Morphological characteristics of the plants obtained following
colchicine treatment were observed. Initially, plant height, plant
breadth and diameter of the basal stem were measured throughout
the entire population resulting from the colchicine-treated
seedlings; this phase of the study was carried out in November
2005 and a group of putative tetraploids (90 plants according to the
analysis of size and distribution-density of leaf stomata) was
identified as those with gross morphological changes. Further
vegetative characteristics (Table 4) and reproductive traits
(Table 5) were measured in 3 diploid and tetraploid plants of 6
‘‘Zi Wei’’, 2 ‘‘Hong Wei’’ and 4 ‘‘Yin Wei’’ (one tetraploid plant of
each cultivar did not flowered), growing under open field
conditions; this phase was carried out in July 2006. Assessments
of pollen vitality were carried out using in vitro germination
medium ME3 (Leduc et al., 1990) supplemented with 16% w/v
PEG4000 and 12% w/v sucrose (note: preliminary experiments
showed that this was the optimal medium for pollen germination
in this species, data not shown), and the I2–KI and 0.5% TTC