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Dehydration tolerance of seedlings of ten cultivars and strains of spring wheat (Triticum aestivum L.) was drastically lowered on the 5th day of germination. The “break” in dehydration tolerance is coincident with intensive mobilisation of seed grain reserves and accumulation of dry mass in vegetative organs. Following rehydration, survival of 4-day old seedlings was almost complete, whereas survival of 6-day old seedlings was drastically reduced. The observed phenomenon seems to be genetically determined.

The aim of the research was to determine the factors causing lower seed quality of hull-less barley cv. Rastik as compared with that of hulled barley cv. Rataj. Barley harvesting was done in seed production fields in 2002 using a plot combine and a regular combine. The seeds harvested with plot and regular combines were evaluated immediately after harvest, and then after processing. The seeds harvested with a regular combine were additionally evaluated after storage and final processing. The following parameters were estimated: moisture content, purity, proportion of damaged seeds and damage type, germination ability and seeds vigour. The hull-less barley grains were found damaged at the higher rate than those of the hulled barley. Even higher proportion of damaged grains was observed in seed lots sampled after final processing. The germinating power of seeds sampled immediately after harvesting with a plot combine and regular combine was 90.7% and 81.7%, respectively. Germination of seeds of cv. Rataj harvested with a plot combine was 89.5%, whereas that of seeds harvested with a regular combine was lower by 6%. Higher differences (up to 13%) were found in the case of hull-less cv. Rastik. The vigour of seeds harvested using a plot combine was greater than that of seeds harvested with a regular combine. The treatments during seed processing as well as storage conditions resulted in further decrease of sowing value of the hull-less barley cultivar.

In the pot experiment, performed during 2000–2002 yielding ability of hulless and hulled barley forms was compared in the conditions of controlled water supply. It was found that the highest yield per pot area was obtained from intact barley plants, as well hulless as hulled ones. It resulted from higher number of ear bearing shoots (average more than 5 per plant). Induced reduction of stem number per plant to one or two shoots resulted in yield reduction by 44 to 49 per cent. Thus reduction of tillering for the both barley forms appeared to be a factor of yield reduction. No cultivar response to the number of productive shoots left was stated.

Grain yield of spring barley and yield components, depending on sowing rate were examined in a microplot experiment (1998–1999) and in a field experiment (2000–2002). The Rastik naked cultivar and several husked cultivars were investigated. Tendency of the naked barley to weaker response to sowing rate, in comparison with the husked cultivars, was observed. By growing of naked barley under superior soil condition density of 300 plants per m2 is optimal. The naked cultivar showed lower grain yield, but higher protein content in grain than the husked cultivars.

Pathogenicity of barley powdery mildew (B. graminis f. sp. hordei) was investigated in Poland in 2000. In this investigation leaf samples of susceptible cultivar Manchuria, infected by powdery mildew collected in 12 locations, were used. From leaf samples collected in each location 20 single — spore isolates were obtained. Virulence of specific single — spore isolates was determined based on their resistance reaction on 32 differential cultivars. Virulences Vg + CP (99.0%), Va7 + Ab (99.5%), Vh (99.5%), V(La) (100%), V(Ru2) (100%), V(Bo) (98%), Vra (100%), V(Kr) +? (90%) were present in Poland in 2000 with frequency more than 90%. Virulences which were present with low frequency (below 50%) were: Va1 +? (37%), V(St1) + St2 (29%), Vat (47%), Va9 + k (41.5%), Va3 (40,5%), Va22 (47%), Va7+ k +? (42.5%) and Vp (0.5%). Virulences Va23 and Vo5 were not present. In 2000 the strong influence of population of B. graminis f. sp. hordei from neighbouring countries was observed on V(Bo) and V(La) frequencies. Virulences Va3, V(St1) + St2, Va1 and Va3+ Tu2 were present in population of barley powdery mildew in Poland in spite of their corresponding resistances have not been used in cultivars grown in Poland in 2000.

Genetic resistance to powdery mildew (Blumeria graminis f. sp. hordei) of 8 winter barley cultivars and 13 spring ones from the Polish Registration trials was presented. All the winter cultivars have one or more genes for resistance in the loci Mlra, Mla6, Mla14, Mlk and Mlh. Nine different resistance genes: Mla1, Mla9, Mla12, Mla13, Mlg, Ml(Ab), Ml(IM9), Ml(St1) and mlo were detected at spring varieties. Only cultivars with the gene mlo have high level of resistance to powdery mildew in Poland.

In the two-year one-factor field experiment, total and fractional protein contents were compared in spring barley and oat seeds leaf-fertilized with solutions of microelements in form of individual inorganic salts and as a multi-component fertilizer that contained the components as chelates (Mikrochelat Gama). The leaf fertilizing with micro-components generally had advantageous effect on cumulation of nitrogen in spring barley and oat seeds. Zinc and manganese were the microelements that significantly increased the content of this element in the both crops. Glutelins appeared to be the most abundant protein fraction, whereas albumins showed the lowest level. The seeds of oat had higher nitrogen content of albumins and globulins (the fractions of advantageous amino acid contents) than the seeds of spring barley. Zinc and manganese were the leaf-applied microelements, which significantly increased total nitrogen of these fractions in seeds of spring barley and oat. The multi-component fertilizer had a less advantageous effect on the fractional protein content in seeds of the both species than the microelements applied in form of individual inorganic salts.

The influence of root excretions of oat seedlings on germination of pea, vetch, blue and yellow lupine seeds was investigated. The effect of oat and barley grain exudates on pea seeds and the influence of extracts from pea seeds on kernels of these cereals was additionally evaluated. The experiments were done in a laboratory. The influence of root excretions of oat seedlings on germination of leguminous crops seeds was stronger than the effect of grain exudates. Root extracts of oat seedlings stimulated or inhibited germination of pea, vetch, blue and yellow lupine seeds and development of germs and rootlets. After four days oats root excretions at higher concentration inhibited the rootlet development of all tested leguminous species and at lower concentration limited the root weight of pea, blue lupine and vetch (also root length of vetch). On the other hand, after 8 days these excretions limited the root development of blue lupine most intensely independently of concentration. Extract of oat seeds soaked for 72 hours stimulated germination of pea seeds after 4 days and extract of oat seeds soaked for 24 hours stimulated pea seeds germination after 8 days. On the other hand such effect of barley seed extract on pea seeds germination was not observed. Pea seeds exudates soaked by 72 hours inhibited germination of oat kernels, strongly limited germination of barley kernels and retarded growth of sprouts and rootlets of the both cereals.

Four methods of field regeneration in spring triticale monoculture were investigated in a field experiment established at the Uhrusk Experiment Station of the Lublin Agricultural University, on a rendzina type soil formed on a light loam. The experiment was established in 1993 and the data (for four randomized blocks of 10 m2 plots) were collected in the years 1997–2000. The first two treatments included yearly application of green manure, Lolium multiflorum var. westervoldicum Wittm. or Ornithpous sativus L, the other two based on farmyard manure (FYM) dosed 30 t/ha every four years or 10 t/ha every year. Triticale cultivated after pea served as the control. Monoculture caused a significant reduction of grain yield. The magnitude of the reduction was dependent on field regeneration method; it amounted 39.1% for the Lolium sown under the crop plant and varied from 35.6% to 36.7% for the remained regeneration variants. The number and dry matter of weeds were significantly higher after the green manures than after the FYM fertilizations. The triticale in monoculture was more severely infected by the Gaeumannomyces graminis and Pseudocercosporella herpotrichoides fungi, when compared to the control objects. The weeds and diseases reduced tillering and mass of grain per spike in triticale.

The numbers of buckwheat varieties were introduced into a long term storage in 1991. At present, 105 varieties of buckwheat are stored at the National Centre for Plant Genetic Resources in IHAR RadzikĂłw. Seed viability was evaluated in germination tests done in 1997 and 2002. The reaction of 26 varieties to long-term storage conditions was examined. After 11 years of storage seed germination capacity decreased, on average, by 2.6 per cent. The highest germination ability (97.7%) was observed with var. JeĹźyk. The level of germination of 25 varieties was found stable.

The term adaptogen was coined in 1947 by a soviet scientist N.V. Lazarev. Adaptogens are a group of pharmacologically active compounds eliciting in an organism a state of raised non-specific resistance, showing antistress activity, increasing perseverance in organisms subjected to great physical effort. Currently, a drug classified as an adaptogen must fulfill the following criteria: cause immunostimulatory effect, influence the central nervous system; show sedative and antidepressant properties, enhance brain functions — learning and memorizing, enhance physical performance in an organism subjected to physical strain and show antioxidative properties. According to some authors, hepatoprotective and anticancerogenic activity should also be present, as well as hypocholesterolemic and hypoglycemic action. Certain properties of adaptogenic drugs (hepatoprotective, antioxidative, immunostimulatory) are now coming into prominence, because of the accelerating process of environmental pollution. The accumulation of toxins, especially in liver cells, leads to numerous diseases. A detoxifying and stimulating treatment, could keep the organism in form in spite of the increasing environmental pressure. This article is a review of latest literature reports concerning adaptogenic plants and their biological activity.

In subtropical regions, especially in India, the root of Withania somnifera (L.) Dun. (Withaniae radix) has been used since immemorial time as an adaptogen: an energizing, immunostimulating drug. The aim of this study was the assessment of yield and quality of the raw material of Withania somnifera (L.) Dun obtained in several variants of field cultivation in moderate climate conditions. We compared the yield of roots, herb, and withaferine A obtained from plantation started by sowing the seeds directly to soil and from plants sown in March and then transplanted from greenhouse to field conditions. Moreover, we tested 10 methods of cultivating plants sown in greenhouse and transplanted to soil. The options varied with spacing, harvesting time and mulching with black plastic foil. It was concluded that Withania somnifera (L.) Dun. might be successfully grown for herb and roots in moderate climatic conditions. Even from the “directly to soil” started plantation the yield of roots was significantly higher than reported in commercial plantations in India. The transplanted plants achieved about 3-fold higher yield and the best results were observed in two methods of cultivation: F/I/9 (plastic foil mulching/ 1 harvesting time in September/ spacing 9 plants/m2) and F/II/30 (plastic foil mulching/ 2 harvesting times: July, September/ spacing 30 plants/m2). More advantageous seems to be the first method, because of much better quality of roots, comparable yield of herb and lower consumption of time and costs. Withaferine A yield is, however significantly higher in the F/II/30 option.

Thirty cultivars and selections of Festuca spp. were assessed regarding their turf characters under medium intensive turf maintenance during 1993–1998. The results of the assessment were the base for formula calculation of some characters synthesis using statistic methods. Tested cultivars were divided into three homogenous groups in respect to their general aesthetic aspect using cluster analysis (k-means method). Based on this division the relationships between general aesthetic aspect and other tested traits (shoot density, slow vertical re-growth, leaf fineness, and colour) were determined. The weight of particular characters in turf cultivar value was estimated by multiple linear regressions, and quality turf index QM has been proposed. Index QM was used for evaluation of turf value of cultivars and selections, and results were compared with other formula indexes proposed by other authors. Significant differences between cultivars value in the indexes were found. The relationships between the indexes mainly depended on the group of cultivars tested. Low relations among the indexes were found with the cultivars of low turf value, and higher with the cultivars of high turf value. The proposed index QM was closely related to a general aesthetic aspect of cultivars, irrespective of the group of cultivars. Our results suggest that index QM may be useful in turf cultivars value evaluation in breeding programmes. However, it requires an additional examination using other turfgrass species and other type of turf maintenance

During periods of natural drought in summer 1999 and spring 2000 5 varieties and 4 breeding lines of 6 turf grass species were evaluated in conditions of close and frequent mowing, no additional watering and low fertilization. Using 1–9 scale the condition of turf plots were evaluated during drought and subsequent regeneration. For the same objects, germination in negative water potential was also evaluated. A relationship was stated between germination in negative water potential and condition of turf plots during natural drought for some tested objects. Species ranked high after natural drought (Lolium perenne and Festuca arundinacea) germinated even at yw = -2.05 MPa, but other species and varieties, ranked lower after drought, germinated only at yw = 0.0 (control) and -0.65 MPa. High correlation was found between mean germination time at -0.65 MPa and turf plots condition during drying and post-drought regeneration. The above results suggest necessity for improving screening test on the basis of seed germination in low water potential. 

Deschampsia caespitosa cv. Brok was investigated in mixtures with Poa pratensis cultivars over three years under shade conditions. Monoculture of Brok and two standard mixtures commonly used one for sport purposes and the other one for park purposes, were used as a control for the comparison. The experiment was located in natural shade, near a building, and the following medium high turf maintenance regime factors were in operation: 157 kg N×ha-1, 22 mowing per year and irrigation during dry periods. The light reaching the plants was reduced by about 80%. The following characters were evaluated: general aesthetic aspect, shoot density, winterhardiness, wintergreenness, tolerance to yellow rust and to snow mould. It was found that the Brok mixtures’ characters were particularly good only in the first year of maintenance. Mean data (from 3 years of maintenance) of the general aesthetic aspect and shoot density for the mixtures with Brok were at the standard mixtures level or even below. The component cultivars of P. pratensis influenced significantly the value of turf characters. The tufted hairgrass Brok in monoculture showed low persistency for shoot density and low value of aesthetic aspect in autumn and winter (wintergreenness).

Thirteen series of experiments to evaluate potato sprouting, the length of tuber dormancy and mass of sprouts were carried out in the years 1985–2001 at the Plant Breeding and Acclimatization Institute, Department Jadwisin. Altogether, 54 potato cultivars were tested. Significant differences between cultivars in the dormancy period, sprouting ability and mass of sprouts were found. It was shown that the length of dormancy, intensity of sprout growth, and particularly the mass of sprouts at 6°C and 10°C, were significantly correlated with optimal temperature of storage of seed potato tubers.

Influence of temperature during storage of seed potato tubers on growth and development of progeny plants was evaluated in the years 1986–2001 at the Plant Breeding and Acclimatization Institute, Department Jadwisin. Altogether, 54 potato cultivars were tested. Prior to planting, seed potatoes of these cultivars were stored in a store-house at 2°, 6° and 10°C, and at RH above 90%. During the vegetation seasons, rate of plants emergence, percentage of missing plants and a number of stems per plant were estimated. It was found that storage conditions largely influenced the physiological state of mother tubers. With decreasing temperature the percentage of blanks in the field increased. All the trials showed that the proportion of missing plants was a very important measure to evaluate physiological quality of seed tubers. Moreover, in the case of cultivars showing a very high rate of physiological ageing during long-term storage, the proportion of missing plants in plantation was significantly correlated with optimal storage temperature.

The aim of the investigations carried out in Bonin, Zachodniopomorskie voivodeship, was to assess and compare infection pressure of PVY, PVM, PVS and PLRV both in different years and periods of the growing season. The incidence of PVY was found to be the greatest. Average infection of tubers with this virus for both periods of studies was 47%. Infection with PVS and PVM was at the lower level (17.1% and 8.6%, respectively). The most intense spread of PVY, PVS and PVM was recorded in the approximate period between 21–30 of June and 21–31 of July or 1–10 of August, although the threat of PVY infection lasted throughout the growing season. The relatively great impact of PVY, as compared to that of other viruses, as early as the first phase of plants vegetation strongly indicates that seed production of cultivars susceptible to PVY might be difficult even in conditions of northern Poland, which has been classified as the first (healthy) zone of virus infection pressure. In contrast, the level of infection with PLRV in the years of studies was very low.

Assessment of the incidence of fungal and bacterial diseases (late and early blights, black leg, soft rot and common scab) in potato crops was based on the surveys performed within the cooperation of the Plant Breeding and Acclimatization Institute in RadzikĂłw, Department of Potato Protection and Seed Science in Bonin, with Plant Health and Seed Inspection Service. In the year 2003, compared to 2002, the first disease symptoms of early blight appeared 7 days later and those of late blight — 12 days later. The proportions of tuber infection with bacterial and fungal pathogens in year the 2003 were lower than those in 2002.

The aim of the investigations was to assess the efficacy of weed control in potato crops using glyphosate (herbicide Sting CT 120 SL). Field experiments were carried out in the years 2001 and 2002 in the arable field near Wrocław. The field trial was laid out as a randomized complete block design including three replications. All farming measures were performed according to both conventional agricultural practice and the recommendations of the advisory service. Herbicide Sting CT 120 SL was applied in spring after weed germination, but prior to germination of potatoes. The efficacy of weed control was evaluated as a proportion of weeds destroyed. Moreover, a yield from each plot was estimated. No phytotoxic effect of the herbicide on potato plants was observed. Sting CT 120 SL applied in a dose of 4 l/ha controlled 97%–100% of Chenopodium album, Amaranthus retroflexus, Echinochloa crus-galli, Polygonum persicaria, P. convolvulus and Veronica persica, which was comparable to the effects obtained with the mixture Glifosat 360 SL + ammonium sulphate, applied in doses 2 l/ha and 5 kg/ha, respectively. Elymus repens was destroyed in 95%, whereas Convolvulus arvensis was found to be resistant to Sting CT 120 SL. The efficacy of this herbicide in a dose of 3 l/ha was distinctly lower. The yield of potato tubers harvested in the plots treated with the herbicide was higher by 35 to 40% than that obtained from the untreated (control) plot.

The results of experiments carried out in Bonin in the years 1996–1998 to assess the efficacy of a herbicide Sencor 70 WG in controlling weeds in potato crops are presented. The herbicide was applied in different doses either prior to potato emergence or after emergence. The greatest efficacy of Sencor 70 WG application was observed when the herbicide was used in a single dose of 1 kg/ha in the preemergence period or in a divided dose, including 0.3 kg/ha and 0.2 kg/ha in the preemergence and after emergence periods, respectively. The phytotoxic effects of plants treatment with Sencor 70 WG were largely diminished when the herbicide was applied in divided doses.

The development of bacterial ring rot symptoms in 8 samples of progeny tubers (90–180 tubers per sample), in which latent infection was detected by immunofluorescence methods, was examined in a field experiment in 2001–2003. First bacterial ring rot symptoms on leaves appeared in the 8th week after tubers planting in samples 27, 40, 170 and 187 (6% of leaves infested). They consisted of wilting of lower leaves, overcolouring and rolling of leaves margins inwards. Progeny tubers were examined twice a year, in autumn and in spring. Internal tuber symptoms ranged from glassy to cream — yellow zones along the vascular tissue near the stolon. In later stages of the disease yellowish rings were observed. Maximum percentage (21.6%) of tubers with visible symptoms was found in a sample no. 170.

The paper reviews the current knowledge of the ways of the ring rot spread in potato and presents agronomical measures that can be applied to reduce a risk of spread of the bacteria causing this disease.

In the years 1999 and 2001–2003, the efficiency of different fungicides in controlling early blight was evaluated in field and laboratory experiments. Two contact fungicides: mancozeb (Dithane NeoTec 75 WG and zoxamide + mancozeb (Unikat 75 WG), a translaminar fungicide fenamidon + mancozeb (Pyton 60 WG) and a systemic fungicide metalaxyl M + mancozeb (Ridomil Gold MZ 68 WG) were compared. The results showed that all tested fungicides significantly reduced early blight development in the field trials. The control of early blight resulted in the increase of potato yield by 4.8 t/ha (metalaxyl M + mancozeb) to 6.2 t/ha (zoxamide + mancozeb). In the laboratory experiments only mancozeb and fenamidon reduced the development of Alternaria alternata fungus.

In the years 2000–2003 the efficacy of a new fungicide Pyton Consento 450 SC in controlling late blight (Phytophthora infestans) and early blight (Alternaria solani and A. alternata) was assessed. The experiments were carried out in two locations: Bonin (northern Poland) and Stare Olesno (south-western Poland). The fungicide effectively reduced the development of late blight (77%–99%) and early blight (40%–61%), compared to the incidence of these pathogens in the untreated (control) plots. When applied in a dose of 2 l/ha, it was found to be as effective as standard fungicides, or even better.

In the years 2000–2003 influence of meteorological conditions in potato growing season on the efficacy of certain fungicides in controlling late blight was assessed. The experiments were carried out in two locations: Bonin (northern Poland) and Stare Olesno (south-western Poland). Chemical protection resulted in a longer time needed for yield gathering. Moreover, it had the positive effect on the yield. The highest yields were obtained both in Bonin and Stare Olesno in the year 2000. The efficacy of the fungicides was high (above 90%), irrespective of the mode of action in the plant.

The variation of aggressiveness and virulence of 12 Phytophthora infestans isolates after artificial inoculation on potato leaflets was examined in a two-year study. The expression of these features varied periodically during the year. The highest level of aggressiveness and the widest spectrum of virulence were observed in early spring and early autumn. The best stability of virulence and aggressiveness expression was presented by MP 324 and MP 423 isolates of P. infestans. Significant correlation between level of aggressiveness and detectability of virulence was noticed. Higher inoculum concentrations were found to enhance both the virulence spectrum and the level of aggressiveness of P. infestans. However, no positive effect of the increased inoculum doses on the level of aggressiveness was observed in the seasons of routine tests to assess potato resistance to P. infestans.

The aim of the studies carried out in the years 2001–2002 was to evaluate effectiveness of fungicides Altima 500 SC, Brestanid 502 SC, Unikat 75 WG and Tattoo C 750 SC in reducing the occurrence of late blight on mid-early potato cultivar Ibis. The results showed that all the fungicides significantly decreased the infestation by Phytophthora infestans both of potato foliage and tubers.

The investigations on duration of potato tubers dormancy were carried out in the years 1999–2002 at the Plant Breeding and Acclimatization Institute in Jadwisin. Twenty-two cultivars, including: 8 — very early and early, 9 — mid-early and 5 — mid-late and late, were tested. The length of a dormancy period was measured in days, counting from the „0” date (1st October) to sprouting of 80% of tubers. For measuring a dormancy period, a 1–9 scale, where 1 — the shortest dormancy and 9 — the longest dormancy, was used. It was found that 6 of the tested cultivars had long dormancy periods (ratings 9–7), 8 cultivars were characterized by the dormancy periods of medium length (6–4), and 8 cultivars had short periods of dormancy (3–1). No close relationship between cultivar earliness and the duration of tuber dormancy was observed. The cultivars differed in the depth of tuber dormancy, i.e. in the length of a period between sprouting of 10% and 90% of tubers in the tested sample. The influence of weather conditions in the vegetation period upon the duration of dormancy was found. The dormancy period of tubers harvested in the dry year 2002 was shorter than those of tubers harvested in the years 1999, 2000 and 2001.

In the years 1999–2002 the experiments aimed to determine the relationships between size of mother tuber and some traits of progeny yield were conducted. In total, 13 cultivars from different groups of earliness and suitabilities were tested. Within each cultivar, tubers ranging in weight from below 20 g up to 200 g were divided into groups, every 20 g in weight. Each group comprised 10 tubers. The following elements of yield were examined: number of tubers per stem and plant, yield of tubers per stem and plant, and average weight of tubers. The linear relationships between the weight of mother tuber and most of the yield features were found. Increase in the size of seed tuber effected: increased number of stems per plant, increased number of tubers per plant, increased tuber yield per plant, decreased number of tubers per stem, decreased tuber yield per stem, and declined average tuber mass. Differences between the cultivars in all of the tested yield traits were also observed. The increased tuber yield per plant, resulting from the increased number of stems, was due to the greater number of tubers per plant but not to the enlarged weight of particular tubers. The following path of relationships could be established: the bigger mother tuber → the greater number of stems → the greater number of progeny tubers → the higher yield → the lower weight of one tuber. The results obtained can be used to regulate a number of stems per plant to obtain tubers of the size that will be most suitable for the given sort of potato production.

The aim of the investigations carried out in the years 1985–2002 on 46 potato cultivars differing in earliness was to assess the length of dormancy period and readiness for sprouting of tubers stored at 2°, 6°, 8° and 10°C and 90% RH in darkness. Minimum temperature of sprouting was determined. Moreover, the dynamics of sprout development was examined. Marked differences between the cultivars both in the length of a dormancy period and intensity of sprouts development in tubers stored under the same conditions were found. However, neither the duration of tuber dormancy nor sprouting dynamics was closely related to cultivar earliness.

The potato (Solanum tuberosum L.) is a species characterized by rather shallow root system which causes low tolerance of this plant to drought. Growth of roots of three potato cultivars differing in sensitivity to drought was examined in the years 1991–1992 in natural soil profile (sandy clay loam), and in the years 1990–1992 in a pot experiment in sandy ground. Moreover, in the years 1994–1998, comparative measurements of root system size in a group of twelve cultivars were carried out. It was found that the sensitive to drought cv. Kalina compared to the tolerant cvs Cisa and San had considerably smaller and shallower root system both in natural soil profile and in pots. The investigations on a group of 12 potato cultivars showed highly significant differences between the cultivars in total root length, content of dry matter and rooting depth. Root length was positively correlated with dry matter yield of tubers produced by the examined plants.

The relationships between vitamin C and nitrates levels in mature tubers of 21 potato cultivars grown at the Experimental Station in Jadwisin in the years 1993–1999 were investigated. Statistical analysis of the results showed significant correlation between contents of the studied components. A negative value of correlation coefficient occurred when vitamin C / nitrates ratio was higher than 2. For the most part tuber samples were characterized by the ratios high enough to prevent the formation of harmful nitrosoamines. However, correlation between vitamin C and nitrates levels can sometimes be positive. This happens due to the excessive accumulation of nitrates in tubers of early and very early cultivars grown under dry and hot weather conditions. The decrease of vitamin C / nitrates ratio to about 1 is then observed.

In the field experiment carried out in the years 1998–2000 at the Experimental Station Uhnin a randomized blocks design with three replications was applied. The studies were performed on 16 potato cultivars, comprising mid-late cultivars Ania, Anielka, Arkadia, Fregata, Grot, Klepa, Omulew, Rybitwa, Rywal, Salto and Vistula, and late cultivars Dunajec, Hinga, Jantar, Meduza and Wawrzyn. Mineral fertilization at constant doses of 90, 90 and 135 kg×ha-1 of N, P2O5 and K2O, respectively, and organic fertilization with 20 t×ha-1 of ploughed under white mustard, were applied. Significant differences in yielding between cultivars within the earliness groups were found. Environmental factors played the key role both in variability of tubers yield and in the yield structure. In turn, genetic factors most strongly determined the phenotypic variation shown in a number of stems per plant. The strongest effect of interaction between cultivars and years was exhibited in variability of commercial yield of tubers.

The aim of the work was to compare some quality characters of Polish and foreign potato cultivars, registered in the Polish National List 2003. The data came from the pre-registration assessments of cultivars usability as well as from additional investigations on agronomical traits, which had been conducted at the Potato Agronomy Department in Jadwisin. The analysis of the data showed that, in general, Polish potato cultivars compared to foreign ones exhibit a higher level of resistance to diseases and stressing conditions but are characterized by the lower quality value, especially in the traits determining tuber appearance. Nevertheless, the marked progress in potato quality has recently been made by Polish potato breeders.

The aim of this work was to analyze the results of investigations carried out by various research units in the area classified by J. DzieĹźyc as the 6th agro-natural region, including mostly the region of Lower Silesia. The experiments were conducted in 93 localities, in different years between 1954 and 1997. The potato varieties met in those experiments were classified into 4 groups, according to their earliness. The groups included: 15 early varieties, 15 mid-early varieties, 20 mid-late varieties and 24 late varieties. Reaction of the varieties to differentiated mineral and organic fertilization was evaluated. It was found based on the respective calculations that organic fertilization at the doses of 31–35 t/ha was sufficient in cultivation of mid-early potatoes. As regards mid-late and late varieties, which take advantage of the treatment for a longer time, manure doses exceeding 35 t/ha resulted in additional yield increases. Moreover, the increase in manure doses caused a significant rise of starch content in tubers of early, mid-early and late varieties. An increase in the level of mineral fertilization in the range from 240 to 400 kg NPK/ha resulted in the successive increase in the yield of mid-early and late varieties. However, fertilization at the doses exceeding 350 kg NPK/ha caused the decrease in starch content of tubers in mid-early, mid-late and late varieties. The highest yields of tubers: 22.5 t/ha with early varieties, 32.0 t/ha with mid-early and mid-late varieties, and 32.5 t/ha with late varieties were obtained by applying nitrogen doses of 120, 160 and 180 kg/ha, respectively. Nitrogen fertilization caused the decrease in starch content of tubers in early varieties. In the other earliness groups, starch content of tubers did not change at 40–120 kg N/ha. It fluctuated around 14.5% in mid-early varieties, and around 16% in late varieties.

The work presents a synthesis of over 11 thousand data from the years 1954–1997, recorded in 93 localities in Lower Silesia (VI agro-natural region), concerning yields and starch content in tubers of various potato varieties. The response of varieties to preparation of seed tubers (initial sprouting), choice of stand, planting time and way of cultivation was estimated. The results were subjected to statistical verification. It was found that proper preparation of planting material can significantly increase the yield, from 2.2 t/ha (medium early varieties) to 5.2 t/ha (medium late varieties). They yields exceeding 30.0 t/ha were obtained using as a forecrop: for early varieties: legume cereals mixture and strawberries for  early varieties, triticale, mixture of cereals, fibre flax, rape and wheat for medium early varieties, fibre flax, mixture of cereals, triticale, rape, oats and cabbage for medium late varieties, and winter wheat for late varieties. Some effects of forecrops on starch content of tubers were also observed. In the habitat conditions of Lower Silesia the optimal timing for planting early varieties seems to be the first decade of April, and for the remaining groups — the second decade of April. Chemical control of weeds in potatoes compared to other methods of weed control mostly resulted in increasing the yield of potato tubers.

This work describes the results of investigations carried out in the years 1997–1999, which were aimed to assess an influence of fertilization with undersown crops on yielding and quality of a table potato variety Rywal. The following experimental combinations of undersown crops: control object (no organic fertilization), farmyard manure, birdsfoot trefoil alone, birdsfoot trefoil with Italian ryegrass, and Italian ryegrass alone were compared. During harvesting of potatoes, yield of fresh tubers mass was estimated in each plot. Afterwards, the tubers were sampled to determine both yield structure and content of dry matter, starch and vitamin C. The highest yield of tuber fresh mass, at the greatest proportion of a table tuber fraction, was obtained with the plot that was fertilized with a combination of birdsfoot trefoil with Italian ryegrass. The quality of potatoes fertilized with undersown crops was as high as that of potatoes fertilized with farmyard manure. It may be concluded from the results obtained that fertilization of potato var. Rywal with a mixture of birdsfoot trefoil with Italian ryegrass as well as with birdsfoot trefoil alone can substitute for fertilization with farmyard manure.

The aim of the investigations carried out in the years 1995–1997 was to evaluate the influence of undersown crops ploughed under together with straw on yielding and nutritive value of tubers of potato variety Ania. The following combinations of organic fertilization were investigated: control object (no organic fertilization), farmyard manure, red clover + straw, red clover + Italian ryegrass + straw, Italian ryegrass + straw. During harvesting of potatoes, a total yield of fresh mass of tubers was estimated in each plot. Next, average tuber samples were taken to specify the commercial yield, and content of dry matter, vitamin C, total protein and macroelements (N, P, K, Ca i Mg). The highest total and commercial yields of fresh mass of potato tubers were obtained from the plot fertilized with red clover with straw. The nutritive value of potato tubers fertilized with these components as well as of those fertilize with a mixture of red clover with Italian ryegrass and straw was as high as the nutritive value of potato tubers fertilized with farmyard manure. The results indicate that fertilization of potato var. Ania with the whole bio-mass of undersown crops with straw, except Italian ryegrass, can entirely substitute for fertilization with farmyard manure.

The aim of the investigations was to determine the effect of interrow spacing and planting density on the structure of potato plants of various earliness in the period of florescence and harvesting. A three-factor experiment was carried out using a subblock method. The investigated factors were: 1) interrow width: 62.5; 75.0; 90.0 cm; 2) planting density in a row: 30 and 40 cm; 3) varieties: very early — Orlik and midlate — Arkadia. At the florescence stage both varieties showed a tendency to increase both a number and mass of shoots, leaves, stolons and tubers with the increased row spacing to 90 cm and planting density to 40 cm in a row. A medium late variety Arkadia compared to var. Orlik was characterized by the higher number and the greater mass of shoots, leaves, roots and stolons per plant. In turn, plants of var. Orlik produced more tubers on stolons and the greater tuber mass per plant. A number of shoots per hectare was higher in var. Arkadia, and decreased with widening row spacing. Moreover, it was smaller at a lower planting density. The percentage content of dry matter and starch in tubers during flowering was low and depended on the features of the investigated varieties. At the harvest stage a wider row spacing and lower plant density resulted in the slightly greater number and mass of stems and tubers per plant. The very early variety Orlik developed both a smaller number of shoots and smaller mass of stems and tubers per plant than midlate var. Arkadia, but yielded the larger average weight of one tuber. The content of dry matter was higher in tubers produced by var. Arkadia, whereas the total protein content was higher in tubers harvested from var. Orlik plants.