Browsing by study line "Växtproduktionsvetenskap"

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.

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.

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.

Bilberry is a soft fruit, growing wild in the forests of Europe, and especially Nordic and East European countries. Its demand is growing on the market, thanks to its heath beneficial components like anthocyanins, present in both skin and flesh of the berry. It however has a very short shelf-life. The goal of this study was to identify pectinase genes, with a focus on two subfamilies, polygalacturonase (PG) and pectate lyase (PL). The main interest was to study those that are expressed during bilberry’s ripening, to get a better understanding of this process. Bioinformatics were used to identify the annotated genes from the bilberry genome, and point out candidates, from which transcripts are found during ripening, with BLAST searches within a transcriptome of ripening bilberry fruit. The expression of the PL candidates was then studied with qPCR analysis. The study identified 70 PG-coding genes and 25 PL-coding genes, of which 35 and 12, respectively, were found in the ripening berry. The expression of five PL genes was increased during ripening, suggesting a role in the softening of the fruit. Two of those had a notably higher relative increase, making them prime candidates for further study.

Turnip mosaic virus (TuMV) is an economically important plant RNA virus causing huge damage to wide range of arable and vegetable crops. A study was conducted in Nicotiana benthamiana to know if a TuMV mutant carrying a mutation in a thoroughly conserved WD-domain interacting motif and WG motif in HCPro protein can be mechanically transmitted to a healthy plant or not. HCPRoWD is a mutation in “AELPR” motif where glutamic acid and arginine are replaced by alanine. This mutated virus is here referred as TuMVWD. Similarly, in TuMVAG the tryptophan residue in the WG pair is changed to alanine and this mutated HCPro is called as TuMVAG. Four treatments, TuMVWT (positive control), Mock (negative control), TuMVWD and TuMVAG were made. Three plants per treatment were agroinfiltrated and five plants per treatment were used for mechanical inoculation experiment. Green fluorescent protein (GFP), a quantitative reporter of gene expression, was measured followed by qPCR for quantification of vRNA (viral RNA) accumulation. In agroinfiltrated plants, newly emerged leaves showed strong fluorescence in TuMVWT and TuMVAG by 14 dpi (days post inoculation), but TuMVWD showed poor GFP as compared to TuMVWT. During mechanical inoculation experiment, none of the treatments developed GFP in systemic leaves by six dpi but by 14 dpi GFP accumulation in the upper leaves of TuMVWT and TuMVAG was increased. TuMVWD was not used for 2nd mechanical experiment as it did not cause systemic infection during 1st mechanical inoculation experiment even by 14 dpi. Results from vRNA accumulation showed that mechanical transmission of virus was reduced with TuMVAG and not possible with TuMVWD. However, mutations had negative effect on vRNA accumulation.

Tiivistelmä - Referat – Abstract Acid sulfate soils are formed from sediment deposits containing sulfides, in which sulfur is present in the form of iron sulfides. In contact with air, the sulfur layer initiates a long-chain of biochemical and chemical reactions that increase the acidity of the soil and the amount of sulfate. Excessive acidity restricts plant development and growth. In acid soil, the aluminum solubility reaches a high level of toxicity for roots and slows down the microbiological degradation of organic matters, resulting in a reduction of nitrogen mineralization. Previous research results have shown that important liming has the potential to raise the pH of sulphate soils, and thereby reduce its acidity. With a high pH, the concentrations of ammonium and nitrate in the soil increase, facilitating nitrogen uptake and thereby also improving the efficiency of nitrogen uptake by plants. It has been speculated that, by increasing the nitrogen uptake efficiency and nitrogen utilization in plants, it will improve nitrogen use efficiency and so will reduce denitrification in sulphate soils and the resulting N2O emissions. However, to date, the studies on the effect of liming on plant nitrogen uptake (UPE) and utilization efficiency (UTE) and, consequently, on plant nitrogen utilization efficiency (NUE) have been minimal. The purpose of this study is to investigate how liming affects the yield formation and nitrogen uptake efficiency for barley (Hordeum vulgare L.) in unfertilized and fertilized acid sulfate soils. The field trial was established in Viikki, Helsinki, in the spring 2018. It followed split-plot design, in which the main plots were combinations of plant and nitrogen fertilization treatments (0 or 100 kg of nitrogen per hectare of fertilized barley (Kaarle) or unfertilized fallow) and lime treatments (0; 7,7; 15,3 t/ha) in four replicates. Liming raised the soil pH as expected and also increased nitrogen mineralization during the growing season, which is reflected in the nitrogen uptake. The effect of liming and fertilization on crop formation was small for barley biomass, yield component and grain yield. On the other hand, the liming effect reduced the nitrogen absorption efficiency and the nitrogen utilization efficiency and thereby the efficiency of nitrogen use. Fertilization also increased nitrogen uptake, but also decreased nitrogen utilization efficiency and nitrogen harvest index. The combined effect of liming and fertilization increased nitrogen mineralization. Liming treatment clearly increased nitrogen mineralization more in unfertilized soils than fertilized (there was no difference between liming levels). The drought in June and the low moisture limited the mobilization of nitrogen released from fertilizer in the soil, which would explain the effect of the nitrogen fertilizer treatment remaining relatively small. The drought also limited the development of the roots and thus the uptake of nitrogen and other nutrients. Lime treatment did not change NUE, UPE and UTE, but increased nitrogen mineralization and nitrogen uptake during the growing season, suggesting that under more favorable conditions the liming treatment could improve the efficiency and therefore improve the profitability and ecology of the barley crop. Further studies are needed as the results of studies performed elsewhere may not be valid under boreal conditions.

The advantages of foliar fertilizers are to provide the necessary plant nutrients to the crop at the optimal time of growth and the miscibility of foliar fertilizers with plant protection products in the same tank mix, thus avoiding additional costs. The aim of this experiment was to determine whether the foliar fertilizers which are most commonly used by sugar beet farmers can be safely mixed with standard Conviso® One herbicide tank mixture without mixing problems or without phytotoxic symptoms on Smart KWS sugar beet (Beta vulgaris subsp. vulgaris Altissima-Group). There was no previous study about the compatibility of foliar fertilizers in the standard Conviso® One tank mix and the result of this experiment were believed to provide significant information for the cultivation of Smart sugar beet. Two subtests were performed; a field trial for phytotoxic symptoms and a miscibility and 24 -hour standing test to determine the effect of hard and soft water on miscibility. The field test was organized at the one trial site of Sugar Beet Research Center in Meltola, Paimio and the mixing and standing trial was performed indoors in the same location. In both experiments, 11 different foliar fertilizers were tested. During the experiment visual mixing and application evaluations of sugar beet were performed. Sugar beet leaf and root samples were collected from the experiment area and one row of sugar beet was harvested for yield and quality analysis. There were two hypotheses; the miscibility of the standard Conviso® One tank mix together with foliar fertilizers doesn`t show any miscibility problems during the mixing or spraying, and the tank mixture doesn`t decrease the yield or quality of Smart sugar beet. The conclusion of this experiment was that the tested foliar fertilizers can be safely mixed into the basic Conviso® One tank mix without any miscibility problems during the mixing, spaying or after 24-hour standstill period. Miscibility problems were not observed with either water type (hard or soft) during mixing or after 24-hour standing time. The tank mixture didn`t have negative effect to Smart sugar beet yield but the treatments showed a difference in the potassium content of the root, which is one of the factors determining the quality of the sugar beet.

Grain legumes are grown on less than 2% of the arable area of Europe, while large quantities of soybean and soymeal are imported for feed for pigs and poultry. Crop rotations need diversifying by adding grain legumes for soil health and for the break-crop effect, lowering pest, disease and weed pressures in the subsequent crop. The economic effects are of interest from adding legumes to crop rotations and can be evaluated by modelling crop rotations and comparing the means of the gross margins (GM) from the rotations. In Finland, cereal-based crop rotations dominate the important crop growing areas of Southwestern Finland. The most common rotation during a five-year-period can consist of a cereal monoculture with two or more cereal species. The largest potential for diversification in crop rotations can be found on pig, poultry, and cereal farms. Modelling of grain legumes in crop rotations has previously been done for Västra Götaland in Sweden, Brandenburg in Germany, Calabria Italy, eastern Scotland in the United Kingdom, and Sud-Muntenia i Romania. The aim of this work was to create modelled crop rotations for Southwestern Finland to evaluate the gross margin, NO3-N-leaching, and N2O-emissions of the crop rotations. Yields were modelled for a ten-year period following actual yield fluctuations. They were analysed and there were no significant differences in gross margin detected in the crop rotations, whether they were a legume or an all-cereal rotation. Significant differences were found in N2O-emissions between the crop rotations

Maatalouden vaikutus vesistöjen rehevöitymiseen on ollut pinnalla useita vuosia. Kalkitus on ikivanha metodi, mutta se on pitänyt pintansa maanparannuskeinona erityisesti Suomessa, jossa peltomaat ovat luontaisesti happamia. Kalkituksen päätarkoitus onkin neutraloida peltomaan happamuutta ja näin parantaa ravinteiden saatavuutta sekä vähentää haitallisten aineiden liukoisuutta viljelykasveille, mikä nostaa viljelykasvin satoa. Kuitenkin erityisesti rakennekalkkien on havaittu stabiloivan savimaan rakennetta tehokkaasti, mikä vähentää mahdollisesti pintamaasta eroosion kautta tapahtuvaa fosforikuormitusta vesistöihin. Rakennekalkituksen vaikutuksista viljelykasvien satoihin puuttuu vielä yksityiskohtaista tieteellistä tietoa viljelykasveittain ja maalajeittain erityisesti Suomen olosuhteissa. Esimerkiksi Ruotsissa tehdyissä rakennekalkituskokeissa on saatu ristiriitaisia tuloksia sen vaikutuksista viljelykasveihin eri pelto-olosuhteissa, eri vuosina. Tämän tutkielman tavoitteena oli selvittää eri rakennekalkitustasojen (0, 8 ja 12 Mg ha-1) vaikutusta vehnän Triticum aestivum L. ’Amaretto’ sadonmuodostukseen korkean (pH(H2O)=6,5) ja matalan (pH(H2O=5.2)) lähtö-pH:n omaavilla savipelloilla. Tutkimus toteutettiin peltokokeina kasvukautena 2020 Sokerijuurikkaan Tutkimuskeskuksella, Hevonpäässä, Varsinais-Suomessa. Koeasetelmana oli sovellettu osaruutukoe, jossa pääruudun osatekijä oli pellon pH ja osaruutuina rakennekalkkikäsittely. Rakennekalkkina käytettiin kalsiumoksidia 19,5 %:a sisältävää tuotetta ja se levitettiin syksyllä 2019. Korkean pH:n lohkolle vehnä kylvettiin 1.5.2020 ja matalan pH:n lohkolle se kylvettiin 26.5.2020. Rakennekalkitusta seuraavana vuotena, etenkin alemman pH:n olosuhteissa, rakennekalkitus paransi vehnän satoja vain hyvin suureella 12 Mg ha-1 käsittelyllä. Päinvastoin korkeamman pH:n olosuhteissa rakennekalkitus ei lisännyt vehnän satoa, vaan aiheutti jopa sadon laskua. Jyvien kokonaistypenotto selitti sadon kasvua, sillä se lisääntyi myös erityisesti alhaisen pH:n sekä suurimman kalkkikäsittelyn olosuhteissa. Rakennekalkitus vaikutti myös ravinteiden kuten kaliumin sekä mangaanin pitoisuuksiin lehdissä ja korsissa sekä tähkien magnesiuminpitoisuuteen molemmilla lohkoilla. Toisaalta rakennekalkituksella ei ollut juurikaan vaikutusta satokomponentteihin eikä sadon laatuun. Kesäkuu 2020 oli kuiva ja aikaisemmin kylvetty lohko kärsi todennäköisesti kuivuudesta, mikä vaikutti todennäköisesti satotuloksiin etenkin korkeamman lähtö-pH:n omaavalla lohkolla, joka kylvettiin aikaisemmin. Tulosten perusteella ei voida tehdä vielä laajempia johtopäätöksiä rakennekalkin vaikutuksista vehnän satoon, vaan tarvitaan myös pitkän aikavälin tutkimusta sekä liittyen satoon, että maaperän ominaisuuksiin.