Research On Induction And Preliminary Identification Of Tetraploid Heicai

Heicai(Brassica campestris L.ssp.chinensis(L.)Makino var.rosularis Tsen et Lee),alias Baoying Heicai,Wucai,walnut black,is a local characteristic variety of Baoying County,Yangzhou City,in 2012,it was awarded the title of "National Geographical Indication Agricultural Products".It belongs to the genus Brassica,a species of Brassica chinensis,but it is easy to cross with other green cultivars,resulting in biological confounding,species degradation,and loss of original typical features and characteristics.The Heicai were induced into tetraploids,which are not only easy to breed,but also easy to keep,and the yield and quality are improved,providing farmers with excellent new varieties.In this study,colchicine was used to carry out the tetraploid mutagenesis test of Heicai,in order to obtain new varieties of Heicai,and to improve the yield,nutritional quality and stress resistance of Heicai.The main findings are as follows;1.The diploid germinated seeds of the Heicai was induced into tetraploid by colchicine.The results showed that with the increase of colchicine concentration and the prolongation of treatment time,the emergence rate,true leaf rate and survival rate decreased,the more serious the damage to the seed.The treatment concentration of colchicine is 0.0!%-0.03%,and the treatment time is about 8 hours.The variation rate of tetraploid mutagenesis is between 0.5%and 2.75%.2.The morphological characteristics of the diploid mutants of Heicai induced by colchicine were significantly different from the diploid of Heicai,and the changes of leaves and flower organs were the most significant.The corolla size,stigma and petal size of the tetraploid of the Heicai were larger than the diploid,and the difference reached a significant level;the stomatal and guard cells were significantly larger than the diploid,the stomataldensity decreased,and the chloroplasts in the guard cells increased.3.Growth retardation of tetraploid Heicai compared with diploid,which is obviously delayed in the bud stage,flowering stage and fruiting stage.Therefore,observing the difference in the growth period of Heicai is one of the methods to identify and screen tetraploid plants.4.The chromosome microscopy method is accurate and intuitive,but it takes time and labor.Pollen microscopic observation and viability test showed that the pollen of black cabbage tetraploid increased significantly,malformed pollen increased,and viability decreased.Pollen grain enlargement can be used as the main screening standard for tetraploid variation,which is simple and easy.5.Hybridization and self-crossing test of Heicai showed that the Heicai tetraploid decreased in seed setting rate,and had higher affinity with Yangzhou blue tetraploid;it had certain affinity with Brassica napus and Brassica juncea;Hybridization with black vegetable diploid and Yangzhou blue diploid was low in seed setting rate,showing incompatibility.Therefore,the comparison of the seed setting rate and the affinity index by the tetraploid hybridization and selfing test of the Heicai can be used as one of the indirect methods for identifying tetraploid.6.The agronomic traits of Heicai were significantly changed due to the doubling of the genome.The results showed that the leaf width,leaf width/leaf length,petiole width,petiole thickness and plant weight of the tetraploid plants were higher than diploid.Plants,while plant height,shortening stems,and number of leaves are lower than diploid plants.The tetraploid plants showed a tendency of dwarfing and vegetative organs enlargement,and the performance was significant,Showing an obvious giantism.7.The physiological characteristics of Heicai were significantly changed due to doubling of the genome.The results showed that the contents of chlorophyll,water,soluble protein,soluble sugar and VC in plants were significantly increased compared with the diploid,and the crude fiber content is significantly decreased.Soluble protein,soluble sugar and VC in Heicai are important nutritional indicators,indicating that the contents of nutrients in the Heicai tetraploid is higher and the nutritional value is greater.