Three cultivars of Hyacinthus orientalis L. were forced in pots under artificial light using fluorescent lamps which emitted white, blue, green, yellow and red light. Daily light dose was 0.54 mol·m^-2 (25 μmol·m^-2·s^-1 × 6 h). Significant effect of light colour on postharvest longevity and quality of plants was observed. The post-harvest longevity of hyacinths depends, among others, on the length of the flowering period and it is the longest after the application of white and blue light colour. Red light decreased flower life and deteriorated the ornamental value. The rigidity of inflorescence shoots depended on the cultivar, but in all flowers, it was significantly lower than it is recommended in market turnover for flowering plants grown in pots. It also refers to leaves, whose elongation is the greatest under lamps with red colour. In the ‘Fondant’ cultivar, elongation caused a maximal flabbiness of inflorescence shoots and leaves.

In the years 2006–2008 in Przybroda near Poznań the objects of studies were peach trees ‘Harbinger’ on rootstocks Manchurian Peach, Sand Cherry and Rakoniewicka Seedling, formed as a spindle, severely damaged by frost in 2005/2006 winter. In May 2006, an intensive tree pruning was carried out. The objective of studies included the estimation of the pruning effect and rootstocks of frostbitten trees on the process of their regeneration and yielding. Pruning caused a decrease of tree height and crown width in relation to control. Trunks of the strongly pruned trees became thicker, as compared with control trees. In the third year after regenerative pruning, the trees decreased their yield by about 30% in relation to control. The best yielding trees were on rootstock Rakoniewicka Seedling, but the weakest on Sand Cherry.

We studied the effect of differentiated nitrogen-potassium fertilization upon the growth, yield and chemical composition of garden rocket leaves grown in unheated greenhouse in autumn. Two nitrogen doses were applied (0.3 and 0.6 g dm^-3) in the form of calcium saltpeter and two doses of potassium (0.3, 0.6 and 0.9 g dm^-3) in the form of chloride and sulfate. The increased amounts of nitrogen and potassium generally contributed to the increase of fresh leaf weight yield. Plants nourished with KCl had larger concentrations of L-ascorbic acid, chlorine and calcium, whereas the contents of protein, sugars in total, as well as sulfates were smaller, as compared to plants nourished with K₂SO₄.

Vaccinium macrocarpon Ait. –the cranberry of the Ericaceae family is cultivated mostly on high peat bogs. In Poland exist a good climatical conditions and considerable acreage of acid soils for cranberry growing. Cranberries can be consumed solely after processing, mostly as juice and sauce. Cranberries are beneficial for the human organism because they are a good source of vitamin A, B₁, B₂ , B₆ and C, flavonoides, organic acids and other substances. Experiments on investigation of 6 cultivars of the American large fruited cranberries were begun in 2004 at the research plantation of Department of Genetics and Horticultural Plant Breeding in Felin, near Lublin. Seedlings were planted out at spacings of 50×50 cm in specialy prepared beds filled with sphagnum peat. During the experiments the following indices were evaluated: growth rhythm, length of horizontal shoots, number of vertical shoots per 1 m², number of flowers and berries per 1 m² in 4 – fold replications, weight of 100 berries and vitality of pollen. Over two years cultivars ‘Pilgrim’ and ‘Cropper’ had the highest yield (average 662 g and 611 g per 1 m², respectively). ‘Stankavich’ had the lowest yields of all 6 cultivars (average 95.5 g). ‘Pilgrim’ and ‘Cropper’ had the largest fruit size (average 1.55 g and 1.51 g, respectively), ‘Stankavich’ the smallest (av. 0.57 g), and ‘Le Munion’, Nr 20 and ‘Stevens’ were intermediate in fruit size. Interaction clone × year proved to be important in the case of such characteristics as: annual increment of shoots, number of flowers per 1 m², number of berries per 1 m² and weight of berries. The number of grains with alieve cytoplasm was the greatest in ‘Cropper’ and ‘Pilgrim’ cultivars.

The aim of the work was to evaluate the risk of cultivation of cucumber pickling cultivars in Poland caused by unfavourable thermal conditions of soil. To achieve the goal of the work used starting data collected from 28 experimental stations of the Research Centre for Cultivar Testing (COBORU) and 47 meteorological stations of the Institute of Meteorology and Water Management (IMGW) in 1966–2005 were used. Curvilinear regression analysis was used to determine the relation between the total and marketable yield of cucumber and soil temperature at the depth of 5 cm in the period of sowing-the end of harvesting. Potential, at least of 5%, reduction in the total yield of cucumber occurred when average soil temperature at the depth of 5 cm in the period from sowing to the end of harvesting amounted to ≤17.9°C and of the marketable yield ≤17.3°C. The highest reduction in yield, occurring in south-west and south-east part of Poland. The reduction was from 15 up to over 18% in the case of the total yield and from 12 up to 15% in the case of the marketable yield. On average, it occurred respectively every 1.5–2 years and 2.5–3 years. Taking into account the data from the whole country area in 1966–2005, a considerable increase appeored by 0.2°C/10 years in soil temperature in the period from sowing to the end of harvesting. The highest increase by 0.4°C/10 years was recorded in southern and central Poland and in the western part of the Masurian Lakeland where a risk of cucumber cultivation caused by too low soil temperature will probably in the incoming years undergo the quickest reduction.

The experiment with cucumber of the variety 'Matilde F₁' was conducted in an unheated foil tunnel in the years 2004–2005. The plants were grown in containers of the capacity of 10 dm³ filled with transitional turf, limed to the pH of 6.0. In our studies we assessed the effect of foliar feeding with Plonochron fertilizers (potassium, magnesium, calcium) and of the differentiated rhizosphere nitrogen fertilization. (1.0 and 1.5 g N·dm^-3) upon the yield, as well as contents of mineral components in cucumber leaves and fruits. The cucumber fruit yield was found to be significantly greater if the plants underwent foliar feeding with Plonochron fertilizers, as compared to control plants. The greater fruit yield (4.30 kg·plant^-1) was given by plants fertilized with a higher nitrogen dose (1.5 g·dm^-3 of substratum). Fruits of cucumber undergoing foliar feeding with Plonochron fertilizers contained significantly more vitamin C, as compared to control plants. The leaves of plants fertilized with a higher nitrogen dose were reported to contain more total nitrogen, potassium and calcium.

In 2006–2008 the field experiment was carried out in Warsaw University of Life Sciences to determine the differences in accumulation of some chemical compounds in the storage roots of carrot cultivars of various colour and shape of the root. Carrot cvs.: ‘Perfekcja’, ‘Interceptor’, ‘Vita Longa’, ‘Nebula’, ‘Purple Haze’, 'Deep Purple', ‘Mello Yello’ and 'White Satin' were the objects of the experiment. In intervals of three weeks dry matter, total sugars, total carotenoid and nitrates(V) contents were determined in the roots. Also a relationship between the increase of storage root mass during the plants growth and changes in the content of chemical compounds was investigated. Results showed a significant differentiation between the cultivars in respect of chemical composition of storage roots as well as substantial changes of the composition during the plants growth. The highest sugars, soluble solids and carotenoid contents at the end of vegetation period were found in storage roots of purple-orange coloured cultivar 'Purple Haze'. Strong relationship (determination coefficient R² above 80%) between dry matter, sugars and soluble solids accumulation in the storage roots and storage roots mass increase was established. The relationship for carotenoid and nitrates accumulation was much weaker (below 50%). The relationship between dry matter of the roots and sugars or soluble solids accumulation was also strong.

During the studies conducted in the years 2004–2005, in the Experimental Farm „Felin” of the University of Life Sciences in Lublin we assessed the effect of irrigation and plant density upon the yield and selected technological features (mean weight of root and the occurrence of empty spaces) in a few currently grown celeriac cultivars. A significant influence of the examined factors upon the quantity and quality of celeriac yield was demonstrated. On average, for the study years, the yield of non-watered plants ranged from 34.7 to 48.8 t ha^–1 and the yield of watered plants – from 47.1 to 66.3 t ha^–1. The increased plant density from 37.0 thousand pcs. to 55.6 thousand pcs. ha^-1 enabled us to obtain greater yield of non-watered plants by 15.6%, and of watered plants – by 21.5%. The examined factors affected the mean weight of root in the assessed celeriac cultivar, the sizes of empty spaces occurring in them, as well as the participation of roots with empty spaces in the marketable yield.