New Germplasm Creation And Character Analysis In Chestnut (Castanea Mollissima Blume)

Chestnut(Castanea mollissima Blume)is one of the most important woody food tree species in China,with a wide distribution range and high nutritional value.It is deeply loved by consumers at home and abroad and has good development prospects.Chestnut industry develops quickly and has become a leading industry in the production area.However,chestnut industry still has the problems of empty buds,small grain,and low yield.The basic methods to solve these problems are to enrich breeding targets and create new chestnut germplasm.Meanwhile,seeding selection is a commonly method,and cross breeding is also involved in the current chestnut research.However simpler and cheaper physical and chemical mutagenesis methods are very few.In this study,chestnut cultivars in Yanshan area was used as the experimental material and the methods of hybridization,physical and chemical mutagenesis were adopted.The breeding goal is to create new chestnut germplasm with high yield,high quality,high light efficiency and high water use efficiency.Morphological and molecular biology methods were used to identify and analyze the characters of experimental material,in order to provide a theoretical basis for exploring effective modern chestnut breeding techniques.The main results are as follows:1.Crosse created chestnut germplasm,hybrid offspring identification and analysisa.A comparative analysis was made in chestnut varietyies,4 superior chestnut strains were selected from main varieties in Yanshan area.Qianxiyouxi1 had the highest photosynthetic efficiency and the best glutinous fruit;Xihuangyudali had high water use efficiency and large grains;the yield of Zijing was higher,and the fat content was lower than the others in fruit;Donghuangyushaoxiong had fewer male flowers and more mixed inflorescences during the flowering period,and it had the largest No.of nuts in the bud after setting,at the same time,it also had the highest content of protein in the fruit.b.Grey correlation method was used to comprehensively evaluate hybrid seeds of different varieties(lines)and to select hybrid parent combinations with better quality.The female tree is‘Yanshanzaofeng'and the male trees are Zijing,Xihuangyudali and‘Dabanhong'.The female tree is‘Qianxizaohong'and the male trees are‘Yanshanduanzhi',Zijing and‘Qianxizhuangli'.The female tree is‘Qianxizhuangli'and the male trees are Zijing and‘Qianxizaohong'.The female tree is Zijing and the male trees are‘Qianxizhuangli',‘Qianxiyouxi 1'and‘Qianxizaohong'.c.6 pairs of hybrid progeny were selected to identify parents of chestnut from 47 pairs of SSR primers,and a pair of SSR primer ICMA018 was selected to identify the progeny of 4 hybrid combination(‘Yanshanzaofeng'בDabanhong',‘Yanshanzaofeng'בQianxizaohong',‘Yanshanzaofeng'בQianxi Zhu-angli',‘Yanshanzaofeng'בYanlong')in this experiment.The results showed that the hybrid offsprings in the test were true hybrids.d.Through the application of stepwise regression analysis on the indexes of leaves,fruit quality and yield,the results showed that leaf length and water use efficiency,kernel percentage,soluble sugar and crude protein content of fruit were used in the early identification indexes of hybrid offspring.2.Study on creating new germplasm use physical mutation in chestnutThe LD₅₀ dose of chestnut graft was 20.26Gy and seed was 12.95Gy withg ⁶⁰Co-?irradiation.After pollination with irradiated pollens in different doses of ⁶⁰Co-?,the fruit set,kernel percentage,No.of nuts per bar generally all decreased and the single grain weight increased with the irradiation dose increased.At the same times,the content of fat and crude protein in fruit quality decreased while the content of soluble sugar increased.3.Study on creating new germplasm use chemical mutation in chestnutThree years after sowing,there was a superior plant named Q3-1 which growed abundantly and harvested more fruit with yield as much as 1.9 kg after 0.3%concentration processing.Packing buds with different concentrations of colchicine solution would significantly affect the number of male branches,the No.of male branches was at least 20 times lower than the CK with 0.3%treatment.After the treatment with 0.2%concentration,there was a superior plant with more single grain per bar and the quantity accounted for 2%of the total.