (L.F.) R.Br.

Whipgrass [Hemarthria compressa (L. f.) R. Br.], a rhizomatous perennial herb in Hemarthria genus (Panicoideae), mainly distributed in tropical and subtropical regions, as well as the Northern Hemisphere temperate humid regions. Being a high quality, adaptability, strong resistance and perennial evergreen forage, whipgrass is one of the most important pasture grass in south china. It has been widely cultivated in the areas along the Yangtze River, including Sichuan, Yunnan, Guangxi, Zhejiang and other provinces and plays a significant role in livestock development and construction of ecological environment. Seed yield of whipgrass is very low; the main breeding method is by vegetative propagation. However it is limited to repeated clone selection, cultivation and domestication, etc. Breeding methods for updating become a serious problem. Younger stems, leaves and immature inflorescences were used as explants in this experiment, in order to obtain granular embryogenic callus and build high efficient regeneration system, optimal concentration combination for callus induction, subculture and regeneration was selected by adding different concentrations of 2,4-D (2,4-dichlorophenoxy), 6-BA(6-benzyladenine) and NAA (α-naphthaleneacetic acid) in MS medium. The main techniques systems were as follows:1. Young stem and young leaf as explants:Sampling time:April-May vegetative growth stage was a relatively appropriate sampling time.Sterilization:submerged in 75% alcohol for 10 seconds, washed with sterile water two or three times, then immersed in 0.1% mercuric chloride that added several drops of Tween-20 for 8 minutes, washed it again three or five times.Callus induction stage:MS+2,4-D1.0mg/L was the best medium. Callus generation rate of young stem and young leaf was 86.96% and 100.00%, respectively.The protection of browning experiment:good effect of browning was controlled by added AC 0.2%/L, changed medium every 10 days and adjusted temperature at 23±2℃.Callus subculture culture stages:dry, granular and milky white embryogenic callus was generated in MS+2,4-D1.0mg/L medium. Callus differentiation stage:MS+6-BA1.0mg/+NAA0.2mg/L was suitable for subculture, and green plants generation induction rate of young stem and leaf were 72.90% and 100.00%.Regeneration shoots multiplication stage:the appropriate medium was MS+6-BA1.0 mg/L+NAA 0.2 mg/L. Prolifeorous coefficient of regeneration shoots was 18.6.Regeneration rooting, hardening and transplanting stage:the root formation rate was 100% in 1/2 MS without any hormone. After 3 days’bottle acclimatization, plantlets were transplanted into cultivation medium (clay:sand:chicken manure) that survival rate was 98.71%.2. Immature inflorescence as explants:Callus induction stage:Middle and lower part of inflorescence as explants should be taken,5-10mm was the suitable length for inoculation. And very significant difference occurred at different 2,4-D concentrations, the highest rate of callus generation happened in MS+2,4-D7.0mg/L medium that was 99.28%.Callus subculture culture stages:the suitable medium was MS+2,4-D1.0mg/L for reproduction, in which dry, granular and milky white calluses were observed.Callus differentiation stage:green plant adventitious ratio was 100.00% in MS+6-BA1.0 mg/L+NAA 0.2 mg/L medium.Regeneration rooting, hardening and transplanting stage:The rate of root formation of regerated plant was 100.00% on 1/2MS medium. After three days’acclimatization, they were transplanted in the medium contained clay:sand:chicken manure=2:3:1 and the survival rate was 100.00%.