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Impact of amelioration system renovation on the growth of mature forest stands 全文
2010
Zalitis, T., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Libiete-Zalite, Z., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
Both forestry theory and practice have proved that amelioration favours the growth of forest stands significantly. The growing stock increases even 10 times, if the amelioration system is well-functioning. Joint Stock Company Latvia State Forests that is managing half of forests in Latvia has started renovation of old amelioration systems aiming to improve the productivity of state owned forests in Latvia. In order to evaluate the impact of the renovation of the old amelioration systems, a tree ring width in 7 pine stands, 5 spruce stands and 3 birch stands was analysed. This study shows that the renovation itself has not affected the productivity of mature pine, spruce and birch significantly 3-4 years after the renovation. Authors have come to a conclusion that the reason for that could be too short observation period or particularities of a stand structure and age.
显示更多 [+] 显示较少 [-]Research on genetic aspects of Scots pine resistance to root rot 全文
2010
Skipars, V., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Baumanis, I., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Rungis, D., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
Scots pine (Pinus sylvestris) is Latvia's most economically important tree species. It accounts for 38% of the total forest area of Latvia. One of diseases affecting P. sylvestris is root rot caused by the fungus Heterobasidion annosum, which causes large economic losses. There is some evidence of Scots pine trees with higher levels of resistance but no absolutely resistant tree clones have been described so far. Many genes encoding peptides and proteins with direct or indirect antifungal activity have been described in various plant species, but only few of them have been studied in conifers. In our study we have utilised various approaches to research genetic aspects of Scots pine resistance to H. annosum. Here we present our initial results. Initially, H. annosum infection was determined in 300 trees and in a subset of twenty seven trees representing fifteen families (progeny of one mother tree) infection levels were quantitatively characterised. Candidate-genes were selected based on previously published research. Gene copy number variation (CNV) analyses were performed on selected samples. Copy number variation polymorphism was detected for a gene encoding a thaumatinlike protein analogues of which are described as potent antifungal proteins in other plants. As increased gene copy number can lead to increased gene product amounts in cells it is possible that an increased copy number of thaumatin-like protein is beneficial to the pine tree in respect to resistance against H. annosum and other pathogens. Further experiments need to be performed to investigate this in more detail.
显示更多 [+] 显示较少 [-]Territorial organisation of game management in Latvia 全文
2010
Baumanis, J., Latvia Univ. of Agriculture, Jelgava (Latvia) | Ozolins, J., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
The number of the most important game animals of artiodactyla species (moose, red deer, roe deer, wild boar) has been increasing in Latvia during the last 10 years. At the same time, the number of hunting districts where the census of these game animals is taken is also increasing, whereas the average area of the districts is diminishing. The studies show that at present the area of many hunting districts is notably smaller than the individual territory inhabited by these species. This particular study aims at establishing whether there is a relationship between the area of a hunting district on which a census is taken and the number of animals counted, as well as whether the number of animals is really increasing or the increase in the number is attributed to an increase in the census unit number. It was established that in respect of the four species there is a significant correlation between the area of the hunting district and the density of animals in the district. The number of moose and red deer may be assessed more objectively in the districts with an area exceeding 5,000 hectares. The census of roe deer and wild boars is notably influenced by the area of the territory where the census is taken, but the analysis does not explicitly show whether the number of roe deer and wild boars is under-assessed in large districts or over-assessed in the small ones.
显示更多 [+] 显示较少 [-]Temporal structure of middle-aged Norway spruce stands of low growth potential on drained sites 全文
2010
Libiete-Zalite, Z., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Zalitis, T., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
Large proportion of 30-50 years old spruce stands originated from overstocked plantations can be characterized by low growth potential and present serious problem to forest managers. Although according to legislation unproductive spruce stands can now be clearcut, possible alternative solution allowing a forest owner to remove only trees with the worst growth potential would be also welcome. To be able to recommend any silvicultural measures, information on the inner structural development of the stands is necessary. The aim of this study was to analyze temporal structure of several spruce stands that have originated from overstocked plantations and now belong to the 2nd (increased risk stands) or 3rd (unpromising stands) growth potential groups. Data for the study from seven sample plots located in Forest Research Station ''Kalsnava'' and thinned with different intensity were used. Tree diameter distribution, volume accumulation patterns and tree mortality were analyzed. Correlation between tree diameter and tree diameter difference in the observation period from 2000 to 2006 was weaker than in the observation period from 2006 to 2009, indicating further decline of growth potential. In most cases the major part of the volume was accumulated in the middle of the diameter class distribution. For most of the trees one or both sawlogs were of good or average quality. In order to develop optimal and profitable stand management model, the effect of different thinning methods in spruce stands of low growth potential should be studied in the future.
显示更多 [+] 显示较少 [-]Survivability of lambs under village management condition: The case around Jimma, Ethiopia 全文
2011
Belay, Berhanu | Haile, Aynalem
The influence of non-genetic factors on lamb survivability at various ages up to 360 days was studied under village management condition in Jimma, Ethiopia. The overall least squares means of lamb survival rate was 89.0 at 0-60, 81.5 at 0-120 and 50.0 % up to 360 days. The survival rate of lambs up to weaning (120 days) was 81.5 %. Season of birth consistently exerted a significant effect (p<0.05)) on lamb survival. Lambs born during the post rain and dry periods showed a higher survival rate than lambs born during the wet season. Districts showed a significant effect (p<0.05)) on survival rates of lambs. Lambs born in land scarce areas (Dedo) had a low survival rate than lambs born in Seka (land available area). Type of birth did not exert an influence (p>0.05) on lamb survival. Sex had a significant effect (p<0.05) on survivability of lambs at later stages and the females showed higher survivability rate than males. Mortality tended to decrease with an increase with birth weight and decreased as parity increased. The birth weight showed a significant effect (p<0.05) on survival rate of lambs. The lambs with birth weight of 2 kg and above were showing higher survival rate. The lambs with 1.5 kg and lower birth weight showed high mortality rate. The study revealed that, adequate measures to be taken to curb mortality of lambs. The selection of heavier weight and larger litter at birth coupled with improved management could be a means to improve lamb productivity in the villages.
显示更多 [+] 显示较少 [-]Demand for applied research of agricultural engineering and crop management in Lithuania 全文
2014
Sarauskis, E., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania) | Kriauciuniene, Z., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania) | Alekneviciene, V., Aleksandras Stulginskis Univ., Akademija, Kauno reg. (Lithuania) | Ruzgas, V., Lithuanian Research Centre for Agriculture and Forestry, Akademija, Kedainiai distr., (Lithuania) | Sakickiene, A., Lithuanian Agricultural Advisory Service, Akademija, Kedainiai distr. (Lithuania)
Great emphasis has been placed on agriculture by the European Union (EU), considering that agricultural production provides a framework for development of the processing industry and ensures food provision. Europe 2020 Strategy presents coordinated objectives of support for the rural development for the years 2014–2020. It has been emphasized that each Member State needs to set its national headline targets. Implementation of strategic provisions of the EU and Lithuania requires adequate identification of the priorities of agricultural scientific research and experimental development. It may significantly contribute to securing competitiveness, economic and social progress of the agricultural sector. The aim of the research was to prepare proposals for the Lithuanian Programme that sets the scientific research and experimental development priorities, long- and short-term research programmes for the period until 2020 in the view of demands of economy. Individual Working Groups (WG) have been formed of specialists of Lithuanian research and educational institutions as well as the advisory services. WG have proposed prospective applied research to develop within different areas of agriculture in 2014–2020. This served as the basis for the survey aimed at identifying a general demand for applied scientific research and potential problem areas in relation to agriculture, food economy and rural development that could be addressed by prospective applied scientific research. An anonymous survey was used across the country and summary results have been presented for two areas: crop management and agricultural engineering.
显示更多 [+] 显示较少 [-]Influence of intercrop on plant growth and yield 全文
2014
Dane, S., Latvia Univ. of Agriculture, Jelgava (Latvia);Pure Horticultural Research Centre, Pure parish, Tukuma municipality (Latvia) | Laugale, V, Pure Horticultural Research Centre, Pure parish, Tukuma municipality (Latvia)
The demand for healthy and reasonably cheap food is growing and governments are expanding policies to preserve soil fertility and nature. In addition, climatic conditions are changing. Arable lands are decreasing. Due to all of these changes food growers are looking for new growing technologies. A monographic method to tackle these problems has been used in this article. Intercropping is one of growing systems how to reduce negative climatic aspects and meet other demands. Intercrop is convenient for growers who grow plants in rows, and a companion plant can be sown or planted between rows. In this case farmers can get two yields from one plot. Thus, growers do not need two plots for growing different plants. The intercrop diminishes spreading of pests and diseases, suppresses weed growth, and reduces need for pesticides. Legume (Leguminosae) intercrop gives extra nitrogen to companion plants. Those are aspects that we know intercrop can give, but we do not know how significant the influence is, what kind of influence on nature intercrops give in long term, what kind of influence they have on incomes, yield and its quality. This article shows that there are many intercropping systems to reduce some negative aspects and increase beneficial ones. Intercropping can reduce some pests and diseases, but promote other problems. Intercropping suppresses weeds. For some systems it gives bigger yield, for some smaller, but in total it gives bigger protein yield. There are still many unanswered questions and completely unexplained points.
显示更多 [+] 显示较少 [-]Stinging nettle - the source of biologically active compounds as sustainable daily diet supplement 全文
2014
Zeipina, S., Latvia Univ. of Agriculture, Jelgava (Latvia);Pure Horticultural Research Centre, Pure parish, Tukuma municipality (Latvia) | Alsina, I., Latvia Univ. of Agriculture, Jelgava (Latvia) | Lepse, L., Pure Horticultural Research Station, Pure parish, Tukuma municipality (Latvia)
Environmental conditions and climate change on a global scale affects the overall agriculture and food supply. Consumers demand for vegetables with high nutritional value is increasing. Consumers more and more are thinking about a healthy and balanced diet, but it is not easy to provide year-round fresh vegetables. Nettle (Urtica) leaves traditionally are used in early spring as a leafy vegetable in salads and soups. Young leaves before flowering are used for human consumption. Nettle contains a lot of vitamins and biologically active compounds. The research aim was to evaluate different stinging nettle clones, which grow in Pūre village (Tukuma district, Latvia). Samples were collected, when shoots were 10 – 15 cm long. Content of chlorophyll, carotenoids and anthocyanins in five nettle clones leaves were analysed. Biochemical analysis was done in Latvia University of Agriculture, Institute of Soil and Plant Science laboratory. Differences were observed between all clones. Significant difference between genotypes was observed in anthocyanins content, but not in chlorophylls and carotenoids content. Higher anthocyanins content was observed in samples, which grow in places with low nitrogen and phosphorus content. Content of biochemical compounds can influence some metal ions, environmental and other factors.
显示更多 [+] 显示较少 [-]Analysis of climatic factors in connection with strawberry generative bud development 全文
2014
Kalnina, I., Latvia Univ. of Agriculture, Jelgava (Latvia);Latvia State Inst. of Fruit-Growing, Dobele (Latvia) | Strautina, S., Latvia State Inst. of Fruit-Growing, Dobele (Latvia)
Strawberries (Fragaria× Ananassa Duch.) are widely grown in Latvia, and it is the first berry crop that ripens in summer. In Latvia, climate conditions are very suitable for strawberry growing. Unfortunately, meteorological conditions have become very changeable in recent years. The short day (SD) strawberry cultivars are the most important ones for Latvia, as they initiate flower buds in autumn. For these cultivars it is important to initiate flower buds at the end of September till the end of October. The day length has to decrease less than 14 hours per day to begin this process. In Latvia, the day length below 14 hours per day is at the end of August. The second important limiting factor for initiation of flower buds is the average day temperature, which must be between 10 and 15 °C. The studies on strawberry flower bud initiation in Latvia were done long time ago, on a very small scale and fragmentary. The current paper analyzes the temperature regime during the period of previous ten years (2004 – 2013) in autumn in Dobele in relation to suitability of this climatic factor to the flower bud initiation and strawberry yield next year. The soil surface temperatures during the last ten years in August were about +20 °C, which means that the flower bud initiation could not occur as early as it was described in the previous study.
显示更多 [+] 显示较少 [-]Lodging cause height at the centre of gravity changes during vegetation period for oat 全文
2014
Brunava, L., Latvia Univ. of Agriculture, Jelgava (Latvia);State Stende Cereals Breeding Inst., „Dižzemes”, Dižstende, Lībagi parish, Talsi municipality (Latvia) | Alsina, I., Latvia Univ. of Agriculture, Jelgava (Latvia)
Height at the centre of gravity is a part of mathematical model to interpret risk of lodging used for cereal crops. Because of the anatomical changes during vegetation period, several measured parameters in early milk stage (stem and panicle weight) will differ from over-ripe stage results in their values. The aim of this study was to define approximate values of calculated parameters describing oat (Avena sativa L.) height at the centre of gravity in early milk and over-ripe stages as well as determine connection with lodging risk. The trial was carried out at the State Stende Cereals Breeding Institute in 2013. There were 5 oat cultivars studied. At the investigated growing stages plant samples were taken from a field and in laboratory conditions stem/panicle weight and length measured. The height at the centre of gravity and gravity ratio were calculated using mathematical model by Berry (1998). Results showed that the value of the height at the centre of gravity in over-ripe stage was significantly higher (p is less than 0.01) than in early milk stage, but correlation with risk of lodging remained. Such lodging resistance describing mathematical model can be useful for oat as well as wheat cultivars.
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