A Study On Improving The Ploidy Of Petunia Hybrida Vilm By Tissue Culture Technology

Common garden petunia is one of perennial herbage flowers, which belong to the Solanaceae of Petunia. Petunia is one of the famous flowers of the world. It is used as a potted flowering crop and a garden ornament. So people specially love it. It has very high values in commerce and ornament. Ploidy breeding is an important approach for improving the view quality of petunia .We try to study the training and technical conditions of polyploid and haploid breeding and optimize the systemic experiment in the study. In order to play the better advantages of tissue culture technology on Improvement of the ploidy, and provide an important basis for Innovation germplasm of petunia.The result showed: The explants were washen 2-3 times by sterilized water, then sterilized 30 seconds by 75% alcohol and 10min by 0.1% HgCl₂, rinsed more 5 times by sterilized water, the buds rate reached 90%. The best of multiplication medium of stems and buds was MS+0.5mg/L BA, multiplication coefficient reached7.3and5.0.The best rooting medium for petunia was 1/2MS +0.05mg/L IBA , the states of plantlets and roots were good, the induction rate was 100%, The surviving rate of plantlets was above 85% after transplanted to the ground.The inducing polyploid of petunia was carried out by colchicines. Three methods were used and compared. The tetraploid plantlets were obtained by immersing buds in various concentrations of colchicine solution, and inoculating buds in the mediums containing colchicines, and dropping colchicine solution in growth point of plant. The result indicated : It was the most effectively induced by immersing buds of petunia in 0.1% colchicine solution for 36h, which had the most tetraploid plantlets, inductive frequency was 20%, had the most tetraploid plantlets. Through the detection, we got tetraploids of petunia(2n=4x=28),and the surviving rate of plantlets was above 96% after transplanted to the ground.The tetraploid plants is shoot and strong ,deep green , having the coarse stem. It have grown shown,and It's flowering period is later 15²0d than diploid,corolla is longer than diploid, petal'fold are more than diploid. And the color change to the white whith green.The leaf, stoma, guard cell characteristics of tetraploids and diploids lily were compared. The result indicated that tetraploids leaves were thicker, but longer and with higher leaf index. The thickness leaves of tetraploids petunia was 160% of those of the diploids respectively; the length of leaves of tetraploids was 138% of those of the diploids respectively. The guard cells' length of tetraploids petunia was 177.5% of those of the diploids respectively. The characteristic of tetraploids stoma with that of diploid was compared. The length of tetraploids stoma was 151.4% of those of the diploids respectively.The tetraploid plants and diploid plantlets of petunia were carried out the low-temperature treatment, then its exosmosis rates of electrolyte and rates of damage of cytomembrane was compared. Under the same temperature, the electrolyte exosmosis rate and damage of cytomembrane of tetraploid plants were lower than diploid plants. It shows that the tetraploid petunia's cold resistance and fight a drought are stronger than diploid petunia.The effective method of petunia buds sterilizing is : 1mol/L HCL(lmin)+75% alcohol(30sec) +0.1%HgCl₂(10min). The best induction medium is MS+ 1.0 mg/L BA + 1.5 mg/L IBA+ Activated carbon 0.5g/L+ Sucrose 4%, inductive frequency was 62.16%. The advisable cold pretreatment for anther culture of petunia is 48h under 4℃, and it was 10-16d earlier than reference in time. MS+ 2.0mg/L BA +0.2mg/L IBA is the best differentiation medium.The buds of petunia buds sterilizing could grown to health plants,and survived when transpl anted to the ground. Through the detection, we got diploids of petunia(2n=14).Through to studing, we have established reproductive system of aseptic for petunia ,and were explored to the conditions and methods of petunia buds sterilizing. Then we got the new tetraploid petunia for breeding the new varieties.