Early Potato Cultivars Research Articles

Response of Solanum tuberosum L. to drip irrigation and nitrogen application: productivity, nutrition composition, bioactive compounds, antioxidant activity

Sustainable crop cultivation is a crucial goal in modern agriculture, aiming to attain high productivity while conserving natural resources. This requires the implementation of rational cultivation techniques, with proper irrigation and fertilization practices playing a crucial role in ensuring plant well-being and providing natural protection against biotic and abiotic stresses. The health-promoting properties of crops are also significantly influenced by irrigation and fertilization. This study investigated the productivity, nutritional composition, bioactive compounds, and antioxidant capacity of Vineta early potato cultivar tubers under drip irrigation conditions, combined with nitrogen fertilization through fertigation or broadcasting. Two-factor trials included drip irrigation (control or drip) and nitrogen application (broadcast or fertigation). Precise treatments, such as drip irrigation and N-fertigation were found to enhance all productivity traits. Both practices positively impacted tuber nutrient content. The highest levels of total polyphenols and chlorogenic acid were observed in non-irrigated and broadcasted tubers. Drip-irrigated and N-fertigated tubers exhibited high levels of vitamin C and antioxidant activity. In summary, the combination of drip irrigation with appropriate fertilization methods positively influenced potato crops, as evidenced by an increase in productivity and the quality of tubers.

Potato tuber yield and quality under potassium and magnesium addition on top of the nitrogen and phosphorus fertilization

The aim of the study to investigate the effect of individual or combined K and Mg addition on potato tuber yield and quality along the gradient of soil and environmental conditions, which was formed by the five experimental plots in the forest-steppe one of West Siberia. Location and time of the study. Microplot field experiment with moderately early potato cultivar Jelly with three fertilization treatments (N100P60, N100P60+K100 and N100P60+K100+Mg100) was setup in five replicates on five experimental plots with agricultural grey soils in the Novosibirsk Region in 2023. Geographical coordinates of the experimental sites varied from 55°15'40" to 54°47'09" NL and from 83°31'42" to 82º37' 56" EL. Methods. Instead of traditional temporal gradient (3–4 years of the experiment at a site) to account for weather variation, with the same purpose we used a spatial gradient, which in addition allowed to assess the effect of soil properties variation among the sites. Soil samples, collected prior to the experiment, were analyzed for organic carbon content, nitrate and ammonium nitrogen, exchangeable phosphorous, potassium and magnesium, as well as soil pH and electrical conductivity. In the course of the experiment air and soil (at 5 and 15 cm depth) temperatures was automatically recorded. At the end of the experiment potato tuber mass and number, as well as the aboveground phytomass, were measured at each microplot. After five months of tuber storage sensory properties (flavour, aroma, colour, mealiness and friability) of boiled tubers were assessed using a Hedonic scale. Analysis of variance, principal components extraction and multiple regression by partial least squares method were performed using Statistica v. 13.1. software. Results. Addition of K at the background NP fertilization (N100P60+K100 treatment) increased tuber yield by 30% and the aboveground phytomass by 40%. Addition of Mg (N100P60+K100+Mg100) did not affect yield properties, but markedly improved potato culinary quality. More than half of the variance of the potato yield properties was accounted for by the variation in soil and environmental conditions of the experimental fields location. Exchangeable Mg, ammonium N and soil pH were the main soil properties, allowing to forecast the current year tuber yield. The contribution of soil and environmental conditions of the experimental fields into the variance of the sensory properties, albeit small, was statistically significant (p≤0,05) for aroma and colour, with the similar trend for flavour and friability (0,05≤p≤0,10). Agrochemical properties, i.e. soil organic carbon, readily exchangeable P and nitrate N contents, as well as soil pH, were the main variables, determining tuber quality for consumers. Conclusions. The study performed on the agricultural grey soil in the forest-steppe zone of West Siberia confirmed the importance of optimizing potato mineral nutrition. Addition of NPK at the balanced rates significantly increased potato yield as compared with NP. Although addition of MG together with NPK did not increase the yield, it markedly improved sensory properties of potato. Some soil properties and temperature conditions, found to determine the yield (effective soil fertility), can be used in prognostic models for potato tuber yields and quality.

The Application of Multiple Linear Regression and Artificial Neural Network Models for Yield Prediction of Very Early Potato Cultivars before Harvest

Yield forecasting is a rational and scientific way of predicting future occurrences in agriculture—the level of production effects. Its main purpose is reducing the risk in the decision-making process affecting the yield in terms of quantity and quality. The aim of the following study was to generate a linear and non-linear model to forecast the tuber yield of three very early potato cultivars: Arielle, Riviera, and Viviana. In order to achieve the set goal of the study, data from the period 2010–2017 were collected, coming from official varietal experiments carried out in northern and northwestern Poland. The linear model has been created based on multiple linear regression analysis (MLR), while the non-linear model has been built using artificial neural networks (ANN). The created models can predict the yield of very early potato varieties on 20th June. Agronomic, phytophenological, and meteorological data were used to prepare the models, and the correctness of their operation was verified on the basis of separate sets of data not participating in the construction of the models. For the proper validation of the model, six forecast error metrics were used: i.e., global relative approximation error (RAE), root mean square error (RMS), mean absolute error (MAE), and mean absolute percentage error (MAPE). As a result of the conducted analyses, the forecast error results for most models did not exceed 15% of MAPE. The predictive neural model NY1 was characterized by better values of quality measures and ex post forecast errors than the regression model RY1.

Biological and Agrotechnical Aspects of Weed Control in the Cultivation of Early Potato Cultivars under Cover

Problems with weed infestation under cover were the reason to conduct research on the regulation of weed infestation in potato cultivation for early harvest. The field experiment was carried out in 2015–2017 at the Experimental Station for Cultivar Assessment in Uhnin (51°34′ N, 23°02′ E) using the method of random subblocks, in a dependent system (split-split-plot). The first order factor was edible potato cultivars ‘Denar’ and ‘Lord’. The second order factor was cultivation technologies: (A) traditional technology, (B) technology using polyethylene film cover, (C) technology using polypropylene agrotextile. The third order factor was weed management methods: (1) mechanical, (2) mechanical and chemical method using Afalon Dispersion 450 SC preparation, (3) mechanical and chemical methods using Racer 250 EC herbicide, and (4) mechanical and chemical methods using a mixture of herbicides Afalon Dispersion 450 SC and Command 480 EC. Mechanical and chemical methods proved to be more effective than the mechanical method. The best effectiveness in limiting both fresh and dry weed mass in potato cultivation under cover was achieved using the mechanical and chemical method using a mixture of herbicides, Afalon Dispersion 450 SC and Command 480 EC.

Effect of Plant Biostimulants on Macronutrient Content in Early Crop Potato Tubers

This paper analyzes the effects of the foliar application of the seaweed extracts Bio-algeen S90 (Ascophyllum nodosum) and Kelpak SL (Ecklonia maxima), as well as the humic and fulvic acids in HumiPlant (leonardite extract) on the macronutrient content in tubers of very early potato cultivars (‘Denar’, ‘Lord’, ‘Miłek’) and their ionic ratios. The field experiment was carried out in central-eastern Poland over three growing seasons, using Haplic Luvisol. The biostimulants were applied according to the manufacturers’ recommendations. Potatoes were harvested 75 days after planting. The use of biostimulants increased potassium (K) content in tubers, on average, by 1.26 g∙kg−1 of dry matter compared with the untreated control tubers. Bio-algeen S90 did not affect the phosphorus (P) content in tubers, whereas Kelpak SL and HumiPlant reduced the phosphorus content, on average, by 0.063 g∙kg−1 of dry matter. The biostimulants did not affect calcium (Ca), magnesium (Mg), or sodium (Na) content in tubers. The use of biostimulants resulted in an increase in the mass ratios of K+:Ca2+, K+:Mg2+, and (K+ + Na+):(Ca2+ + Mg2+) in early crop potato tubers, compared with the untreated control tubers, but did not affect the mass ratios of Na+:Ca2+ and Na+:Mg2+ or the mass ratio of Ca:P. The macronutrient content in early crop potato tubers and their ionic ratios depended on the cultivar and environment conditions.

Productive and Physiological Response of Organic Potato Grown under Highly Calcareous Soils to Fertilization and Mycorrhization Management

The enhancement of the actual low yields is the most important challenge regarding organic farming management. In this view, a valid tool may arise by the improvement of fertilization management and efficiency. In this regard, arbuscular mycorrhizal fungi (AMF) can play an important role, especially in low fertility soils such as calcareous ones, through a better nutrient uptake and by alleviating abiotic stresses. A replicated-space experiment was carried out to investigate the role of mycorrhizal-based inoculants combined with full or halved fertilizer doses on yield and physiological traits of three early potato cultivars organically grown in highly calcareous and alkaline soils. The results indicate that AMF symbiosis ameliorated, in comparison to the not-inoculated plants, the potato tolerance to limestone stress by enhancing the potential quantum efficiency of photosystem II (Fv/F0) and plant gas-exchange parameters (photosynthesis rate and stomatal conductance). Moreover, a significant improvement of marketable yield (+25%) was observed, mainly due to an increase of the number of tubers plant−1 (+21%) and, to a lesser extent, of average tuber weight (+10%). The AMF efficiency was higher applying halved fertilizer doses and in the location where soil conditions were unfavourable for potato growth. Moreover, the qRT-PCR highlighted that AMF colonization was similar in each location, demonstrating their tolerance to limestone, alkalinity and P stresses. These findings outlined that AMF are good candidate to bio-ameliorate calcareous soils and are very useful for improving potato yields under organic farming, limiting external fertilizers supply and environmental pollution.

Quality of New Potatoes (Solanum tuberosum L.) in Response to Plant Biostimulants Application

Background: In sustainable crop production focusing on high-value products, biostimulants have been gaining increasing importance, thus the hypothesis that plant biostimulants could contribute to improving new potatoes quality; Methods: The effects of the seaweed extracts Bio algeen S90 (Ascophyllum nodosum) and Kelpak SL (Ecklonia maxima), as well as the humic and fulvic acids in HumiPlant (leonardite extract) on the tuber quality of very early potato cultivars (‘Denar’, ‘Lord’, ‘Miłek’) were investigated. Potatoes were harvested 75 days after planting (the end of June); Results: The biostimulants did not affect dry matter, protein, total sugars, monosaccharides and sucrose or L-ascorbic acid content in new potatoes. Bio-algeen S90 increased the starch content in tubers of all potato cultivars tested, on average, by 4.8 g∙kg−1 compared with control treatment without biostimulant, whereas Kelpak SL and HumiPlant reduced nitrates content only in tubers of ‘Denar’ cultivar, on average, by 8.50 mg∙kg−1, and increased ascorbate-nitrate index (IAN) by 0.29. The biostimulants did not affect potato after-cooking darkening. Both the nutritional value of new potatoes and after-cooking darkening depended on the cultivar and weather conditions during the potato growing period to a great extent; Conclusions: Plant biostimulants slightly affected quality of new potatoes.

Changes in Assimilation Area and Chlorophyll Content of Very Early Potato (Solanum tuberosum L.) Cultivars as Influenced by Biostimulants

This paper analyses the effects of foliar application of the seaweed extracts Bio-algeen S90 (Ascophyllum nodosum) and Kelpak SL (Ecklonia maxima), as well as the humic and fulvic acids ini HumiPlant (leonardite extract), on the assimilation area and chlorophyll content of very early potato cultivars (‘Denar’, ‘Lord’, Miłek’). The field experiment was carried out in central-eastern Poland over three growing seasons, using Luvisol. The biostimulants were applied according to the manufacturers’ recommendations. The use of biostimulants resulted in enlargement of the assimilation area, but had no effect on the specific leaf area (SLA) or chlorophyll content (Soil Plant Analysis Development (SPAD) value). The assimilation area was larger, on average, by 0.0505 m2 and leaf area index (LAI) was higher by 0.30 compared with the plants from the control group without a biostimulant. The SLA and SPAD depend on the cultivar and weather conditions, or nitrogen and magnesium content in soil, to a greater extent. The biostimulants enhanced abiotic stress tolerance and increased marketable tuber yield (diameter above 30 mm) 75 days after planting (the end of June), on average by 2.15 t·ha−1. Bio-algeen S90 and Keplak SL produced better results in a warm and very wet growing season, whereas HumiPlant produced better results in a year with lower air temperature and with drought periods during potato growth. No correlations were found between the tuber yield and assimilation area or between the tuber yield and SPAD value, although a significant negative correlation was found between the tuber yield and SLA.

The Use of the WOFOST Model to Simulate Water-Limited Yield of Early Potato Cultivars

In this work, an attempt was made to use the WOFOST (WOrld FOod Studies) model to simulate the potential and water-limited yield of early potato cultivars Lord and Denar. Data from cultivar experiments carried out at the Polish Research Centre for Cultivar Testing in 2004–2013 were used in the study. The Lord cultivar yielded 22.4–67.8 t fresh tuber weight per ha and 3.8–11.5 t ha−1 dry tuber weight during the study period. The highest tuber yields (over 10 t ha−1 dry weight) were obtained in 2009, 2011 and 2012, and the lowest in 2005 (3.8 t ha−1) and 2006 (2.65 t ha−1). The water-limited tuber yield simulated by WOFOST ranged from 3.6 to 10.9 t ha−1 dry weight and was about 0.45 t ha−1 higher on average than the actual yield. The planting period each year was between days 104 and 120 of the year, and harvesting took place between days 216 and 232. Water availability was a factor limiting the yield. The yield limited by water deficiency was 38.7% lower (irrespective of the cultivar) than the potential yield. The WOFOST model was sensitive to water deficiency, and the simulated (water-limited) yields were close to the actual yield or showed a clear downward trend indicating evident rainfall shortages in 2005 and 2006.

Możliwość zwiększenia plonu ziemniaków wczesnych przez stosowanie dolistne ekstraktów z wodorostów i kwasów huminowych

Under climate change conditions, biostimulants play an important role in plant adaptation to abiotic stress. This paper analyses the effect of the seaweed extracts Bio-algeen S90 (Ascophyllum nodosum) and Kelpak SL (Ecklonia maxima) and humic and fulvic acids HumiPlant (leonardite extract) on early crop potato yield and yield components. Three very early potato cultivars Denar, Lord and Miłek were tested. Biostimulants did not affect the number of tubers produced by potato plants but increased the tuber weight per plant and average tuber weight and, as a result, the tuber yield. The yield-increasing effect of biostimulants depended on the hydro- thermal conditions during potato growth. Bio-algeen S90 and Kelpak SL produced better results in a warm and very wet growing season, whereas HumiPlant produced better results in a year with lower air temperature and with drought periods during potato growth. The use of biostimulants in early crop potato culture assured higher yield under abiotic stress conditions, and also contributed to improving its marketable value by an increase in the productivity of the marketable-size tubers and, simultaneously, decreasing the share of large tubers with a diameter above 50 mm. The tested potato cultivars showed a similar response to the biostimulants applied.

Nitrates content in table potato tubers under the influence of herbicides and biostimulants

ABSTRACTThe objective of the study was to determine the effect of herbicides and biostimulants on the potato tuber content of nitrates. The experimental material consisted of tubers harvested in a field experiment which examined the following factors: three medium early potato cultivars (Bartek, Gawin, Honorata) and five methods of herbicide and biostimulant application (Harrier 295 ZC (linuron + chlomazon), Sencor 70 WG (metribuzin), growth regulator Kelpak SL (algae extract from Ecklonia maxima − auxins and gibberellins), growth regulator Asahi SL (sodium para-nitrophenol, sodium ortho-nitrophenol, sodium 5-nitroguaiacol) and a control unit where weeds were mechanically controlled). The tuber content of nitrates was determined in fresh matter with an ion-selective nitrate electrode and silver–silver chloride reference electrode. Herbicides and biostimulants increased the potato tuber content of nitrates compared with control tubers. However, they did not pose a threat to consumer health. Tubers of plants sprayed with the herbicide Sencor 70 WG (metribuzin) and the biostimulant Asahi SL (sodium para-nitrophenol, sodium ortho-nitrophenol, sodium 5-nitroguaiacol) contained the most nitrates whose accumulation was also affected by cultivars and weather conditions in the study years.

The effect of different production systems on the content of micronutrients and trace elements in potato tubers

ABSTRACTThe aim of this study was to determine the effect of different production systems (conventional, integrated and organic) on the content of micronutrients and trace elements in the tubers of very early, early and medium-early maturing potato cultivars. Five Polish potato cultivars were grown in three production systems under field conditions. In plant material selected microelements (chemical elements essential for living organisms) were analysed: boron (B), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) as well as some trace elements (not regarded as essential element for living organisms): chromium (Cr), nickel, (Ni) and lead (Pb). The content of micronutrients and trace elements in potato tubers was modified by production system, genotype and weather conditions during the growing season. Organically grown potatoes had a higher content of B (8.6–8.9 mg kg−1) and Cu (2.8–3.1 mg kg−1), and a lower content of Fe (47.0–47.1 mg kg−1), Mn (6.0–6.4 mg kg−1) and Zn (11.9–12.2 mg kg−1), than potatoes grown in conventional and integrated systems. Potatoes grown in the conventional system had the highest Pb content. Organic cultivation can assure better alimentation of potato tubers with B and Cu, which are important microelements often deficient in the soils. On the contrary, when cultivating potato in conventional system, one should supply this element with fertilisers.

The effect of sous vide packaging with rosemary essential oil on storage quality of fresh-cut potato

Selection of suitable raw materials and technologies are essential for the fresh-cut segment, since they represent key factors to be competitive in the modern markets. This study aimed at assessing the suitability of six early potato cultivars, grown in an experimental field, for minimal processing. In particular, the sous vide packaging method, in association with rosemary essential oil (REO), was evaluated as a strategy for the quality preservation of sliced potatoes. Physical, mechanical, chemical, microbiological and sensory characteristics were monitored in order to estimate qualitative changes of the product over refrigerated storage. Results demonstrated that the synergic use of REO and sous vide packaging had a positive effect on texture, and limited the growth of mesophilic bacteria and Enterobacteriaceae over the storage period; it also ensured a certain retention of ascorbic acid, total polyphenol content, and antioxidant activity. Hence, the proposed technological strategy could represent a valid solution for the preservation of sliced potatoes, contributing to limit, for the most suitable cultivars identified as Fontane and Marabel, the quality decrease until 11 days of cold storage.

Wpływ Tytanitu na zawartość suchej masy i makropierwiastków w bulwach ziemniaka

This paper analyses the effect of the dose (0.2 L*ha-1 or 0.4 L*ha-1) and date (a single application at the leaf development stage – BBCH 14-16 or at the tuber formation stage – BBCH 41-43, and a double application at the BBCH 14-16 and BBCH 41-43 stages) of the application of Tytanit® (8.5 g Ti per liter in the form of Ti-ascorbate) on the dry matter and macroelement contents in tuber of very early potato cultivars (‘Lord’ and ‘Milek’). Potatoes were harvested 75 days after planting (the end of June). Tytanit® did not affect the content of dry matter and nitrogen, phosphorus, potassium, calcium, magnesium or sulphur in potato tubers. Following Tytanit® application, there was only an increase in sodium content. The sodium content in the immature potato tubers was higher after the application of 0.2 L*ha-1 of the Tytanit®. Regardless of the Tytanit® dose, the sodium content in tubers was the lowest when the growth stimulant was applied only once in the leaf development stage (BBCH 14-16), particularly under the more favorable thermal and moisture conditions for early crop potato culture. Following Tytanit® application, the weight ratios of Ca:P, K:Ca and K:Mg in potato tuber were similar, and the weight ratios of N:S, Na:Ca and Na:Mg were broader compared to the cultivation without the growth stimulant, although the ratio of the sum of univalent cations to the sum of bivalent cations (K+Na):(Ca+Mg) was at the same level, both in the cultivation with and without Tytanit®.

English

In this work, we studied agro-morphological parameters that could be used to define variaton among early, mid-early, mid-late and late potato cultivars, cropped in the main season by quantitaive and qualitative parameters (characters of mother tubers, vegetation cover, height of plants, number of leaves, number of true leaves, number of stems, number of stolons, lenght of first stolon, median diameter of first stolon, caliber of first tuber, final number of tubers per plant and final yield per plant). For the main agro-morphological characters, there were a great variation compared to the control Spunta. Challenger and Fabula showed the heighest caliber of mother tubers (49.16 mm), while heighest weight of seed tubers was determined on cv. Alegria (125.7 g). Among other characters, challenger produced the largest leaf area (9940.3 mm²). Panamera cultivar has considerable plant height (13.77 cm), the heighest number of leaves per plant (63.33) and also the heighest number of true leaves (48.48). Moreover, Panamera has the largest lenght of first stolon with 8.66 cm, (6.16 cm for Spunta). It has also the largest value of median diameter of first stolon with 2.17 mm and followed by Mondial (2.23 mm), Bellini (1.63 mm) and Liseta (2.01 mm). The difference among the cultivars in terms of median diameter of first stolon was statistically significant (P≤0.05). Liseta has the largest value of caliber of first tuber (37.4 mm), followed by Bellini (37.71 mm), while, Spunta has presented the lowest measures (13.36 mm). For final yield per plant, Bellini outyielded other cultivars with 0.96 kg per plant. Key words: Potato cultivars, earliness character, variation, agro-morphology, main season.

BREEDING ASPECTS OF POTATO IN LITHUANIA

Potato (Solanum tuberosum L.) breeding and seed production in Lithuania is performed at Voke Branch of Lithuanian Institute of Agriculture. It was started in 1958. The main potato breeding object is to produce very early potato cultivars resistant to the nematodes and to the main potato diseases. As the result of breeding work eleven cultivars were produced: 'Meta', 'Vilnia', 'VB Aista', 'Nida', 'Mirta', 'Goda', 'VB Venta', 'Voke', 'VB Liepa', 'Vaiva' and 'VB Rasa'. The aim of the present work was to ascertain the resistance of Lithuanian potato varieties to the agent of potato blight Phytophthora infestans (Mont.) de Bary. The results have shown that potato varieties of different maturation time are unequally infected with potato blight. The disease spreading was more intense in early potato varieties, while in maincrop varieties the disease spreading was less intense. Other advantages - good yield, suitability for processing industry, excellent cookery qualities, good taste or attractive shape - were also the main items in producing of Lithuanian potato cultivars.

The effect of biological and chemical control agents on the health status of the very early potato cultivar Rosara

Abstract The external appearance and quality of table potatoes are determined, among other factors, by the health status of the plants during the growing season. Chemical control methods are often combined with biocontrol agents to effectively fight potato pathogens. Potatoes of the very early cultivar Rosara were grown in experimental plots. The plots were located in Tomaszkowo (NE Poland, 2007-2009). The experiment involved the following treatments: 1) biological control − mycorrhizal Glomus spp. inoculum was applied to the roots, − tubers were dressed and plants were sprayed with Polyversum three times during the growing season, 2) chemical control - at two-week intervals, plants were sprayed with the following fungicides: Infinito 687.5 SC and Tanos 50 WG, Valbon 72 WG and Tanos 50 WG. In the control treatment, potato plants were not protected against pathogens. During the growing season, the severity of late blight and early blight was evaluated on a nine-point scale. The composition of fungal communities colonising potato stems was analysed. The fungistatic properties of the fungicides used in the field experiment were evaluated in an in vitro test. The symptoms of infections caused by Phytophthora infestans and Alternaria spp. were significantly reduced in the treatment which used the integrated chemical and biological control. The least diverse fungal community was isolated from fungicide-treated plants. In the in vitro test, fungicides at all analysed concentrations inhibited the linear mycelial growth of selected pathogens.

Efekti stosowania nawozow kompleksowych w uprawie ziemniaka na wczesny zbior na glebie piaszczysto-gliniastej

To obtain a high tuber yield of early crop potato good conditions for plant growth must be ensured. Potato has a relatively shallow root system and requires significant nutrient inputs to maintain tuber productivity and quality. The paper presents the results of the research on the effect of complex fertilizers type NPK MgS with and without microelements from the nitrophoska (HydroComplex, Nitrophoska Blue Special and Viking 13) and the amophoska group (Polimag S), and single-nutrient fertilizers on the plant growth and tuber yield of very early potato cultivars (‘Aster’, ‘Fresco’, ‘Gloria’) on loamy sand soil. The field experiment was carried out in mideastern Poland (52°03'N, 22°33'E). Potatoes were harvested 75 days after planting (the end of June). The type of fertilizer (single-nutrient or complex fertilizer) slightly affected the growth of potato plants. With the use of complex fertilizers, the assimilation leaf area and leaf area index (LAI) were similar to the application of single-nutrient fertilizers. Of the examined complex fertilizers, Viking 13 (representing the nitrophoska group without microelements) resulted in a smaller increase of assimilation leaf area in comparison with the cultivation without mineral fertilization. The type of fertilizer exerted a greater influence on the plant growth of ‘Aster’ (Poland) than ‘Fresco’ (The Netherlands) and ‘Gloria’ (Germany). The productive effects of complex fertilizers in early crop potato culture on loamy sand soil were comparable with single-nutrient fertilizers. The highest tuber yield was achieved with the application of Nitrophoska Blue Special (from the nitrophoska group with the lowest NNH4+ concentration); the total tuber yield was higher on average by 2.94 t*ha-1 (21.0%) and the yield of marketable tuber fraction (diameter above 30 mm) by 2.55 t*ha-1 (20.4%) in comparison with the cultivation without mineral fertilization. Although the total tuber yield was a little lower, the share of large tubers (diameter above 51 mm) in the yield was recorded with the use of Polimag S (from the amophoska group and with the most Mg, S, Zn and B concentration of all complex fertilizers applied) and Viking 13 (from the nitrophoska group with Ca). The single-nutrient and complex fertilizers applied in the experiment had no effect on the dry matter, starch or Lascorbic acid content in potato tubers. Regardless of the type of fertilizer applied, the tuber yield, average weight of one tuber and the share of medium-sized tubers (diameter of 4150 mm) in the yield of ‘Aster’ were highest. The yield of marketable tuber fraction of the ‘Aster’ was higher than ‘Fresco’ and ‘Gloria’ on average by 3.03 t*ha-1 (22.0%) and 4.57 t*ha-1 (37.4%), respectively. About 25% of the ‘Gloria’ yield made up of non-marketable tubers (diameter below 30 mm). Tubers of ‘Aster’ contained more dry matter and starch than ‘Fresco’ and ‘Gloria’, however, the content of Lascorbic acid in tubers of the tested potato cultivars was similar.

Effect of organic and nitrogen fertilization on selected components in potato tubers grown in a simplified crop rotation

Fertilization is one of the factors of agro-technical practice that determines potato yield volume and quality. This research involved the early table potato cultivar Bila grown in the first year of the tenth (2006) and the eleventh rotation cycle (2009) in a long-term, static field experiment (set up in 1979). A three-year simplified crop rotation included potato – winter rye 1 – winter rye 2. The experimental factors covered: I organic fertilization (without FYM and with FYM at the amount of 30 t ha-1), II nitrogen doses 0, 60, 120, 180 kg N ha-1 under potato and 0, 40, 80, 120 kg N ha-1 under rye. The aim of the present research was to evaluate the yielding and content of selected chemical components of the tubers of cv. Bila potato grown in a simplified system depending on different organic and mineral fertilization regimes, implemented for many years. The results show a significantly positive effect of FYM and nitrogen fertilization on the tuber yield volume and on the content of total protein and magnesium, as well as a negative effect on the content of nitrates(V). However, FYM fertilization increased but nitrogen fertilization decreased the content of ascorbic acid. The highest nutritive value of tubers was achieved after the application of 60 kg N ha -1 . However, a dose higher than 120 kg N ha -1 applied with FYM increased the content of nitrates(V) above the toxicity threshold (200 mg NO3 ¯ kg -1 of the fresh product).

Effect of UV-B radiation on growth and antioxidative enzymes activity in Lithuanian potato (Solanum tuberosum L.) cultivars

The impact of ultraviolet-B (UV-B) radiation on most cultivated plants is negative. It reduces plant height and leaf area, increases leaf thickness and affects plant growth and development. The aim of this research was to compare the effects of UV-B on growth, photosynthetic pigments in potato cultivars and determine the activity of antioxidative enzymes in response mechanisms to the UV-B. Five Lithuania-bred potato (Solanum tuberosum L.) cultivars (three early, one medium and one late) were studied. The plants were treated with a UV-B radiation dose of 6 kJ m-2 d-1. The research demonstrated that after the UV-B exposure the plant height of early potato cultivars reduced. However, fresh and dry biomass of leaves, the concentrations of chlorophylls a, b and carotenoids in potato cultivars remained unchanged after UV-B exposure compared to the control. Increased activity of antioxidative enzymes in potato cultivars after the UV-B radiation suggested an active plant response to UV-B-induced stress which depended on the plant genotype.