| Camellia gauchowensis Chang is an important woody oil-bearing tree species in South China.Because of its strong adaptability and large fruit,it is planted in various parts of Guangdong Province.Jieyang is located in the northeast of Guangdong,the mainly plantation region of C.gauchowensis.However,since most of the oil tea planted 20 years ago were seedling in Jieyang,the differentiation was large,and the good and the bad were uneven.It is urgent to select the best varieties for extension.To this end,the research team carried out a large number of excellent tree screenings in Xinheng Town,Xichang Town and Baita Town where the distribution of C.gauchowensis Chang,Jieyang,Guangdong is concentrated from 2019 to 2021.52 fine individual plants were initially selected from C.gauchowensis Chang with disease resistance over 20 years old.In this study,52 fine individual plants were used as test materials.Through the determination and analysis of the economic traits of their fruits,the "reasonable-satisfaction" and multi-dimensional value theory were used for comprehensive evaluation.10 fine individual plants were selected to enter the re-election stage.The growth characteristics,photosynthetic physiological characteristics and oil quality of the re-selected excellent plants were compared and analyzed,and the gray correlation degree was used to synthesize 15 indicators such as the yield,fruit economic characteristics,oil quality and photosynthetic performance of the 10 re-selected excellent plants.The evaluation is intended to provide a basis for local screening of high-quality C.gauchowensis varieties.The main results are as follows:1.Comparative analysis and comprehensive evaluation of the economic characters of 52 pre-selecting trees.The 10 indicators of fruit economic traits of 52 pre-selecting trees have varying degrees of variation.The coefficient of variation between indicators ranges from 6.73%to 32.72%,of which 100-kernel weight(32.72%),single fruit weight(31.24%)and dry seeds rate(27.8%)have large variations and good selection potentials.,The average and range of fruit weight of the 52 excellent plants was 121.26 g and 58.19～203.67 g,respectively.HMZ31 has the heaviest single fruit;the average fresh seed rate was 33.62%,with a range of 11.63%-49.10%,and HMZ13 was the highest;The average dry kernel rate was 52.99%,and the range of variation was 34.91%～63.20%,with A11 being the highest;the average and range of dry kernel rate was 40.28%and 27.94%～55.13%,respectively,and HM349 was the highest.Fruit weight,average peel thickness,fresh seed yield,dry kernel yield and oil yield were carried out to comprehensively evaluate the 52 pre-selecting trees.The top ten excellent plants,named HMZ31,A5,HM349,HMZ32,HMZ23,HM19,HMZ13,HMZ22,HMZ33 and HMZ11,were selected according to the evaluation of fruit economic traits and the breeding rules,which are which were re-selected further.2.Comparative analysis of the traits of 10 selected plants.The results of oil quality of 10 selected plants indicated that the physical,chemical and biological properties varied significantly,and the variation coefficient varied from 0.53%to 45.35%,of which the squalene content(45.35%)and the total phenol content 42.79%,the relative mass fraction of linolenic acid(33.67%)varied greatly,and had great potential for selection.The acid value and iodine value of oils can reach the first grade oil standard of Camellia seed oil;the average relative mass fraction of oleic acid was 78.66%,and the highest was HMZ13(80,99%);the average linoleic acid is 8.14%,and the highest HMZ11 content was 10.77%;the average content of α-Ve was 17.92 mg/100 g,and the highest content was HMZ33(17.92 mg/100 g);the average total phenol content was 8.4 mg/kg,and the highest content was HMZ11(13.02 mg/kg);the average value of squalene in the 10 selected plants was 374.82 mg/kg,and the average content of β-sitosterol was 326.36 mg/kg.The highest content of the excellent plants was A5,which reached 695.6 mg/kg and 382.4 mg/kg,respectively.The result of growth traits of 10 selected plants indicated that variations of leaf and flower traits were significant.The top three indicators of the coefficient of variations of leaf phenotype and anatomical structure indicators were leaf area(22.92%),phloem thickness(21.85%)and stoma density(19.04%).The leaf area varied from 14.55 cm2 to 29.25 cm2,and HMZ33,HMZ31 and HM349 were significantly higher than those of other superior plants.The phloem varied from 75.75 to 157.95 μm,and HMZ13 was the highest.The stomata density varied from 126.75 to 232.82 mm2,and HM349 was the highest.The top three indicators of flower traits coefficient of variations were the number of anthers(38.21%),pollen quantity(30.03%)and pollen vigor(22.02%).the average amount of pollen per anther was 5359.The number of anthers varied from 49.4 to 180.6,and the pollen amount per anther of HMZ13 and HMZ23 were significantly higher than that of other excellent strains(8080 and 8030)respectively.The pollen germination rate varied from 45.31%to 87.45%,and the pollen germination rates of HMZ33,HMZ13 and HM19 all exceeded 80%.The results of photosynthetic and physiological characteristics of 10 selected plants indicated that the variations of photosynthetic performance indexes of the 10 selected plants were relatively stable,except that the coefficient of variation of stomatal conductance(12.08%);the net photosynthetic rate ranged from 6.72 to 8.53 μmol·m-2·s-1,and HM349 was the highest;The average water-use efficiency was 2.787 mmol/L,and the highest of the excellent strain was HMZ13(2.937 mmol/L).Regardless of re-selected plants,the net photosynthetic rate was significantly positively correlated with the thickness of the palisade tissue in the anatomical structure of the leaf,the tightness of the tissue and the stomata density.3.Comprehensive evaluation of selected plants.In accordance with the breeding goals of high yield,high quality,high photosynthetic efficiency and disease resistance,and the Technical Regulations for Selection and Breeding of Camellia Varieties,the yield,fruit economic traits,oil quality and photosynthesis of 10 re-selected plants were conducted with Grey correlation analysis and comprehensive evaluation.The results showed that the comprehensive traits of the 10 re-selected plants were much different,and the relative correlation degree was between 0.400～0.489;the rank of comprehensive evaluation of the 10 selected plants was HMZ23>HMZ13>HM349>HMZ33>A5>HMZ11>HMZ32>HM19>HMZ31 and HMZ22.It is suggested that clonal propagation and regional trial should be carried out on the top five plants to enter the final selection stage. |
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