In greenhouses, artificial lighting is applied in winter and early spring as supplementary light source to increase photosynthesis and plant growth. The objective of this study was to evaluate the cultivation of sweet pepper transplants under LED lamps that were developed to supplement HPS lamps used in greenhouses. The experiments were carried out in the greenhouses at the Lithuanian Research Centre for Agriculture and Forestry Institute of Horticulture. Sweet peppers (Capsicum annuum) L. cultivar ‘Reda’ and the hybrid ‘Figaro’ F1 were used for investigation. Four types of solid-state lamps were used with light-emitting diodes (LEDs) with peak emissions at blue 455 nm and 470 nm, cyan 505 nm, and green 530 nm. PPFD of each type of LED lamp was 15 μmol m^-2 s^-1, and the PPFD of HPS lamps was 90 μmol m^-2 s^-1. The reference transplants were grown under the illumination of HPS lamps (110 μmol m^-2 s^-1). The photoperiod of artificial lighting was maintained at 18 hours. Our experiments revealed different responses to supplemental LED lightings between the cultivar and the hybrid. The supplemental 470 nm illumination with HPS lamps mostly resulted in increases in the following areas: leaf area, fresh and dry weight, and the photosynthetic pigment content of the sweet pepper ‘Reda’ transplants. A similar positive effect was determined using supplemental 455 and 505 nm LED lights. However, the supplemental green 530 nm LED lights had no effect on growth, and they inhibited the development of the sweet pepper ‘Reda’ transplants. The HPS light had a positive effect on the growth parameters of the ‘Figaro’ F1 transplants, but all of the supplemental LED lights suppressed their growth and development.

Efficiency of arbuscular mycorrhizal fungi (AMF) to host plants depends mainly on the chemical composition and properties of the rhizosphere. This is especially important in soilless cultures, in which the amount of nutrients supplied to the rhizosphere has to be strictly controlled. The effect of AMF and two nutrient solution concentrations: standard (S) with average EC 2.6 mS·cm^-1 and reduced (R) with average EC 1.9 mS·cm^-1, on the yielding and chemical composition of fruit and leaves of tomato, was investigated. Tomato plants cultivar ‘Admiro F₁’ were cultivated in greenhouse with fertigation system in rockwool and straw medium in 2012–2013 years. In the research, no effect of AMF on the total and marketable yield as well as on number of fruit per plant, was detected. A significant lower marketable yield in treatments fertigated with standard nutrient solution (S), compared to reduced solution (R) was detected, which was the effect of smaller number of fruits. Fruits of tomato inoculated with AMF contained significantly more sugars as compared to plants growing without mycorrhization. Significant higher dry matter content was detected in fruit of tomato fertigated with standard nutrient solution (S), compared to reduced solution (R). More total nitrogen was recorded in leaves of plants mycorrhized with AMF, although this increase was not statistically confirmed in every treatments. More calcium was determined in fruits of tomato inoculated with AMF as compared to those harvested from non-mycorrhized plants.

In this paper we report the research on the effect of the different light in vitro conditions on growth and development of interspecific hybrid Cattleya intermedia × C. aurantiaca (Orchidaceae) maintained as stock in vitro shoot culture. Callus was obtained from shoots explants on initiation medium which was composed of MS mineral salts and vitamin set, supplemented with 30 g l^-1 sucrose, 2.0 mg dm^-3 adenine sulphate, 9.7 mg dm^-3 ascorbic acid, with addition of 1.0 µM TDZ, whereas callus maintenance medium was instead supplemented with 4.95 µM BA, and 1 µM NAA. Proliferating protocorm-like bodies (PLBs) of that precious plant material were exposed to the irradiation with monochromatic light characterized by different wavelength. Some interesting lines have been obtained on white, blue, red, far red, and ultraviolet light respectively, which proved to be diversified in the proliferation rates as well as in the morphological and anatomical features. The light treatment also significantly affected regenerative potential of studied culture. Blue light applied during two subsequent culture passages was proved to be the best option in order to regenerate shoots via PLBs. Nevertheless blue, red and far red irradiation of cultures led to distinctive reduction in the content of chlorophyll and carotenoid pigments, compared with culture irradiated with either white or ultraviolet light.

In Poland sweet maize is a small-acreage crop, and because of this no complex plan for the protection of this plant against pests and other harmful organisms has been developed. Since the enforcement of integrated pest management (IPM) in the EU in 2014 the use of chemical control methods has to be supported by relevant data on the biology of the controlled pest. A very limited number of studies have been carried out in Poland on the harmful entomofauna of sweet maize, including aphids. Studies were carried out in 2009–2014 on a field of sweet maize (Zea mays L. var. saccharata), ‘Candle’ cultivar, in south-eastern Poland. In the study years the infestation with aphids was from very low to moderately high. Seven aphid species were identified on sweet maize. The above-ground plant parts were infested with Rhopalosiphum padi L., Metopolophium dirhodum Walk., Sitobion avenae F., Rhopalosiphum maidis Fitch., Aphis fabae Scop. and Myzus persicae Sulz. A small number of individuals representing Tetraunera ulmi L. were found on the root systems of plants. R. padi was the dominant aphid species in all study years. M. dirhodum and S. aveane occurred in lower numbers, while other aphid species formed single colonies. Aphids began to infest maize plants from the last ten days of April or from May, and ended feeding at the end of September or in the first half of October. Two or three peaks of mixed-species aphid populations were observed on sweet maize plants, with the first peak being the most abundant. Individual aphid species had from one to three population peaks on plants, but the general dynamics of insect occurrence was affected mainly by the two most abundant species: R. padi and M. dirhodum.

Drought is one of the most common limiting environmental factors affecting plant growth and productivity. Strawberry is a plant of large demand for water along with a high susceptibility to drought. In the present study, the response of three strawberry cultivars (‘Elsanta’, ‘Honeoye’, ‘Grandarosa’) grown under greenhouse conditions to water deficiency was examined by evaluating the yield and morphological (leaf and root development) and physiological (leaf gas exchange, leaf water potential) parameters. Plants were subjected to two different water regimes: optimal irrigation (control, water potential in the growing medium was maintained at the level of -10 kPa), and reduced irrigation (stress treatment, water potential in the growing medium was maintained at the level of -30 kPa). Genotypes differed in their response to water deficiency. Cultivar ‘Elsanta’ presented high rates of net photosynthesis with high value of water use efficiency (a ratio of photosynthetic rate to transpiration rate) under water shortage conditions. Water stress affected plant vigor. The weight and total leaf area of the stressed ‘Honeoye’ plants were considerably reduced as compared to these of the control. No significant differences in weight and root length were observed between the well-irrigated and stressed ‘Elsanta’ plants, while the root development in two other cultivars was retarded. Under water deficiency conditions ‘Elsanta’ gave the highest yield whereas ‘Honeoye’ the lowest. Among examined cultivars, ‘Elsanta’ appeared to be more drought tolerant which was reflected by both growth and yield parameters.

A two years’ field study was conducted to compare the influence of perennial ryegrass (Lolium perenne L.), white clover (Trifolium repens L.), perennial ryegrass + white clover mixture and mowed weeds used as living mulches with the influence of linuron 675 g∙ha^-1 on weed infestation and yield of carrot (Daucus carota L.) ‘Flakkese 2’ under ridge cultivation. Living mulches did not affect growth of weeds during first five weeks after carrot sowing and they reduced weed infestation significantly at the end of vegetation period. Living mulches and mowed weeds caused decrease of total and marketable yield of carrot roots and in a less degree also decrease of carrot leaves fresh weight. Share of roots damaged by insects and snails and with disease symptoms in nonmarketable yields harvested on plots covered with living mulches and mowed weeds was smaller and share of bifurcated roots and roots with diameter < 20 mm was bigger than that on plots sprayed with linuron 675 g∙ha^-1. Mowed weeds were less useful as a living mulch under carrot ridge cultivation than perennial ryegrass, white clover and perennial ryegrass – white clover mixture.

The aim of this study was to assess the growth and development of plants of three strawberry cultivars fertilized with selected biofertilizers under greenhouse conditions. The experiments were conducted in a greenhouse complex of the Research Institute of Horticulture in Skierniewice from February to July in 2013 and 2014. Plants of three strawberry cultivars, ‘Elsanta’, ‘Honeoye’ and ‘Elkat’, were planted in rhizoboxes and grown under the following fertilization regimes: 0-control (no fertilization), NPK control, Micosat F (bacterial-mycorrhizal substrate), manure, Humus UP, and Vinassa. Applications of Humus UP resulted in beneficial effects on plant height, leaf surface area, leaf fresh and dry weight, the degree of mycorrhizal colonization in the roots, and on the number of spores of arbuscular mycorrhizal fungi in the rhizosphere of strawberry plants. Biopreparations Humus UP and Vinassa also had a positive influence on the size of the root system, the total number of bacteria, including spore-forming bacteria, and the total number of filamentous fungi in the rhizosphere soil, compared with mineral NPK fertilization under greenhouse conditions.

The practice of simultaneous biofortification (enrichment) of plants with iodine (I) and selenium (Se) is based on solid grounds. Their low content in soils is the cause of an endemic deficiency of I and Se in several billion people worldwide. There is still no objective information as to the impact of I and Se interactions on mineral nutrition of plants. The study (conducted in 2012–2014), included soil fertilization of the lettuce cv. ‘Valeska’ in the following combinations: control, KI, KIO₃, Na₂SeO₄, Na₂SeO₃, KI + Na₂SeO₄, KIO₃ + Na₂SeO₄, KI + Na₂SeO₃, KIO₃ + Na₂SeO₃. I and Se were applied twice: before sowing and as top-dressing (each 2.5 kg I·ha^-1 + 0.5 kg Se·ha^-1) – a total dose of 5 kg I·ha^-1 and 1 kg Se·ha^-1 was used. Fertilization with Na₂SeO₄, KI + Na₂SeO₄ and KIO₃ + Na₂SeO₄ considerably reduced the dry matter yield of the plants – it also lowered the content of P, K, Mg, Ca, B, Zn and Cd in the lettuce. Fertilization with Na₂SeO₃, KI + Na₂SeO₃ and KIO₃ + Na₂SeO₃ had a less negative impact on dry matter yield than the use of Na₂SeO₄ – every year it affected the mineral content in the lettuce in a highly varied manner. Dry matter productivity of the plants after fertilization with KI and KIO₃ varied between the research years – in those plots, I content in lettuce was negatively correlated with the content of K, Mg, Ca, S, Na, B, Cu, Fe, Mn, Zn, Cd and Pb. Combined fertilization with KI and KIO₃ with Na₂SeO₄, and with Na₂SeO₃ reduced the negative correlation between I content (in the KI and KIO₃ plots) and the content of K, Mg, Ca, S, Na, B, Cu, Fe, Mn, Zn, Cd and Pb. After fertilization with Na₂SeO₄, Se content was positively correlated with Na content and negatively correlated with the content of Mg, Ca, Fe, Mn and Cd. Se content in the lettuce after fertilizing exclusively with Na₂SeO₃ was positively correlated with the content of P, K, Na, Mn, Mo and Zn. The changeable climatic conditions “disguised” the influence of fertilization with I and Se on the mineral composition of the lettuce plants.

The impact of the addition of indole-3-acetic acid (IAA) to three commercial growing media and three self-prepared growing media on rooting of cuttings of two ornamental plants: Hydrangea L. and poinsettia Euphorbia pulcherrima ‘Prestige Early Red’ was evaluated. According to the assessment of root system, length of roots, fresh and dry mass of roots, percentage of rooted cuttings the best rooting of cuttings of Hydrangea L. in Ceres and GM2 and of Euphorbia pulcherrima in Klasmann Steck Medium, GM2 and GM3 independent of the doses of IAA was observed. The addition of 200, 300 and 400 µg kg^-1 IAA for GM2 and GM3 improved some of the parameters rooted cuttings of Euphorbia pulcherrima. The worst assessment of root system and percentage of rooted cuttings for both ornamental plants with the lowest pH in GM1 as compared to other growing media was shown. Furthermore, 400 µg kg^-1 addition of IAA for Klasmann Steck Medium caused significant on higher length of roots and dry mass of roots of Euphorbia pulcherrima.

The bacterium Xanthomonas campestris pathovar campestris (Xcc) as the causal agent of black rot of cruciferous plants causes considerable losses in agricultural yield all over the world. The control of black rot is difficult as well as the determination of Xcc on the basis of morphological parameters or by pathogenicity testing. Ten different possibilities for extraction bacterial DNA followed by PCR detection method were tested to optimize PCR protocol. On the basis of ISTA validated method, three sets of primers UBP 1052F-BACR, DLH 120-125 and ZUP 2309-2310 were used. The results of measured concentration and quality of DNA and efficacy for PCR amplification were compared. Finally, three approaches for DNA extraction within Xanthomonas campestris pv. campestris detection protocol were recommended – commercial kits used for isolation from tissues by Macherey-Nagel and MO BIO and kit intended for microbial cultures by MO BIO.

The main aim of the study was to investigate the viability of pollen of a boreal relict, Salix lapponum, an endangered species in Poland as well as to evaluate the possibility to introduce the plant into a tissue culture. Two approaches were taken to estimate pollen viability: staining pollen with dyes and in vitro germination assay. The study results showed high pollen viability of the species, with regard to both fresh pollen and pollen stored for 12 months. The effectiveness of pollen tube growth was also found to be largely dependent on glucose content in a medium and thermal conditions. The study results have provided necessary information on the most optimal combinations for pollen germination of boreal willow in artificial conditions. The research on tissue culture initiation of S. lapponum was also undertaken. The most contamination free explants were obtained, when the shoot pieces had been soaked in a solution of fungicides, followed by the dip in 70% alcohol and surface disinfected in 2% NaOCl for 30 minutes. The most good quality shoots were obtained on the MS media supplemented with 0.1 mg·dm^-3 BA and 0.01 mg·dm^-3 IBA.

The living mulch is one of the orchard floor weed control option suitable for the organic production, which especially adds orchard biodiversity. The covering plant competes with the fruit tree, what can result in the reduced growth and yield. At the Fruit Experimental Station of the Wrocław University of Environmental and Life Sciences, in a young apple orchard mulched with blue fescue (Festuca ovina L.), the growth, cropping, and fruit quality were evaluated. In spring 2009, trees of the ‘Ligol’ cv. budded on the M.9, M.26, and P 60 rootstocks were planted, and in the following four years (2010–2013) blue fescue was being sown in the tree rows. Prior to the introduction of the living mulch, a herbicide fallow was maintained. The sowing of blue fescue as early as in the second year following the tree planting caused a significant decrease of the total yield per tree obtained in the first four years of the cropping. On the other hand, it contributed to an improved coloration of the fruits. Postponing of the cover plant sowing until the third and fourth year following the orchard establishment mitigated the negative influences of the living mulch on the tree growth and yielding, as well as on the fruit quality. As in addition blue fescue satisfactorily protects the soil from weed occurrence, its application in form of a late-sown living mulch could be considered as a promising alternative to the herbicide fallow.

Repeated cultivation of caraway in the same agricultural regions creates favorable conditions to develop infectious diseases which reduce the quantity and quality of the herbal material. The aim of the present research was to determine the composition of fungi species colonizing different organs of caraway variety Konczewicki. Observations of plant healthiness were carried out, in the years 2011–2013, on plantations in the region of central and eastern Poland. The one-spore cultures of fungi were identified with good results on PDA or on standard media. A new fungus species Mycocentrospora acerina was detected for the first time in Poland. The fungus causes necrotic spots on the above-ground and underground parts of plants. An epidemic of caraway septoriosis caused by Septoria carvi occurred in the central region of Poland, during the hot and humid weather. At temperature reaching up to 28°C and low relative humidity an epidemic of powdery mildew Erysiphe heraclei appeared. Moreover, growing threat for caraway by Colletotrichum spp., causing anthracnosis as well as by soil fungi, i.e. Sclerotinia sclerotiorum and Rhizoctonia solani was shown.

Dahlia, together with chrysanthemums and tulips, is one of the most beautiful and the most willingly cultivated perennials in green areas and home gardens. Therefore, the producers seek for more effective methods of its propagation. In the years 2011–2014 in the Felin Experimental Farm of the University of Life Sciences in Lublin the research was undertaken to estimate the crowns efficiency of four Polish border dahlia cultivars. The tubers were taken out from storage in early spring, then planted in trays filled with peat and placed on the tables in a glasshouse. The soft stem cuttings snipped off from the sprouts arising from tubers were used for experiments which aim was to evaluate the quality of four types of rooted soft cuttings. It was stated that the number of sprouts appearing in spring on a mother plant depended on a cultivar and a season. Tubers of ‘Krynica’ and ‘Halinka’ cultivars formed the most sprouts. The most effective were crowns from which apical cuttings were snipped off (90–115) pieces from the 10th of February till the 20th of April. The number of soft stems that were used to obtain cuttings ‘with heel’, ‘without heel’ and 2-node’ ones ranged on average from 50 to 80 per season. The best quality rooted cuttings, in terms of a fresh weight, number of leaves and a fresh weight and number of roots, were the heel cuttings.