Fennel (Foeniculum vulgare var. azoricum Mill.), despite its high dietary value, is not a very popular vegetable in Poland. It bulbs constitute a low-calorie food, abundant in vitamins and mineral salts. They also contain, though in smaller amounts, the essential oil, determining the use of fennel fruit in medicine. In the field experiment with fennel growing the influence of soil mulching and flat plant shielding, as well as sowing term upon the nutritional values of two fennel cultivars, was examined. The studies covered 3 kinds of covers (covering the soil with black polyethylene film PE, covering the soil with black polypropylene unwoven PP 50 g m^-2 and flat covering of plants with white unwoven PP 17 g m^-2 (the controls were plots without covers), 3 sowing terms directly in the field, 2 cultivars (Rudy F₁ and Zefa Fino). The applied covers did not significantly affect the nutritional value of fennel bulbs. The bulbs of plants from June sowings contained the most protein, total nitrogen and nitrate nitrogen, as compared to earlier sowing terms. The most dry matter, vitamin C, sugars,0 phosphorus and potassium were determined in fennel bulbs from May sowings. The least protein, sugars and potassium was contained in plant bulbs from April sowings. The bulbs of Rudy F₁ cultivar were more abundant in protein, phosphorus and calcium than those of Zefa Fino cultivar. The cultivars did not differ in dry matter, nitrate, vitamin C, total sugars, fibre and potassium contents in the bulbs.

Foliar application of growth regulators or fertilizers containing biostimulators can influence the uptake and accumulation of mineral elements by plants. The aim of the research was to determine the influence of foliar application of ‘Pentakeep V’ and diverse nitrogen fertilization on the content of: Ag, Al, Ba, Cd, Co, Cr, Ga, Li, Ni, Pb, Sb, Sr, Ti and V in spinach leaves. In 2006–2007 pot experiment with spinach Spinacia oleracea L. ‘Spinaker F₁’ cultivation on silty medium loam was carried out. The experiment design included two sub-blocks: with and without foliar nutrition. Plants with foliar nutrition were sprayed twice with 0.02% w/v ‘Pentakeep V’ fertilizer (3000 dm³ water per 1 ha). In each sub-block soil nitrogen fertilization (in the form of ammonium nitrate) was applied in following combinations: 1 – control (without N), 2 – 50% N dose prior to seed sowing (25 mg N∙dm^-3 of soil), 3 – 100% N dose prior to seed sowing (50 mg N∙dm^-3 of soil). Foliar application of ‘Pentakeep V’ resulted in (compared to not treated plants): a) significant reduction of the Ag, Al, Ba, Ga, Sr and Ti concentration in plants not fertilized with nitrogen, b) increase in Sr content in spinach fertilized with 100% of N dose, c) relatively weak tendency to lower V accumulation in control plants. The lowest concentration of cobalt was found in plants fertilized with 50% of N dose and not treated with ‘Pentakeep V’. No interaction between foliar nutrition and nitrogen fertilization was found in reference to Cd, Cr, Li, Ni, Pb and Sb content in spinach plants.

Foliar application of fertilizers containing biostimulators can influence yield and the uptake and accumulation of NO₃^- by plants. The aim of the research was to determine the influence of foliar nutrition with ‘Pentakeep V’ and diverse doses of nitrogen fertilization on yield, plant nitrogen metabolism and nutritional quality of spinach. The experiment design included two sub-blocks with and without foliar nutrition. Plants with foliar nutrition were sprayed twice with 0.02% w/v ‘Pentakeep V’ fertilizer (3000 dm³ water per 1 ha). In each sub-block soil nitrogen fertilization (in the form of ammonium nitrate) was applied in following combinations: 1 – control (without N), 2 – 50% N dose prior to seed sowing (25 mg N∙dm^-3 of soil), 3 – 100% N dose prior to seed sowing (50 mg N∙dm^-3 of soil). The interaction between foliar nutrition and nitrogen fertilization had a significant effect on the content of: nitrates(V), soluble oxalates and ascorbic acid in spinach leaves. The effect of tested factors on the content of nitrates(V) and ascorbic acid was additionally modified by the weather conditions in both years of research. Foliar application of ‘Pentakeep V’ resulted in decreased concentration of soluble oxalates in control plants (without N) as well as higher amount of these compounds in plants fertilized with 100% of N dose. No significant effect of tested interaction was observed in the case of yield and the content of: dry matter, nitrates(III), ammonium ions, free amino acids, N-total, soluble sugars and phenolic compounds in spinach leaves.

The aim of carried out research was comparing the effect of different pruning time on cropping and fruit quality of several early ripening plum cultivars. The experiment was conducted at Fruit Experimental Station – Samotwór near Wrocław in 2001–2004. Objects of studies consisted of 8 year-old plum trees of ‘Herman’, ‘Č ačanska Rana’, ‘Sanctus Hubertus’ and ‘Č ačanska Lepotica’ cultivars budded on ‘Myrobalan’ seedlings (Prunus divaricata). The experiment was established in a randomised block design in three replications with six trees per plot. In 2001–2003, time of tree pruning was differentiated. Half of trees was pruned only at the end of August (summer pruning after harvest of fruit) and the other one only at the end of March (dormant pruning before blooming time). Time of pruning had no influence on yielding and chemical composition of fruit. Soluble solids, vitamin C, magnesium, calcium, potassium and phosphorus contents in fruit were similar independently of pruning time. Mean fruit weight was significantly higher from trees with dormant pruning.

Priming is a treatment applied for seed enhancement. Brassica vegetable seeds are commonly affected by Alternaria brassicicola. The changes in germination and vigour of kohlrabi (Brassica oleracea L. var. gongylodes L.) seeds subjected to two priming methods in the presence of A. brassicicola were investigated. The following treatments were applied: uninoculated non-primed seeds (control), seeds inoculated with A.  brassicicola (2∙10⁴ spores ml^-1), uninoculated and inoculated seeds hydroprimed for 1–2 days, and uninoculated and inoculated seeds osmoprimed for 1–4 days. The percentage of germinating seeds, germination capacity, the percentages of diseased seedlings and dead seeds were determined. The speed of germination, tetrazolium staining index, and electrical conductivity described seed vigour. The presence of A. brassicicola on/in seeds was confirmed on CW semiselective agar. Osmopriming was conducive to penetration of A. brassicicola into kohlrabi seeds. The presence of the fungus had no influence on the percentage of germinating seeds, but a significantly lower germination capacity and a higher percentage of diseased seedlings and dead seeds were observed after inoculation. Non-primed inoculated seeds germinated faster than uninoculated ones. Despite the presence of A. brassicicola, osmotic priming improved seed vigour as measured by the speed of seed germination and electrical conductivity. The results of the tetrazolium vigour test showed its limited usefulness for seeds heavily infected with A. brassicicola.

Foliar feeding of plants is an important supplementation of soil fertilization in vegetable cultivation. Foliar-fertilized plants deliver high yields of good quality at lower rates of mineral fertilization. In horticultural practice foliar fertilization is also recommended as the most effective method of supplying plants with nutrients under deficiency conditions. An experiment was established to evaluate an effect of foliar application with Florovit and combination Ekolist-Warzywa+Urea on the yield quality of six large-fruit melon cultivars (‘Pacstart’, ‘Yupi’, ‘Gattopardo’, ‘Polydor II’, ‘Seledyn’, ‘Legend’) cultivated in the climatic conditions of central-eastern Poland. The total yield was achieved from Florovit and Ekolist-fertilized plants did not differ significantly. A higher total yield was achieved from Florovit-fertilized plants compared with control object. ‘Yupi’ was characterised by higher total yields compared with the other cultivars. The greatest fruit number per 1 m² was set by ‘Gattopardo’. On the basis of the results obtained it was found that, due to the highest share of marketable fruit, ‘Yupi’ is the cultivar recommended for cultivation under the growing conditions of central-eastern Poland. ‘Seledyn’ was gave at least unripe fruit whereas ‘Pacstart’ produced the lowest share of disease-affected fruit. An application of the foliar fertilizers reduced the total sugar and monosaccharides content in melon fruit. Regardless of the kind of foliar feeding, most dry matter in the fruit was produced by ‘Pacstart’, total sugar and monosaccharides by ‘Yupi’ and ascorbic acid by ‘Legend’.

One of the more important species of herbal plants, grown in many countries for medical and nutritional purposes is sweet marjoram. The marjoram herb is an abundant source of valuable biologically active substances and mineral components. Considering the vast application of this plant studies were undertaken on the assessment of growth and yielding of sweet marjoram, depending on harvest time. The studies were conducted in the years 2004–2005. The sweet marjoram plantation was established from seedlings produced in a glasshouse. The marjoram herb was collected in two harvest time: in mid July (beginning of flowering) and in early September. The yields of fresh, air dry and grated herb were assessed. The contents of essential oil in grated herb, as well as the mineral composition of the herb were determined. The significant effect of harvest time upon the yield of fresh, air-dried and grated herb was demonstrated: the greater yield was achieved in the second harvest time (early September). The herb collected at the beginning of September contained more essential oil than that cut in mid July. Total nitrogen content was significantly greater in marjoram herb from the first harvest than in that from the second harvest.

Soil structure depends on several factors, among which are farming system and soil tillage. The state of aggregation determines the water-air relations in soil and influences the thermal conductivity, porosity and density of soil, availability of nutrients, as well as biological processes, etc. In the field experiment with conservation tillage for onion we studied the influence of various methods of conventional tillage, no tillage, and disking as well as the biomass of the inter-harvest plants on the aggregation and structure of soil. Secale cereale and Vicia sativa cultivated as inter-crop cover plants favourably influenced the soil aggregation. It was expressed by greater share of valuable soil aggregates (ø1–5 mm) and better soil structure index in comparison with conventional tillage (CT), without plant mulches. The leaving of mulches from cover plants on the surface of the soil from fall to spring and direct sowing on onion without tillage (NT) decreased soil cloddiness index. The positive influence of plant mulches on soil structure was mainly observed after wintering and in the initial period of onion vegetation. The changes in indicators of soil aggregation under the influence of mulching and simplifications of the soil tillage system for vegetables were predominantly recorded in the soil arable layer of 0–20 cm.

The main factors determining the quantity and quality of the yield of plants grown in the soilless system is the kind of cultivation substrate used and the level of supplying the plants with nutrients. Studies conducted in the years 2005–2006 were aimed at determining the effect of substrates (peat, peat mixed with pine bark in the proportion of 1:1, peat with pine sawdust in the ratio of 1:1), as well as of differentiated nitrogen dose (140 and 210 mg N·dm^-3) upon yielding, chemical composition of strawberry (Fragaria × ananasa Duch.) leaves and fruit, cultivar „Elsanta”, grown in unheated foil tunnel. In those studies no significant differences were found in total and marketable yield of strawberry fruit grown in peat, as well as in peat with pine bark. Significantly smaller total (435.8 g·plant^-1) and marketable (286.5 g·plant^-1) fruit yield was reported when strawberries were grown in peat mixed with pine sawdust. In plants grown in peat mixed with sawdust significantly smaller fruit unit weight (10.7 g) was found, as compared to plants that grew in the remaining substratums. In our studies no significant effect of differentiated nitrogen fertilization upon strawberry yielding was demonstrated. In the leaves of strawberries fertilized with nitrogen in the dose of 210 mg N·dm^-3 we found significantly more nitrogen and phosphorus, as well as less calcium and magnesium, as compared to plants fertilized with smaller doses of this nutrient. The fruit of strawberries fertilized with a higher nitrogen dose contained significantly more nitrogen and potassium, as well as less vitamin C and soluble solids, as compared to the fruit collected from plants fertilized with nitrogen in the dose of 140 mg N·dm^-3.