This study investigated the geographical variation patterns and climatic drivers of fruit phenotypic traits in Quercus variabilis across different provenances.

The fruits of 27 Q. variabilis provenances distributed in north China were systematically analyzed by means of variance analysis, cluster analysis, correlation analysis and principal component analysis.

The variation in fruit phenotypic traits of Quercus variabilis was predominantly manifested in fruit weight and size, nutshell thickness, fruit shape, as well as starch content and amylose content. Among the morphological traits, the fresh weight exhibited the highest mean coefficient of variation (CV) of 29.62%, while the fruit length showed the smallest CV of 9.79%. Regarding nutritional components, soluble sugar content had the highest mean CV of 22.13%, whereas starch content had the lowest CV of 3.88%. Cluster analysis classified 27 provenances of Q. variabilis into five clusters. The amylose content in group I was the highest, while the fruit weight and starch content were second only to those in group V. Among these, the heaviest fruits were found in group V from Xintai City, Shandong Province. The thickest fruit nutshells were from Xichuan County, Henan Province, while their amylose content was low. Starch and amylose content showed a significant positive correlation with fruit weight and size. Nutshell thickness was significant negatively correlated with amylose and soluble sugar content. Precipitation, longitude, and altitude were significant negatively correlated with fruit weight and size. Fruit shape and nutshell thickness were significant positively correlated with temperature during hot and humid season while negatively correlated with equivalent latitude. Starch and amylose content was significant positively correlated with equivalent latitude, while soluble sugar content showed a negative correlation with it. Interestingly, starch content and amylose content exhibited significant negative correlations with precipitation during the coldest quarter of 2021, while showing significant positive correlations with soluble sugar content. Additionally, starch content was significant positively correlated with precipitation seasonality of 2022 but negatively correlated with quarterly precipitation and mean temperature.

The variation in fruit traits of Q. variabilis showed significant differences among provenances. Group I exhibited prominent advantages for fruit utilization, while Group V demonstrated distinct superiority for forage purposes. Both soluble sugar content and amylose content showed significant negative correlations with fruit shell thickness. Soluble sugar content also exhibited a significant negative correlation with endocarp thickness. Fruit weight and size were predominantly influenced by longitude, precipitation, and altitude, whereas nutshell thickness was mainly governed by temperature and latitude, indicating distinct geoclimatic drivers between these two trait categories.

In order to explore the influence of various factors on the development and maturation of Quercus variabilis Blume var. pyramidalis embryo, and further improve the embryogenesis system of Q. variabilis Blume var. pyramidalis.

The main factors affecting the proliferation and maturation of Q. variabilis Blume var. pyramidalis embryo were explored by using the embryonic callus induced by Q. variabilis Blume var. pyramidalis embryo as materials: single-factor experiments were used to screen the types of light conditions (strong light, weak light, no light) and hormones (naphthaleneacetic acid (NAA), cytokinin 6-benzylaminopurine (6-BA), auxin 2, 4-dichlorophenoxyacetic acid (2, 4-D)) suitable for the proliferation of Q. variabilis Blume var. pyramidalis embryo. The concentration and ratio of hormones affecting embryonic proliferation were analyzed by two-factor tests. Univariate experimental analysis was carried out on sucrose concentration, activated carbon concentration and ABA concentration affecting embryo maturation. Finally, a two-factor test was carried out on the concentration and ratio of hormones affecting embryonic proliferation.

1) Among three different light intensities, the induction rate of embryonic proliferation was the highest in the strong light environment; 2) There were significant differences in the proliferation of embryos by different plant hormone ratios, with the highest proliferation rate of 83.33% with 0.10 mg/L2, 4-D and 0.80 mg/L 6-BA; 3) When the sucrose concentration was 5.00%, the maturity rate of the embryo was the highest which was 77.80%; When the ABA concentration was 0.50 mg/L, the maturity rate reached up to 50.00%; When the concentration of activated carbon was 1.00g/L, the growth was good, and the maturity rate reached 57.10%; 4) When the concentration of NAA and 6-BA was 0.25 mg/L at the same time, the maturity rate of embryo reached up to 90.50%.

1) The body embryo of Q. variabilis Blume var. pyramidalis has a good proliferation effect in a strong light environment; 2) The optimal proliferation medium is: MS + (6.0 g/L) agar + (3.00%) sucrose + 2, 4-D (0.10 mg/L) + 6-BA (0.80 mg/L); 3) The optimal maturation medium is: MS+(7.0 g/L) agar + (5.00%) sucrose + NAA (0.25 mg/L) + 6-BA (0.50 mg/L) + ABA (0.50 mg/L) + activated carbon (1.50 g/L).