Browsing by Subject "vernalisaatio"
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(2014)Finland is the northernmost cultivation area in the world and the selection of forage grass species is mostly limited by long winters and short growing seasons. Forage grasses are usually grown as mixtures of species and produced intensively for silage. The grass species most commonly used in mixtures are timothy (Phleum pratense L.) and meadow fescue (Festuca pratensis L.) which are both winter hardy species. As the climate changes in the future, more southern and more productive species like perennial ryegrass (Lolium perenne L.) and festulolium (Festuca sp. x Lolium sp.) may become more usable. The duration of snow cover has been predicted to shorten to 46 days in southern Finland by year 2050 (compared with 98 days at present). The autumns, when plants develop their tolerance against winter stresses, are also predicted to become warmer in the future. Changes in winter weather may also increase the frequency of problems such as plant exposure to freezing temperatures, associated with decreased snow cover and ice encasement due to fluctuating winter temperatures. This study presents the results of experiments carried out in Helsinki (Finland) between years 2009–2013. The experiments were done to assess the freezing tolerances and vernalisation of forage grasses and cereals hardened under field conditions. The vernalisation of plants was detected in all species as a decrease in days to heading during the vernalisation period. Perennial ryegrass and meadow fescue started flowering after the vernalisation was fulfilled during December-January. Winter cereals had already vernalised already in November. Hardening periods started at their earliest in the beginning of October. However, a deeper freezing tolerance developed during December in 2009–2010 and 2011–2012. During the winters of 2009–2010 and 2011–2012 hardening periods were long and hardening-induced temperature sums were the highest. During these winters the freezing tolerances were better in all species than during the other two winters.
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(2021)This thesis was undertaken to determine effects of genotype, vernalization and harvesting on the root growth of grass plants. Greenhouse experiments were carried out at Viikki experimental farm of University of Helsinki. The thesis was a part of a larger research of grasses. Grass species were two timothy (Phleum pratense L.) parental lines, northern (021/1) and southern (B112) genotype (Boreal Plant Breeding Ltd). The trial material was propagated using the plant material conserve of Viikki. A half of the trial material got a vernalization treatment (10 weeks) after pre-breeding (2 weeks, DL 12 h) and the other half of plants got only pre-breeding (3 weeks, DL 12h) before establishment of two separate trials in rhitsotubes and rhitsotrones. High, growth stage, dry matter of shoots and roots, depth of the root system and shoot to root ratios were measured from rhitsotubes seven times during the study. The growth samples from rhitzotrones were collected twice. The harvesting was done in the middle of the study from both separate trials. Genotype had an influence on all measured growth features in both separate trials. Treatments of southern genotypes were mainly higher, development was faster and dry matter of shoots was greater at harvest time compared to the same treatments of the northern genotype. There were no differences on growth features between genotypes in the end. The dry matter of roots was also greater at the harvest time with treatments of the southern genotype. In the end of the trial there were no differences between genotypes or treatments, but the genotype influenced on root growth in repeated measurements between weeks 6-8. The root system of the southern genotype spread out in deeper soil layers with both treatments and survived better after harvesting compared to treatments of the northern genotype. The vernalization had influence on growth features and the root system with most of the occasions of measurements with both the genotypes. The vernalization reduced biomass of roots in the both separate trials. This was partly due to low weight of shoots especially in the beginning of the study. In the other hand the vernalization improved on development before the harvesting and the carbohydrates allocated on shoots instead of roots. This was visible especially in the rhitsotubes. Differences between vernalized and non-vernalized treatments were levelled towards the end of the study. The vernalization increased growth of roots to deeper soil layers comparing to the non-vernalized treatment with the northern genotype. In weekly monitoring the growth of roots of both the vernalized genotypes were strong before ending the study. This might cite better overwintering but in the other hand shoot to root ratios were almost the same in all treatments. This study showed out that a plant tries to keep the growth of shoots and roots in balance but also that the biomass allocates in shoots in the beginning of the growing season and more in roots after harvesting. According to this study adding the southern genetic heritage to the timothy refinement programs brings higher yield level and moreover more abundant and deeper root system.
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(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.
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(2018)Timoteitä (Phleum pratense L.) viljellään Suomessa karjalle rehuksi. Sen kasvuston rakenne vaikuttaa satoon ja sadon ominaisuuksiin. Typpilannoituksen, vernalisaation ja genotyypin kaikkia vaikutuksia näihin ominaisuuksiin ei vielä tiedetä tarkkaan. Tietoa tarvitaan uusien lajikkeiden typpilannoitussuositusten kehittämiseen sekä avuksi timotein lajikejalostuksessa sopeuduttaessa ilmastonmuutokseen ja maataloustuotannon kestävään tehostamiseen. Tämän tutkimuksen tavoitteena oli selvittää miten typpilannoitus, vernalisaatio ja kasvin perimä vaikuttavat timotein kasvustorakenteeseen ja miten typpi vaikuttaa vernlaisaatio geeneihin ja kukintaan. Kokeessa oli mukana kaksi timotein genotyyppiä, eteläinen (BorE) ja pohjoinen (BorP), jotka eroavat toisistaan vernalisaatiovaatimukseltaan. Typpitasoja oli kolme, jotka vastasivat peltolannoituksen tasoja 11,6 kg N/ha (N1), 278,3 kg N/ha (N2) ja 545,0 kg N/ha (N3). Kasvit joko vernalisoitiin 10 viikon ajan tai niitä ei vernalisoitu ennen siirtoa kasvihuoneelle pitkään päivään. Kasveista mitattiin viikottain korren pituus, versojen lukumäärä ja lehtien lukumäärä, sekä kokeen lopussa kuiva-aineen kertyminen sekä versotyyppien lukumäärä (GEN, ELONG, VEG). Kasveista kerättiin näytteitä ennen pitkään päivään tai vernalisaatioon siirtämistä sekä 1-4 vk kasvihuoneelle siirron jälkeen RNA näytteet, joista analysoitiin PpVRN1 ja PpVRN3 geenien ilmeneminen qPCR analyysillä. Typpilannoitus vaikutti tilastollisesti merkittävästi kaikkiin mitattuihin tekijöihin kasvustorakenteessa. Typpi lisäsi erityisesti versojen lukumäärää ja se alensi tai viivästytti erityisesti PpVRN3 geenin ilmenemistä. Vernalisoimattomassa BorE kasveissa typpi lisäsi myös GEN versojen lukumäärää. Typellä oli kaiken kaikkiaan tilastollisesti merkittävä vaikutus VRN geenien ilmenemiseen. Lisäksi genotyyppi vaikutti kasvustorakenteen siten, että BorE olivat keskimäärin korkeampia. Timotein genotyyppi vaikutti typen vasteeseen ainoastaan korsijakauman kautta. Typpilannoituksella ja sen määrällä havaittiin olevan vaikutusta timotein kasvustorakenteeseen, kukkivien versojen lukumäärään sekä vernalisaatiogeenien ilmenemiseen. Typen vaikutukset eivät kuitenkaan olleet yksiselitteisiä vaan yhdysvaikutuksia esiintyi runsaasti. Typen vaikutukset kukintaan oli selkeämpi BorE kasveissa, mikä voi viitata siihen, että vernalisaatiolla ja sen vaatimuksella voi olla merkitystä genotyypin typpivasteeseen.
Now showing items 1-4 of 4