Browsing by study line "Plant production sciences"
Now showing items 1-20 of 70
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(2023)Tutkimuksen tavoitteena oli selvittää, onko aluskasvillisuuden monimuotoisuudella vaikutusta virustautien esiintyvyyteen ohran viljelyssä ja mikä on monimuotoisuusasteen vaikutus kirvojen esiintyvyyteen. Ohranäytteitä oli vuosilta 2021 ja 2022 sekä molempien vuosien näytteet olivat kerätty Viikin koe- ja tutkimustilalta. Näytteissä esiintyvät virukset selvitettiin eristämällä ohranäytteistä sRNAt ja lähettämällä ne sekvensoitaviksi. Aluskasvillisuuden vaikutusta kirvojen määrään selvitettiin käyttämällä imurinäytteitä kirvoista ja tarkastelemalla kirvojen määrän ja monimuotoisuusasteiden suhdetta. Vuoden 2021 näytteissä esiintyi viruksia huomattavasti enemmän kuin vuoden 2022 näytteissä. Syitä tälle erolle ei pystytty tarkasti sanomaan, mutta mahdollisia eroon vaikuttavia tekijöitä on voinut olla näytteiden keräysajankohtien erot, sääolosuhteet tai muut ympäristölliset tekijät. Monimuotoisuusasteiden ja virusten välillä ei pystytty muodostamaan mielekästä vertailua. Monimuotoisuusasteiden välillä ei huomattu kirvojen esiintyvyydessä tilastollisesti merkitsevää eroa, mutta eri näytteiden keräys ajankohtien välillä oli huomattavissa eroja kirvojen esiintyvyyden ja monimuotoisuusasteiden välisten suhteiden regressiosuorissa. Ohranäytteissä esiintyvät virukset pystyttiin menestyksekkäästi selvittämään sRNA:n eristyksen kautta. Imurinäytteet osoittautuivat toimivaksi tavaksi selvittää kirvojen esiintyvyyttä, mutta luotettavien tulosten saavuttamiseksi näytteitä olisi tullut kerätä useammalta vuodelta. Vuoden 2022 näytteiden huomattavasti alhaisempi virusten esiintyvyys vaikeutti myös osaltaan mielekkäiden vertailujen ja luotettavien tulosten aikaansaamiseen. Lopulta aluskasvillisuuden monimuotoisuuden vaikutusta virustautien esiintyvyyteen ohran viljelyssä ei pystytty määrittämään puutteellisen datan vuoksi.
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(2022)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.
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(2023)Efforts to cultivate American cranberry (Vaccinium macrocarpon Ait.) across Finland have not been successful. Even Helsinki is located north (60 ºN) as compared to the main production area of cranberry in North American (39-48 ºN), which causes challenges with cold and frost resistance, as well as with overwintering and low heat sum. Recent research has shown that cranberry could possibly survive in the conditions of Southern Finland. Low temperatures around 0 ℃ break endodormancy during winter. The aim of this research was to find out how growing site affects the dormancy release in four cranberry cultivars, and whether inadequate chilling causes ”umbrella bloom” growth, where the plant blooms but does not grow vegetatively. Samples were taken every fourth week during winter and the depth of dormancy was measured by observing the growth of terminal buds in a greenhouse. In addition, the effect of chilling temperature (-3, +2 and +7 ℃) and duration (8, 10 ja 12 wk) of chilling in controlled condition on the growth of terminal buds of cv. Pilgrim were studied. Under natural chilling conditions, the plants which had grown in a high tunnel during the growth season, needed more chilling units (CU) to achieve normal growth (2755 CU) than the open field growth plants (853-1525 CU). The chilling units accumulated every hour when T < +7 ℃. The amount of normally flowering terminal buds increased with increasing chilling duration. Same time, the amount of ”umbrella bloom” flowering decreased, which refers to the role of inadequate chilling in ”umbrella bloom” flowering. When the plants were chilled under controlled conditions (temperatures +7 ja +2 ℃), chilling units were accumulated more efficiently which caused dormancy release earlier than under natural conditions. Chilling under controlled conditions in temperature -3 ℃ is not recommended because the plants dried up too much. In conclusion, natural chilling in Helsinki (60 ºN) is sufficient for breaking dormancy in American cranberry. Recommendations for chilling cranberry under controlled conditions are in temperature of +2 ℃ for 10 weeks.
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(2024)Amerikankarpalo (Vaccinium macrocarpon Ait.) on Pohjois-Amerikasta kotoisin oleva terveysvaikutteinen marja, jota viljellään kotimaassaan allastyyppisillä turvesoilla. Myös Euroopassa amerikankarpaloa on viljelty käytöstä poistetuilla turpeennostoalueilla erityisesti Latviassa. Amerikankarpalon viljelyssä suurimpia haasteita on sen alttius useille eri sienitaudeille, jotka aiheuttavat marjojen pilaantumista jo viljelmillä, mutta myös varastoinnissa. Laajavaikutteisten fungisidien käyttö on yleinen käytäntö pohjoisamerikkalaisilla karpaloviljelmillä, kun taas Latviassa, missä niiden käyttö on vähäisempää, varastotaudit aiheuttavat merkittäviä sadonmenetyksiä. Amerikankarpalon viljelyä on tutkittu Helsingin yliopiston maataloustieteiden osastolla Viikissä vuodesta 2015 lähtien. Suomessa amerikankarpaloa on mahdollista viljellä kasvutunnelissa, jolla viljelyyn tarvittavaa lämpösummaa saadaan nostettua amerikankarpalon tarvitsemalle tasolle. Menetelmä on hyvin erilainen verrattuna turvesuoviljelyyn muualla maailmassa. Toistaiseksi tutkimuksissa ei ole havaittu merkittäviä kasvinsuojelullisia haasteita. Kasvutunneliviljelyn vaikutusta amerikankarpalon varastolaatuun ja -kestävyyteen ei ole aiemmin tutkittu. Tässä tutkimuksessa selvitettiin kolmen lajikkeen (’Pilgrim’, ’Stevens’ ja ’Early Black’) ja kahden kasvupaikan (kasvutunneli ja avomaa) vaikutusta marjojen varastolaadun muutokseen ja varastokestävyyteen, sekä eristettiin ja tunnistettiin morfologian perusteella sekä sekvensoimalla varastotauteja aiheuttavia sienipatogeeneja. Amerikankarpalon marjojen laatua arvioitiin pilaantumisprosentin, kiinteyden, happamuuden, liukoisten kuiva-aineiden määrän ja antosyaanipitoisuuden perusteella. Kaikilla lajikkeilla kasvutunnelissa kasvaneista marjoista pilaantui varastoinnin aikana huomattavasti pienempi osuus kuin avomaan marjoista. Tämä voi johtua kasvutunnelin antamasta suojasta ja kasvuston kuivemmasta mikroilmastosta. Varastointi laski kiinteyttä ja tunnelissa kasvatetut marjat olivat pääasiassa kiinteämpiä kuin avomaalla kasvaneet marjat. Liukoisten kuiva-aineiden pitoisuus laski varastoinnissa. Antosyaanipitoisuus kasvoi varastoinnin aikana ja oli suurempi avomaalla kasvaneissa marjoissa, mikä voi johtua eroista marjojen kypsyydessä sadonkorjuun aikana, sekä kasvupaikkojen välisistä eroista valo-olosuhteissa. Kokonaishappamuus laski varastoinnin aikana ja oli suurempi kasvutunnelissa kasvaneilla marjoilla. Tunnelikasvatuksella oli erityisen suuri positiivinen vaikutus ’Early Blackin’ marjojen varastokestävyyteen ja laatuun. Tutkimuksessa tautioireisista marjoista saatiin eristettyä viisi eri sienisukua tai -lajia, jotka aiheuttavat neljää eri varastotautia. Tunnistetut varastopatogeenit olivat Botrytis cinerea (keltamätä, yellow rot), Coleophoma -lajit (oranssimätä, ripe rot), Allantophomopsis lycopodina/Allantophomopsis cytisporea (mustamätä, black rot) ja Colletotrichum -lajit (kitkerämätä, bitter rot). Ne aiheuttavat vaihtelevasti varastotappioita Pohjois-Amerikassa ja Latviassa.
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A META-ANALYSIS OF THE IMPACTS OF AGROFORESTRY ON SOIL ORGANIC CARBON STOCKS IN TEMPERATE CLIMATES (2022)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.
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(2022)In order to achieve carbon neutrality and slow down climate change, it is necessary not only to curb greenhouse gas emissions but also to remove carbon from the atmosphere. In agricultural sector, adding biochars to soils has proven to be one of the most effective methods to sequester carbon. Using biochars in urban planting soils could be simple and effective way to create carbon sinks also in urban environment. Wood based biochars are already available in the market and their viability as soil amendment is supported by an extensive body of research. Despite large evidence from agricultural and greenhouse sectors, research focused on biochars in planting soils for urban trees is scarce. To assess and demonstrate viability of biochars as component of urban planting soils, an experiment was established in 2019-2020 in Hyväntoivonpuisto-park in Helsinki. The experiment consists of four tree species and nine different planting soils, seven of which include biochars. Three of the planting soils were structural soils installed below a sealed surface. Tree growth in planting soils was followed and biomass accumulation was estimated with allometric equations. Planting soil nutrient composition was analysed at the time of soil application and nine months later after first growing season. Pyrogenic carbon fractions were analysed by BPCA analysis. Planting soil physical and hydrological properties were analysed by water retention curves with pF range of 0 – 4.2. After two growing seasons, biochars had increased tree growth in two planting soils compared to the control while in other planting soils with biochar, the growth was similar to control. In structural soils biochars had improved growth, but there were no statistically significant pairwise differences between treatments. Biochars increased the macroporosity of planting soils, indicating they could improve aeration and water conductivity in planting soils. Effects to total porosity and water retention capacity were mixed, but highest total porosity and water retention capacity was observed in planting soil with the highest amount of biochar. Planting soil nutrient composition varied a lot due to different raw materials, limiting the possibilities of making mechanistic analysis of effects of biochars. These results indicate that biochars are viable and safe constituent for planting soils which may increase tree growth by improving soil physical properties and improve carbon sinks in urban infrastructure.
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(2023)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.
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(2023)Puutarhamansikan (Fragaria × ananassa Duch.) kysyntä on Suomessa suurta ja mansikka onkin tärkein Suomessa viljelty marja. Suomen olosuhteissa mansikan satotaso jää kuitenkin suhteellisen matalaksi ja satokausi on yleisesti käytetyillä kausisatoisilla lajikkeilla lyhyt. Jatkuvasatoiset lajikkeet ja tunneliviljely pidentävät mansikan satokautta huomattavasti ja ovatkin tehokas tapa kehittää tuotantoa ja mahdollisesti lisätä viljelyn kannattavuutta. Biologisten kasvunparanteiden, biostimulanttien, käyttöä on ehdotettu osaratkaisuksi mansikan satotasojen nostamiseen. Biostimulantit ovat kasvien kasvuun ja kehitykseen positiivisesti vaikuttavia aineita ja parantavat kasvin sietokykyä erilaisia stressejä vastaan. Tutkimuksen tarkoituksena oli selvittää kahden biostimulanttivalmisteen, Rhizocell (nyk. Lalrise Vita) ja Greenstim (nyk. Lalstim Osmo) vaikutusta jatkuvasatoisen ’Ria’ mansikan kasvuun ja satoon, sekä kasvinterveyteen. Käsittelyitä kokeessa oli neljä: kontrolli, Rhizocell, Greenstim ja Rhizocell+Greenstim. Tutkimus toteutettiin Luonnonvarakeskuksen Piikkiön tutkimuslaitoksella vuoden 2020 kesällä. Rhizocell on hyötymikrobi Bacillus amyloliquefaciens IT45 sisältävä valmiste, joka nestemäisenä liuoksena kasvin juurelle annettuna vaikuttaa kasvin kasvuun juuriston kehittymisen kautta, ja Greenstim suurimmaksi osaksi glysiinibetaiinista koostuva valmiste, joka kasvustoon annettuna lehtiruiskutuksena vaikuttaa kasvin kasvuun etenkin stressiolosuhteissa. Tulosten perusteella valmisteiden käyttö suomalaisittain ajoittain melko kuumissa oloissa kasvaneilla, mutta hyvin hoidetuilla mansikoilla ei tuonut merkittäviä hyötyjä. Biostimulanttivalmisteiden vaikutus mansikan kasvuun ja satoon oli vähäinen, eikä yksikään valmiste selkeästi hyödyttänyt kasvua, sadontuottoa tai kasvinterveyttä. Valmisteiden käyttö saattoi kuitenkin vaikuttaa kasvien stressinsietokykyyn, sillä Rhizocell+Greenstim -käsittely alensi lehtien flavonoli-indeksiä ja Greenstim-käsittely lisäsi puolustusreaktioissa tärkeän kalsiumin kertymistä lehtiin. Huomioitavaa onkin, että tässä tutkimuksessa kasvit eivät olleet altistettuina stressille ja stimulanttien vaikutuksesta stressiolosuhteissa ei voida olla varmoja.
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(2022)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.
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(2022)Inflorescence meristem development in plants generally falls into two types: one is the indeterminate type when the main axis keep growing and new flowers are initiated on its flank; while the other is the determinate type when the main axis terminates as a flower and growth continues sympodially. The Asteraceae plant family harbors a unique type of inflorescence, called the flower head. It combines up to hundreds of individual florets into a single structure, but its infloresecence meristem has a determinate fate and can only produce a certain number of florets before getting consumed. The genetic regulation of such determinacy has been recently brought into attention in Gerbera hybrida, a model system used for studying inflorescence and flower development in Asteraceae. So far, several genetic regulators have been identified regulating the determinacy of inflorescence meristem in Gerbera. This thesis aims to characterize new Gerbera transgenic lines to study the function of the Gerbera homolog of TERMINAL FLOWER 1 (GhTFL1). In Arabidopsis and other species, TFL1 is known to counteract with the flower meristem identity genes and maintain the indeterminacy of the inflorescence meristem. Previous results by overexpressing GhTFL1 under constitutive 35S promoter in Gerbera convert the determinate fate of inflorescence meristem into indeterminate. To better study the GhTFL1 function, an inducible overexpression system pOpON2-pOp6/LhGR-N was introduced, and the transgenic lines have been made for GhTFL1. In this this thesis, in total of 19 candidate lines were screened with GUS staining assay and RT-PCR. Two promising lines (TR4 and TR7) with strongest responses in GUS staining and high expression of the target gene were identified. Further treatment of dexamethasone was conducted in these two lines to the growing rosette; however, no clear phenotypes was observed in these lines. The treatment results suggested that further optimization should be made, in particular, the timing of treatment shall be the determining factor for a successful treatment.
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(2024)Climate change is challenging farmers around the world, undermining food security and livelihoods. Smallholder farmers are encountering changing environmental conditions and extreme weather events as a significant negative impact on their livelihoods and food security when the resources needed to adapt are not sufficiently available. Previous studies show that the impacts of climate change are currently most noticeable in the developing countries of the Global South, where local agriculture and smallholder farming still remain an important part of people's livelihoods and local food security. This study focused on the experiences and outcomes of the Building Resilience -tool I (BR-I) for smallholder farmers in 5 different African countries between 2021 and 2022. Through the tool, farmers assessed the impacts of climate change on their livelihoods and their own capacities and needs to adapt to the challenges caused by climate change. The data used in this study consisted of reports filled in when using the tool collecting farmers' responses, and separate feedback on their experiences of using the tool. The results showed that climate change reduced the predictability of environmental conditions and increased the irregularity of the growing seasons. Drought, floods, and storms were the main threats to crops, often leading to yield losses or poor crop quality. Other losses included livelihood-related losses of material assets, for example during floods and storms. Indirect negative impacts of climate change included loss of farmers' livelihoods, increased poverty and reduced local food security and weaker nutritional quality of food. To adapt to climate change impacts, farmers often used more sustainable and higher quality crop varieties and, for example, built more efficient irrigation systems. However, the results showed that to adapt to climate change, farmers need more material and financial resources and research-based knowledge to improve their livelihood activities.
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(2024)Weeds have been identified as a threat to arable crop production because crop-weed competition may result in considerable yield losses. Weeds and crops often possess similar characteristics, making weed control challenging. Chemical weed control may lead to environmental and health issues, as well as troubles in crop production. Nowadays the tendency is towards more sustainable agricultural practices to control weeds including mixed cropping systems. In earlier studies, mixed cropping systems were observed to reduce weed biomass, whereas weed diversity was affected by environmental and temporal factors. The present study was conducted at the Knehtilä organic farm in Hyvinkää to evaluate the competitive ability of mixed cropping systems against weeds. Crop stands were 50:50:50% and 33:33:33% oat, pea, and camelina mixtures, along with 100% oat, 100% pea, and 100% camelina stands. Plant sampling was conducted 24 Days after seeding (DAS), 38 DAS, 52 DAS, 66 DAS, and 97 DAS. Crops and weeds were separated and the number of plants in each species was counted. Weeds at the species level were identified. Dry biomass of crops and weeds was recorded at each sampling time. Weed species richness, Shannon-Weiner diversity index, species evenness, and species dominance were calculated. The most common weed species was Chenopodium album L., while the least common species was Cerastium fontanum Baumg. Crop stands accumulated in weed biomass until 52 DAS, followed by a gradual decline over sampling times. Weed biomass was lower in 50% and 33% mixes than sole crop stands in early growth stages. Significant differences in the Shannon-Weiner diversity index, species richness, evenness, and species dominance were found in crop stands at 24 DAS and 66 DAS. There was a positive correlation between weed evenness and crop biomass. The study proved that mixed crop stands (50% and 33% mixes) have effective weed control ability, indicating low weed biomasses compared to sole cropping systems. Weed diversity indices fluctuated at 24 DAS and 66 DAS, indicating that sampling time influences weed diversity. The positive correlation between weed evenness and crop biomass indicates the impact on species dominance and intraspecific competition. The study suggests that mixed cropping systems are effective at controlling weeds and highlights the importance of understanding temporal dynamics and weed-crop interactions in cropping systems to enhance crop yield. Future research should focus on understanding the fundamental mechanisms behind weed-crop interactions across cropping systems.
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Development of sustainable practices for using lake sediment as growing medium for grass production (2023)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.
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(2023)During the last 50 years, agriculture in Finland has become more intensive, open semi-natural farmland habitats have disappeared and the number of animals and plants has been declining. Nectar plants are beneficial resources in agroecosystems. They support crop pollinators, and natural enemies of pests and other species dependent on nectar. Nectar plants can also be indicators of biodiversity. Nectar source plants in field margins provide nectar (and pollen) over the growing season. Various plants benefit from different margins, and their frequency and distribution can be connected with the landscape structure and latitude. This study examined the distribution of nectar plants in field margins of farmland in Southern Finland and determined what plant species provide nectar and at what time of the season. The objectives of the research were to describe the species composition of nectar plant communities in Southern Finland, and hence the biodiversity of plants, and to study the distribution of nectar source plants in the most common margin types. The data were obtained from the Luonto-Mytvas Project research programme “Significance of the Finnish agri-environment support scheme for biodiversity and landscape (Nature MYTVAS)” in 2000-2006. In order to find out what plants have good nectar (pollen) availability literature sources and bee calendars were used. The results shows that the majority of 50 most frequent plants species included in the analysis have value as nectar and pollen sources available for pollinators. There were four different functional groups (f) of plants in the research, depending on their nectar availabilities. The frequent plants in the field margins are available as nectar/pollen sources to pollinators, from April until September-October. There are only few species dependent on margin type in their occurrence. Frequencies of most of the species from all the four groups varied, however, between field-to-field and field-to-road margins.
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(2023)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.
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(2023)Nutrients get deposited in lake sediment from agricultural areas and other anthropogenic activities resulting in internal P loading and eutrophication. On the other hand, the situation with P rock (non renewable resource) used for production of mineral fertilizer is alarming that result in the depletion of P rock and increase P fertilizers price. The issue can be minimized by sediment removal and recycling nutrients from sediment for crop production. The existing results on sediment P availability for crops showed contradictory results and suggested that sediment P bioavailability for the crop is influenced by sediment iron to phosphorus mass ratio. However, comprehensive studies confirming their relationship are currently lacking. Hence, the study aims to determine the potential of sediment as fertilizers for crop (ryegrass) from several eutrophic lakes (in Finland and Estonia). The aim is to identify the effect of different lake sediments on ryegrass aboveground biomass and nutrient uptake. The study was conducted on greenhouse for around 6 months. Randomised complete block design was used for the experiment. The experimental treatments include sand with six different lake sediments: Peipsi, Lämmijärv, Kutajärvi, Kymijärvi, Matjärvi and Enonselkä basin of Vesijärvi, mineral fertilizer (positive) and without P fertilizer (negative) control. The biomass (yield) and nutrient uptake by the plants were measured and then analyzed for nutrient content. Significant effect of lake sediment was observed on ryegrass yield and P uptake. The significantly higher yield was observed for Lake Peipsi sediment treatment than in both controls. The ryegrass dry matter yield was greater in sediment treatments than negative control. Also, ryegrass yield was found to be greater in some sediment treatments than positive control. The concentration of nutrients (sulphur, calcium, magnesium, and potassium) was sufficient in ryegrass plant in all lake sediment treatments. The P uptake from Enonselkä sediment treatment was the highest whereas from Kutajärvi sediment treatment was the lowest. The P uptake was the highest (16.3 kg ha-1) in Enonselkä sediment treatment with the lowest Fe:P ratio of 12. Moreover, the result suggests that Fe:P mass ratio is one of the factors/sediment properties that determine P availability to the crops. However, other sediment properties may also affect P availability in the plants as organic P fraction was also used as an additional P source in some cases. The sediment increased C content and organic matter content compared to controls which improved ryegrass growth in sediment treatments. The increase in nutrient uptake and biomass in lake sediment treatments showed that lake sediment can be potential alternatives for fertilizers in nutrient deficient soil.
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(2022)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.
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(2024)Trees are the most visible part of urban vegetation, and they provide many ecosystem services which cannot be replaced. The ability to sequester and store carbon (C), balance peaks of storm water flows, regulate microclimate and provide shade in heat waves are dependent on the size and the vitality of a tree. Through the root system, abiotic and biotic factors in growing medium have a role in tree health and size. Tree fine roots and ectomycorrhizal (EcM) root tips, which are the most distal part of root system, have a crucial role in maintenance of tree vitality as they are responsible of water and nutrient uptake. Growing conditions in urban environments differ from those in natural environments. However, urban tree fine roots and EcM root tips are a scarcely studied subject. In this thesis I studied fine root growth, phenology, depth distribution, annual production, and the number of EcM root tips of three different tree species (Tilia cordata, Tilia × europaea and Betula pendula) growing in three different urban greenspaces (park, street site, unmanaged forest patch). In addition, I studied the effect of site, soil temperature, and soil moisture on root elongation. Fine root elongation was observed by a minirhizotron image system below ground from May until November 2020. Root production and the number of EcM root tips was studied by the ingrowth core method. Betula pendula had the highest fine root elongation among the three tree species, which can at least partially be explained by species-specific differences. Growing site had a statistically significant effect on root elongation, but also the thermal sum of soil temperature and the level of relative extractable water affected root elongation. Average height and trunk diameter between Tilias grown at the Garden and Tilias grown at the street side were different relative to their age. Tilias had clearly less EcM root tips on the street side, their fine roots elongated more, and the amount of dead roots was slightly higher than at Garden, indicating that root turnover rate was faster for street trees as they tried to absorb nutrient in a poorer environment. Based on previous studies, differences in fine root elongation between sites were expected, as e.g. rising of the temperature has been found to affect positively to root elongation. Additionally, the poor nutrient status of the growing medium has also previously been found to increase root growth. The site and the characteristics of the growing medium can has a significant effect on the fine roots and thus on the growth and vitality of the entire tree.
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(2022)Faba bean (Vicia faba L.) is an annual herbaceous cool-season food legume widely cultivated worldwide, especially for its high seed protein content. However, its major limitation in being used as food and feed, is the presence of antinutritional factors in its seeds, especially vicine and convicine (VC), two related compounds, which may be harmful to livestock and G6PD-deficient humans. To remove VC, the most sustainable method is breeding for low-VC faba bean cultivars. To improve the efficiency and speed of breeding programs, breeders use marker-assisted selection (MAS). The identification of genes responsible for VC content allows the development of reliable DNA markers and a better understanding of the molecular basis of this trait. The major-effect QTL controlling VC content named “VC1”, was identified in faba bean chromosome 1, and a few minor-effect QTLs were detected in previous studies. Hence, a total of 165 RILs from the cross Mélodie/2 (low-VC) x ILB 938/2 (high-VC) were genotyped and evaluated for VC content. Composite interval mapping was run on R/qtl software with accurate phenotypic data associated with a high-density SNP-based genetic map. Results revealed two minor-effect QTLs in addition to VC1. One was on chromosome 4 and had about 15% effect on convicine content. The other was on chromosome 5 and had 15% effect on vicine and total VC content. This research also reports candidate genes for the newly detected minor-effect QTLs through comparative genomics with the Medicago truncatula genome. Hypotheses were proposed on the role of these candidate genes on the VC biosynthetic pathway or transportation into the embryo beans for further testing.
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(2021)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.
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