Counteracting the negative effects of drought in vegetal production should include drought monitoring, determination of drought tolerance and, thus, the assessment of risk, limitations and losses of yield for various species of cultivated plants. The aim of the work was to assess temporal and spatial variability of the occurrence of atmospheric drought in Poland and to determine the risk of cultivation of pickling cucumber caused by this phenomenon. To carry out the task, starting data concerning the marketable and total yield of cucumber, durations of cucumber development stages and also daily atmospheric precipitation totals, collected respectively from 28 experimental stations and 51 meteorological stations through 1966-2005, were used. Atmospheric drought of different intensity: moderate, severe and extreme, in four analysed cucumber development stages was determined on the basis of the standard precipitation index. On the other hand, relationship between cucumber yield and precipitation deficiency in the period of the highest demand for water was determined by means of curvilinear regression analysis. In Poland, drought occurred mostly in the central-western part of the country. In this area, an average decrease in the cucumber total yield amounted to over 12% every 2-3 years, and the marketable yield over 15% every 2 years. The results obtained in the present work can be used in the research concerning the assessment of drought influence on growth, development and crop productivity of other cultivated plants.Additional key words: cultivation risk; regression analysis; standard precipitation index; vegetable. ResumenDiversidad temporal y espacial de la incidencia de la sequía atmosférica en Polonia (1966-2005) y su efecto sobre la producción de pepino encurtido (Cucumis sativus L.)Para contrarrestar los efectos negativos de la sequía en la producción de las plantas se debe incluir una vigilancia de la sequía, determinando la tolerancia a la sequía y evaluando riesgos, limitaciones y pérdidas de producción de las plantas cultivadas. El objetivo de este trabajo fue evaluar la variabilidad espacial y temporal de la ocurrencia de la sequía atmosférica en Polonia y determinar el riesgo existente en el cultivo de pepino encurtido causado por este fenó-meno. Se utilizaron datos de producción comercial y total de pepino, y de precipitación atmosférica diaria, recogidos de 28 estaciones experimentales y 51 meteorológicas, respectivamente, entre 1966 y 2005. Se determinó, sobre la base del índice de precipitación estándar, una sequía atmosférica de diferentes intensidades: moderada, severa y extrema, en cuatro etapas de desarrollo del pepino analizadas. Por otro lado, se determinó la relación existente entre la producción de pepino y la deficiencia de las precipitaciones, en el período de más alta demanda de agua, mediante un análisis de regresión curvilínea. Se observó que la sequía se concentró en la parte centro-occidental del país; en este área, la disminución media en la producción total de pepino fue de...

Abstract:The recognition of changes in the course of agricultural thermal periods is vital when it comes to determining appropriate measures for adapting agriculture to climate change. The present study examined changes in air temperature between 1951 and 2014 in the area of south-western Poland. A statistically significant, positive linear trend was confirmed for the annual average temperature, seasonal averages, and monthly averages in the periods spanning February-May and July-August. From the beginning of the 21st century, the period of winter dormancy of plants started increasingly later; farming and plant vegetation periods started increasingly earlier, and the period of active plant growth was prolonged. Among the considered agricultural periods, the growing season was the most prolonged. The duration of the farming period was also significantly longer, but the winter dormancy period was shortened. The negative linear trend of days when the temperature stood at <0 • C was statistically confirmed for temperature in the entire region and most of the stations. In terms of predicting the consequences of the changes that were observed today over the next decades, this is not an easy task. However, the nature of these changes suggests that further cultivation of winter crops may require far-reaching adaptation measures.

ABSTRACT:The aim of the work was to determine whether and how the frequently observed trends in air temperature changes affect the dates of phenophases of field cucumber (pickling variety) cultivated in Poland. Completion of the task included gathering of monthly and seasonal data concerning average air temperature in the vegetation season of cucumber collected from 53 stations of the Institute of Meteorology and Water Management and of phenological and agrotechnical dates collected from 28 experimental stations of the Research Centre for Cultivar Testing over 1966-2005 all over Poland. Dependence between the dates of phenological phases and average air temperature, their trend and the size of the changes for the 40-year research period of 1966-2005 were determined on the basis of a linear regression analysis. Moreover, the generalized cluster analysis was employed to group years, similar in terms of the course of cucumber phenophases: emergence, flowering and fruit setting, together with thermal conditions of air in the period preceding their occurrence. If the current tendencies hold slight acceleration of phenophases: emergence (+1.2 days/10 years), flowering (+1.9 days/10 years), fruit setting (+2.1 days/10 years) and growing acceleration of the dates of harvesting (the beginning by +3.1 days/10 years, and the end by +6.4 days/10 years), it leads to the shortening of the fructification period and it may thus deteriorate conditions for achieving good cucumber yields in Poland.

Our aim was to determine relationships between the tropospheric ozone concentration and the nitrogen dioxide concentration, selected meteorological factors and radiation-effective temperature in the suburban area of the city of Wroclaw. Hourly data from 2006-2011 used in the study included concentrations of tropospheric ozone, nitrogen dioxide concentrations, air temperature, air humidity, wind velocity and total irradiance of the sun. Radiation-effective temperature (TRE) was determined on the basis of the four meteorological elements. Concentrations of ozone in southwest Poland show annual, seasonal and daily variation. The highest values occur in the warmest time of the year and day, while the lowest ones are noted in the cold season of the year, in October and in the morning. The variation of ozone concentrations was found to be shaped by changes in nitrogen dioxide concentrations, meteorological elements and the bioclimatic indicator. Ozone and nitrogen dioxide were mutually most strongly correlated in the winter season. In the warm season of the year, from April to October, the ozone concentration was mainly shaped by air temperature, solar radiation, wind velocity and TRE (positive effects), and by relative humidity of the air (a negative influence). The multiple regression equation best described the ozone concentration variation in May. Increased concentrations of ozone were found to appear during thermal stress, expressed as a sensation of warmth/heat, but could also occur under thermal comfort conditions.

Changes in annual tree ring width (TRW) and its size depends not only on the changing climate and natural stress factors such as extreme air temperatures, shortages in rainfall and excess rainfall during the growing season, but also on anthropogenic stress, including chemical compounds emitted to the atmosphere or lowering of the groundwater table caused by the operations of plants with high environmental impact. The purpose of this article is to assess the impact of meteorological conditions and anthropogenic factors on the size of annual growth of Scots pine tree-stands in the conditions of the climate of central-eastern Poland. On the basis of five created site chronologies in the vicinity of Zakłady Azotowe Puławy (nitrogen factories in Puławy) and using the moving correlation analysis and multiple regression analysis, a significant influence of temperature and precipitation conditions on the TRW size is proved. A significant, positive influence of air temperature on TRW was proved for the majority of chronologies created in the period of January–March, as well as in June, while it remained negative in May. The wide rings of Scots pines were formed when the precipitation of October and January (prior to the resumption of cambium activity) was lower than the average, and higher in April and in June–August. After including the anthropopressure factors in the regression equations, the description of the variability of the annual tree ring width was corrected. The coefficient of determination ranged from approx. 29% to even above 45% and was higher, on average by 10%, for all studied chronologies of Scots pine compared to the one calculated for constructed equations considering only meteorological conditions. The strength and direction of the impact of the independent variables (SO2, NH3, NOx) analysed on TRW mainly depended on the distance from the plants, as well as on the direction of inflow of industrial pollution to the stands examined. In light of the proven climate changes in central and eastern Poland, the growth conditions of pine stands will most likely deteriorate.

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The onion is the most common vegetable cultivated in Poland and yield is marked by high year to year variability. The yield quantity is predominantly affected by variable meteorological conditions, especially by precipitation deficiency. Data were collected from the Research Centre for Cultivar Testing and the Institute of Meteorology and Water Management for the period 1966-2005 to evaluate the effect of precipitation conditions on the yield of onions (Allium cepa L.) cultivated in Poland using multiple regression analysis. Verification of the curvilinear regression equation was conducted on the basis of relative forecast error and average relative forecast error. For this equation the ARFE amounted to 9.6%. The threshold precipitation value, i.e. the value at which reduction by at least 5% of the total yield occurs, was determined by curvilinear regression. Reduction of potential yield caused by precipitation deficiency and the frequency of precipitation deficiency were determined. Reductions of at least 5% in the average domestic onion yield in Poland occurred when atmospheric precipitation was ? 183 mm. This level of precipitation constituted 87% of the norm and took place in the period between the end of emergence to the beginning of leaf bending. Potential reduction in onion yield in Poland caused by precipitation deficiency in this period varied between 9 and 18%. In Poland, the frequency of atmospheric precipitation deficiency between 1966 to 2005 varied from 10% in the south-east to 50% in the central west and north west. The average frequency of atmospheric precipitation deficiency amounted to about 37%.

The differences in plant phenology between rural and urban areas are the subject of research conducted all over the world. There are few studies aimed at assessing the impact of the urban heat island on plant vegetation only in urban areas. The aim of this study is to assess the impact of the distance from the city center and the form of land cover on the phenological development of trees using the example of the horse chestnut (Aesculus hippocastanum L.). The research area covered the entire city of Wrocław. In order to best capture the impact of the distance from the city center on the rate of changes of individual phenophases, 3 areas were designated—at a distance of 1 km, 2 km and 5 km. The study assessed the average duration of individual phenological phases along with the variability characteristics for leafing, flowering and fruiting in relation to the designated zones and classified forms of land cover based on mean value (x¯) and standard deviation (±SD) in individual weeks of the year. For the leafing and flowering phases, the frequency of the occurrence of phases in individual weeks of the year was analyzed in relation to the designated zones and classified land use methods. The results obtained on the basis of phenological observations carried out in 2017 in Wrocław confirmed the extension of the period of vegetation in the city center in relation to its peripheries. Trees growing in road lanes entered the vegetation period later and defoliated faster, which confirms the negative impact of street conditions on the development of trees in urban space. Thus, the growing season in road lanes is shorter and due to the 1-year observation period, it is justified to conduct further observations.