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The first principal component of PCA explained 76 % of the variance and consisted of
the c ontribution b y five l ife-history t raits: e mergence rate (r=0.44), pl ant w eight ( r=0.96),
biomass (r=0.99), number and weight of articles per plant (r=0.89 and r=0.95). The resulting
value on the first axis was significantly lower for the BG region than for BT, the other two
regions being intermediate (Fig. 4.10; and contrast test). TukeyHSD test showed that NM was
significantly higher than BG.
Discussion
Variation of flower and silique characteristics
Silique and flower characteristics in wild radish sampled from four regions were significantly
different. Silique characteristics discriminated the BT wild radish from others: BG and DM
together, a nd N M i ntermediate ( Fig. 4.5) . A l arge va riation of m orphological t raits w as
already reported for wild radish in Europe, which lead nomenclaturists to distinguish several
subspecies ( Tutin e t al. 1993) . T hey m ainly t ook i nto c onsideration t he s ilique di ameter:
diameter less than 5 mm would correspond to subsp. raphanistrum (3-4 mm) and microcarpus
(1.5-2 mm), while diameter more than 5 mm to subsp. maritimus, rostratus and landra. Wild
radish from BT region had the largest silique, with a mean value of 5.51 mm (ranging from
3.41 to 7.83 mm), and could tentatively correspond to the subsp. maritimus as the BT region
borders the sea. However, NM and DM that border the sea too, had silique diameter ranging
from 2.1 to 6.13 mm for NM and 1.92 to 3.62 mm for DM. It is therefore difficult to arrange
the plants from the four regions to every subspecies based on silique diameter. Similarly, all
plants in the four regions belong to subsp. landra based on petal length (10-15 mm), but they
will belong to subsp. maritimus when based on beak length (6-20 mm) (Tutin et al. 1993; Fig.
4.4). In c ontrast, B G p lants w ith s ilique di ameter r anging f rom 1.7 t o 3.37 m m c ould
correspond to typical subsp. raphanistrum. However, nobody knows the biological validity of
the subspecies classification. All the plant types inter-crossed in the cage experiment, so that
there is no r eproductive isolation. The apparent differences just could be the consequence of
regional f ixation of a lleles e ncoding f or s ilique s hape a nd f lower c olor, w ithout a ny
taxonomical value and ecological meaning.
In California, based on two distinct traits, predominantly silique diameter of less than
5.1 mm and yellow flowers (85-93%), Panetsos and Baker (1967) distinguished pure wild R.
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