Browsing by study line "Plant production sciences"

This study investigated the frost hardiness of cranberry (Vaccinium macrocarpon Ait.) in four cultivars (’Early Black’, ’Howes’, ’Pilgrim’ and ’Stevens’), focusing especially on the frost hardiness of roots in soilless cultivation. Plants for the study were forced in a greenhouse from cuttings of mother plants. The cuttings were rooted in pots diameter of 10 cm x 10 cm in forest peat. Plants were set to grow in the high tunnel over the growing season. Two experiments were conducted during winter 2020–2021. In the experiments, whole plants with pots were exposed to freezing treatments in a controlled freeze chamber at the temperatures of -10, -15, -20 and -30 °C. Control plants were exposed to cooling at +2 °C for an equal time. In the first experiment, plants were exposed to freezing treatment in November straight from the high tunnel. The second experiment took place in January, and plants were overwintered outside until the experiment. After the freezing treatment one upright in each plant was cut, set in a glass tube containing distilled water, and forced in the greenhouse for 14 days. The vitality of the buds, leafs and stems in the cuttings was observed with a stereomicroscope. After the freezing treatment the vegetative growth of the plants grown in pots was cut off exluding the main shoot, which was cut 5 cm above the soil surface. Thereafter plants were forced in the greenhouse over 10 weeks (the light period of 18/6 h, temperature +20 °C). The vitality of the roots was determined by measuring the amount of the new vegetative growth. All the plants tolerated -10 ° C freeze in November and -15 ° C in January, respectively without injury. Some new growth was observed in plants exposed to freezing treatments of -5 ° C below the temperature mentioned above, but frost damage occurred, and the re-growth was decreased compared to control plants. Cultivar Stevens was more tolerant than the others in both experiments conducted. It maintained its growth potential after -15 °C freezing treatment in November, and -20 °C in January respectively. Frost hardiness (LT50) of buds ranged in November from -19 °C to -27 °C. In January ’Stevens’ buds had the highest frost hardiness (LT50 =-36 °C) and ’Pilgrim’ buds had the lowest (LT50 =-27 °C). The environmental conditions throughout the whole growing season may affect frost hardiness, thus, this experiment should be repeated for verifying the results obtained. Also the potential impact of dormancy in the experiment conducted in November cannot be ignored.

The objective of the thesis is to review and characterize (i) typical agroforestry systems in the temperate zone, (ii) levels of soil organic carbon (SOC) in agroforestry and control plots, and (iii) identify the conditions under which agroforestry farming is most likely to enhance SOC. A meta-analysis was conducted to investigate the impact of agroforestry farming systems on SOC stocks at soil depths of 0 – 20, 0 – 40 and 0 – 100 cm. Data was collected from 15 published studies and all sites are located in temperate climates. Studies had to report at least measurements on SOC concentration or stock for an agroforestry plot and a control plot (arable land, grassland, forest). Investigated treatment variables were soil depth, agroforestry system type, soil type, tree species and age. The results have shown significantly higher SOC stocks under agroforestry in comparison to controls in all three soil depth datasets. The largest amount of SOC in agroforestry was found in the first 20 cm of topsoil and at a soil depth of 60 – 100 cm. There were no significant differences found between alley cropping, silvopasture and shelterbelt systems. The most popular tree species in temperate agroforestry were Populus spp., M.domestica, Juglans regia and Picea. But no significant differences in C sequestration could be observed between tree species across all datasets. The assumption that systems with older trees have higher stocks of SOC could not be confirmed. Most common soil types of temperate agroforestry systems were Luvisol, Fluvisol and Chernozem. The meta-analysis did not verify results of other studies, which have shown that clay contents in the soil promote C sequestration. The wide variability and diversity of agroforestry systems has shown to be problematic in conducting a meta-analysis, indicated by a high heterogeneity. Furthermore, different types of study designs, lack of standardized sampling procedures and explanatory variables may have influenced the results. However, the study showed that agroforestry can be a promising carbon dioxide (CO2) mitigation option, also for the temperate climate zone.

Securing food production is an important objective, especially as climate change affects production conditions. Good crop yields are part of food security, but disease pressure and abiotic stress factors limit yield potential. Chemical plant protection products, which have traditionally been used in plant protection, pose an environmental risk and efforts are therefore being made to reduce their use and replace them with, for example, biological plant protection products. Biostimulants aim to improve crop yields. The aim of this study was to determine whether biomass products produced in different ways have antifungal or biostimulant effects. Three different concentrations of biomass products were used in the experiments. In screening experiments, the antifungal activity of biomass products was investigated in petri dish experiments to test their effect on the growth of two plant pathogenic fungi, Fusarium graminearum and Rhizoctonia solani. The biostimulant effect was investigated by a germination experiment on barley. In the following experiments, the effect of biomass products was investigated in the model organism Physcomitrium patens moss. P. patens was inoculated with two fungal isolates, Rhizoctonia solani and Sclerotinia sclerotiorum, and treated with biomass products. Biostimulant properties were observed on uninoculated P. patens. In addition, the study examined, whether the gene expressions of P. patens change due to the influence of biomass products using RT-qPCR. In Petri dish experiments, biomass products inhibited the growth of both F. graminearum and R. solani fungi. The highest concentration tested was most effective against fungi. The lowest biomass product concentration tested was most effective in inducing barley growth. Biomass product in combination with S. sclerotiorum infection caused death of P. patens, but the combined effect with R. solani infection induced P. patens growth. Gene expression of the three transcription factors tested and one defense gene changed by the interaction of biomass products and R. solani infection. Based on the results obtained in the study, biomass products have potential to be used in fungal disease control. The use of biomass products as biostimulants also seems promising. A lot of further research on biomass products is needed to understand their effects on different crops and pathogenic fungi.

Cell walls (CWs) are the safeguards of plant cells and have a crucial role in controlling cell integrity and plant-environment interactions. Perception of cell wall damage (CWD) results in activation of signaling pathways leading to activation of plant defiance responses. Previous research utilizing murus1 GDP-L-fucose deficient mutant has shown the role of GDP-L-fucose biosynthesis in controlling the structure and integrity of the CWs. Here, we investigated whether phenotypical consequences provoked by the lack of GDP-L-fucose, observed in mutants lacking MURUS1 can be suppressed by blocking signal transduction pathways involving THESEUS1 (THE1) receptor-like kinase or WALL-ASSOCIATED KINASE 2 (WAK2)- MAP KINASE 6 (MPK6) signaling module involved in CWD responses. For this, mur1 the1 and mur1 mpk6 double mutants were generated and analyzed. We found that the phenotypes of double mutants closely resemble that of mur1 mutants, indicating that the morphological consequences of GDP-L-fucose deficiency develop independently of THE1 and MPK6 signaling. Further, we aimed to investigate whether GDP-4-keto-6-deoxymannose-3,5-epimerase-4-reductases GER1 and GER2 controlling the final step of GDP-L-fucose synthesis are functionally redundant. Due to the inability of generating ger1 ger2 double mutants, we have applied the artificial microRNA (amiRNA) strategy to generate ger1 ger2 amiRNA knockdown plants. We found that these knockdown plants exhibit severe developmental growth defects similar to those observed in plants impaired in import of GDP-L-fucose into the Golgi apparatus and these growth defects exceeded those observed in plants lacking MUR1. Therefore, we have concluded that GER1 and GER2 are functionally redundant.

Anthropogenic activities have resulted in huge accumulation of plant nutrients in lake sediments. These nutrients can be recycled back to the overlying water and sustain eutrophication. The release of phosphorus (P) from sediments, i.e. internal P loading, has often been a reason for delay in improvement of lake water quality, after reduced external nutrient loading. By removing the sediment, the internal lake nutrient load can be effectively reduced, and it is widely used in lake water quality restoration. By redirecting the reclaimed nutrients back to primary agricultural production, the need for using mineral fertilizers and virgin materials can be reduced. Currently there is, however, a lack of field-scale experiments and determination of best practices to enable efficient nutrient uptake and minimized nutrient leaching back into the lakes. A field experiment was conducted to study the effects of using P-rich lake sediment in different application methods for growing a mixture of forage grasses. The study focused on soil fertility, plant growth and nutrition, and species composition over a period of four growing seasons in central Estonia. Treatments for reducing nutrient losses included applying the sediment alone (Sed), with surface-incorporated biochar (Sed+BC), and as incorporated with surface-mixed biochar-topsoil mixture (Sed+Soil+BC). A treatment consisting of sandy loam topsoil was set up as control (Soil). The mean dry mass yield in the sediment treatments exceeded the local average grass yields and the N and P uptake rates in above-ground biomass (AGB) exceeded the international estimates for grasses. The sediment had no significant effect on AGB yield in comparison to the control. Similarly, no effect was observed in the yield of weeds, but temporary changes in weed species composition and an increasing trend particularly in nettle abundance on the sediment treatments were recorded. Apart from a transient increase in the amount of soluble potassium, no relevant effects were induced by the incorporated biochar. In conclusion, the sediment performed well and served as a plentiful source of P for grasses for four years. Based on the sufficient concentrations of P, sulphur, calcium and potassium in the plant tissue, yield increase could have been expected but most likely the good fertility of the control topsoil evened out yield differences between growing medium treatments. Based on this study, similar lake sediments can be advised to be used as soil amendments on grass cultivation on an agricultural field. Due to high nutrient concentrations, a lower rate could be applied on a wider field area to control excess in nutrient supply, given that the need of nitrogen fertilization is ensured to match plant-specific requirements.

The cultivation possibilities of American cranberry (V. macrocarpon) have been investigated in Finland, and tunnel cultivation has given promising results. However, the growing season in Finland is short and the ripening of all berries is not guaranteed. Anthocyanins are health promoting color pigments in berries. Light has been found to affect expression of genes related to anthocyanin biosynthesis, anthocyanin levels, and quality in Vaccinium berries in pre-, and postharvest. The purpose of this thesis was to investigate the effect of wide spectrum-, red-, and blue light, exposure time (7 or 14 days) and the expressions of six selected genes related to anthocyanin biosynthesis in different ripening stage in American cranberries under postharvest. Furthermore, the aim was to compare previously measured results of antho-cyanin levels with the selected gene expressions. The genes were CHS, DFR, F3’H, F3’5H, ANS, and UFGT. The ripening stages of berries were green, white, and turning red. The light quality, exposure time, and ripening stages significantly affected the expres-sion of genes related to anthocyanin biosynthesis and the levels of anthocyanins. Blue light significantly increased UFGT expressions and anthocyanin levels in green berry stages. The effect of light quality on gene expression decreased during the ripening pro-cess. However, the wide spectrum with longer exposure time significantly increased the levels of anthocyanins in the turning red stage. With the right light quality and exposure time, gene expression related to anthocyanin biosynthesis can be increased, as well as anthocyanin levels in American cranberry under postharvest.

Late blight, caused by Phytophthora infestans (Mont.) de Bary, is considered the most devastating disease in potato (Solanum tuberosum L.) production worldwide. Control methods involve mostly the use of fungicides, which are costly and are under political pressure for reduction in Europe. Potatoes from the major potato cultivar in Sweden, King Edward, previously stacked with three resistance (R) genes (RB, Rpi-blb2 and Rpi-vnt1.1) were tested in a local Swedish field, with spontaneous P. infestans infection over three seasons to evaluate the effectiveness and stability of the resistance on leaves. In addition, testing of resistance was done in both in leaves and tubers. Field results demonstrated that the 3R stacked into the cultivar King Edward, showed practically full resistance to infections of P. infestans, with no difference to fungicide use. Moreover, the resistance was effective in both leaves and tubers. The results reveal the 3R potatoes offer a functional field resistance, that could, alone, reduce the total use of fungicides in agriculture by several percent in Sweden, in an event of modifications in the EU legislation.

Fragaria x ananassa is a widely appreciated berry with its production growing all around the world. Thus, there will be a huge demand for strawberry breeding in the future especially since the climate change is casting an extra shadow upon the growing conditions which is also why there is a need for better understanding of different cultivar types. There are everbearing and seasonally flowering cultivars of both Fragaria x ananassa and Fragaria vesca. The seasonally flowering types such as ʻHapilʼ flower once during the growing season whereas everbearing types such as ʻCalypsoʼ flower for a longer period. The gene behind the change in the flowering habit has been tracked to the photoperiodic pathway of F. vesca although the gene behind the trait in F x ananassa remains unknown. The aim of this project was to compare flowering and vegetative responses of in vitro propagated everbearing F x ananassa cultivar ʻCalypsoʼ and seasonally flowering ʻHapilʼ in long and short day photoperiodic conditions in order to find out differences between everbearing and seasonally flowering cultivars. This was done by collecting data from phenotype observations linked to the vegetative and generative stages of the development of strawberries. The phenotype data was then combined with gene expression data of FaSOC1, FaTFL1, FaGA20ox4 and FaAP1 which are genes known to work on the photoperiodic pathway that regulates the switch between the vegetative and generative development of both F x ananassa and F. vesca. In addition, the expression of an everbearing phenotype associated gene FaFT2 was analysed. This study was a part of a larger project aimed to find out the genetic basis for the everbearing habit of F x ananassa. Part of the ʻCalypsoʼ plants were induced to flower already during the acclimatization period and the rest at the very beginning of the treatment period which then caused differential flowering times between the ʻCalypsoʼ groups. Short day grown ʻHapilʼ was induced to flower between weeks three and six whereas long day grown ʻHapilsʼ remained vegetative. Phenotypic observations were also backed up by the expression of FaTFL1 and FaAP1. Instead the FaSOC1 expression was repressed in short day conditions more than in the long days regardless of the cultivar type. ‘Calypsos’ were capable of producing runners regardless of photoperiod or flower induction. Consequently the runner production seemed to be regulated by factors outside of the photoperiodic pathway. However, the expression of runnering associated FaGA20ox4 was low and variable due to the sampling strategy. Interestingly most of the axillary meristems of short day grown ‘Hapils’ remained dormant for an unknown reason. Expression of FaFT2 was low on the apical meristems and further support for the role of the gene in everbearing phenotype was not found.

Strawberry breeding in Finland began 60 years ago and has largely relied on traditional breeding methods. The geography of Finland, as well as local consumer preferences for darker-coloured strawberries, have been the main focus of selection in all implemented Finnish breeding programs. With several successful and popular cultivars have been released, the current focus is on increasing yield and disease resistance while maintaining the excellent fruit quality of breeders' selections. A panel of 175 garden strawberry accessions was created and trialled at the Natural Resources Institute Finland (Luke) as part of a Nordic-Baltic pre-breeding collaboration between the institute and the Norwegian breeding company Graminor AS. A medium-density, genome-wide scan for 50K SNPs has been performed on each individual of the panel. This panel represents the genetic diversity present and typical for cultivated strawberry in the Nordic-Baltic region, and it is expected to provide Nordic breeders with markers tailored to their plant material diversity, supporting their future selection decisions and accelerating their breeding cycles. In this study, symptom severities of two strawberry leaf diseases (leaf spot caused by Mycosphaerella fragariae and leaf scorch caused by Diplocarpon earlianum) and seven fruit quality traits (berry weight, skin colour, flesh colour, evenness of flesh colour, basket appearance, predominant berry shape and tip type) were scored in the panel. GAPIT and statgenGWAS statistical packages in R were used to run five different GWAS models: Significant SNP-trait associations were found using single-locus (GLM and MLM) and multi-locus (FarmCPU and BLINK) association mapping analyses. The study had shed a light on the importance of considering several statistical models and parameters for a maximum benefit of association mapping studies. Among significant SNP-trait associations for fruit weight, fruit skin colour and fruit flesh colour, four were partially characterized by inspecting their allelic effects. On chromosome Fvb6-1, appearance of consensus, significant signals from the flesh colour trait of secondary-position berries is discussed. Nine significant SNP-marker associations were detected for berry weight.

Nykypäivänä maatalous on suurissa määrin niin Suomessa kuin globaalistikin riippuvainen teollisista typpilannoitteista, ja ne ovat olleet oleellinen osa maatalouden tuottavuuden kasvua. Niiden tuotantoprosessissa tarvitaan kuitenkin fossiilisia energianlähteitä ja mineraalilannoitteiden käytön yleistymisen myötä viljely on yksipuolistunut. Palkokasvien, kuten härkäpavun lisäämisellä viljelykiertoihin on mahdollista korvata teollisia typpilannoitteita biologisella typensidonnalla. Tämän tutkimuksen tavoitteena oli selvittää härkäpavun esikasvivaikutusta kauran kuiva-aine- ja typpisadon muodostukseen. Tavoitteena oli myös tutkia typpilannoituksen vaikutusta kuiva-aine- ja typpisatoon sekä kauran biomassan ja typenoton kehitystä ajan suhteen, nettomineralisaatiota ja kumulatiivisia N2O-N-emissioita. Aineisto saatiin Leg4Life-hankkeen peltokokeen erilaisia viljelykasvijärjestyksiä edustavista koejäsenistä, joissa kasvoi kauraa kasvukaudella 2021. Kaurasta oli neljä koejäsentä, joilla oli eri esikasvit ja typpilannoitustasot: 1) lannoittamaton kaura, jonka esikasvina oli härkäpapu-rapsi-seos, jolla oli aluskasvina raiheinä 2) lannoitettu kaura (90 kg (N)/ha-1) jonka esikasvina oli härkäpapu-rapsi-seos, jolla oli aluskasvina raiheinä 3) lannoitettu kaura (90 kg (N)/ha-1) jonka esikasvina oli härkäpapu, jolla aluskasvina oli raiheinä, 4) monokulttuurina viljelty lannoitettu kaura (90 kg (N)/ha-1). Kasvustosta kerättiin biomassanäytteitä koko kasvukauden ajan ja sadonkorjuun yhteydessä kerättiin jyväsatonäytteet. Koeruuduista otettiin pintamaanäytteitä NH4+- ja NO3- -pitoisuuksien laskemiseksi ja N2O-emissioita mitattiin pimeäkammiomenetelmällä kahden viikon välein. Kaikkien kaurakoejäsenten kuiva-aine- ja typpisadot olivat samaa suuruusluokkaa, eikä käsittelyiden väliltä löytynyt tilastollisesti merkitseviä eroja. Ennakko-odotusten vastaisesti ei havaittu, että kauralla, jonka esikasvina oli härkäpapu tai härkäpapu-rapsi-seos olisi merkittävästi suuremmat kuiva-aine- ja typpisadot verrattuna monokulttuurikauraan. Toisaalta kuiva-aine- ja typpisadot eivät olleet myöskään pienemmät verrattuna monokulttuurina viljeltyyn kauraan, mikä vastasi toista ennakko-odotusta. Myöskään typpilannoitetuilla koejäsenillä satojen ei havaittu olevan merkittävästi suurempia kuin ei-typpilannoitetun kaurakoejäsenen. Tulosten mukaan koeruuduissa, joissa oli härkäpapu esikasvina, kasvukauden alussa pintamaan NH4+- ja NO3- -pitoisuudet olivat suuremmat kuin monokulttuurikaurassa, mutta kasvukauden sääolosuhteiden vuoksi typpeä todennäköisesti poistui pintamaasta denitrifikaation tai huuhtoutumisen muodossa. Esikasvi- ja typpilannoituskäsittelyiden laskennalliset vaikutukset vaihtelivat. Korsien kuiva-ainesadon osalta ainoastaan härkäpavun satoa lisäävä vaikutus oli trendinomaisesti tilastollisesti merkitsevä. Typpisadon osalta härkäpavun positiivinen vaikutus oli trendinomaisesti tilastollisesti merkitsevä ja härkäpapu-rapsi-seoksen positiivinen vaikutus tilastollisesti merkitsevä. Vaikka tässä tutkimuksessa ei havaittu tilastollisesti merkitseviä eroja eri koejäsenten kuiva-aine- ja typpisatojen välillä, ei myöskään ilmennyt, että härkäpapu esikasvina aiheuttaisi merkittäviä negatiivisia vaikutuksia sitä seuraavan kauran kuiva-aine- ja typpisatoon verrattuna monokulttuurikauraan, vaan sadot olivat samaa suuruusluokkaa. Kasvukausi 2021 oli sääolosuhteiltaan poikkeuksellinen vähäisen sadannan ja korkean keskilämpötilan suhteen, ja sen aiheuttamat sadonalenemat tässä tutkimuksessa voivat olla ennuste Suomen viljelyolosuhteiden tulevaisuudesta. Lisätutkimuksia aihepiiristä erityisesti Pohjoismaiden viljelyolosuhteissa tarvitaan.