Study On Apricot Fruit Characteristics Of Domesticated And Leaf Anatomy In Pamir Plateau Of Xinjiang

Pamir Plateau is the "roof of the world" where apricots are distributed.It is also the place through which apricots spread to other parts of the world along the ancient Silk Road.The unique geographical environment and climate breed very precious and ancient germplasm resources of apricot,which is the model of human domestication and cultivation of apricot.Understanding fruit characters from the perspective of domestication and introduction is the key to understanding the formation mechanism of cultivated apricot fruit characters.In this study,62 samples of ancient apricot germplasm in Pamir Plateau were collected from Kurgaz Azetze,Kukosiluge Township,Kochat Village,Jilediti Pasture,Kuksiluke Village and Qiruketong Village of Tashkurgan Tajik Autonomous County,Kashgar Prefecture,Xinjiang.The important traits of the fruits and seeds of the samples were investigated and determined.Nested variance analysis,coefficient of variation,diversity index analysis,correlation analysis,principal component analysis and cluster analysis were used to analyze the characteristics of domesticated apricot.Drought tolerance was evaluated by membership function method based on leaf anatomy.To provide theoretical basis for the important kernel characters of cultivated apricot by domestication and introduction.The main results are as follows:1.Apricot fruit sweetness is an important selective domestication trait among fruit phenotypic traits.Through the investigation and analysis of the fruit characters of 62 apricot germplasm cultivated in Pamir Plateau,The soluble solids of 80.65% of the fruits ranged from 11.27% to 24.98%.the fruit flavor was mainly sweet,96.77% of the fruits had hairs on the surface,and the sutures on the fruit surface were mainly light.The base color of peel and fruit color are mainly orange yellow.The fruit was mainly were smaller than 20 g and 56.25% were round.2.The sweetness and bitterness of apricot kernel are determined by the level of amygdalin,and is also an important character of apricot in human domestication.According to the investigation and analysis on the appearance traits of seed stone and seed kernel,the seed kernel flavor was mainly sweet(77.42%),The amygdalin content of sweet kernel was detected to ranged from 0.41mg/g to 2.24 mg/g with an average content of 0.97mg/g,and the amygdalin content of bitter kernel was detected to ranged from 2.76mg/g to14.69mg/g.The average content of amygdalin in bitter kernel was 11.25mg/g,which showed that the content of amygdalin in bitter kernels was higher than that in sweet kernels.The main kernel stone shape were oval(51.61%),freestone(74.19%),large kernel stone(43.55%),small kernel(0.51g～0.60g),35.48%,0.51g～0.60 g,the proportion of rate of kernel rate was 27.5%～34.5%,accounting for 50%.3.Leaf anatomy is one of the important indexes to evaluate drought resistance of plants.The anatomical structure of leaves showed that there were significant differences among germplasm.Five anatomical indexes,namely main vein thickness,spongy tissue thickness,leaf tissue structure porosity,leaf tissue structure tightness and upper epidermis thickness,were selected by principal component analysis as the main indexes for drought resistance evaluation.The membership function method was used to divide 16 germplasm of the strong drought resistance type(0.55～0.74),19 germplasm of the strong drought resistance type(0.43～0.55),20 germplasm of the moderate drought resistance type(0.34～0.43)and 7germplasm of the weak drought resistance type(0.28～0.34).Through the investigation of leaf appearance traits,The main leaf color was dark green(96.83%),the main leaf surface type was wavy(88.06%),the main leaf base was wedge-shaped(67.95%),the main leaf shape was oval(65.48%),the main leaf margin was blunt toothed(56.92%),and the main surface was hairless(50.84%).The leaf tip was mainly long tail tip(49.47%).4.There is a close relationship between apricot fruit and seed stone and kernel.Through the correlation analysis of the appearance traits of apricot germplasm on Pamir Plateau,the single fruit weight was significantly correlated with the size of seed stone and seed kernel,and negatively correlated with the yield of apricot.The results showed that the larger the apricot fruit in Pamir Plateau was,the larger the seed stone and seed kernel were.The longitudinal diameter,kernel diameter,kernel diameter and fruit shape index were significantly positively correlated with kernel shape index,indicating that the different shapes were mainly related to the longitudinal diameter.The samples were divided into 3 groups by cluster analysis.The common characteristics of the first group were high fruit hardness,soluble solid,seed stone shape index and yield,and small leaves.The second germplasm had high fruit shape index and kernel shape index,low soluble solid content,small leaf shape index,small fruit,seed core and seed kernel.The main characteristics of the third germplasm were large leaf,fruit,seed stone and seed kernel,small fruit hardness,fruit shape index and kernel index,and low yield.In the first germplasm,"Kuer 15","Jile 1","Kuke 6" and "Qiru 15" were screened out to have greater development potential in fresh food and kernel use,and could be used for breeding excellent resources.