Winter hardiness of oilseed rape | L'hivernage du colza d'automne
2002
Pellet, D. | Gindrat, D. | Frei, P. (Station federale de recherches en production vegetale de Changins (RAC), Nyon (Switzerland)) | Hebeisen, T.
Weather conditions during fall and winter 2001-2002 made it possible to observe differences in winter hardiness among winter oilseed rape varieties grown in Switzerland. Cultivars Colosse and Capitol scored best and Synergy the worst. Winter hardiness and resistance to black leg were positively correlated among 20 genotypes. In Goumoens-la-Ville (618 m a. s. l.), field survival was low for plants of the cultivars Synergy and Express. In Changins (420 m a. s. l.), on the other hand, no frost damages were observed for the same varieties. On both sites, hypocotyl elongation has been observed. Negative extreme temperatures were similar in both sites. Following factors can explain differences in oilseed rape winter hardiness between both sites: - The number of days with mean temperature favorable to plant hardening (between 0 and 5 °C) was higher in Changins than in Goumoens. - In Goumoens, plant available nitrogen sustained vegetative growth during the fall, which is negative for plant frost resistance. - The pressure of black leg was higher in Goumoens than in Changins. Low field survival during winter time is the consequence of additive negative factors such as climatic conditions, excessive plant available nitrogen and plant elongation during the fall, as well as high black leg disease pressure. Even in situations of high risks, sensible cultivar choice and suitable seed density can provide high winter survival.
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