Browsing by Subject "Betula pendula"

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  • Rousi, Matti (The Society of Forestry in Finland - The Finnish Forest Research Institute, 1990)
    Literature was reviewed on genotypic variation between tree species (especially Betula spp.) and within species with regard to their resistance to feeding by voles (Microtus spp., Clethrionomys spp.) and hares (Lepus spp.). Mechanisms of resistance and the phenotypic plasticity of Betula spp. are described. The experimental methods used to study this subject are compared and the practical forestry applications of differences in resistance discussed. The studies evaluated gave no indication that breeding for growth and quality will decrease the level of resistance in Betula spp. and it is concluded that the prospects for resistance breeding are good.
  • Liepiņš, Rob. (Suomen metsätieteellinen seura, 1933)
  • Luomajoki, Alpo (The Society of Forestry in Finland - The Finnish Forest Research Institute, 1999)
    Male flowering was studied at the canopy level in 10 silver birch (Betula pendula Roth) stands from 8 localities and in 14 downy birch (B. pubescens Ehrh.) stands from 10 localities in Finland from 1963 to 1973. Distributions of cumulative pollen catches were compared to the normal Gaussian distribution. The basis for the timing of flowering was the 50 per cent point of the anthesis-fitted normal distribution. To eliminate effects of background pollen, only the central, normally distributed part of the cumulative distribution was used. Development up to the median point of the distribution was measured and tested in calendar days, in degree days (> 5 °C) and in period units. The count of each parameter began on and included March 19. Male flowering in silver birch occurred from late April to late June depending on latitude, and flowering in downy birch took place from early May to early July. The heat sums needed for male flowering varied in downy birch stands latitudinally but there was practically no latitudinal variation in heat sums needed for silver birch flowering. The amount of male flowering in stands of both birch species were found to have a large annual variation but without any clear periodicity. The between years pollen catch variation in stands of either birch species did not show any significant latitudinal correlation in contrast to Norway spruce stands. The period unit heat sum gave the most accurate forecast of the timing of flowering for 60 per cent of the silver birch stands and for 78.6 per cent of the for downy birch stands. Calendar days, however, gave the best forecast for silver birch in 25 per cent of the cases, while degree days gave the best forecast for downy birch in 21.4 per cent of the cases. Silver birch seems to have a local inclination for a more fixed flowering date compared to downy birch, which could mean a considerable photoperiodic influence on flowering time of silver birch. Silver birch and downy birch had different geographical correlations. Frequent hybridization of birch species occurs more often in northern Finland in than in more southern latitudes. The different timing in flowering caused increasing scatter in flowering times in the north, especially in the case of downy birch. The chance of simultaneous flowering of silver birch and downy birch so increased northwards due to a more variable climate and also higher altitudinal variations. Compared with conifers, the reproduction cycles of both birch species were found to be well protected from damage by frost.
  • Bhat, K. M.; Kärkkäinen, Matti (Suomen metsätieteellinen seura, 1980)
  • Mõttus, Matti; Aragão, Luiz; Bäck, Jaana; Clemente, Rocío Hernandez; Maeda, Eduardo Eiji; Markiet, Vincent Robert Leon; Nichol, Caroline; Oliveira, Raimundo Cosme; Restrepo-Coupe, Natalia (2019)
    The spectral properties of plant leaves relate to the state of their photosynthetic apparatus and the surrounding environment. An example is the well known photosynthetic downregulation, active on the time scale from minutes to hours, caused by reversible changes in the xanthophyll cycle pigments. These changes affect leaf spectral absorption and are frequently quantified using the photochemical reflectance index (PRI). This index can be used to remotely monitor the photosynthetic status of vegetation, and allows for a global satellite-based measurement of photosynthesis. Such earth observation satellites in near-polar orbits usually cover the same geographical location at the same local solar time at regular intervals. To facilitate the interpretation of these instantaneous remote PRI measurements and upscale them temporally, we measured the daily course of leaf PRI in two evergreen biomes—a European boreal forest and an Amazon rainforest. The daily course of PRI was different for the two locations: At the Amazonian forest, the PRI of Manilkara elata leaves was correlated with the average photosynthetic photon flux density (PPFD) ( R2=0.59 ) of the 40 minutes preceding the leaf measurement. In the boreal location, the variations in Pinus sylvestris needle PRI were only weakly ( R2=0.27) correlated with mean PPFD of the preceding two hours; for Betula pendula, the correlation was insignificant regardless of the averaging period. The measured daily PRI curves were specific to species and/or environmental conditions. Hence, for a proper interpretation of satellite-measured instantaneous photosynthesis, the scaling of PRI measurements should be supported with information on its correlation with PPFD.
  • Rikala, Risto; Jozefek, Helen J. (Suomen metsätieteellinen seura, 1990)
  • Ollinmaa, Paavo J. (Suomen metsätieteellinen seura, 1960)
  • Raulo, Jyrki (Suomen metsätieteellinen seura, 1978)
  • Muranen, Sampo (Helsingin yliopisto, 2019)
    Tree shoot architecture research is important due to its significance in fields such as timber production, fruit and nut production and aesthetics of common areas. Also, research on genetic factors that regulate shoot and root system architecture might provide novel methods to store more carbon in forests and, hence, mitigate global warming in the future. LAZY1 is one of the major genes that affects branch and tiller angle in herbaceous and woody species such as Arabidopsis, rice and peach tree. LAZY1 has been under scrutiny over a decade but its molecular function remains unknown. However, it is known that lazy1 mutation affects polar auxin transport. Here it is studied how LAZY1 affects initial branch angle, fiber length and reaction wood development in silver birch (Betula pendula). Also, transcript levels of few shoot architecture related genes were analyzed. LAZY phylogenetic analysis provided evidence of a duplication of LAZY1 in three studied tree species (Betula pendula, Prunus persica, Populus trichocarpa), duplicated genes are here named LAZY1a and LAZY1b. Plant material employed in this study was a segregating population (50:50) of back-cross 1 of weeping birch (B. pendula ´Youngii´) which has a truncated lazy1a. Histological samples of branches were prepared by cryo-sectioning, stained with carbohydrate binding Alcian Blue and lignin binding Safranin dyes to reveal patterns of tension wood development. Due to the large size of branch sections, samples were imaged with a microscope and the images were merged together in a Photoshop application. Branch angles were measured manually with a protractor (angle) tool from stem to the middle of a branch. The data was analyzed using mixed linear models due to the nature of used plant material. We could not use clones because of major issues in in vitro propagation. Branch samples were macerated, fibers imaged and measured by ImageJ software. LAZY1a gene expression levels were analyzed by RT-qPCR method. RNA-sequence analysis indicated that the expression pattern of LAZY1a and LAZY1b is similar in B. pendula. However, one should construct a promoter-reporter line to study with better resolution if their expression is spatially analogous. Initial branch angle was significantly different in wild type compared to lazy1a mutant. For future, one could generate single and double knock out lines of lazy1a/b to study if they have cumulative effect on the branch angle, an important factor in timber quality. Tension wood formation was difficult to quantify with the employed method, due to issues in segregating G-layered tension wood from thick-walled reaction wood. A chemical analysis of cellulose content might provide a more objective method to observe tension wood in branches. RT-qPCR method indicated that LAZY1a transcript levels are higher in wild type compared to mutant. A complementation or knock down experiment would provide sound evidence that lazy1a induces the weeping phenotype. X-ray diffraction method could be employed to study the orientation of cellulose microfibril angle in branches of the wild type vs. mutant. Generation of effective tensional stress requires a cellulose microfibril angle less than 10 and this angle is affected by auxin concentration. It is possible, that this angle is larger in lazy1a due to defect in polar auxin transport.
  • Christita, Margaretta; Overmyer, Kirk (2021)
    Witches' broom of birch (Betula spp.) caused by Taphrina betulina is an understudied disease that causes the formation of woody tumours, from which ectopic axillary buds and branches grow to form a broom-like structure. We have addressed two aspects of this disease using naturally infected mature trees in the field. Broom symptoms offer a convenient means of scoring susceptibility in the field. Variation in broom symptom presentation suggests possible variation in resistance against witches' broom disease. We tracked the local distribution of susceptible individuals among 721 trees at 159 independent sites. The analysis supports the hypothesis that there was genetic resistance segregating in these birch populations. Anatomical changes in broom symptom bearing branches of European silver birch (Betula pendula) were also addressed by comparing sections of tissues from three locations in the same branch, which were normal, swollen in infected tissue adjacent to a tumour, and inside a tumour. Examination of tumours revealed disorganized and swollen xylem, expanded secondary phloem and expanded periderm. Swollen tissues newly infected from spreading disease adjacent to tumours exhibited enhanced growth only in secondary phloem and the periderm, which also exhibited distortions. This finding suggests that tumour formation and possibly pathogen colonization may initiate in these tissues.
  • Pätiälä, Risto-Veikko; Blomberg, Kari; Piepponen, Sulo; Paakkanen, Juhani (Suomen metsätieteellinen seura, 1978)
  • Eriksson, J.; Bergholm, J.; Kvist, K. (Suomen metsätieteellinen seura, 1981)
  • el-Khouri, Hanna (Helsingin yliopisto, 2015)
    Ilmaston muuttuessa puiden kasvuolosuhteet muuttuvat lämpötilan ja hiilidioksidipitoisuuden kasvaessa. Vaikka puiden fysiologiset vasteita on tutkittu jo pitkään, tarkempi tieto puiden vuosirytmin muutoksista ja mahdollisista vaikutuksista vuosittaiseen kasvuun on kiinnostavaa. Hiilidioksidin ja lämpötilan vaikutuksia keväiseen lehtien kehitykseen tutkittiin keväällä rauduskoivulla (Betula pendula roth). Tavoitteena oli selvittää tarkemmin silmujen puhkeamisen jälkeistä fotosynteesikapasiteetin kehittymistä ja kohotetun hiilidioksidipitoisuuden ja lämpötilan vaikutusta siihen kaasunvaihtomittausten avulla. Toisena työn tavoitteena on verrata fluoresenssimittauksilla mitattua PSII:n valoreaktioiden maksimitehokkuutta kaasunvaihtomittauksiin. Koe-asetelma toteutettiin kasvihuoneolosuhteissa neljällä eri huoneella. Nykyilmastoa vastaavissa kontrollihuoneissa ilman hiilidioksidipitoisuuden tavoitteeksi asetettiin 380 ppm, ja lämpötila +2 °C ulkolämpötilaan verrattuna. Loppi2100-olosuhteet kuvaavat tulevaisuuden skenaariota, hiilidioksidipitoisuus tasolla 700 ppm ja lämpötila kontrolliin verrattuna +2 °C. Jokaisessa huoneessa kasvatettiin viittä rauduskoivua, joista mitattiin viikoittain kaasunvaihtomittausten avulla mm. hiilen assimilaatiota ja muita fotosynteesiin liittyviä tunnuksia. Eri huoneiden erilaisen lämpötilakehityksen ja eri mittauspäivien takia erot tasattiin laskemalla huonekohtainen lämpösumma, jonka avulla tulokset saatiin vertailukelpoisiksi eri huoneiden välillä. Tulosten mukaan hiilen assimilaatio on suurempaa ja kehittyy nopeammin Loppi2100-olosuhteissa verrattuna kontrolliin. Lämpösumman avulla aineistosta muodostettiin ennustemalli, jonka residuaalien avulla voidaan todeta, että ero käsittelyjen välillä on tilastollisesti merkittävä. PSII:n maksimitehokkuus korreloi kaasunvaihtomittausten tulosten kanssa, vahvistaen käsitystä siitä, että valoreaktioiden tehokkuus antaa hyvän kuvan koko fotosynteesikoneiston kapasiteetista.
  • Pääkkönen, Elina (University of Helsinki, 1991)
  • Keltikangas, Matti; Tiililä, Pekka (Suomen metsätieteellinen seura, 1968)
  • Laitakari, Erkki (Suomen metsätieteellinen seura, 1934)
  • Ollinmaa, Paavo J. (Suomen metsätieteellinen seura, 1955)
  • Kärkkäinen, Matti (Suomen metsätieteellinen seura, 1986)