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Impact of amelioration system renovation on the growth of mature forest stands Полный текст
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.
Показать больше [+] Меньше [-]Research on genetic aspects of Scots pine resistance to root rot Полный текст
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.
Показать больше [+] Меньше [-]Territorial organisation of game management in Latvia Полный текст
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.
Показать больше [+] Меньше [-]Temporal structure of middle-aged Norway spruce stands of low growth potential on drained sites Полный текст
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.
Показать больше [+] Меньше [-]Productivity of Abergelle, Central Highland and Woyto-Guji goat breeds in Ethiopia Полный текст
2020
Jembere, Temesgen | Haile, Aynalem | Dessie, Tadelle | Kebede, Kefelegn | Mwai, Ally Okeyo | Rischkowsky, Barbara
The objective of this paper was to evaluate the productivity of three indigenous goat breeds from Ethiopia namely Abergelle (AB), Central Highland (CH) and Woyto-Guji (WG) based on their kids’ total live weight at three months (LWW), survival rate to three months (S3M) and average daily milk yield (ADM, for AB only). The LWW were standardized by year and post partum weight (ppw) of does. In addition, productivities expressed as the body weight of three months old kids produced per doe per year (index I) and per kg ppw per year (Index II) were also assessed. The overall least squares means of LWW for AB, CH and WG were 7.6, 15.3 and 10.2 kg, respectively. The overall mean of the ADM for AB was 367.10±139.79 ml. The S3M was 76.30%, 78.50% and 77.70%, for AB, CH and WG, respectively. Overall means of index I and index II were 14.7 kg and 0.50, respectively. Year of birth affected (p<0.05) LWW and S3M of AB, CH and WG as well as the indices. The ADM and S3M of AB and LWW of WG were also influenced ( p<0.001) by village of kidding. The LWW and S3M of the three breeds were not influenced (p>0.05) by sex of lambs. On the other hand parity of birth had clear influence (p<0.05) on ADM and S3M of AB and index I. Season of birth also had influence (p <0.001) on LWW of AB only. The CH does produce about 200% LWW of AB does and about 150% LWW of WG does. The CH was found to be the most productive breed in terms of all assessed parameters followed by WG. The AB was best suited for dual services (meat and milk). Hence, goat meat investment priorities in Ethiopia could target Central Highland goats. However, the productivity of these goat breeds should be improved in their respective localities by minimizing possible factors hampering their productivity
Показать больше [+] Меньше [-]Characterization of fish production and marketing practices under small-holder fish farming systems of eastern Kenya Полный текст
2013
Oyieng, Edwin P. | Charo, H.K. | Kahi, A.K. | Ojango, Julie M.K.
Aquaculture, a sub-component within the fisheries sector is a vital economic activity and livelihood component of rural communities living beside rivers and river floodplains in East Africa. It provides a good alternative source of income and proteins for rural communities. This study aimed to characterize fish production and marketing practices in smallholder farming systems under a national Economic Stimulus Programme (ESP) in the Eastern province of Kenya, and to determine the traits of economic importance to the farmers. Information was collated from 198 farmers, 13 traders and three key informants within Meru District of Eastern Province. The predominant species of fish reared was the Nile Tilapia, followed by the African Catfish and in some instances a combination of the two species were reared under polyculture. Good growth rate and survival of fish were noted to be the most important traits of economic importance to the farmers. Fish produced was mainly sold to the local community and within local markets. Traders, however, indicated that the demand for fish was much higher than the supply, hence also sourced fish from Lake Victoria in Nyanza for sale. It was also indicated that the taste of fish differed greatly depending on the source, with wild fish strains from Lake Victoria having a “sweeter” taste than the farmed strains. Strains of fish selected for improved growth and reproduction were not available for aquaculture. Feeds and feeding management of farmed fish was also a challenge. It was evident that there is a great need for supportive research on environmental impacts, productivity and quality of fish reared, and marketing of fish products within the riverine environments of Kenya. Key words: aquaculture, fish marketing, traits of economic importance
Показать больше [+] Меньше [-]Demand for applied research of agricultural engineering and crop management in Lithuania Полный текст
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.
Показать больше [+] Меньше [-]Influence of intercrop on plant growth and yield Полный текст
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.
Показать больше [+] Меньше [-]Stinging nettle - the source of biologically active compounds as sustainable daily diet supplement Полный текст
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.
Показать больше [+] Меньше [-]Analysis of climatic factors in connection with strawberry generative bud development Полный текст
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.
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