2018, Vol. 16, No. 4

Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/5377

Sirvi

Nüüd näidatakse 1 - 20 33

Effect of environmental temperature on bending strength of the finger jointed aspen lumber
(2018) Iejavs, J.; Spulle, U.; Jakovlevs, V.; Buksans, E.; Zelmenis, A.
Glued sauna wall boards are used as non-load-bearing structures. These products are subject to aggressive microclimate impact and very often for the gluing in length and width thermoplastic polyvinyl acetate adhesives (PVAC) are used. In the performed research sauna wall boards made of common aspen (Populus tremula L.) with mean wood moisture content 8% were used. For the gluing in length with finger joint PVAC glue of D4 (LVS EN 204) group was used. The aim of the research is identifying the impact of the environmental temperature on the strength of finger jointed aspen timber in 4 point static bending (in compliance with standard LVS EN 408). As a result of the study it was established, that after holding the finger jointed testing pieces visible in flat wise for 3 hours at the temperature of 100°C , the mean bending strength decreased by 56% or 31.7 MPa in comparison to that held in the standard atmosphere. In case of the aspen timber with finger joints visible in edge wise held for 3 hours at the temperature of 100°C , the bending strength decreased by 60% or 29.3 MPa in comparison to the testing pieces of the same type held in the standard atmosphere.
Faults and the physical workload in sawing and packing-related woodworking processes when considering potential ergonomic solutions
(2018) Kalkis, H.; Roja, Z.; Babris, S.
The forest sector is a high - risk economic sector in Latvia, one in which manual work, awkward postures, the tightening up of individual muscle groups, and work monotony still exists. The aim of this study was to analyse the physical workload and fault modes, and their effects on the sawing and packing proce sses in woodworking when considering potential ergonomic solutions. Results show that packing operators and saw operators alike are exposed to severe loads, and these results coincide with survey results in which employees in these professions complain abo ut the physical load and mention lower back pain. Fault modes and their effects on the sawing and packing processes were analysed using Failure Mode and Effects Analysis, and the main errors which were revealed in packing operations were related to machine ry and lifting equipment, as well as to ergonomics and errors involving the human factor. The risk priority was calculated in terms of a figure. Financial indices were compared before and after any potential improvement in the sawing and packing processes. Analysis proves that investments in the improvement of ergonomics in relation to the automation of the production process saves human resources and is economically favourable when it comes to ensuring the sustainable development of the business in questio n.
Optimization of arable land use to guarantee food security in Estonia
(2018) Põldaru, Reet; Viira, Ants-Hannes; Roots, Jüri; Estonian University of Life Sciences. Institute of Economics and Social Sciences. Department of Business Informatics and Econometrics
Agricultural and food sector has an important role to play in ensuring food security. A competitive agricultural sector warrants fo od security through increasing level of self - sufficiency in food, and export of surplus production in the sub - branches where it has a comparative advantage. One of the strategic tasks of the state is to secure food supply for the population. To perform thi s task, the state should estimate if the agricultural producers have the necessary capacity and resources to produce food to meet the needs of population. Mathematical modelling can be used as a tool in solving this analytical problem. The paper demonstrat es possibilities of implementing linear programming model in optimizing the use of arable land for ensuring the food demand of Estonian population. The Estonian arable land use optimization model is essentially a static balancing model that simulates the d emand and supply of basic food products (meat, dairy products, cereal products and potatoes). The basis for the demand side in the model is Estonian population, divided into 10 groups according to gender and age. The energy and protein needs of the respect ive population groups are taken into account. The supply side of the model is a typical agricultural production model that guarantees the consistency of crop and livestock farming. The model consists of 163 variables and 178 constraints (equations). The ob jective of the model is to minimize the use of arable land for field crops to ensure fodder for animal feed, and food for human food consumption. The model is used to analyse various land use strategies. According to the modelling results for ensuring food security of Estonia and to maintain export of dairy products, for which Estonia has a comparative advantage, in the 2016 volume, the total optimal arable land equals to 490,688 ha . There should be 83,600 dairy cows (with average milk yield 9,000 kg cow - 1 ) . It is necessary to grow 755,700 piglets per year in order to secure 40 kg of pork per inhabitant. Land use optimization results indicate that Estonian agriculture is able to supply Estonian people with the minimum necessary main food products to guarante e food security, and allows to export essential products (cheese, butter, skimmed milk powder, whole milk powder).
Effect of PTO-driven tillage machines on soil particles transfer
(2018) Buřič, M.; Novák, P.; Hůla, J.
Displacement of soil particles by erosion can be seen as a major threat to the quali ty of agricultural land in the conditions of Czech Republic. While the effects of water and wind erosion have long been investigated and reported, the effect of soil tillage technology on soil particles translocation are relatively new area of agriculture research. Soil tillage may contribute to the undesirable translocation of soil particles towards lower - lying parts of fields especially on slopes. The effect of soil tillage implements on soil particle translocation has not been sufficiently explained yet. The object of this research was to assess the influence of PTO (power takeoff) - driven tillage machines on soil particle translocation during secondary tillage (soil preparation). Measurements to determine the displacement of soil particles were performed in location Nesperská Lhota in the Central Bohemia Region. Measurements were performed on a sandy loam cambisol after harvest winter cereals (winter wheat). To indicate displacement of soil particles was used grit of white limestone (size 10 – 16 mm). Limest one was put down into the trench with known position orthogonal to the direction of working operations. Subsequently were performed working operations in the specified sequence. Limestone particles were counted and weighed in each section. It was detected by measuring the different nature of displacement for each machine. Statistical significance of differences in the weight of translocated particles was evaluated for different type of machines.
Assessment of potato plant development from Minitubers
(2018) Dimante, I.; Gaile, Z.
In production of minitubers, mani pulation of their weight by modifying production method is common. Under field conditions plant development from minitubers can be affected by their weight, as well as cultivar. This objective of this study was to compare plant development from four minitu ber weight classes (MtC) (3 to 4.99 g, 5 to 9.99 g, 10 to 19.99 g, and > 20 g) with broken apical dominance of cultivars ‘Monta’, ‘Prelma’ and ‘Mandaga’. ‘Prelma’ and ‘Mandaga’ had a similar development pattern, and minitubers > 20 g required significantly less growing degree days (GDD) to emerge than minitubers from the lightest classes. The heaviest minitubers needed on average 176 GDD for 50% emergence and 207 GDD were needed for the lightest class. The difference in GDD between the marginal MtC was more pronounced in period between 50 and 80% emergence. MtC did not affect the final rate of emergence. Number of above ground stems (1.4 – 4.0) was significantly affected by MtC. ‘Monta’ had significantly different development – delayed emergence, lower emergen ce rate, less above ground stems, faster canopy closure. Our study showed that plant development was significantly affected by MtC and cultivar. Differences between MtC were more pronounced under adverse meteorological condi tions.
Assessment of the actual hand position on the steering wheel for drivers of passenger cars while driving
(2018) Hruška, M.
This work deals with the assessment of the actual position of the hands on the steering wheel of drivers of passenger cars in specific driving modes. The findings are compared with the location that is generally considered to be optimal in terms of both active and passive safety, and the long - term effects on the health of the driver. The research desc ribed in this work was carried out on a sample of randomly selected drivers in the Czech Republic. For all of the measurements, one identical neutral passenger middle - class vehicle, with which none of the test subjects had previous experience, was selected . The reason for this research was to model a normal situation where the driver controls a vehicle with his hands on the steering wheel in a position that is only the result of his or her own intuition and the subjective sense of the driver’s comfort. On t he basis, of a statistical evaluation of the obtained data, it was found that the introductory hypothesis, which states that a significant part of the tested sample of drivers holds the steering wheel in an unsuitable manner, can be confirmed. This fact ne gatively impacts not only on the reduction of active and passive safety, but also affects the health of drivers who drive a large amount of kilometres annually. The results of this work can be used in the design of cabs and modern passenger car systems tha t will be able to motivate the driver to hold the steering wheel in an optimal way. This will directly affect road safety and positively influence the health of drivers.
Mathematical model of cleaning potatoes on surface of spiral separator
(2018) Bulgakov, V.; Nikolaenko, S.; Arak, Margus; Holovach, I.; Ruzhуlo, Z.; Olt, Jüri; Estonian University of Life Sciences. Institute of Technology
Cleaning potato tubers from soil impurities and plant debris after digging them out of soil is a topical problem in the work process of potato production. Therefore, the engineer ing of new designs of potato heap separators necessitates the further studying of them and the optimisation of their kinematic and design parameters, which must not only ensure the high quality of cleaning, but also rule out the possibility of damaging the tubers. The aim of this study is to determine the design and kinematic parameters of the improved design of the spiral potato separator, which will ensure the high quality of cleaning and rule out the possibility of damaging the tubers, on the basis of th e development of the new theory of potato tuber’s motion on the surface of the separator. An analytical study has been carried out resulting in the construction of the equivalent schematic model of the interaction between the potato tuber and separator, th e tuber being approximated by a material point on the surface formed by the two cantilevered spirals, which are the separator’s tools. The separator’s spirals are driven to rotate and at the same time they can perform oscillations in the vertical and axial plane under the action of the varying load generated by the continuous feeding of the potato heap for separation. In the model, the forces acting on the potato tuber’s body are applied to it, the coordinate axes that have been selected and appropriately o riented are shown. A system of equations has been set up for the constructed equivalent schematic model, comprising three differential equations of the potato tuber body’s motion on the surface of the trough formed by the two cantilevered spirals. The dete rmined kinematic and design parameters will allow to raise the quality of cleaning potato tubers from soil impurities and plant debris. .
The impact of weather conditions on microclimate in storage facilities
(2018) Bradna, J.; Šimon, J.; Hájek, D.; Vejchar, D.
The key to maintaining good qualitative parameters of stored grain on farms is to achieve and maintain suitable storage temperatures relative to the outside temperature. In the framework of this research, the main focus was on typical representatives of grain storage facilities used in the Czech agriculture. In the post - harvest period after the crops were stored in the chosen storage facilities, the temperature of the material was monitored at 15 - minute intervals using an external temperature probe as well as the temperature and dew point of the outdoor air. A simple linear regression model was used for data analysis. The correlated temperature d ependence of the stored grain varies considerably in the monitored storage facilities. The storage halls were characterized by a low dependence (r = 0.2208) of the temperature of the material on the outside air temperature in the first 4 months following t he harvest when the grains were being stabilized by active aeration. In addition to the grain and the air temperature, the second focus was monitoring the dew point, i.e. assessing the risk of water vapour condensation on the surface in the upper layer of the stored grain, which is very undesirable for maintaining the quality of the stored grain. The results show that the monitored storage hall can be characterized by the ability to maintain the required climate due to outdoor climatic conditions. In genera l, this ability mainly depends on the type and design of the storage facility, the aeration system and also the storage capacity. Mainly during spring the dew point and water vapour condensation can often happen within the grain, therefore the need to focu s on appropriate measures such as reduced aeration or increased grain mixing, and thus avoiding the formation of critical spots.
Analysis of indoor temperature in the workshop building during the summer: a pilot study
(2018) Cao, D.V.; Kic, P.
The aim of this paper is the presentation of measurements' results and the calculation method for analysis and evaluation of climate conditions as well for using of natural illuminance in two large simple buildings during summer which could be used to calc ulate power demand for the air cooling to reduce the indoor temperature caused by solar radiation. In this research, we carried out experiments of measuring the indoor temperature at level of working place which is 1.1 m, in two similar large workshops wit h floor area 260 m 2 and height 6.5 m, during several hot summer days. The indoor conditions were strongly influenced by the solar radiation as the buildings have large wall and roof windows. The indoor air temperatures in the first building achieved 39.5 ° C, which caused the heat stress for workers. The indoor air temperatures in the second building achieved only 29.5 °C. The calculated power demand for the air cooling to reduce the indoor temperature to 25 °C is 25 . 6 kW in the first building, the cooling p ower for second building is 14 . 9 kW. We investigated measured construction of the workshop and we set up the formula in order to calculate thermal balance. The measurement results and calculated results in two buildings are compared and summarized in the t ables and in the graphs for analysis. As a general conclusion, it must be said that solar radiation has a big influence on the air temperature and methods of passive air - conditioning should be more applied also on the production buildings in industry, agri culture and other branches of civil engineering to release heat increasing air temperature inside the building.
Application of conversion model for designing hydrodynamic pumps in turbine mode
(2018) Polák, M.
The use of the smallest water resources has been coming again to the centre of interest in recent years. A water engine – turbine, is the heart of these power plants. This is usually the highest expense for the investor, in terms of cost. The effort is therefore to seek investment less demanding alternatives. One of them is the use of hydrodynamic pumps in reverse turbine operation. This paper provides a methodology for conversion of parameters of the smallest power pumps (micro hydro sites) to turbine operation. The conversion model is based on the results of experimental research at the author's workplace and is suitable for pumps with low specific speeds and outputs. The pump design process for turbine mode is complemented by a practical example for a specific deployment site. This example also serves to verify the accuracy of the conversion model.
The impact of the termination technology of agro-ecological service crops on soil properties in open field vegetable production
(2018) Tamm, Kalvi; Bender, Ingrid; Nugis, Edvin; Edesi, Liina; Võsa, Taavi
The agro - ecological service crops (ASC) are introduced in the agro - ecosystems to provide or enhance ecological services, thus promoting the whole soil - plant system equilibrium. To avoid competition with the subsequent cash crops, the growth of the interposed ASC is terminated in advance of the cash crop planting. The traditional, most widespread technique to terminate the ASC is incorporation as green manure into the soil by tillage (GM). However, since tillage includes energy and labour consuming and soil dis turbing operations, the use of no/reduced tillage techniques (as the roller crimping technology - RC) has received increasing interest. An international research consortium (SOILVEG) including Estonian Crop Research Institute, was established in 2015 with th e aim to study among others the impact of ASC termination on soil dry bulk density (BD), water content, soil structure and microbiological activity. Data are collected from Estonian tri als in 2016 and 2017 at Jõgeva. The physical properties of 0 – 40 cm soil layers were determined. Higher BD in soil layers (0 – 20 cm) of plots with ASC and RC was determined comparing to the GM and control plots. Bigger water content in same layer of plots with ASC and the RC was determined comparing to the GM plots. The use of the ASC - s helped to arise ratio of agronomically preferred soil particles. Microbial activity was estimated by assessing of enzyme dehydrogenase activity in 0 – 20 cm soil layer. There were no statistically relevant differences in soil dehydrogenase activit y (DHA) be tween the RC and GM treatments.
Field trajectories proposals as a tool for increasing work efficiency and sustainable land management
(2018) Kroulik, M.; Hula, J.; Brant, V.
Together with the requirement for higher productivity the average performance and the weight of agricultural machines are increasing. Agricultural land is increasingly exposed to pressures caused by agricultural machinery. The heavy agricultural machinery passes across a field are frequently associated with technogenic soil compaction. Soil compaction is one of the main problems of modern agriculture. From the previous measuring of the traffic intensity it was found 86.13 % of the total field area was run - o ver with a machine at least once a year, when using conventional tillage and 63.75 % of the total field area was run - over when using direct seeding technology, with dependence on the working width of the machines. Field passes are inevitable in present agri culture. As a result of the increase of total machines weight, it is necessary to optimize the traffic lines trajectories and limit the entries of the machines in the field. At present, the choice of traffic lines direction is based primarily on the experi ence of drivers or the practice of farmers. There are a number of influences that affect the machine work efficiency. Monitoring of the tractor, on an irregular 8 fields showed the following results. Eight - meter working width tiller or seeder brought short ening of total length of turns at headlands with the change in trajectory azimuth. For purposes of measuring the monitored tractors were equipped with monitoring units ITineris. An overview of the chosen directions of the trajectories and the lengths of wo rking and non - working passes was obtained. Based on the shape of the plot, the trajectory of the lines was also modelled. Suitable traffic lines directions in terms of the ratio of work and non - work passes were searched. Based on records of real trajectori es, the ratio of working and non - working path ranged between 6.3 and 15.2%. It was obvious from the results that the shortening of non - working passes and turns in comparison with the originally chosen trajectory directions was achieved by optimization. Thi s was especially valid for complex shapes of fields. Trajectory optimization leads to a reduction of total le n g th of path in all cases. The reduction in total length of path ranged from 69.7 m to 1 , 004.8 m. Changing the length of the working path ranged fr om 10.9 m to 264.9 m with the change in azimuth. The extension was observed in three cases. The highest part on the change of the overall length of the path presented nonworking rides.
Human factors and ergonomics in safety management in healthcare: building new relationships
(2018) Sepp, Jaana; Reinhold, Karin; Järvis, Marina; Tint, Piia
Human factors are playing an essential role in ensuring occupational health and safety at work. In the healthcare sector, relevant factors include optimizing the interaction of humans with their technical, social working environment, and human characteristics such as knowledge and motivation. Those fac tors affect the ability to provide good quality of healthcare and safety performance. The aim of this paper is to analyse factors related to safety knowledge, communication and professional competence among caregivers in nursing homes. A group of professio nals studied (n = 241, includes nurses and caregivers) completed a validated questionnaire. Descriptive statistics and correlation analyses were applied, using SPSS Statistics 24. Our study revealed that over half of the respondents possess an occupational certificate and the majority of employers organize regular in - service training at workplaces. Respondents who claimed that in - service trainings are not regular still stated that they generally receive safety and ergonomic related trainings, trainings for working with special equipment. However, only a quarter of responden ts have access to occupational safety trainings that f ocus on specific risks at work. Based on the results of the study, we emphasize the need of integrating human factors in the safety ma nagement system in nursing homes with a special focus on adequate safety training in order to develop necessary skills and knowledge of workers. This would enhance employees’ ability to cope successfully with the elderly and people with special needs, to p rovide safe and high - quality care as well as confidence and the knowledge how successfully they manage conflicts in order to ke ep good relationships at work.
Importance of microclimate conditions and CO 2 control in educational buildings: a case study
(2018) Merisalu, Eda; Mugur, Danel; Kic, P.; Estonian University of Life Sciences. Institute of Technology
Current efforts to minimize energy losses and maximize energy savings for heating of all houses are most often gained by insulating facades and replacing windows. However, these measures can have a significant negative impact on human health and these problems can occur in buildings with a high concentration of people, such as school buildings. The aim of this paper is to analyse the results of measurements of air temperature, relative air humidity and carbon dioxide in winter period in the classrooms of two universities, Estonian University of Life Sciences (EULS) in Tartu and Czech University of Life Sciences (CULS) in Prague. The measurements have carried out in 2017  2018 in eight classrooms of the EULS and two classr ooms of the CULS. The external and internal temperature, relative humidity and concentration of carbon dioxide have measured in the classrooms during a few days in the winter period. In the lecture rooms of CULS, when the air conditioning was off, the leve ls of CO 2 exceeded the recommended levels about two times. The average internal temperature and CO 2 concentrations in the classrooms of EULS follows the norms and refers on good ventilation. The extremely low relative humidity in the classrooms of EULS at 17.1 ± 2.6% refers to a high risk of allostatic load and respiratory symptoms among students. It is important to pay attention on regular ventilation and relative air humidity control in the teaching rooms, especially with high number of students to preven t seasonal sickness of upper respiratory tract.
Fodder beans and peas in the diet of dairy cows
(2018) Trūpa, A.; Ošmane, B.; Konošonoka, I.H.
The Holstein - Friesian Black - and - White cows were grouped into four treatments groups according to the analogue principle (n = 4 × 5). Lactating dairy cows were included in the trial in the initial lactation phase with the average milk yield of 23.00 kg per day, fat content 4.10% and 3.20% protein content in milk. The analyses of the chemical composition of legume grains show, that crude protein and undegraded intake protein (UIP) were higher in fodder beans than in peas, respectively 29.97% and 25.04% of dry matter but UIP content, respectively 40.51% and 39.69% of crude protein. There was a total of 17 amino acids detected in legume grains and soybean meal. The highest concentration of arginine, leucine, glutamic acid, aspartic acid and isoleucine was in fod der beans, respectively 0.76%, 0.58%, 0.67%, 0.42% and 0.29% more than in peas. Even though the daily milk yields decreased for all the cow groups during the experiment, which was normal during the lactation period, yet the milk yield decreases for the tri al groups. The highest total amount of amino acids in milk was detected in 3 rd and 2 nd trial cow groups, respectively, 4.00 g kg - 1 and 3.90 g kg - 1 which was fed fodder beans and peas. The milk sale and feed cost summary records for the trial that lasted 90 days show that economic efficency of peas plus beans has been positive.
Agronomic evaluation of a Colombian passion fruit (Passiflora edulis Sims) germplasm collection
(2018) Galeano Mendoza, C.H.; Cerón-Souza, I.; Arango, L.V.
Passion fruit (Passiflora edulis Sims) is one of the most promissory crops in Colombia with approximately 7,400 ha cultivated, an average production of 89,000 t and an average yield of 15 t ha-1. However, low yields as well as harvest problems including fruit quality, generate important losses, mainly due to lack of improved cultivars with particular characteristics for each market (fresh consumption, agroindustry) and specific adaptations to biotic and abiotic stress factors in producer areas. Therefore, as a pre-breeding phase, this study aimed at characterizing preliminary the production and physiochemical characteristics of 60 passion fruit germplasm accessions maintained in Corporación Colombiana de Investigación Agropecuaria (AGROSAVIA). We cultivated these accessions in the field for 22 months between 2014 and 2015, measuring 17 variables associated to both yield production and fruit quality. We analysed data using phenetic and multivariate methods to establish levels of genetic diversity. Additionally, we constructed a selection index (SI) with the most informative variables to select individuals according to fruit weight, shape and colour, as well as juice percentage. Results of genetic grouping and principal components showed a broad genetic diversity across the working collection, without any population substructure. Fruit volume, pulp and seed weight were the variables that explained 80% of the phenotypic variation. Finally, we identified 30 promissory accessions as parental for the first cycle of recurrent selection using the SI. We conclude that this core collection represents the diversity included in the working collection with promissory accessions to initiate an intra-population recurrent selection program.
Biostability of cotton fibers with different natural colors and selection
(2018) Kotomenkova, O.; Vinogradova, A.
Biodamageability is one of the weak sides of the cotton - plant fiber. Economic loss from the cotton damage caused by microorganisms is significant. Toxic chemical compounds are used to preserve the cotton fiber. This has a negative impact on environment and cotton consumer s. The degree of the cotton biodamage depends on selection variety, types of cultivation, storage conditions and other factors. One of the directions in cotton planting is selection of the boll - stained cotton. It was established that naturally colored cott on of different varieties has high biostability. It allows to product hypoallergenic, eco - friendly textile and reduces impact on the environment. The purpose of the work is stability evaluation for microbiological damage of different cotton varieties inclu ding those naturally colored during long - term storage in different temperature and humidity conditions. The research lasted for 10 years. The species composition of the cotton microflora was determined, the impact of fiber on microorganisms and dynamics of samples biodamage was studied in the work. The results obtained show preservation of microflora viability on cotton fiber when storing it under normal conditions for a long - term period. With an increase in temperature and humidity necessary for microorgan isms’ growth, the fiber destruction processes are amplified. It was established that cotton damage degree depends on the regimes and terms of its storage as well as the color of the fiber. Nature - colored cotton is more resistant for microorganisms, some va rieties inhibit the growth of mold fungi.
Ergonomic modelling parameters and the influence of ergonomics on planning workplaces
(2018) Maksimov, D.G.; Kalkis, H.
Modern economic research divides all economics into structural levels: mega - economics, macroeconomics, meso - economics, micro - economics, and nano - economics. From the point of such traditional divisions, the research is topical in the primary economic struct ure of society – nano - economics – and thanks to this work operations can be subdivided into workplaces in the form of transformation processes. The aim of the research is to develop ergonomic modelling parameters and to discover the influence of ergonomics on the planning of workplaces ba sed on a case study. The research involved a study of workplace ergonomic planning methods and principles. Solutions for a series of problems which are related to the improvement of workplace ergonomics may be discovered in the following ways: improving wo rk organisation in every workplace by using work process - related micro - elemental methods and a determination of work expenditure, the levels of physical strenuousness involved in the work, the complexity of the work, and the social importance of the workpl ace. These parameters will allow the workplace quantity characteristics to be discovered, such as in terms of a generalised parameter which conforms to the requirements which describe a workplace, and in terms of operational management via the condition of workplaces and the salary systems being utilised. The research provides a case study in which ergonomic modelling parameters are developed and concrete workplace interventions are introduced.
POST herbicide programme for effective weed control in winter wheat (Triticum aestivum L.)
(2018) Pacanoski, Z.; Mehmeti, A.
Field experiments were conducted during two winter wheat - growing seasons to evaluate the efficacy of some new POST herbicides and herbicide combinations for those effective controls of weeds in winter wheat crops in the Republic of Macedonia. The weed population consisted mainly of annua l winter and spring and some perennial weeds. Weediness comprised 116 and 208 plants m - 2 in 2012 – 2013 and 2013 – 2014, respectively, in the Skopje region, and 93 and 114 plants m - 2 in 2012 – 2013 and 2013 – 2014, respectively, in the Probištip region. All POST h erbicides effectively reduced dominant weeds density ( > 93%) in the Skopje region in both years, as well as in the Probištip region in 2012 – 2013, but not in 2013 – 2014. In this year, lower temperature directly following application decreased efficacy of POS T applied herbicides, which provided control of Lolium perenne that was between 76 and 84%; control of A. ludoviciana was less than 85%; control of B. radians was no more than 83% and no one treatment controlled P. convolvulus more than 82%. Wheat yields i n the Skopje region were not significant among years for the different POST herbicide applications and ranged between 3,580 and 3,720 kg ha - 1 in 2012 – 2013, and between 3,760 and 3,910 kg ha - 1 in 2013 – 2014. A significant treatment by year interaction resulted in two distinct years for wheat yields in the Probištip region with POST herbicides. In 2012 – 2013, wheat yields were between 3,230 and 3,390 kg ha - 1 , but in 2013 – 2014, wheat yields ranged from 3,060 to 3,4 90 kg ha - 1 and weed - free control showed a significant higher wheat yield compared to all evaluated herbicides.
Study of effect of arbuscular mycorrhiza (Glomus intraradices) fungus on wheat under nickel stress
(2018) Heydarian, A.; Tohidi Moghadam, H.R.; Donath, T.W.; Sohrabi, M.
In many regions of the world soils are contaminated with heavy metals and therefore restricted in their use. For instance, the absorption of nickel (Ni) in the tissue of plants increase the plant’s metabolism and cause physiological disorders or even death. Arbuscular mycorrhizal fungi are known to enhance the tolerance of host plants to abiotic and biotic stress. Thus, we investigated the potential of the arbuscular m ycorrhizal fungi Glomus intraradices to mitigate deleterious effects of Ni in wheat. The experiment was conducted using four levels of Ni (0, 60, 120 and 180 mg per kg of soil) and two levels of mycorrhizal fungi application (with and without Glomus intrar adices ). Nickel stress significantly decreased seed number per spike, thousand - seed weight, seed yield per plant, concentration of chlorophyll a and b. At the same time, we found increased catalase (CAT) enzyme activity and dityrosine (DT) treatments. Mycorrhizal fungi application attenuated Ni effects, i.e. fungal presence increased seed number per spike, thousand - seed weight, chlorophyll a and b. Furthermore mycorrhizal fungi application reduce CAT enzyme activity and DT. In general, our results sugge st that mycorrhizal fungi application reduces harmful effects of Ni stress in wheat.

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