Browsing by Subject "cold tolerance"

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  • Kärenlampi, Lauri; Friedland, Andrew J. (Suomen metsätieteellinen seura, 1988)
  • Hänninen, Heikki; Pelkonen, Paavo (Suomen metsätieteellinen seura, 1988)
  • Hänninen, Heikki; Pelkonen, Paavo (Suomen metsätieteellinen seura, 1988)
  • Christersson, Lars; Fircks, Heinrich A. von (Suomen metsätieteellinen seura, 1988)
  • Toivonen, Tiina (Helsingfors universitet, 2014)
    Timothy (Phleum pratense L.) and meadow fescue (Festuca pratensis Huds.) are generally grown forage grasses at high latitudes. Growing of perennial ryegrass (Lolium perenne L.) and xFestulolium hybrid is possibly increasing in the future. The climate change will alter autumn growth conditions in Finland. The aim of this study was to investigate differences in autumn growth and accumulation of reserve carbohydrates between forage grass species and cultivars from different geographical origin. The objective was also to study autumn growth ability after third cut, cold tolerance, tiller density and content of soluble sugars in chosen cultivars in field conditions during winter. This study was carried out at growth chamber experiment and field trial. There were four different autumn growth conditions in growth chambers: first 5 °C/14 h and 10 °C/14 h and secondly 15 °C/12 h and 15 °C/14 h. Vegetative factors like ligule height and activity of photosynthesis and concentration of soluble sugars were measured from timothy, meadow fescue, perennial ryegrass and xFestulolium lines. Autumn growth yield after third cut, cold tolerance (LT50) and reserve carbohydrates of perennial ryegrass and xFestulolium cultivars during winter were measured in field trial (Nov. & Jan./Feb.). According to this study low temperatures (5 and 10 °C) prevented formation of lateral tillers effectively in timothy but not in other species because they formed new lateral tillers and accumulated biomass. Low temperatures (5 and 10 °C) prevented height growth in all studied lines and long day length (14 h) allowed height growth only in higher temperature (15 °C). Perennial ryegrasses and xFestulolium cultivars grew similarly in short (12 h) and long (14h) day length but the growth of timothy was delayed in short day length. Southern timothy breeding line grew significantly height in the 15 °C and 14 h growth conditions whereas northern timothy breeding line formed more lateral tillers. The photosynthesis activity of all tested genotypes was high in all growth conditions and concentration of soluble sugars increased in low temperatures but not in high temperatures except in northern timothy. According to the field trial the overwintering of perennial ryegrasses and xFestulolium cultivars was challenging especially in second winter and the decline of low temperature tolerance was connected to vernalization saturation of xFestulolium cultivars during winter. There was strong variation in autumn growth between years.
  • Repo, Tapani (Suomen metsätieteellinen seura, 1988)
  • Johnsen, Øystein; Apeland, Inger (Suomen metsätieteellinen seura, 1988)
  • Lähdesmäki, Pekka; Pietiläinen, Pekka (Suomen metsätieteellinen seura, 1988)
  • Luhtanen, Juha (Helsingfors universitet, 2011)
    Forage crops are an important part of agriculture in worldwide since about 69 % of the agricultural area is covered with permanent meadows and pastures. In Finland forages cover up to 29 % of the agricultural area and production is based on intensive cultivation. The most cultivated species in Finland is timothy grass (Phleum pratense ssp. pratense L.). It is very frost resistant and that is why it is suited for northern growth environment. Timothy cultivars can be divided based on their genotypic origin to southern, northern and intermediate types. Cultivars differ in their growth and development habit. Along climate change extreme weather conditions become more frequent, mean temperature will rise and winters will be rainier. This research tries to find out how the different cultivars from different origins differ in their cold tolerance, growth and development speed and how vernalisation affects. Besides these it was researched if different methods for evaluating the vernalisation response in winter crops were useful methods to evaluate vernalisation response in forage grasses. Research composed two years long field trial and growth chamber trial. Vernalisation accelerated the growth and development of timothy. Based on this research the southern cultivars already had readiness for growth and development despite of the vernalisation if environmental conditions were favourable. Northern cultivars attained this readiness along the vernalisation. Vernalisation affected also to the architecture of the grasses. The number of generative tillers, that produce the inflorescence, increased due to vernalisation response. The number of vegetative tiller, not inflorescence tiller, became less due to vernalisation. The research revealed that cold tolerance was dependent on the temperature of the autumn hardening period (FH-COLD). High mean temperature during the hardening period decreased the cold tolerance. If the temperature was between 0 °C and + 5 °C cold tolerance increased. According to this research vernalisation had a clear effect on timothy growth and development for example. Northern cultivars do not necessarily need such a long vernalisation as Finnish winter is. Also methods for evaluating the vernalisation response in winter crops are partly useful in pure timothy cultivars too.