Evaluation And Hybrid Progeny Analysis Of Superior Clones Of Malus Sieversii

Xinjiang wild apple is important wild resources and excellent breeding resource for apple in China.This study compared and analyzed the cold resistance and fruit quality of Xinjiang wild apple elite clones selected from the Tianshan region of Xinjiang,explored differences in cold resistance and fruit quality of Xinjiang wild apples and selected asexuality with potential excellent breeding potential.Crossbreed breeding with Xinjiang wild apple clones and Begonia,the growth characteristics and physiological indexes of hybrids progeny were also measured,which provided a scientific basis for the selection of hybrid progenies with potential for breeding.The main conclusions are as follows:（1）There are significant differences between the cold resistance of Malus sieversii clones.The relative conductivity of 8 Malus sieversii clones were significantly dirrerent at-20℃in 2 periods;The semi-lethal temperature calculated by r_e,r₁ and the conductivity method were significantly correlated in 2 periods;The semi-lethal temperature in March（-31.87～-26.33℃）was significantly higher than that in January（-33.97～-32.33℃）,and the difference among some clones reached the extremely significant level.The semi-lethal temperature of each clone had no significant correlation at 2 periods;The calculated semi-lethal temperature of clones M-3,M-12,and M-18 were lower which were-32.76℃,-33.97℃,-33.52℃in January,-30.47℃,-30.26℃,-31.87℃in March.The germination rate of clones M-3,M-12 and M-18 were higher in the growth and recovery experiment in March which were 76.19%,75.71%and67.38%under-30℃and 16.67%,17.72%and 18.89%under-50℃.Clones M-3,M-12and M-18 had better performance in 2 periods cold resistance and germination experiment,which are the good resources for cold-resistant breeding.The results provide a scientific basis for further study of cold hardiness of Malus sieversii in different periods and select high-quality resources of cold-resistant breeding.（2）There are abundant genetic diversity in fruit quality of Malus sieversii clones.According to the number of fruit and size of fruit,4 apples of Xinjiang wild apple were selected for fruit quality determination.Some of quality indicators revealed a significant difference among 4 Malus sieversii clones;54 aromatic compounds（retrieved through NIST14）were identified in 4 Malus sieversii clones.The main aromatic components were（E）-2-hexenal,1-hexanol,（E）-2-Hexen-1-ol,etc.,representing 98.22%of the total aromatic content;There were differences in both aromatic components and relative contents among 4 Malus sieversii clones,and each clone contains unique aroma components,so aroma was an important criteria in evaluation of Malus sieversii clones.There were good selection potential in 4 Malus sieversii clones which has great genetic differences and its own characteristics.（3）Bagging had a significant effect on the internal and external indicators of fruit quality of 4 Malus sieversii clones.Compared with the Unbagging fruit,the bagging fruit had the tendency to decrease the quality of the fruit,the content of the soluble solid,the acidity,and some of quality indicators revealed a significant difference between bagging fruit and unbagging fruit.There was no significant difference in the fruit shape index between bagging and unbagging fruit.The effect of bagging on the aroma components of4 Malus sieversii clones was not consistent.The relative contents of aldehydes and acids of M-11 and M-15 were decreased,the relative contents of alcohols and esters were increased.The relative contents of aldehydes and acids in M-12 and M-13 were increased and esters were decreased.The relative content of alcohols of M-12 was decreased and the relative content of M-13 was increased.The effect of bagging on the diversity of aroma components of 4 Malus sieversii clones was not consistent.The richness of aroma components of bagging fruit were decreased.The diversity index and evenness index of aroma components of M-12 and M-13 were less affected by bagging and M-11 and M-15were obviously affected.（4）Xenia has a significant effect on the internal and external indicators of fruit quality of 4 Malus sieversii clones.Compared with the natural pollination,control pollination fruit had the tendency to increase the fruit mass,fruit longitudinal diameter,fruit transverse diameter,shape index,acidity,while had the tendency to decrease the content of the soluble solid,fruit stalk length,and some of quality indicators revealed a significant difference（P<0.05）between natural pollination and control pollination fruit.The effect of control pollination on the thickness of fruit stalk was not consistent;Aldehydes and alcohols were the main aroma components of 4 Malus sieversii clones by natural pollination and control pollination;The effect of control pollination on the aroma components of 4 Malus sieversii clones was not consistent.The relative contents of the aldehydes of M-11 was increased and the alcohols did not show obvious change under control pollination;The relative contents of the aldehydes of M-12 and M-13 were decreased and the alcohols were increased under control pollination;The relative content of aldehydes and alcohols of M-15 did not show obvious change under control pollination;The control pollination had a significant effect on the species and proportion of aldehydes,alcohols,acids and esters of 4 Malus sieversii clones;The control pollination had obvious effects on the fruit quality of 4 Malus sieversii clones,but the effect on the aroma components of fruit was not regular.（5）The hybrids of Malus sieversii clone and Malus‘Radiant’have obvious differentiation and the leaf color of some plants is red.The content of chlorophyll a,chlorophyll b and carotenoid in the hybrid progeny were lower in July 30th;The relative content of anthocyanin in the No.1,No.2 and No.4 plants was obviously higher than that of the parent in the determination time.The plant of maximum height and ground diameter were not the same at different times;The growth rate of height decreased slightly from August to September,and the growth rate of ground diameter of progeny was relatively stable.There were significant differences in photosynthetic parameters among different plants,but the difference of leaf color combinations was not significant.Spectral curves of different progenies and their parents are similar in shape;In the reflectance spectrum,the range of 520 to 600 nm is the best spectral band for distinguishing different color leaf combinations in progeny;The range of 710 to 1000 nm is the best spectral band to distinguish individual plants;In the first order differential spectrum,it is not easy to distinguish individual plants;It is easy to distinguish between different leaf color combinations within the range of 515 to 525 nm peak emission and560 to 580 nm valley output.