Browsing by discipline "Växtproduktionsvetenskap"

Sphagnum moss could be used as a substitute for Sphagnum peat as a growing medium. It has the same positive physical properties as peat and it is also a more sustainable option. However, there are some indications that Sphagnum moss may have some inhibitory effects on vascular plant seed germination and seedling development. The aim of this study was to find out whether this is true and due to the low pH of different Sphagnum moss species. The tested moss species were Sphagnum fallax, Sphagnum medium, Sphagnum rubellum and Sphagnum spp. The seed germination on Sphagnum moss substrate was tested with lettuce, radish, basil, pine and ryegrass. Also, two additional seed germination experiments were done with lettuce. Seedling growth experiment on Sphagnum substrate was tested with lettuce. The first germination experiments indicated that the dicotyledon species basil, radish and lettuce are sensitive to the allelopathic effect caused by Sphagnum moss. In the case of ryegrass and pine no indication of seed germination inhibition was found. The two additional germination experiments confirmed that Sphagnum moss and white peat substrates and Sphagnum moss and white peat organic matter/water extracts were inhibiting lettuce seed germination. Added lime didn’t conclusively explain the inhibition in germination percentages of Sphagnum moss substrate when compared to control treatment gauze. Only in the case of radish the raised pH had positive effect on the germination percentage. Therefor it was concluded that the low germination percentage is not explained only by the naturally low pH of Sphagnum mosses and Sphagnum mosses’ other characteristics should be investigated in the future. In the seedling growth experiment done with lettuce on Sphagnum medium growing medium there was no indication of allelopathic effect on seed germination or seedling development. The allelopathic compounds were thought to have been lost in this experiment through leaching when the substrates were watered.

Stress response in plants is influenced by several external and internal factors and is executed in a modular way. Environmental stimuli or stress is sensed by cellular receptors and the signal is transduced inside cell via the phospho-activation of highly conserved intracellular signaling cascades like mitogen activated protein kinase (MAPK) cascades. The signal then activates biosynthesis pathways of major stress response hormones like Salicylic acid (SA). In Arabidopsis about 90% SA is synthesized via isochorismate pathway and Isochorismate synthase 1 (ICS1) is a rate limiting enzyme in this pathway. In this study, goal was to select transgenic ICS1 (homozygous) candidate lines from parent ICS1-CFP by selective regeneration. Then, by molecular and physiological characterization of transgenic ICS1-CFP plants, the function of ICS1 phosphorylation, more specifically, impact of different photoperiods (Long day; LD and Short day; SD) and stress conditions on ICS1 activity would have resolved. However, there were no homozygous candidate line from any parent ICS1-CFP plants after several screening. Nevertheless, ozone treated stress sensitivity test was performed with heterozygous ICS1-CFP candidate plants (T2 generation). Ozone treated stress depends on stomata factor because ozone enters into plants through stomata. Therefore, stomata index analysis was performed with sid2 and WT (Col-0) phenotypes and grown in LD and SD conditions. Since, stomata number was different between LD and SD plants of both sid2 and WT phenotypes, a different method named Xanthine-Xanthine oxidase (X/XO) treatment was applied that induce oxidative stress regardless of stomata. Although, WT and sid2 had shown sensitivity to the treatment, the overall cell death percentage was very low. Lastly, our aim was to observe the impact of different photoperiods on the activation of two particular MAPKs i.e MPK3 and MPK6 under stress conditions. The phosphorylated (P-MPK3 and P-MPK6) are found abundantly in ozone treated plants as an early response. In this experiment, plants were grown in both LD and SD, stressed with both ozone and X/XO treatments, the activation of P-MPK3 and P-MPK6 was observed by protein level analysis (western blotting) in detailed time course. Although, the activation was visualized in both LD and SD plants, qualitatively the pattern was similar between day type samples and activation signal was very weak in both stress methods. In addition, anti-ICS1 antibody provided by Agrsera TM was tested for its efficiency to detect endogenous ICS1 protein in plants in two experimental set-up. Although the antibody could detect overexpressed ICS1-CFP protein in samples, it was not that efficient to detect endogenous ICS1 in any of the experiments.

This research was conducted to examine the effect of biochar on drought tolerance and growth of a grain crop. Biochar is a multipurpose charcoal that heals the soil and promotes crop yield. The experiment was part of University of Helsinki biochar research during the summer and autumn of 2011. The effect of biochar was studied in a greenhouse experiment to determine how well it can improve sorghum (Sorghum bicolor Moench) yield. The experimental factors were amount of water given at low, intermediate and full watering levels, and the absence or presence of Acacia-biochar at level of 10 t/ha in the pots of soil used. The number of leaves per plant, leaf surface area, number of panicles, number of grains per panicle, plant and panicle height, root biomass, and whole plant (above ground) biomass was obtained. The plants were grown in a high greenhouse temperature to mimic the Sudanese extreme weather temperature according to the Khartoum Sudan weather forecast at the time of the experiment. The plants got same amount of water from cultivation until the emergence of 5 leaves. Early drought was proposed to determine its effect as the plant move from vegetative to reproductive stage and the effect of biochar on the soil water holding capacity (WHC). The drought stress started at 5 leaf stage of the plant life cycle. The data were analyzed using 2-way analysis of variance (Anova) statistical tools in SPSS (version 20.0, SPSS Inc., Chicago, IL, USA) software. Drought stress affected panicle development, grain yield, plant height, leaf surface area and overall biomass yield. Grain yield and whole plant biomass weight was higher in non-stressed plants. The results indicated no relief to drought stress by biochar addition. In this experiment, the addition of low biochar might be responsible for it inefficiency.

Brown-heart disorder in rutabaga is a boron deficiency syndrome that renders the inside of the roots brown and makes the crop unfit for market. The connection between boron deficiency and brown-heart was first reported in 1930’s. Brown-heart continues to be a concern for rutabaga growers all over the World, especially in Northern Europe, Canada, United States of America and New Zealand. The aim of this thesis was to compare the effects of various methods of applying boron, in terms of rutabaga yield and brown-heart. The field experiments were done in 2013 and 2014 on Räpi research farm of Apetit Ruoka Oyj in municipality of Köyliö, as part of collaboration between Apetit Ruoka Oyj and Yara Suomi Oyj. The companies aimed to find the best fertilizer solution for the prevention of brown-heart in rutabagas. Treatments were either fertilizer placement or broadcast application. In addition, foliar spraying treatment was used. Nutrient levels of the soil were analysed before planting and after harvest. The nutrient levels of rutabaga leaves before harvest, and nutrient levels of rutabaga roots by the time of harvest, were analysed. Additionally, the yield and number of rutabagas with brown-heart were determined. In experiments done in 2013, the effect of boron treatment on yield was statistically insignificant. In 2014, the fertilizer placement increased the yield as compared to broadcast application. In 2013 the number rutabagas with brown-heart disorder was significantly less within the samples treated with fertilizer placement, as compared to samples treated with broadcast applications. In 2014 the overall number of rutabagas with brown-heart was low, and the differences between treatments were statistically insignificant. Of the rutabaga boron treatments compared in this thesis, the fertilizer placement was more efficient than the broadcast application. Generally, the effect of foliar spraying treatment on yield or quality of the rutabagas was insignificant. In order to achieve high quality rutabaga crop, applying boron with fertilizer placement simultaneous to sowing, is recommended.

'Candidatus Liberibacter solanacearum' (CLso) is a frequent bacterium in carrot in southern and western Finland but is also occurring in South Savonia. The bacterium is unculturable, lives as a parasite and multiplies in the phloem vessels and is transmitted by the carrot psyllid Trioza apicalis. In Spain, France and Finland the bacterium has also been found in parsnip. The aim of this thesis was to study the occurrence and genetic variation of this bacterium in carrot and parsnip in Satakunda, Southwest Finland and South Savonia from such parsnip and carrot fields where psyllids and discolouration symptoms in foliage have been detected. All the samples were collected based on foliar discolouration symptoms. Four wild plants from the family Polygonaceae were collected from one carrot field and one parsnip field in Satakunda. These plants showed similar foliar discolouration as the carrots. Other criteria for collecting the carrot samples was based on occurrence of psyllids and leaf curling. Samples of parsnips were collected from vegetable farms, where parsnips were grown nearby the carrot fields and where psyllids had been detected. The samples were analysed by real-time PCR with primer combination specific to CLso. Those samples that had high amounts of bacteria were chosen for sequencing and detection of haplotype. CLso was detected in 62,9 % of the carrot samples, in 90,8 % of the parsnip foliage samples and in 76,9 % of the parsnip root samples and in all the samples of symptomatic wild plants. Based on the ftsZ gene sequence, a new haplotype of CLso, named haplotype H, was identified in three of the parsnip samples from Satakunda and in two samples of pale persicaria (Persicaria lapathifolia (L.) Gray). This is the ninth haplotype of CLso identified.

Conifers are used for forest plantations and as landscape trees. Norway spruce is the main softwood species in Finland and can occasionally be observed in urban areas. However, root rots of conifer trees caused by Heterobasidion annosum leads to huge economic losses not only in Finland but also in other European countries. Due to the availability of complete genome sequence for both host and pathogen, in this study using Norway spruce and its root rot pathogen (Heterobasidion annosum) as an experimental model, the host-pathogen interaction was investigated. Conifer trees have established a variety of defense mechanisms to repel microbial infections, including constitutive barriers, accumulation of antimicrobial chemicals, activation of signaling pathways and induction of defense-related compounds resulted from an intra-organismic response including cell death. In the conifer pathosystem, cell death associated necrotic browning reactions promote tissue colonization by necrotrophic pathogens such as Heterobasidion annosum. By contrast, in crop plants, cell death associated hypersensitive response (HR) is known to inhibit invasive growth of biotrophic pathogens. However, not much is known about the chemical and molecular characteristics of necrotic cell death responses observed in different developmental stages of conifers from seedlings to mature trees. In addition, the term reaction zone is often used to describe responses of tree tissues bordering the heartwood to pathogenic infections, but nothing is known on whether there are any similarities between the necrosis response and reaction zone. To investigate this, Norway spruce at different developmental stages (seedlings, young trees and mature trees) were challenged with Heterobasidion parviporum. Six major indicators were assayed: necrosis lesions, cell death, pH, reaction zone, reactive oxygen species (ROS) and expressions of defense-related genes (Per1, Per2, LAC, JAZ1, OPR, and STS2). Increased transcript levels of the following genes Per1, Per2, LAC and JAZ1 were documented in seedlings but higher expression of Per2 and LAC was recorded in mature trees. Results revealed that all infected tissues were strongly necrotic or had increased lesion size. This is accompanied by increasing pH units up to 6.0 similar to levels documented in the reaction zone. Furthermore, ROS-generating peroxidase activity increased in infected tissues compared to the control. All these changes were found to be similar to observations in the reaction zone of woody trees. However, cell death was only measured in seedling roots and the method needs to be optimized for woody tissues. Further tests are therefore required for the clarification of relationship between necrotic cell death in seedling plants and reaction zone responses in mature woody tissues.

The EC regulations for organic farming (OF), No. 834/2007 and 889/2008, apply in all EU countries but still, different rules are being implemented. Every country in the EU has its own certification bodies and certification systems, and the interpretation of the EC regulations for organic farming is done nationally. The purpose of this research is to fill a gap in the understanding how rules of organic farming differ between three countries in Europe: Finland, Sweden and Austria. In particular, this study aims to examine the role of the national interpretations of the EC regulations for OF at different stages in the food supply chain. The main interest lies in why these differences in interpretation occur, and what interpretations are made at what stage in the system. The methods chosen for answering the research questions is a literature review, a survey with qualitative interviews for gathering relevant topics from the field and finally a comparison of the EC regulations for OF and the national legislations and guidelines in Finland, Sweden and Austria for these topics. This study shows that there are many topics in OF where the EC regulations for OF leave room for variable interpretations and hence, it is unclear to the implementing authorities in the member states how to interpret these. The most significant result is that some of the differences in interpretation lead to the organic farmers being unequal across the countries. Even for statements with clear reasoning and precise instructions there can be significant differences in interpretation between the countries. Based on the results of this research I can state that the farmers in OF would benefit from a more harmonized landscape of OF rules on EU-level, as this would lower the inequality between farmers in OF in the different countries. One mean of doing this would be to reduce the number of statements of qualitative character.

The faba bean (Vicia faba L.) has increased its cultivation area in Finland because of its high protein content. It replaces some of the imported plant proteins, such as soybean (Glycine max) meal, as feed for livestock and has increasing interest as an ingredient in plant-based meat-substitute food products. The faba bean is partly self-pollinating, but insect pollination has been shown to increase yield and reliability. Honeybees (Apis mellifera) are one of the most important pollinators for the bean in Finland. The aims of the thesis were to study the effects of honeybee interactions with faba bean flowers and pollination. This was done mainly via a cage experiment about the pod count and distribution along the plant stem, with and without pollination from honeybees. The second and third aims were to find out more about the honeybee behaviour on the faba bean flowers and the abundance of pollinators and species richness on faba bean fields. For these parts a field survey was conducted on eight different faba bean fields in Southern Finland. The increase in pod count following bee activity was found to be as high as 65% and the increase in pods per node 19%. The distribution of the pods was increased towards the middle of the plant in the plants that were insect pollinated, compared to the plants that were not. There was a strong correlation between the number of honeybees (Apis mellifera) on the fields and the pod counts per plant node. Honeybees visited 1.5 flowers per plant on average and frontal visits constituted 55% of all visits recorded. Pollinator numbers and species diversity varied greatly from field to field. The results show that pollination by of honeybees benefits faba bean yield. They give a good understanding into the potential yield effects and provide pointers for future research on the topic. The study is aimed to prepare the background for introducing a better basis for cooperation between beekeepers and faba bean farmers. The main goal is to increase knowledge about honeybee pollination effects on the faba bean yield and give a solid start into building prospects for commercial pollination services in Finnish agriculture in general. The study was done in collaboration with The Finnish Beekeeping Association.

Agriculture and other human activity has considerably affected the nitrogen cycle, which initially doubled the amount of nitrogen on the planet. The most well-known consequence of this phenomenon is eutrophication. The objective of this thesis was to study nutrient balances and their usefulness in evaluating the nitrogen usage in beef cattle farms, the nitrogen load and nitrogen use efficiency in those farms as well as how well the farms utilize their inputs. This study based on three organic beef cattle farms which took part in BERAS Implementation –project in 2010-2013. All farms specialized in suckler cow production. The data was collected in July-August 2013 when the farmers were interviewed about their inputs and outputs during the years 2010-2012. On the basis of this information different type of nitrogen balances were calculated. The farm gate nitrogen balances were 27, 36 and 70 kg/ha. Except for the last one, the feed self-sufficiency of the farms was very high, more than 90 %. The farm with the largest nitrogen surplus utilized a considerable amount of input from outside the farm which reflected in low feed self-sufficiency (64 %). The other two with smaller surpluses received excellent primary nutrient ratios (1,38 and 1,40) which indicates active nutrient recycling. However, despite of these results, it is important to remember that nutrient balances should be viewed with a critical eye. The uncertainties primarily concern the amount of biologically fixated nitrogen and the amount of yields of cultivated plants. These variables were taken into consideration in sensitivity analysis. Instead of nutrient balances, it would more useful to draw attention to other indicators such as feed self-sufficiency or animal unit density when evaluating nitrogen load of farms. The efficiency of beef cattle production depends also on how the production is actually implemented. It is especially important to acknowledge the importance of feeding and manure handling. The feed conversion ratio is always low in beef production since it is less than 10 %. Nevertheless, there are other benefits in cattle breeding such as utilization of natural pastures and cultivation of perennial grasses which not only are excellent for soil fertility, but also decrease nutrient leaching.

In previous studies of Natural Resources Institute Finland it was noticed that Sphagnum moss had almost as good growing media properties as the white horticultural peat. In addition the Sphagnum moss based growing media prevented efficiently seed-borne Alternaria seedling blight and mosses were not molded with Peziza ostracoderma Korf that appears commonly on white horticultural peat. This thesis was part of the project of Natural Resources Institute entitled “Disease suppressive features of Sphagnum mosses”. The research aimed to survey the existence and applicability of fungistasis of Sphagnum moss as growing media. In the greenhouse experiments comparisons were made between mosses from six different sphagnum bog origins in their ability to suppress damping-off caused by Alternaria, Rhizoctonia and Pythium. Disease suppressive features of four sphagnum bogs mosses from three harvest depths were also determined. In the end of experiments the coverage by molds was determined and the fresh weights of seedlings were measured. In laboratory the amounts of common antagonist microbes in Sphagnum mosses were studied using different selective growth media. Results of different experiments were compared to white peat. In greenhouse experiments it was noticed that disease suppressive features varied a lot depending on the origin of the mosses and had different effects against different damp-ing-off pathogens. Mosses in the uppermost layers had best disease suppressive features against all three pathogens. The healthiest and biggest seedlings were obtained in growing media that contained mainly Sphagnum mosses and only a minimum amount of other peatland vegetation. There were only small amounts of molds on the top of Sphagnum moss growth media but also some phytotoxicity on seedlings was obtained Sphagnum mosses had only small amounts of antagonistic microbes as compared with peat. The results indicated that Sphagnum mosses have potential as growing medium that could efficiently prevent damping-off diseases and molds. However variation of disease suppressive was observed, which calls for more experiments to verify these effects. Minor amounts of antagonistic microbes detected in Sphagnum, as compared with white peat, suggests that disease suppressiveness may be caused by the phenolic compounds of Sphganum mosses.