The provenance experiment, consisting of 12 plots, was established
in middle-March, 2008, using 1-year-old seedlings cultivated
in 2007. The planting space was 100 120 cm and the
provenance units were represented by 48–168 plants, which were
distributed randomly in the field. The experimental site (27400
N
latitude, 108260
E longitude) is also located at Zhenjiang nursery,
Jiangsu Province, China. In the site, the average annual temperature
is 14.1 C and the average growing season is 220 frost-free
days, while the average annual precipitation ranges from 1000 to
1100 mm, with most of the precipitation distributing from June
to September, accounting for 60%. The soil from 0 to 40 cm depth
is a sandy loam with an organic matter content of 1.77%, available
nitrogen content of 77 mg/kg, and available P (phosphorus) and K
(potassium) contents of 14.9 and 133 mg/kg, respectively.
2.