Predisposing Effects of Low Temperature on Resistance to Winter Stress Factors in Grasses

Abstract

Abstract Seed propagated and vegetatively propagated plants from Phleum pratense and Phalaris arundinacea, hardened and unhardened, were exposed to the winter stress factors freezing and/or inoculation with snow mould fungi, Fusarium nivale and Typlutla ishikariensis. Exposure to both freezing and fungal inoculation in combination resulted in more severe damage than exposure to either factor alone. Artificial hardening increased resistance to the winter stress factors, the effect was especially pronounced on plants exposed to the combination of two stress factors. Resistance to freezing was significantly correlated with resistance to T. ishikariensis in hardened plants, but not in unhardened ones. Hardened and unhardened plants of the same genotype showed correlated resistance to T. ishikariensis, but not correlated freezing resistance. In the plant material investigated the variation in resistance due to environmental factors was greater than the genetic variation.