Establishment Of Regeneration System And Chemical Mutation Breeding Of Haworthia

The genus Haworthia is a small succulent plant with excellent ornamental value and economic value.Because of its slow growth and low natural reproduction rate,it is important to use tissue culture techniques to breed Haworthia.This study selects four popular Haworthia,Haworthia maughanii 'Gold',Haworthia truncate 'Nara',Haworthia comptoniana 'Aboukyuu' and Haworthia cooperi 'OB-1' to construct regeneration systems.Mutagenesis breeding studies were earried out.Ethyl methane sulfonate(EMS)was used to induce the variegated mutant plants.Colchicine was used to induce polyploid plants.The main findings are as follows:1.Obtaining sterile seedlings.When Haworthia cooperi 'OB-1' seeds were soaked in 2%NaCIO solution for 20 min,the pollution rate(5.60%)was significantly lower than other treatments,the germination rate(71.2%)was between the other two treatments,and the final survival rate(62.40%)was higher than other treatments significantly.2.Callus induction of Haworthia.The callus induction was carried out on the thin leaf layers of four species of Haworthia plants.It was found that the induction rate under dark conditions was significantly higher than that under light conditions.For Haworthia maughanii 'Gold' and Haworthia comptoniana 'Aboukyuu',the optimal ratio of hormones was 6-BA0.5mg/L+NAA0.5mg/L;the optimal hormones ratio of Haworthia truncate 'Naraf was 6-BA0.5mglL+NAA0.2mg/L+KT1.0mg/L;the optimal hormones ratio of Haworthia cooperi 'OB-I' was 6-BA2.0mg/L+NAA 0.5 mg/L+KT 0.5 mg/L.The callus induction of the leaves of Haworthia comptoniana 'Aboukyuu' and Haworthia cooperi 'OB-1',the optimal ratio of hormones for Haworthia comptoniana 'Aboukyuu1 was 6-BA1.Img/L?NAA0.5mg/L+KT0.5mg/L,the optimal hormones ratio of Haworthia cooperi 'OB-1'was 6-BA0.5mg/L+ NAA0.5mg/L.Through the induction of the callus of Haworthia comptoniana'Aboukyuu' and Haworthia cooperi 'OB-1' leaves,the order of induction rate of different parts from high to low was:leaf base>middle leaf block>middle thin layer>leaf window.3.Buds differentiation of Haworthia.The best medium formula of Haworthia maughanu 'Gold'was MS+6-BA0.1mg/L+NAA0.01mg/L.At this time,the differentiation rate was 71.67%,which was significantly higher than other treatments.In this medium formula,Haworthia truncate 'Nara',Haworthia comptoniana 'Aboukyuu' and Haworthia cooperi 'OB-1' were able to differentiate normally,and the differentiation rate was above 50%.4.Rooting and transplanting of Haworthia.The optimal rooting medium formulation of Haworthia maughanii 'Gold' was 1/2MS+AC1.0g/L+NAA0.2mg/L.In this medium formula,Haworthia truncate 'Nara',Haworthia comptoniana 'Aboukyuu' and Haworthia coqperi 'OB-1' can take root normally,and the average rooting rate was above 90%.For these four Haworthia,the survival rate(over 95%)was the highest in the cultivation medium of red jade soil:vermiculite=1:1,compared with other treatments.5.EMS mutation breeding research.The survival rate and differentiation rate of Haworthia comptoniana 'Aboukyuu' decreased with increasing EMS concentration and time,and the concentration and time had significant effects on survival and differentiation rate.Fifteen strains of variegated mutants were obtained from 0.4%EMS+2h,which was the best mutagenic treatment.Under this treatment,a large amount of mutagenesis was perfonned on four species of Haworthia.Amortg them,Haworthia comptoniana 'Aboukyuu' and Haworthia maughanii 'Gold' obtained 29 strains of variegated mutants,and 78 strains of variegated mutants were obtained from Haworthia truncate and Haworthia cooperi,which callus came from the colored leaves.6.Study on polyploid breeding.There were four ways to induce colchicine in Haworthia maughanii 'Gold',118 polyploids were obtained by callus soaking,12 polyploids were obtained by callus mixing,no polyploid plant was obtained by leaf soaking,11 polyploids were obtained by leaf mixing method.Morphological,stomatal and chromosome observations of Haworthia maughanii'Gold' polyploids revealed that the number of tetraploid chromosomes was 2n=4x=28.Polyploid was significantly different from diploid in plant height crown ratio and leaf window area,the stomata became larger and the density decreased.