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The reaction of addition lines, 1B/1R substitution line and initial forms: wheat, rye, octoploid triticale to the treatment with gibberellic acid (GA3) was estimated. The gibberellic test was performed in a vegetation chamber under controlled conditions. Seedlings were watered with gibberellic acid solution, at 50mg/g concentration, during 18 days, then the seedlings and coleoptyles were measured. The tested lines differed from each other and in comparison with wheat with regard to the reaction to GA3. The longest seedling and coleoptile were stated for the 2R addition line. On the ground of received results it was found that genes controlling the metabolism connected with utilization of gibberellins are situated on the 2R chromosome of rye cv. Dańkowskie Złote.

The aim of the study was to determine productivity of hybrid winter rye under low sowing densities. The experiment was conducted on soil classified as a very good rye type. Four sowing densities (100, 150, 200 and 250 grain/m2) were tested on background of different nitrogen doses (0–160 kg N×ha-1). The lowest density (100 grain/m2 ) resulted in the grain yield reaching 5.5 t×ha-1. Increase of sowing density influenced yield weakly, below 0,5 t×ha-1. Interaction between sowing density and nitrogen fertilization was not confirmed. The highest yield was obtained at 120 kg N×ha-1.

A short characteristics concerned preharvest sprouting, frost resistance and yield structure traits of six winter triticale strains developed by H. Grzesik in Plant Breeding and Acclimatization Institute, Department of Cereals in KrakĂłw, is reported. The obtained strains were resistant to preharvest sprouting for 5–6 years of tests, so they may be considered as a sources of this trait in further breeding work to developed a new winter triticale varieties resistant to preharvest sprouting.

The effects of sowing time, sowing density and nitrogen fertilization on grain yield and its components were tested for new winter triticale varieties in a pot experiment conducted in the years 1999-2001. The investigated forms showed different requirements in regard to all the experimental factors.

An experiment with crop rotation systems for spring triticale was conducted at the Agricultural Experimental Station of Uhrusk in 1998–2001. Four crop rotations with varying proportion of spring triticale (25, 50, 75, 100%) and two plant care systems: a — basic (harrowing) and b – intensive (harrowing, herbicides, fungicides) were evaluated. The grain yield of Migo spring triticale, was affected by weather conditions during growing seasons, by the rotation systems and by plant care. Spring triticale cultivation in monoculture  caused decreased of grain yield by 38,4% in relation to the crop rotation A (25% of triticale). An application of pesticides increased the grain yield by 5,2% in comparison to non-treated ones treatment.

The effect of the laser light on seeds sowing value and yield of Rataj and Klimek  barley cultivars was examined. Seeds were exposed to He-Ne laser light with the wave length of 632.8 nm and the power of 4 mW/cm2. Laboratory and field experiments were conducted using control seeds and seeds irradiated with tree (doses: double, fourfold and sixfold) of laser light. Before sowing, standard germination, seed health and seedling vigour were determined. After harvest the sowing value and chemical composition of seeds derived from plants grown from biostimulated and non-biostimulated seeds were assessed. In the field experiments the following parameters were determined: the seed yield and its structure plants/m2, height of plants, ear length, number of the kernels in the ear and thousand seeds weight. Pre-sowing biostimulation of seeds of both cultivars favourably affected the yield, and fourfold and six fold doses of irradiation caused significant yield increase of Klimek cultivar. Pre-sowing seed treatment with laser light influenced yield structure. The stimulating effect of laser on height of plants and thousand seeds weight (cv. Klimek)was noticed. Field emergence of irradiated seeds depended on the cultivar, irradiation dose and weather conditions in the year of harvest. There were no differences in germination capacity of seeds irradiated with different doses. However germination capacity of seeds harvested from plants grown from biostimulated seeds was higher than from non-irradiated. Viability of seeds that were exposed to laser light was lower. Seedlings grown from irradiated seeds cumulated less dry weight than that from control seeds. In both cultivars the accelerated ageing test showed the percentage increase of vigorous seeds and germinating seeds (cv. Rataj) after laser irradiation. Growth test showed that double dose influenced favourably growth of plumula, and all doses of irradiation did not modify the length of root. Tetrazolium tests showed, that irradiated barley seeds lowered their vigour. The highest six fold dose tend to limit the occurrence of pathogens in seeds of Klimek cultivar. Pre-sowing seeds irradiation did not affect the protein and starch content, but increased the fibre content in seeds of cv. Rataj.

An experiment with forecrops for spring barley was conducted at the Agricultural Experimental of Uhrusk in 1998–2000. The experiment consists of five forecrops for spring barley: pea, potato, spring barley (1x), spring barley (2x), spring barley (3x), and two plant care systems: basic (spring harrowing) and intensive (spring harrowing, herbicides, fungicides). The yield of spring barley was significantly higher in rotation after pea and potatoes composing to monoculture spring barley (3x). Spring barley sown 2x and 3x after itself showed significant increase of plants infections by Gaeumannomyces graminis and Pseudocercosporella herpotrichoidesas well as increase of number and mass of weed. Pesticides increased the grain yield of barley about 6,6%, in comparison to minimalized care.

The study concerned variability and phenotypic/genotypic correlations between the important useful traits in oat, basing on field experiments with strains and varieties. The investigation was carried out in the years 1996–2000, in 5 localities. The traits under study were following: grain yield per plot, plant height, date of heading, resistance to crown rust, resistance to powdery mildew, lodging, hull content, 1000 grain weight. The investigation confirmed a small regress in yield of new strains of oat in the years 1996–2000. On the contrary, the progress was observed in resistance to crown rust and shortening of straw, which resulted in higher resistance to lodging. The highest variability was stated for resistance to crown rust (CV = 24,9–43,2%). The , resistance to crown rust (0,77–0,89) and heading date (0,82–0,97) showed high and constant heritability in all years of the study except for 1999. A highly significant positive coefficients of phenotypic and genotypic correlation were observed between grain yield per plot and resistance to crown rust (rP = 0,66 to 0.77, rG = 0.81 to 0.98) and, on the contrary, the correlations between grain yield and % of hull were negative (rP = -0,37 to -0,42; rG = -0,80 to -0,93). Furthermore, negative correlations were found between plant height and lodging resistance hull content and date of heading. The analyses have shown that unfavourable correlations between studied traits have not been overcome yet.

Germination of seven Polish soybean cultivars was analysed in laboratory conditions. The varieties (Aldana, Jutro, Polan, Progres, Mazowia, Gaj, Nawiko) were tested at the water potentials 0,0; -0,20; -0,40; -0,65 and -0,90 MPa, developed by polyethylene glycol (PEG-8000). Besides, growth of the soybean cultivars was examined in the Hoagland's solution at the water potential -0,5 Mpa, obtained by addition of PEG. The received results showed, that decline of water potential in a solution significantly reduced the number of germinated seeds, the speed of their germination as well as mass increment of shoot. Proper germination of soybean seeds was possible at water potential from 0,0 to -0,4 MPa. Low water potential in the nutrient medium slowed down also the growth of soybean stem, as well as increment of fresh and dry mass in shoots and roots of plants. However, conditions of simulated drought influenced to a greater extent the germination of seeds than the growth of plants. According to the results on germination and seedling growth Nawiko, Mazowia and Progres showed high level of  drought resistance. The Gaj cultivar was out to be the least resistant.

The purpose of this study was to analyze the spatial distribution and yielding of red fescue seed crops in the period 1991–2000, and to determine the suitability of regions for seed production. The interpolate lines were drown on the map, using „a posteriori” method, and four regions with different suitability for seed production were outlined. The most suitable for seed production appeared to be region I than suitable region II both localized in the central part of Poland. Region IV submountain as well north and northeaster parts of Poland are of the lowest suitability. The relationships between 12 anthropological and anthropogenic factors which may influence the seed crop, were estimated. Cultivated area was negatively correlated with relative soil quality estimate index and rainfall but positively with air temperature. Significant, positive correlation coefficients were obtained also for anthropogenic factors (agriculture level, species cultivation tradition, levels seed production organization).

Leaf spot and melting out caused by Drechslera poae (Baudys) Shoemaker is one of the most destructive disease on Kentucky bluegrass. Kentucky bluegrass (Poa pratensis L.) is one of the primary perennial turfgrass species throughout the world. The pathogen occurs throughout the major Kentucky bluegrass growing regions, e. g. in Poland. Therefore, in this review taxonomy, biology and economic importance of D. poae were presented.

Leaf spot and melting out resistance caused by Drechslera poae (Baudys) Shoemaker is crucial for commercial value of new cultivars of Kentucky bluegrass and breeding for resistance against this disease is a major goal of most breeding programs. Therefore, breeding for resistance, as much more ecological approach to control leaf spot and melting out in comparison to fungicide application, was described in this review. Importance of ecotypes as a sources of resistance and several screening methods under greenhouse and field conditions were presented.

Two terms of harvesting the first cut (1— bud-froming, 2 — full flowering), three phosphorus and potassium fertilization levels (70 kg P2O5 and 70 kg K2O; 105 kg P2O5 and 105 kg K2O; 140 kg P2O5 and 140 kg K2O per 1 ha) as well as four microelements fertilization levels (0; B — 2 kg; Mo — 0,5 kg; B — 2 kg + Mo — 0,5 kg per 1 ha) were taken into account during investigation on tetraploid red clover (Ulka variety). The field experiment was carried out in 1993–1996 with the use of split-split-plot method on a soil classified as a good wheat type. The yields of tetraploid red clover seed were determined  mainly by weather conditions during plants flowering and ripering, which significantly differentiated the basic elements of yield structure. The significantly higher seed yield from the second cut was attained when the first cut was harvested for forage most early —at bud-forming. The applied fertilization levels of macroelements (P, K) did not influence significantly the seed yields. The separate application of boron as well as joint fertilization with boron and molybdenum significantly increased seed yields in relation to the control object. The number of heads per 1 m2 and weight of 1000 seeds were significantly higher. The weight of 1000 seeds and number of seeds per fruit head were the most important components of the seed yield structure.

The effect of laser light on the seed yield and elements of yield structure, as well as on the sowing value of amaranth seeds, cultivar Rawa, was studied in 1998–2000. Before sowing, seeds were biostimulated with red laser light (He-Ne), of 632,8 nm wave length and the power of 4 mW/cm2. Three irradiations variants double, fourfold and sixfold and control were evaluated. In the laboratory tests, before sowing, seed germination was determined, and after harvest — seed germination and protein content. In the field experiments the following parameters were determined: field emergence, seed yield and its structure (plant height, weight of green mass and weight of thousand seeds). All variants of pre-sowing irradiation of amaranth seeds favourably influenced the seed yield. The highest yield was obtained after sixfold dose, lower yield after double dose, and the lowest after fourfold dose of laser energy. The height of plants grown from irradiated seeds and weight of green mass/plant did not differ in comparison to control, but these traits were influenced by weather conditions. Pre-sowing biostimulation of amaranth seed influenced field emergence, weight of thousand seeds and protein content in seeds harvested from plants grown from irradiated seeds.

The effect of He-Ne laser irradiation on seed sowing value and on the fruit yield of Betalux and Promyk tomato cultivars and cucumber cv. Polan F1, was examined. Before sowing, seeds were exposed to He-Ne laser light, with the wave length of 632.8 nm and the power of 4 mW/cm2. Four variants were evaluated: control-without biostimulation and three irradiation doses (double, fourfold and sixfold). In the laboratory, before sowing, standard germination and seed and seedling vigour were determined. In the field the following parameters were evaluated: emergence (cucumber), fruit yield, fruit number and weight of the individual fruit. Biostimulation of seeds of cv. Promyk with double dose of energy resulted in the highest yield and weight fruit. The remaining doses caused non significant increased the fruit yield. The highest weight of the individual fruit was obtained from plants originated from seeds sixfold irradiated. Irradiation of seeds of Betalux tomato cultivar did not influence significantly the fruit yield, fruit number and weight. Pre-sowing irradiation of cucumber seed with higher doses of energy stimulated field emergence, and all applied doses of laser light treatment caused increase the fruit yield of cucumber. Higher yield resulted from significantly higher number of harvested fruits with slightly lower in individual fruit weight. Germination capacity of seeds of both tomato cultivars was differentiated dependently on irradiation dose, but germination of cucumber seed did not change in comparison to control. Growth test showed significant impact of laser energy on length of hypocotyl and primary root produced by tomato and cucumber seeds. Seedlings of tomato and cucumber grown from stimulated seeds cumulated more dry weight than those from control seeds. Irradiation treatment of tomato and cucumber seeds did not influenced seed vigour assessed by the conductivity test. Pre-sowing irradiation caused the increase of percentage of normal seedling only in case of tomato, cv. Betalux in the accelerated ageing test.

Physiological age of tubers of eleven potato cultivars: Albina, Baszta, Bila, Dunajec, Glada, Hinga, Ikar, Irga, Oda, Sumak and Vistula was regulated in a way of pre-sprouting to create five treatments. The significant influence of physiological age on all tested elements of plant structure and canopy architecture in the field experiment was confirmed. Tubers pre-sprouting caused the acceleration of plant phenological stages up to 16 days, particularly at early cultivar Albina and middle early cultivars Irga and Oda. At the end of May and the beginning of June the phases end of emergence on one plot and blooming on another were observed at the same time, for a given cultivar. The range of modification of remaining elements of canopy structure 60 days after planting was as follow: stems number — 136 to 172 thousand/ha, haulm mass — 18 to 28 t/ha, height of plants — 58 to 66 cm, leaf area index — 2,63 to 4,53. The highest values of all indicators of physiological plant development took place at 4 or 10 weeks of pre-sprouting of mother tubers.

The aim of the experiment was to determine the influence of physiological age of mother tubers of eleven potato cultivars with different growing period on their ability to yielding. It was regulated in a way of tubers treatment in the period from autumn to planting. Five treatments were obtained and among them two extremal: the treatment A mother tubers physiologically youngest, stored from autumn to planting at the temperature about 2° C and the treatment E mother tubers physiologically  the oldest, stored at the same time at the temperature about 18° C in darkness. The significant influence of physiological age of mother tubers on yield in three dates of harvest, at 60, 75 days after planting and at maturity and on distribution of tubers size, was confirmed. The effect of tested factor was depending on the date of harvest. Three cultivars: Albina, Irga and Oda characterized by a very slow physiological ageing in light. Strong negative influence of darkness with additional desprouting on tuber vigour in comparison to light conditions under the same temperature was observed.

The study results were based on a field experiment carried out in Parczew in the years 1993–1995 on a soil of light loamy sand composition. The experiment was designed as sub-blocks, with three replications. Sub-blocks of the first class were growth regulators: Mival — in concentration 0,05%; Moddus 250 ME — in concentration 0,2% and distilled water as control; the second class sub-blocs were made by two dates of application of the growth regulators: before planting and before flowering; the third class sub-blocs were composed of five potato cultivars: Drop (very early), Perkoz (early), Irga (middle early), Grot (middle late), Elba (late). Full manuring and uniform mineral fertilization was applied in the amounts: 100 kg N, 100 kg P2O5, 150 kg K2O and 250 dt.ha-1 farm manure. The investigation revealed a more intense darkening in the stolon part than in the apical part of a tuber. The examined varieties responded differently to the growth regulators application.

The aim of the studies, conduced in the years 1999–2000, was to determine the species composition of fungi, which occurred on potato tubers with dry  rot symptoms. Fungi were isolated from dry rotting tubers of medium-late variety Atol in autumn and in spring of each storage season. The fungi of Fusarium genus were detected more frequently in spring. Fusarium sulphureum and F. coeruleum were the dominant species among those isolated from the potato tubers with dry rot symptoms.

The data on level of virus resistance, reaction to virus infection and agronomic value of 24 potato cultivars (11 Polish and 13 foreign) registered in Poland in 2001–2002 are presented in this paper. The average level of resistance to PVY (Potato virus Y) of Polish cultivars (7.5) was higher than foreign cultivars (5.3). The major its of Polish cultivars were not infected after mechanical inoculation with PVY0 and PVYN in the greenhouse. The mean level of resistance to PLRV (Potato leafroll virus) of Polish cultivars (6.4) was higher than foreign cultivars (5.8). The resistance to PVM (Potato virus M) of Polish and foreign cultivar is low, and only Korona cv. represents high level of resistance to PVM (7) comparable to that one of Triada cv. The major its of foreign cultivars were characterized with high culinary quality. Among 13 foreign cultivars five (Asterix, Cycloon, Delikat, Innovator and Victoria) are classified as suitable for French fries processing and four (Lady Claire, Redstar, Romula and Saturna) as good chipping cultivars. Among 11 Polish cultivars two: Felka and Gracja were evaluated as good chippinig, and cultivars Dorota and Felka — as suitable for French fries processing.

An enhanced infection potential of Phytophthora infestans can be observed world wide in recent years, due to the genetic changes of the pathogen population composition and the growing infection pressure of late blight on potato crops. Some of the results of those changes are: earlier epidemics development and intensified severity of the disease, enhanced fungus pathogenicity, and changes in incidence and development of first symptoms of late blight on potato and tomato plants. The changes are connected with common appearance of the A2 mating types that result in possibility of sexual reproduction. An effect of the sexual development of the pathogen is occurrence of oospora as additional source of early infections. More composed races and forms of P. infestans resistant for some of fungicides (phenylamides) are observed in European pathogen populations.

The article is a review of the literature on different kinds of polymorphism described in isolates of Phytophthora infestans, the organism which causes an important potato disease — late blight. The article is focused on methods for revealing these kinds of polymorphism. The methods for revealing mating type, metalaxyl resistance, virulence, aggressiveness, pathogenicity, isoenzymes of peptidase and glucose-6-phosphate isomerase, restriction fragment length polymorphism of nuclear DNA (probe RG-57) and mitochondrial haplotype are described in a more detailed way. PCR-based tests for examining mating type, polymorphism inside the known DNA sequences and also RAPD markers are mentioned as well.

The purpose of various forecasting and monitoring systems using in the late blight control strategy is to define precisely the disease appearance and undertake decision about dates of recommended fungicide applications during the season. All the running in Europe systems needs basic meteorological data (air temperature, relative humidity, precipitation) and implementation of basic biological data (variety and variety resistance against late blight, crop emergence, end of season). Results of trials carried out at commercial fields in 2001 have confirmed usefulness of the NegFry system for potato field protection against late blight under Polish weather conditions. By using the NegFry system, number of fungicide applications could be reduced for 1–2, compared to intensive, routine protection. In spite of decreasing the number of sprays, significant inhibition of disease development and good control effectiveness were observed.

The aim of this work was to define the subsequent influence of different storage conditions of seed potatoes on tuber yield of 54 potato cultivars. Seed tubers were stored at the temperatures of 2°, 6°, 10° C and RH about 90%. It was found that storage temperature modified the physiological state of mother tubers. Moreover, it was found that each cultivar required its own specific storage conditions of potatoes seed in order to obtain the optimal field growth of plant and yielding. All the cultivars were divided into the groups depending on optimum storage temperature of seed potato tubers expressed in 1–9 degree scale.

Potato seed tubers were dressed with the chemicals: Vitavax 200 FS, Monceren 12,5 DS and Monceren 250 FS 2–3 days before planting. Field trials were carried out in a randomized complete block design. Each plot of 25 m2 size was replicated four times. After harvest, 10 kg samples of tubers (from each plot) were washed and visually assessed for diseases. Tuber were scored for: black scurf (Rhizoctonia solani), common scab (Streptomyces scabies) and silver scurf (Helminthosporium solani). The results showed that all the tested chemicals were efficient in the black scurf control in the years 1999 and 2001 (statistically significant).

The purpose of the study was to determine the effects of distances between rows (62.5, 75 and 91 cm) and planting densities in a row (30 and 40 cm) on plant growth and development, viral and fungal infections and also the yields of two potato cultivars (Arkadia and Orlik), exhibiting different levels of resistance to diseases and different lengths of the growing season. The plant potatoes of the two cultivars under investigation were reproduced from the elite in 1999 until class A in 2001. The observations of growth, development and occurrence of viral and fungal diseases were carried out during the growing season. Potatoes were harvested at the stage of physiological maturity. After harvesting, the yield and its structure were determined. The results were analyzed statistically using the method of the analysis of variance. The significance of the impact of the factors under investigation were analyzed using an F test in the analysis of variance. The weather conditions in the years under investigation were different; the most favourable for plant development and yielding were those in 2001, while less favourable were the weather conditions in 1999 and 2000. Viral infections increased in subsequent years of reproduction; more infections were observed in the Orlik cultivar with narrow distances between the rows. The occurrence of potato blight was weather-dependent. The yields of potato tubers were higher with Arkadia cultivar and in 2001, but decreased with the increasing distances between the rows, due to a lower number of plants per ha. Higher planting density resulted in increased rates of planting potatoes, but lower rates of commercial potato tubers in the total yield.

The field experiment was carried out in the experimental farm Bezek near Chełm in the years 1997–2000. The field was situated on light and sandy clay soil. The phosphorus content in soil was high, that of potassium was medium, and the magnesium content was low. The soil contained 1.2% of humus. The purpose of this work was to determine influences of the conventional and ploughless tillage systems and two differentiated fertilization and plant protection levels upon potato tubers yield and its structure as well as yields of total protein starch and dry matter. The potato cultivar Ania was cultivated in the crop rotation: potato — spring barley — winter rye. It was stated that the tillage systems did not differentiate potato tubers yield. Intensive fertilization and plant protection levels significantly increased yields of tubers, starch, dry matter and total protein, compared with the basic levels. Simultaneously, intensive fertilization and plant protection levels increased weight and number of tubers per plant as well as average weight of a tuber.

The experiment was carried out in 1996–1998 on the soil of light loamy sand type and acidic reaction by the method of randomized sub-blocks. Three varieties (Biała Kulista IHAR, Czerwona Kulista IHAR, Swojecka Czerwona) and five weeds control methods (sprays with: Linurex 50 WP dosed 2.0 kg×ha-1; mixture of Afalon 50 WP + Bladex 50 WP dosed 1.5 l + 1.5 kg×ha-1, respectively, Azogard 50 WP dosed 3 kg×ha-1, mixture of Afalon 50 WP + Command 480 EC dosed 1 l + 0.2 l×ha-1, respectively; mechanical tillage without herbicides as the control object) were the factors of the experiment. Soil was fertilized with 100 kg N, 120 kg P2O5 and 180 kg K2O and 250 dt×ha-1 of manure. The mixture of Afalon 50 WP and Bladex 50 WP was most effective but the Linurex 50 WP was the best herbicide limiting weed mass. The cultivars differently reacted to the herbicides. For the cultivars Biała Kulista IHAR and Czerwona Kulista IHAR mixture Afalon 50 WP + Bladex 50 WP was most effective for the yield of green matter and herbicide Linurex 50 WP — for the yield of tubers. For the cultivar Swojecka Czerwona Azogard 50 WP was the best herbicide for the yield of green matter and mixture of Afalon 50 WP + Bladex 50 WP — for the yield of tubers.

The effect of different doses of thickened municipal sludge fertilization on initiation and intensity of soil formation process on a tip of flotation tilling from sulphur mine at JeziĂłrko (south-east of Poland was studied) in relation to a species of reclamation plant. The growth of Salix viminalis was a separate aspect of the research. The tip of flotation tilling was fertilized with sewage sludge at the amount of 250; 500 and 750 m3/ha together with mineral NKP fertilization. Next tubers of Helianthus tuberosus or seed of Festuca arundinacea were planted. On flotation tilling enriched additionally with 250 m3/ha of thickened municipal sludge, Festuca pratensis was planted in mixture with Lolium perenne, Trifolium pratense, and Medicago varia. The canopy of Festuca arundinacea and mixtures of grasses were cut or fed to cattle, however dried shoots of Helianthus tuberosus, were cut and crushed and left over early in spring. Prior to setting up the plantation of Salix viminalis the tip of flotation tilling was fertilized with 100 m3/ha of municipal sludge together with post-harvest residues of preceding crop (rye). In the collected soil samples soil texture, pH and content of P, K, Mg and organic matter were determined. It was found that all doses of municipal sludge applied to flotation tilling caused clear increase of organic matter content and concentration of P, K, Mg. The highest doses of municipal sludge together with organic matter from Helianthus tuberosus influenced most efficiently the soil formation process, formation of humus layer and accumulation of the mineral ingredients was most intense. Salix viminalis grew well on flotation tilling fertilized with municipal sludge together with post harvest residues of rye straw. Weak or dead basket willow plants found on a part of the plantation seem to be caused by other factors than the lack of nutrients in soil. Mechanical composition of ground was much differentiated, but it had almost no effect on organic matter and P, K, Mg contents. In the surface layer of the flotation tilling the process of soil recovery was more intensive and this layer contained more organic matter and minerals than the lower one.

Demographic processes due to fast growth of the global population and urbanization are the main reason for increasing demands for food and feed. Due to urbanization processes about 50% of food is exported into towns. In consequence on a world scale about 83 million t NPK are also transferred into towns and hardly recycle to the land where they came from. In the last decade the global production of cereals, oilseed crops, sugar crops showed some specific trends, i.e. the sown area declined (cereals, sugar beets), but the production level has been almost constant due to higher yields per ha. It means higher nutrients removal from the field with the harvest. The increasing intensity of oilseed crops, root crops and sugar crops production requires, in turn, higher level of soil fertility due to relatively poor root systems when compared to cereals. However, the current fertilizer use patterns are much worse that at the end of the 80-ies. The consumption of fertilizers, generally decreased, but also the structure of NPK use underwent some negative changes. The special attention should be focused on the potassium consumption. The resulting NK ratio in global fertilizer use depreciated rapidly from a fairly balanced ratio of 1:0,4 to currently 1:0,27. This ratio dramatically worsened in the Central Europe countries, including Poland. It has been documented, through long-term experiments, that negative K balance results in a huge reduction in the content of soil K, causing its mining. On the other hand, numerous field trials give evidence that adequate use of potassium fertilizers, i.e. in balance with the other essential nutrients increases yield and improves its quality. It is important to many countries, like Poland, that adequate K fertilization also increases crops response to water deficits, increases resistance to diseases. There are some other benefits of balanced potassium use (i) environmental — higher efficiency of nitrogen (ii) economic — increasing farmer’s profits generates income, which is partly used for purchase of non-agricultural products; business attraction to the rural areas (iii) social — rural areas development, social security, etc.

The first part of this review documents the mechanisms of plant resistance to water shortages during growth. It has been indicated, that appropriate supply of crop plants with potassium improves their water management and consequently results in higher resistance to stresses, including droughts. The anti-stress potassium action is a consequence of higher K+ ions concentration in the soil solution (due to natural fertility or K fertilization); greater perpendicular range of the root system; faster growth rate of above-ground parts of a plant and, consequently, earlier coverage of soil surface. In the second part an attempt was made to explain the major reasons of considerable sugar beet yield losses in Poland, as well as their considerable dependence on weather conditions, i.e. year to year variability. The importance of factors was as follows (i) low, natural, level of available potassium (ii) high frequency of periods with water deficiency and (iii) insufficient, in relation to the nutrient requirement, K fertilization. Using experimental data it was shown that appropriate nutrition of sugar beet plants with potassium allowed them to survive during the critical growth stages and, consequently, reduced the risk of yield losses caused by drought.

In a long-term field experiment with a duration of 19 years the impact of different rates of potassium (0–100–200–300 kg K2O/ha/year) with and without farmyard manure (FYM) (30 t/ha every 3 years before sugar beet) on yields, crop quality, K-content in the soil and the economic effects in a sugar beet — wheat — barley crop-rotation was studied. K-rates below crops K-uptake led to a distinct decline in soil fertility. Sugar beet as well as wheat showed an average yield decrease of 35% and 12%, resp. during the whole trial period. FYM increased the yield level especially of sugar beet, but did not affect the optimum K-rate. With negative K-balances and a falling K-content in the soil, sugar yields decreased over the whole trial period combined with a lower sugar content in the roots. For that reason the efficiency of K-fertilization increased with the duration of the experiment. At the described site an extractable K-content of about 250 ppm K2O was optimum. In order to maintain this soil-K-value a K-application rate exceed the K-removal by 45 kg K2O/ha/year was necessary.

Agricultural research on plant nutrition cannot be supported without results of long-term field experiments. The Central Institute for Supervising and Testing in Agriculture established four long-term field experiments in four experimental places of the sugar beet production region of the Czech Republic, in the years 1972–1979. Each experiment comprised 12 combinations of fertilization and had an eight years crop rotation. The following five combinations were used for evaluation of yields of sugar beet (roots and leaves) and quality of the products: the control treatment without fertilization, the treatment with farmyard manure (FYM) and three treatments with FYM applied together with comparative mineral fertilization at three different levels. In the control treatment, average yield of the main product (roots) was 52.0 tons×ha-1 with sugar content 18.5%. In the other treatments increase of fertilization caused gradual rising of the roots and leaves yield (for roots: from 57.5 to 68.3 tons×ha-1) and, on the other hand, the decrease of sugar content (from 18.6 to 16.8%). The nitrogen and potassium balances were negative, except for the highest level of mineral fertilization. The phosphorus balance was highly positive at all levels of mineral fertilization.

The low level of sugar-beet production profitability forces the necessity of outlays decreasing and induces planters to search for new solutions, which will ensure the improvement of production efficiency. The investigation was carried out in a static three crop rotation experiment, at varying doses of nitrogen (0, 60, 90, 120 and 180 kg N per hectare) and at three levels of organic manures (without organic fertilizations, cow dung, straw + intercrop — phacelia). The economic estimation was based on the direct surplus, used in incomplete calculations. The results made possible to show the relative profitability of the compared fertilization variants. During the period of investigation (2000–2001) the best economic effects from sugar-beet production were obtained under the treatment of fertilization with cow dung and 120 kg N per hectare. However, in case of the lack of organic fertilization or when straw + phacelia were used the dosage of 180 kg N per hectare was well founded economically.

In the years 1996–1998 an assessment of sugar beet plants response to four rates of potassium (0, 80, 160, 240 kg K2O/ha) was performed in 8 locations, i.e. plantations of the Sugar Beet Factory Kościan, yearly. Yields of beets, irrespective on experiments localization and K rates, ranged from 66 to 78 t/ha. In four of eight experimental sites a positive response to the applied potassium was found and the lack of it or even negative effect was stated in the remained four sites. The main factors responsible for the found trends were precipitation in summer months and also potassium buffering capacity of soil. Yields of recoverable sugar in both groups of stands highly depended on yield of roots and sugar content. However, in the group of responsive stands the diagnostic value of sugar content was very high (up to 50%), but in the non-responsive stands this parameter was only of the secondary importance (16%).

In the first part of the dissertation the basic characteristics of sugar beet yields were discussed. The second part deals with the nutritional status of beet plants assessed 50–60 days after germination using the Bergmann’s (1992) threshold values. It was found the optimal nutritional status for the secondary nutrients such as magnesium and calcium but not for the primary ones such as potassium, nitrogen and phosphorus. The high obtained yields of beets and sugar (details in the I part) and found correlations in the K-responsive group between potassium, calcium contents and sugar yields suggest that the Bergmann’s threshold values are too high respecting the stage of sugar beet plant growth. On the other hand, in the K-non-responsive group, contents of potassium and calcium appeared to be good indicators of sugar yields.

In the first two parts of the dissertation the basic characteristics of sugar beet yields were discussed. This part concerns the effect of potassium application on its uptake and its effect on sugar yields. In the group of stands responsive to potassium application the final K uptake ranged from 287 to 319 K/ha and in the non-responsive one from 277 to 295 K/ha. The weather conditions, mainly precipitation, were the main factor affecting K uptake. In 1998, i.e. in the year with soil drought, the increase of K rates negatively influenced potassium uptake by crops cultivated in non-responsive sites. In addition, sugar beet yields in this specific year were highly and positively related to the amount of potassium off-take, but at the same time, negatively related to the specific uptake.

Plant-available soil potassium resources are an important factor of sugar beet plants growth over the whole vegetative season. In the K-responsive sites positive relationships were found between yield and the sum of soil available potassium as determined by the Egner-Riehm procedure, and added K-fertilizer. The coefficient of determination — R2 for this relationship, amounting to 0,41, was significant. For the K-non-responsive sites this relationship was not significant. In order to determine the critical soil K level the Cate-Nelson scatter diagram was developed. The found K critical level, irrespective of a site responsiveness to K-fertilizer, amounted to 190 mg K/1 kg of soil. In both groups of sites 4 sub-groups were distinquished. The most numerous was the subgroup I representing sites of the highest probability of response to increase of soil available K, and also to a K-fertilizer applied. Both the main groups differed by the 3rd subgroup containing sites with high content of plant available K, but still responsive to the K application. In this subgroup no sites were found of the main K-non-responsive group.

An assessment of the effect of calcium saltpetre and ammonium saltpetre nitrogen fertilizers in relation to potassium fertilization applied alone or enriched with sodium and magnesium (two variants: KNaMg; KNa3Mg) on roots and sugar yields were conducted in 1999 and 2000 at Donato­wo, Wielkopolska. Yields of root, sugar and technological quality of roots depended on interaction of both experimental factors, i.e. N and K-Na-Mg fertilizers. Sugar beet plant fertilized with calcium saltpetre and potassium chloride or ammonium saltpetre together with KNaMg fertilizer resulted in similar level of roots and sugar yields. The calcium saltpetre in comparison to ammonium saltpetre caused increase of sugar content and some molasses forming substances such as α-amino N and K as well. It was found that sugar yields from the combination fertilized with calcium saltpetre depended more on yields of roots, but fertilized with ammonium saltpetre on both yield of roots and sugar content.