Table 2. The frequency of mutations in endosperms of chronically irradiated pine trees.

Experimental site	Number of locus-tests	Null mutation frequency	Duplications frequency	Changes in electrophoretic mobility frequency	Total frequency of mutations
Ref	2457	0.002 ± 0.001	0	0.001 ± 0.001	0.003 ± 0.001
Ref1	999	0.003 ± 0.002	0.001 ± 0.001	0.004 ± 0.002	0.008 ± 0.002
VIUA	2459	0.005 ± 0.001	0.001 ± 0.001	0.003 ± 0.001	0.009** ± 0.002
SB	2313	0.011***▲ ± 0.002	0.004*** ± 0.001	0.004* ± 0.001	0.020***▲▲ ± 0.004
Z1	2589	0.024***▲▲▲ ± 0.003	0.007***▲ ± 0.002	0.007*** ± 0.002	0.041***▲▲▲ ± 0.004
Z2	2228	0.029***▲▲▲ ± 0.004	0.011***▲▲▲ ± 0.002	0.010***▲▲ ± 0.002	0.054***▲▲▲ ± 0.050

t-test revealed a significant difference with: *Ref site, p < 0.05; **Ref site, p < 0.01; ***Ref site, p < 0.001%; ^▲Ref1 site, p < 0.05; ^▲▲Ref1 site, p < 0.01; ^▲▲▲Ref1 site, p < 0.001.