Table 1 Definition of analyzed phenotypic variables at individual tree level

Acorn weight

(g)

Acorn weight was measured just before sowing.

Survival (2017)

(Y/N)

Measured once a year, at the end of the growing season in 2009–2010–2011–2012, the in spring (after budburst, in May) in 2014–2015–2016–2017.

Survival in spring 2017 was used as “final” survival, which was the analyzed variable.

Height

(cm)

Height of the highest living bud, measured at survival assessment each year. Height at the end of the first growing season (in 2009) was used for a generalized linear model (“Height in 2009”, Model 3), and Height at the end of 2012 was used in the SEM and GWAS analyses (“Height (late 2012)”).

Mean infection (2009–2013)

(%)

The percentage of total leaf area infected by powdery mildew was assessed at tree level by trained observers at several times in each year (except no assessment in 2014–2015). Only one value per year was then retained, corresponding to the highest value (not necessarily the latest since defoliation of highly infected leaves may occur).

The analyzed variable in the different models (including SEM) was the mean disease severity in the first five years, calculated as the mean of the 2009–2010–2011–2012–2013 values of percentage of total leaf area infected.

Frost damage (2013)

(Y/N)

Presence or absence of significant damage (necrosed leaves) in May 2013, when a major frost episode took place.