Browsing by Subject "Kasvintuotantotieteet (kasvinviljelytiede)"

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  • Martínez Meyer, Marcela Raquel (Helsingfors universitet, 2010)
    Protein-energy malnutrition and mineral deficiencies are two of the three forms of nutritional deficiencies that affect most developing countries due to inadequate access to food and diets based on a sole crop. Common bean (Phaseolus vulgaris L.) is the staple crop of Nicaragua and it has the potential to improve the nutritional status of the poorest group of the nation. Its high content of both protein and nonhaem iron provides many nutrients, but inhibitors also may prevent absorption of iron and zinc by the human consumer. A proper production chain must be followed to ensure the best grain quality for the consumer. To achieve food security, both production and high nutritional content must be maintained. Four nationally important accessions of common bean, with different harvesting dates, were selected to be submitted to two treatments: to evaluate the impact of storage conditions on the end quality of the grain. The duration of the study was six months with sampling every six weeks, and the two treatments were controlled one stored at 40°C and 75 RH %, and the other was stored in in-situ conditions. Proximate and mineral composition was evaluated as well as tannin, phytate and bioavailability. Significant differences among different accessions were found, being the most significant in protein, Fe and Zn content, tannins and phytate. Protein values ranged from 21-23%. Iron content was 61-81 mg/kg but only 3-4% was bioavailable. Zinc content was 21-25 mg/kg and 10-12% was bioavailable. The concentration of phytate ranged from 8.6-9.6 mg/g while tannin values ranged within 37.7-43.8 mg/g. Storage at high temperatures was demonstrated to have an impact on certain nutritional compounds and proved detrimental to final grain quality. Soluble sugar content and tannin content decreased after six months in both storage conditions, IDF decreased in the in-situ and SDF in the stress. The iron content and bioavailability in INTA Biofortificado were not as outstanding as expected, so experiments should be conducted to compare its iron uptake and delivery with other cultivars.
  • Korhonen, Panu (Helsingfors universitet, 2014)
    Finland is the northernmost cultivation area in the world and the selection of forage grass species is mostly limited by long winters and short growing seasons. Forage grasses are usually grown as mixtures of species and produced intensively for silage. The grass species most commonly used in mixtures are timothy (Phleum pratense L.) and meadow fescue (Festuca pratensis L.) which are both winter hardy species. As the climate changes in the future, more southern and more productive species like perennial ryegrass (Lolium perenne L.) and festulolium (Festuca sp. x Lolium sp.) may become more usable. The duration of snow cover has been predicted to shorten to 46 days in southern Finland by year 2050 (compared with 98 days at present). The autumns, when plants develop their tolerance against winter stresses, are also predicted to become warmer in the future. Changes in winter weather may also increase the frequency of problems such as plant exposure to freezing temperatures, associated with decreased snow cover and ice encasement due to fluctuating winter temperatures. This study presents the results of experiments carried out in Helsinki (Finland) between years 2009–2013. The experiments were done to assess the freezing tolerances and vernalisation of forage grasses and cereals hardened under field conditions. The vernalisation of plants was detected in all species as a decrease in days to heading during the vernalisation period. Perennial ryegrass and meadow fescue started flowering after the vernalisation was fulfilled during December-January. Winter cereals had already vernalised already in November. Hardening periods started at their earliest in the beginning of October. However, a deeper freezing tolerance developed during December in 2009–2010 and 2011–2012. During the winters of 2009–2010 and 2011–2012 hardening periods were long and hardening-induced temperature sums were the highest. During these winters the freezing tolerances were better in all species than during the other two winters.
  • Zou, Ling (Helsingfors universitet, 2009)
    Andean lupin (Lupinus mutabilis Sweet) is a potential oilseed crop, with a very high protein content (40–45%) and 15–20% oil content. It is valued as an alternative protein source for both human and animal consumption, and like several other lupin species, has a potential role in phytoremediation. Previous experience in central and southern Europe has shown the crop to have low and unstable yields with high sensitivity to heat and drought during the grain–filling stage. The species may therefore be more suitable for cool–temperate climates, as it comes from similar altitudes and latitudes as potato. Therefore, an experiment was set out to quantify the responses of Andean lupin to heat stress, using both gradually and suddenly rising temperatures during grain filling. In preliminary tests 60 accessions from 4 germplasm banks were screened for time to flowering and daylength sensitivity. For this experiment, 3 accessions were chosen, 478435, 457972, 457977, with vegetative phase durations of 44, 53, 64 days from sowing to first flower, respectively. Forty two plants of each accession were sown and reduced to 30 on the basis of uniformity. Plants were grown in a glasshouse with 22 °C, 18 h days and 18 °C, 6 h nights until about 25 days after flowering. Ten plants of each accession were subjected to one of the following treatments: control (continuing in the same glasshouse conditions), sudden heat stress (transferred to a growth chamber and subjected to 38 °C from 11:00 to 15:00) or gradual heat stress (transferred to a growth chamber and subjected to temperature increases of 4 °C day temperature and 2 °C night temperature, with the final two days at 38 °C from 11:00 to 15:00). The plants were returned to the glasshouse and when mature, the seeds were harvested and pooled into 3 replicates per accession and treatment for quality analysis. Seed protein, oil, soluble sugar, ash and moisture content were determined. Data were calculated on the basis of percentage of overall seed mass and also on a milligrams per seed basis in order to reflect the seed physiology at grain–filling stage. Sudden heat stress had greater effects on seed composition than gradual heat stress. When compared with control, sudden heat stress resulted in more loss of every component than gradual heat stress, on a per–seed basis, in all 3 accessions and the responses of the accessions to the sudden stress were not statistically different. Under sudden heat stress, mean seed weight declined by 70%, protein content by 70%, oil content by 85%, ash content by 50%, and soluble sugar content by 75%. The accessions responded differently, however, to the gradual heat stress. Accession 478435 experienced significantly greater reduction in seed weight, protein and ash content than accessions 457972 and 457977. Oil content per seed and soluble sugar content per seed were also lower in 478435 than in the other two cultivars, but the difference was not significant. On the flour basis, sudden heat stress increased ash content and decreased oil content and soluble sugar content significantly in all accessions. Accession 478435 had highest value in ash content at significant level. Under gradual stress, protein and ash content were increased while oil mass and soluble sugar mass were decreased. 478435 had significantly higher protein mass and ash mass in flour with respectively 57% and 5.1%, 457977 had significantly higher soluble sugar content with 112 mg/g. The results showed that heat stress can have a significant effect on the quantity and quality of seed yield in Andean lupin. While all tested accessions were severely susceptible to sudden heat stress, gradual stress identified differences between accessions, with one being much more susceptible than the other two. The most susceptible accession was the earliest to flower. Gradual heat stress allows better resolution than sudden heat stress when screening germplasm for heat tolerance.
  • Baarman, Axel (Helsingfors universitet, 2014)
    Nitrogen leaching is the main cause of nitrogen loss from Finnish agricultural soils. Nitrogen leaching can exceed 20 kg/ha/year. The Finnish waters and the Baltic Sea are affected by nitrogen leaching due to that nitrogen increases algae blooming. Studies have shown that the loss of nitrogen can be decreased by cultivating catch crops. Nitrogen leaching can in some cases be decreased by up to 90 %. In Finland catch crops are seldom grown. Catch crops are thought to be too costly and time consuming. The aim of this study was to investigate how efficiently winter wheat, rye and winter turnip rape function as catch crops and what effect the preceding crops of fallow, barley and peas have on autumn sown crops, with regard to nitrogen levels. A three year-long field experiment was established in 2010 at Viikki research farm in Helsinki. Winter wheat, rye and winter turnip rape were cultivated as catch crops; the preceding crops were fallow in 2010-2011 and barley and pea in 2011-2012. In 2012 winter wheat, rye and winter turnip rape were cultivated with fallow, peas and barley as preceding crops. In this study the soil’s mineral nitrogen content was measured before sowing in autumn and in spring. In 2010-2011 the soil’s mineral nitrogen content was also measured after harvest. The nitrogen content of the plants was measured in autumn. The seed quality and the seed yield were also measured. In autumn 2011 the mineral nitrogen content of the soil was higher after barley than after peas. However, there was more mineral nitrogen after cultivating fallow, compared to peas and barley in autumn 2012. The loss of mineral nitrogen between autumn 2010 and spring 2011 was slight. The nitrogen loss was greatest where winter turnip rape was cultivated, due to the plant’s high nitrogen assimilation. Winter turnip rape accumulated much more nitrogen than rye and winter wheat, whereas rye accumulated more nitrogen than winter wheat in 2010 and 2011. Mineral nitrogen loss between autumn 2011 and spring 2012 was high, over 80 % of the nitrogen was lost due to heavy rainfall and a mild winter.
  • Lizarazo Torres, Clara Isabel (Helsingfors universitet, 2010)
    Drought is one of the most important abiotic stresses that causes significant reductions in crop yield, and thus hinders the food security of the growing world population. In consequence, it is urgent to select crops able to resist drought, maintain high yield and have a good nutritive content. The purpose of this project was to evaluate the responses of different accessions of Andean lupin to drought stress, and identify if there are significant differences in their physiological responses. To identify germplasm for further investigation, thirty accessions of Lupinus mutabilis Sweet. and one accession of L. albococcineus Hort. were screened in two sets, A of 15 and B of 16 accessions. From these sets, four lines were chosen on the basis of extreme values in the measurements, and this set of four was investigated in depth (set C). In all experiments, ten seeds of each chosen accession were sown in pots and grown in a glasshouse with 22°C, 18 h days and 18°C, 6 h nights, and were well watered until day 50 after planting. The pots were arranged in a randomized complete block design. The eight most uniform plants were chosen, and four were exposed to water stress while watering of the other four was continued. Water stress consisted of controlled water loss from the soil, 20% water holding capacity at 2% per day over 9 days, so the soil reached 2% moisture content and was held at this level for 2 days more. In all experiments, leaf temperature, stomatal conductance, relative water content, water potential, ion membrane leakage, and shoot dry weight were measured and transpiration efficiency was calculated. In set C, carbon isotope discrimination, root length, root dry matter, proline content and soluble sugar content were also determined. The analysis of set A and B revealed significant differences between treatments for all the parameters measured, except for relative water content, and there were also differences amongst accessions in certain parameters. PI 457972 and PI 457981 were selected for further investigation because of their low stomatal conductance under water stress conditions and low water use, and PI 510572 was selected as sensitive to drought stress due to its high water use, ion membrane leakage and water potential under water stress conditions. In addition AC 2792 (L. albococcineus) was selected due to its low stomatal conductance and water use, and high leaf temperature under water stress conditions. In the final experiment, PI 457981 and PI 457972 appeared to avoid drought through appropriate stomatal characteristics. PI 457981 showed low stomatal conductance, high leaf temperature and also high root length, similarly, accession PI 457972 showed low water potential, low stomatal conductance, low carbon isotope discrimination and accumulation of soluble sugars. Accession PI 510572 contrasted for these stomatal traits, but interestingly it showed low membrane ion leakage, high proline content and soluble sugars content, suggesting that it was capable of drought tolerance by osmotic adjustment. Finally, accession AC2792 showed low water use, low water potential and low carbon isotope discrimination. This survey thus identified accessions of Andean lupin that were able to avoid drought stress through stomatal traits and root traits, and other that were able to tolerate drought through the accumulation of osmotically active substances. Thus, there are good prospects for breeding of Andean lupin to improve its drought resistance.
  • Pennala, Tuomas (Helsingfors universitet, 2013)
    Wheat is one of the world's three most important arable crops among rice and maize. Therefore, the study of fertilization is important, especially in the long run, to provide reliable information on the impact on potassium fertilization to farming land, spring wheat growth and its yield. The aim of this study is to find out how potassium fertilization affects spring wheat yield and soil properties, as well as straw yield in long-term field experiment. I wanted to find out whether the current recommendations for potassium fertilization are sufficient to spring wheat varieties on sandy loam and which factors are most affected wheat grain and straw yield. The experiment was conducted on sandy loam in Hausjärvi as field experiment, in which four fertilization treatments were used, two of which contained the same amount of potassium and two were left without potassium. Wheat grain and straw yields were sampled and analyzed. In addition, the wheat crop samples were taken during the summers. Wheat straw was collected each year from the field, except in 1978, when they were plowed in the field. According to the results of spring wheat grain and straw yield year affect both fertilization and year. Year explained the differences in yields better than fertilization. Potassium fertilization levels significantly affected the straw yield. Most fertilized wheat took the most soluble and reserve potassium. The amount of soluble potassium in topsoil decreased in all treatments, but reserve potassium remained almost unchanged. The study shows that the current recommendations for potassium fertilization of fields potassium balance fall in the long run. Also, wheat other macronutrient intake significantly affect potassium commissioning. The amount of potassium in topsoil decreased during the experiment and some of potassium probably leached from the field. The test use 60 kg of K / ha are sufficient for current wheat varieties. Without potassium fertilization may occur potassium deficiency after decades, especially if the natural potassium resources are small. In the future, therefore, should pay attention to improving the use of potassium and to prevent potassium leaching.
  • Kymäläinen, Anni (Helsingfors universitet, 2013)
    In Finland, potato is cultivated on more than 22 000 hectares, which makes it one of the most important crops. Potato is considered drought sensitivive because of it´s shallow roots. Thus, irrigation is recommended to improve not only the yield but to ensure good tuber quality. However irrigation is increases production costs. Nitrogen fertilization also affects yield and tuber quality but excess nitrogen can increase costs, nutrient leaching and reduce tuber quality. Thus, the equipment that can be used to estimate nutrient deficiencies have become more common. The effect of irrigation and nitrogen fertilization on growth and tuber yield of potato was investigated during 2001 – 2003 at Potato Research Institute in Lammi, Finland. Irrigation methods were surface irrigation and subsurface drip irrigation. Nitrogen was applied as a single dose when planting or as sidedress. Further interest was to find out whether SPAD values could be used to evaluate both the demand and timing of potato nitrogen fertilization. Irrigation did not affect potato development, tuber yield or starch content. Irrigation methods had no effect on tuber yield either. However, irrigation reduced the yield of marketable tuber yield. The benefit of drip irrigation was the possibility of combined irrigation and fertilizer application. Nitrogen increased tuber yield. The potato stand that received nitrogen as a single dose produced the greatest yield. However, even the potato stand which did not receive nitrogen produced quite large yield, over 30 tn/ha. In 2003, the stands which were given sidedress nitrogen with drip irrigation produced even greater yield than the ones that had been given nitrogen as a single dose. The stands which did not receive nitrogen had highest starch content. The SPAD values were used when estimating the demand of nitrogen fertilization with drip irrigation. SPAD measurements are easily conducted and non-destructive. SPAD values can be used to estimate the demand and timing of fertilization, even though there seems to be slight delay until the values indicate the nutrient deficiency.
  • Räfså, Tomas (Helsingfors universitet, 2014)
    More than half of the agricultural land in Finland is cultivated with cereals, and on many farms, cereals are also grown in monoculture. Studies have shown that crop rotation can decrease the need of inputs and also increase crop yields. At the same time more knowledge is needed about qualities and benefits of different crops. The aim of this study was to investigate the qualities of white lupin as a one year green manure crop, and to investigate its impact and nitrogen effect on barley yield formation and yield quality during the subsequent growth period. The aim was furthermore to investigate if white lupin affected soil mineral nitrogen content. A two year long field experiment was established during the growth season of 2010 at Viikki research farm in Helsinki. In year 2010 white lupin, barley and fallow was cultivated as precrops for the following growth period. In year 2011 only barley was cultivated and different nitrogen treatments were included in the experiment to be able to evaluate precrop nitrogen effect. In year 2011 cultivation of white lupin and barley was also repeated in a second field experiment. In the experiments, white lupin lenght development, ground coverage and biomass accumulation were recorded and compared with barley. The total amount of nitrogen that white lupin accumulated was also determined. In year 2011 precrop and nitrogen treatment effects on barley yield formation and yield quality was determined. Precrop and nitrogen treatment effects on soil mineral nitrogen was investigated from fall 2010 to fall 2011. White lupin was successfully cultivated without any input of fertilizers. White lupin showed less ground coverage in early summer, and therefore showed inferior weed competition compared with barley. White lupin achieved the same plant lenght and total biomass as barley, but accumulated over 200 N kg/ha. In the precrop and nitrogen treatments, barley grain yield did not indicate any need of nitrogen fertilizer, where white lupin had been used as precrop. Grain protein content, however, showed that even with white lupin as precrop, a 20 kg/ha nitrogen starter was not sufficient. Soil mineral nitrogen content was clearly increased by white lupin only before sowing in year 2011.
  • Toivonen, Tiina (Helsingfors universitet, 2014)
    Timothy (Phleum pratense L.) and meadow fescue (Festuca pratensis Huds.) are generally grown forage grasses at high latitudes. Growing of perennial ryegrass (Lolium perenne L.) and xFestulolium hybrid is possibly increasing in the future. The climate change will alter autumn growth conditions in Finland. The aim of this study was to investigate differences in autumn growth and accumulation of reserve carbohydrates between forage grass species and cultivars from different geographical origin. The objective was also to study autumn growth ability after third cut, cold tolerance, tiller density and content of soluble sugars in chosen cultivars in field conditions during winter. This study was carried out at growth chamber experiment and field trial. There were four different autumn growth conditions in growth chambers: first 5 °C/14 h and 10 °C/14 h and secondly 15 °C/12 h and 15 °C/14 h. Vegetative factors like ligule height and activity of photosynthesis and concentration of soluble sugars were measured from timothy, meadow fescue, perennial ryegrass and xFestulolium lines. Autumn growth yield after third cut, cold tolerance (LT50) and reserve carbohydrates of perennial ryegrass and xFestulolium cultivars during winter were measured in field trial (Nov. & Jan./Feb.). According to this study low temperatures (5 and 10 °C) prevented formation of lateral tillers effectively in timothy but not in other species because they formed new lateral tillers and accumulated biomass. Low temperatures (5 and 10 °C) prevented height growth in all studied lines and long day length (14 h) allowed height growth only in higher temperature (15 °C). Perennial ryegrasses and xFestulolium cultivars grew similarly in short (12 h) and long (14h) day length but the growth of timothy was delayed in short day length. Southern timothy breeding line grew significantly height in the 15 °C and 14 h growth conditions whereas northern timothy breeding line formed more lateral tillers. The photosynthesis activity of all tested genotypes was high in all growth conditions and concentration of soluble sugars increased in low temperatures but not in high temperatures except in northern timothy. According to the field trial the overwintering of perennial ryegrasses and xFestulolium cultivars was challenging especially in second winter and the decline of low temperature tolerance was connected to vernalization saturation of xFestulolium cultivars during winter. There was strong variation in autumn growth between years.
  • Mustonen, Arja (Helsingfors universitet, 2014)
    In Finland 90% of all farmers and 95% of cultivated land are committed to the environmental support program of agriculture. One of the goals of this program is to reduce phosphorus (P) runoff from fields to the water system by limiting the amount of P used in cultivation process. Experiments on P rates allowed in environmental support program and practices of P fertilization were conducted at two sites on ley during 2003-2011. The research aimed to define the effects of annual fertilization, incorporated fertilization and the use of liquid manures on ley yield and P status of the soil. Earlier studies have shown that more water soluble P runs off from leys than from cereal fields and that reserved P hasn’t been sufficient for the whole ley rotation. The experiment consisted of seven different fertilization treatments in which phosphorus treatments were done as incorporate fertilization or annual fertilization. Low or high-release mineral fertilizer was used for incorporate fertilization and either mineral fertilizer or at first mineral fertilizer and liquid manures in next rotation for annual fertilization on the surface. P given as liquid manure was used by three members of the experiment group. The experiment included cultivating ley for seven years and cereal forage for two years. The control group used no P fertilization. P given in fertilization treatments had no effect on ley yields compared with control treatment. Negative P balance in all treatments caused the P rate in ploughed layer of the soil to decrease, however the P levels of surface layer fluctuated greatly regardless of the way P treatments were done. The study indicated that using liquid manures for fertilizing ley cultivations does not pose any greater threat to the environment than mineral fertilizers. However, balanced fertilization, sufficient nitrogen and reducing nitrogen loss of liquid manures are required in order to achieve high yields. The results also indicate that it should be made possible to raise the amount of P fertilization of highly productive leys closer to the zero level of the nutrient balance so that productivity of the soil measured by acid ammonium acetate (PAC) would be preserved. Depending on the other qualities of the soil, this can be done when PAC has reached the value nearby 10 mg l-1. More information on controlling P of the surface soil by means of cultivation management is needed.
  • Uusitalo, Tuomas (Helsingfors universitet, 2013)
    Sulfonylureas is large, widely, especially in cereal production, used herbicide group since 1980’. Continual unilateral use of sulfonylureas has resulted in development of sulfonylurea resistant weeds. Common chickweed [Stellaria media (L.) Vill.] is common weed in Finland, which is known to have developed sulfonylurea resistance. The aim of this work was to investigate herbicides to control sulfonylurea resistant chickweed as well as to optimize the timing of the weed control. Further attention paid to the effect of weed control to the barley grain yield and its quality. This study was organized as a field experiment in Somero during summer 2012 a randomized complete block design. Sulfonylurea resistant chickweed population was found from this specific field. Experiment included 14 herbicide treatments. One of the herbicides studied was sulfonylurea. Herbicides applied at early and late timing. After treatments, the number of chickweed was counted, its biomass was weighed and N content analysed. Furthermore, the coverage of chickweed and the herbicide efficacy was evaluated visually. Barley was harvested and the grain yield and its quality was analysed. Sulfonylurea Express 50 SX did not control chickweed as effectively as expected. Starane 180 was effective only when 0,6L/ha dosage was used. Ariane S, K-Trio and Primus were effective, with efficacies over 90%. Efficacies of these herbicides were not dependent of timing. Oxyril did not control chickweed as well as was assumed. Efficacy of Oxytril was better when applied at early timing. It seems that the best options to for weed management in case of sulfonylurea resistant chickweed are Starane 180, K-Trio and Ariane S.
  • Ohralahti, Kalle (Helsingfors universitet, 2013)
    Barley is the most cultivated cereal in acreage in Finland. Barley has many plant diseases that cause yield reductions like net blotch, scald and mildew. The weather conditions and the disease resistance of the cultivar are affecting the appearance of the plant diseases. Plant diseases can be controlled by certified seed, seed treatment, crop rotation, fungicide treatment and by cultivating resistant cultivars. Net blotch causes reduction in green leaf area, thousand grain weight and thereby it reduces yield. The aim of this study was to study what is the yield response of barley to fungicide treatment when cultivars are either susceptible or tolerant to net blotch. The data of this study was based on The profitability of plant protection -trial series. The field trials were conducted at three locations in Finland during 2006–2009. The cultivars in the trials were divided based on their net blotch resistance to susceptible and tolerant groups. Fungicide treatment was made with Acanto Prima as a single treatment at the flag leaf stage. Tolerant and susceptible groups differed significantly in the amount of the net blotch. Fungicide treatment decreased the appearance of net blotch more in the susceptible group although the amount of net blotch was significantly less in the tolerant group. In the tolerant group the disease level was low even before the fungicide treatment. The conclusions of this study were, that tolerant cultivar group had better yield, but susceptible cultivar group had better yield response to the fungicide treatment. The yield response was in average 400 kg/ha in the susceptible and about 200 kg/ha in the resistant cultivar group. The yield response was due to the higher thousand grain weight. The yield security of disease resistant cultivar is better also in higher disease pressure. Resistant cultivar is one way to reduce the usage of plant protection products in IPM farming. Breeding of resistant cultivars is needed because the plant diseases are altering in their disease infection capability.
  • Luhtanen, Juha (Helsingfors universitet, 2011)
    Forage crops are an important part of agriculture in worldwide since about 69 % of the agricultural area is covered with permanent meadows and pastures. In Finland forages cover up to 29 % of the agricultural area and production is based on intensive cultivation. The most cultivated species in Finland is timothy grass (Phleum pratense ssp. pratense L.). It is very frost resistant and that is why it is suited for northern growth environment. Timothy cultivars can be divided based on their genotypic origin to southern, northern and intermediate types. Cultivars differ in their growth and development habit. Along climate change extreme weather conditions become more frequent, mean temperature will rise and winters will be rainier. This research tries to find out how the different cultivars from different origins differ in their cold tolerance, growth and development speed and how vernalisation affects. Besides these it was researched if different methods for evaluating the vernalisation response in winter crops were useful methods to evaluate vernalisation response in forage grasses. Research composed two years long field trial and growth chamber trial. Vernalisation accelerated the growth and development of timothy. Based on this research the southern cultivars already had readiness for growth and development despite of the vernalisation if environmental conditions were favourable. Northern cultivars attained this readiness along the vernalisation. Vernalisation affected also to the architecture of the grasses. The number of generative tillers, that produce the inflorescence, increased due to vernalisation response. The number of vegetative tiller, not inflorescence tiller, became less due to vernalisation. The research revealed that cold tolerance was dependent on the temperature of the autumn hardening period (FH-COLD). High mean temperature during the hardening period decreased the cold tolerance. If the temperature was between 0 °C and + 5 °C cold tolerance increased. According to this research vernalisation had a clear effect on timothy growth and development for example. Northern cultivars do not necessarily need such a long vernalisation as Finnish winter is. Also methods for evaluating the vernalisation response in winter crops are partly useful in pure timothy cultivars too.
  • Nikkari, Saara (Helsingfors universitet, 2013)
    A field experiment was conducted at Potato Reseach Institute during 1997-2002 in Lammi, Finland. The first aim of the work was to find out the suitability of three- and four-year crop rotation on potato production. The second aim was to investigate the effect of three different tilling methods and four different preceding crops on yield and quality of potato. The tilling methods were autumn and spring ploughing and light cultivation. The preceding crops were barley with straw left in the plots, barley with straw harvested, oat with straw harvested and two-year-grass. There were no differences on yield or quality of tubers between the studied crop rotations. The tuber yield did not differ between the tilling methods or the preciding crops. There was an interaction between all studied rotation and tilling methods. Three-year rotation resulted in approximately 5 % higher tuber yield and 14 % higher marketable yield following spring ploughing and light cultivation in comparison to autumn ploughing. However, four-year rotation resulted in an opposite result, since the tuber yield was 7 % and marketable yield 17 % higher following autumn ploughing in comparison to both spring ploughing and light cultivation. The most effecting factor on tuber quality was the two-year-grass as a preceding crop. Starch content was a little less than one percentage point higher following grass in comparison to all other preceding crops studied. Plant stand was also slightly sparser and tubers were slightly larger following grass in comparison to other preceding crops studied. This was due to grass lumps which caused problems in planting and resulted in uneven plant stand density. There were more green tubers following grass in comparison to other preceding crops studied. The starch content was a little less than one percentage point lower following spring ploughing in comparison to other tilling methods. Common scab was observed somewhat more following spring ploughing. The light cultivation resulted in the highest number of green tubers. Three- and four-year crop rotations seem to fit for potato cultivation, and oat and barley are suitable as preceding crops for potato. Yield is not affected when spring ploughing- and light cultivation is applied with cereals as preceding crops. The two-year-grass is also suitable preceding crop for potato. It increases the tuber starch content, even tough it can decrease the quality. Thus, autumn ploughing is the best option as a tilling method to be used for grass as a preceding crop in potato cultivation.