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3. MORPHOLOGICAL VARIATION...
plant flowers for the fist time or not. Response to temperature and photoperiod is closely
related to geographic origin of a population and this is probably the reason that the only
L. perenne flowered in the 1 st year of cultivation originated from warm climate (New Zealand).
Date of ear emergence is also a subject of selection according to agronomic management
and would, therefore, reflect the selective pressure during breeding programmes.
Winterhardiness is the second important species determination character. The data
obtained from this study revealed that this character is also quite variable in both species.
It is not surprising either that almost all Scandinavian ecotypes survived the winter
without damage or low winterhardiness in L. perenne from New Zealand. Similarly,
L. multiflorum accessions from Italy rather did not survived the winter while the German
ecotype did quite well. Although significantly greater winterhardiness has been observed in
L. perenne, it seems that this feature strongly depends on geographical origin of a population.
Very high winterhardiness of the Italian ecotype of L. multiflorum (80% of plants recovered
after winter) appears quite surprising. However, Italian ryegrass may behave as
a biennial or even short-lived perennial. In areas with reliable snow cover, it can survive for
five and more years (Cosgrove et al. 1999). Unexpectedly, excellent snow cover in northern
Poland could increase the chances of more southern ecotypes to survive even in comparison
with areas of milder climate but often suffered from little snowing. Moreover the transgressive
segregation observed in many populations suggests that winterhardiness can be increased
above the average level.
On the other hand L. perenne is best adapted to mild-temperate climates. Plants do not
stockpile well and must have good snow cover to survive the winter. This explains why some
L. perenne cultivars were hardly recovered after the winter. It was especially true for Japan
cultivar Kyosato and Polish line Ba012 (about 30% of plants). While the low winterhardiness