In the years 2005 and 2006, spring and autumn experiments were carried out with greenhouse lettuce ‘Michalina’ cultivar, which was fertilized with three iron chelates, i.e.: Fe-DTPA, Fe-EDTA+DTPA, Fe-AM-4 in the following doses (mg Fe·dm^-3): 20  (control), 50, 75, 100 and 125. The objective of the work were the after effect of the mentioned chelates investigated in the autumnal experiments. Containers with peat that were used in spring experiments were stored in the greenhouse until autumn. In mid-September, lettuce seedlings were planted into the stored peat-filled containers after supplementation of the macro- and micro-elements with the exception of iron. No negative action of chelates was found. Plants yielded well without any symptoms of chelate excess which were observed in spring. After the application of the studied chelates, independent of the levels of Fe, the lettuce yields were similar. Increasing Fe levels, independent of chelates, were accompanied by a similar Fe content in leaves, by an increasing content of copper and decreasing contents of manganese and zinc.

In the years 2002–2003, in a foil tunnel, vegetation experiment in the growing of two eggplant cultivars ‘Epic F₁’ and ‘Solara F₁’ were carried out. Plants were grown in cylinders of 6 dm³ capacity filled with substrate which consisted of: 1) raised peat (from Lithuania), 2) pine bark + low-moor peat (v :  v = 1 :  1). In the vegetation period, top-dressing with nitrogen, phosphorus and potassium was applied. Fruit harvest was carried out many times. The total fruit yield was determined. Index parts of plants were sampled for analyses in which the following values were identified: in ‘Epic’ cultivars: 1.12–3.40% N; 0.42–1.14% P; 1.80–4.81% K. In ‘Solara’ cultivars, the following values were found: 1.17–3.50% N; 0.53–1.27% P; 1.96–4.00% K, depending on the substrate and the fertilization level. Differences were found in the total yield and in the nutritional status of plants, depending on the substrate, fertilization level, cultivar and term of sampling.

In the spring-summer season in the years 2005 and 2006 (every year) three vegetation experiments were carried out with three species of ornamental plants: common sunflower (Helianthus annus ‘Pacino’), scarlet sage (Salvia splendens ‘Fuego’), tagetes erecta (Tagetes erecta ‘Inca Yellow’). These plants were planted in a substrate artificially contaminated by cadmium. Doses of cadmium applied in the experiment represent different degrees of contamination. The dose of 1 mg Cd ∙ dm^-3 indicates natural contents; 5 mg Cd ∙ dm^-3 – small contamination; 10 mg Cd ∙ dm^-3 – large contamination. The objective of the presented studies was the determination what quantities of cadmium pass from the substrate to the organs of the studied plants and which plant organs accumulate the greatest amounts of cadmium. Cadmium was mainly accumulated in leaves and shoots, then in inflorescences. While the least amount of this metal was found in the roots with the exception of Tagetes erecta where the greatest amount of cadmium was found in roots, then in leaves and shoots, while the lest amount was in inflorescences. The greatest cadmium contents were found in the roots of Tagetes erecta, in leaves and shoots of Salvia splendens, and in the inflorescences of Helianthus annus. Among the studied ornamental plant species, the plants of Tagetes erecta were characterized by the highest cadmium uptake.

The aim of the experiment conducted in 2003–2006 was to estimate the effect of dose of nitrogen on yielding and antioxidant activity of lavender. The experiment was established in one factorial design in four replications and plot area 3.0 m². Nitrogen was supplied in three different rates: as a preplant dose 50 kg N·ha^-1, or split application 100 (50 +  50) and 200 kg N·ha^-1 (100 +  100) with one top dressing provided on first week of May. Results obtained from two years of the study indicate that the most suitable for lavender yielding appeared to be nitrogen fertilization at the rate of 100 kg N·ha^-1. The results of the study also demonstrated that heavy nitrogen fertilization decreased concentration of phenolic compounds and have negligible effect on chlorophyll and carotenoids concentration in lavender flowers and increased content of phenolics, total carotenoids and chlorophyll a +  b in leaves. The antioxidant activity of lavender flowers was higher in treatment fertilized with nitrogen in dose of 50 kg N·ha^-1 and decreased at the rates of 100 and 200 kg N·ha^-1.

The results of three year investigations with ‘Galaxy’ F₁ cabbage grown under field conditions are presented. The effect of the rate of ammonium sulphate and RSM (solution of ammonium nitrate + urea), the method of application (placement and broadcast technique) and foliar fertilization (urea and Supervit K) on the yield and nitrate accumulation was studied. The form of N fertilizer significantly increased the cabbage yield only in 2007. In this year the better nitrogen source was ammonium sulphate in comparison with RSM. In the other years no differences between the kind of N fertilizer were observed. The method of application did not affect cabbage yield any year. However, slightly better cropping was noted for following treatments 75% N broadcasted at planting + 25% N during growth season, 75% N broadcasted at planting + foliar fertilization, and after placement fertilization with reduced rate (75% N) as compared to control (100% N broadcasted at planting), in every year of the experiment. In 2006 and 2007 fertilization at the rate of 75% N and supplemented with addition 25% N during the growth or foliar sprays significantly increased nitrate content in cabbage as compared to control treatment.

The experiment was founded in the spring of 1999 on the grey brown podzolic soil created from boulder clays. The trees of ‘Golden Delicious’ were planted on rootstock M 26 at 3.5 ×  1.2 m spacing (2381 trees ha^-1). The first factor in the experiment consisted the levels of potassium in the arable soil layer: 12, 16 and 20 mg K∙100 g^-1 of soil d.m., on the basis of annual chemical analyses. The second factor of the investigation was three forms of potassium fertilizers: potassium chloride (KCl), potassium sulphate (K₂SO₄) and potassium nitrate (KNO₃). Each year the analyses of macro- and microelements in the soil and leaves were made. The controlled of potassium fertilization made the possible to maintain the planned potassium levels in the soil. Different potassium levels did not cause the significant differences in yielding of the trees. Different potassium levels and fertilizer forms did not cause any significant changes in flesh firmness, soluble solids, in the weight loss of fruit after harvest as well after storage. The using of fertilizer in the form of potassium sulphate caused an increase of the participation of fruit with bitter pit.

In a field experiment with conservation tillage of Wolska variety of onion the influence of cover plants such as spring rye (Secale cereale) and common vetch (Vicia sativa) as well as varied pre-sowing cultivation measures: no-tillage, disc harrowing during the spring, disc harrowing before the winter in comparison with conventional cultivation, on the content of mineral elements in soil and onion were studied. The content of mineral elements in soil and in onion was modified in greater degree by the changes in weather than by the agro-technical factors. No significant influence of conservation tillage on the content of mineral components in soil or in the onion was found. Soil covered with plant mulch contained slightly more potassium and magnesium in the arable layer in comparison with bare soil. The onion cultivated by using cover plants accumulated slightly more dry mass, N-total and potassium.

Studies were carried out in 2003–2005. The dependence between harvest date and yielding of marjoram (cv. ‘Miraż’) was investigated. The plantation was set from a seedling produced in a greenhouse. Plants were set in 30 × 40 cm spacing. Two weeks after setting, part of plants were cut and shoot tips with the first leaf pair were removed. The herb harvest was made twice: in the middle of July and at the end of August. Ground herb was subjected to determinations of essential oils. Qualitative and quantitative composition of marjoram oil was determined by means of gas chromatography coupled with mass spectrometry (GC/MS). The harvest date had significant influence on marjoram yielding. Higher yield of a fresh herb was achieved at the end of August (44.6 dt^.ha^-1) than in the middle of July (30.5 dt^.ha^-1). The essential oil content in the herb of marjoram cv. ‘Miraż’ was 1.7–2.2%. Trans-sabinene hydrate, terpinen-4-ol, and sabinene dominated in marjoram essential oil.

The presented studies have shown the effect of soil fatigue on the decrease of resistance to low temperatures in one-year old apple-tree shoots. The highest frost resistance was demonstrated by the shoots of apple-trees grown in localities so far not utilized for fruit-tree cultivation.In a replanted apple-tree orchard, the plantation of trees in the grass inter-rows of the old apple orchard did not cause any explicit increase of frost resistance by the apple-tree shoots.

This study was to discover if there is any relationship between antioxidant status after harvest and bioactives fate during apple storage. The clearer link in this issue concerned enzymatic part of antioxidant apparatus, for which the particularly high year effect was noted. Except for anthocyanins, non-enzymatic bioactives end-status was not strictly related to their harvest size. However the content during the first months of storage might be closely connected with antioxidant status measured after harvest. A significantly higher concentration of majority assessed antioxidants was characterized by apple harvested and stored in 2005/2006 season, on the average. Simultaneously many, statistically proved, correlations over storage between the examined antioxidants at that time existed. Total antioxidant power (FRAP assay) significantly increased after the first storage period, probably as a result of fruit acclimatory response to storage conditions, and next decreased. In general, changes of FRAP value reflected fluctuations of individual compounds measured in this study.