Am. Tronsmo, RESISTANCE TO WINTER STRESS FACTORS IN HALF-SIB FAMILIES OF DACTYLIS-GLOMERATA, TESTED IN A CONTROLLED ENVIRONMENT, Acta agriculturae Scandinavica. Section B, Soil and plant science, 43(2), 1993, pp. 89-96
Improved winter hardiness is an important objective in Norwegian grass
breeding. Selection for winter hardiness based on performance in a co
ntrolled environment is a means to obtain this goal faster than relyin
g on field trials. Progress in selection will depend on the genetic va
riation and the heritability of the traits. This investigation shows t
hat artificial screening for winter survival traits reveals significan
t genetic variation in Dactylis glomerata in all three characters test
ed: resistance to Fusarium nivale, resistance to Typhula ishikariensis
and resistance to freezing. The broad sense heritability of resistanc
e to snow mould fungi between 0.4 and 0.5, and for freezing resistance
between 0.5 and 0.7, indicates good possibilities for improving the t
raits by selection for resistance. The genotypic correlation calculate
d from the analysis of covariance of two half-sib families was found t
o be approximately 1. Although associated with contradictory data, thi
s finding supports the theory that resistance to different winter stre
ss factors is based on the same genetic trait(s).