The aim of this research was to study the physiological and biochemical responses of pelargonium growing in saline substrate. Salt stress caused an increase of sodium and chlorine, and decrease potassium ions concentrations in pelargonium leaves depending on their level in peat substrate. About 4-16-fold increase of sodium, 4-6fold increase of chlorine were found in leaves of plants growing in substrate treated with the lowest (452 mg dm-3) and highest (2992 mg dm-3) NaCl doses, respectively. The concentration of potassium ions decreased by 20 to 27 % in leaves of plants growing in substrate supplemented with NaCl doses from 1976 to 2992 mg dm-3 , respectively. However, lower doses of sodium chloride did not affect the content of potassium ions in pelargonium leaves. The increasing salinity of substrate after the addition of 960-2992 mg NaCl dm-3 caused the reduction of plant fresh matter in the range of 25-65 %, plant height 10-37 %, and leaf area 15-55 %. There were no changes in relative water content (RWC) and no signs of damage in the form of necrotic spots for any of the used salt concentrations. The content of chlorophyll pigments decreased proportionally to salt concentration, but the content of carotenoids did not change. Maximum photochemical activity of PSII (F v /F m) was reduced only in plants growing at the highest dose of NaCl. Proline and anthocyanin levels increased in response to elevated NaCl concentration. At the highest dose of NaCl proline level increased by 30 % while the content of anthocyanins increased about 2.5-fold in relation to the control. It can be assumed that proline and anthocyanins accumulated in pelargonium leaves may be responsible for the amelioration of the adverse effects of salt stress. The results revealed that the investigated pelargonium 'Survivor Dark Red' is somewhat tolerant to salinity and it can be cultivated in substrate and soil polluted with NaCl at the level lower than 1976 mg dm-3 .

Robinia pseudoacacia L. is an interesting example of how one plant species can be considered invasive or useful depending on its environment. In the past this tree species was planted for decorative purposes and for wood in Poland. For many years it was recommended in poor and degraded habitats because it facilitated late-successional plant species. The aim of this study was to verify if black locust can still be regarded as a resistant tree species in urban greenery. The health condition of old tree specimens growing along streets and in parks was compared. The occurrence of pests and pathogens on R. pseudoacacia trees was assessed and the content of mineral elements in leaves was examined. The research results showed that the health of black locust trees growing in the urban environment in Polish cities, especially along streets (in comparison to park sites), deteriorated significantly due to the interaction of harmful biotic and abiotic factors. Increased level of toxic metals (Fe, Zn, Pb, Mn and Cd) in plant tissues and the accumulation of pests and pathogens negatively influenced the health of R. pseudoacacia.

Experiments were conducted to evaluate the effect of incorporated hydrogel amendments to a soilless growth medium on ammonium, nitrate, and water retention and tomato (Lycopersicon esculentum Mill.) seedling growth. HydroSource and Agri-gel were incorporated into a 1 peat: 1 perlite: 1 vermiculite soilless medium at rates of 1, 2, or 3 g·liter-1 with 0.88 g of ammonium nitrate fertilizer. Water retention by the growth medium increased linearly with gel application; HydroSource generally was more effective than Agri-gel. Between 90% and 96% of the applied nitrate-N was recovered in the resulting leachate of the gel-amended media, while 33% to 55% of the ammonium-N was recovered. Nitrate-N and ammonium-N retention was higher when 3 g·liter-1 of either gel was added to the growth medium than when lower amounts or no gel was added. Gel amendment did not affect tomato seedling growth. Total foliar N concentration in tomato leaves was significantly higher in the HydroSource treatments than in the control or Agri-gel treatments.

In the years 1997-2008, 131 water samples were analysed. The concentration of N-NH 4 , N-NO 3 , P, K, Ca, Mg, Na, Cl, S-SO 4 , Fe, Mn, Zn, Cu, B, and HCO 3 -was measured. In addition, the pH value and the electrolytic conductivity (EC) were determined and the sodium adsorption ratio (SAR) was calculated. The assessment of water was done on the basis of the classifications of water for the irrigation of greenhouse crops grown in soil or traditional media. According to guide values, water samples had to have high concentration of ions, especially HCO 3 , Mg, Na and K. The questioned quality in about one half of the water indicates that the limits proposed by different researchers are too restrictive. The criteria to be met by water admissible for irrigation and fertigation should take into consideration the regional differences in water characteristics. The adaptation of recommendations elaborated on the basis of analyses originating from other geographical and geological regions can lead to the elimination of waters possessing favourable quality parameters. For irrigation of field and greenhouse crops, the following concentrations of components in water might be recommended as safe ones: 30 mg N-NO 3 , 100 mg K, 150 mg Ca, 50 mg Mg, 100 mg Na, 100 mg Cl and 100 mg S-SO 4 in 1 dm 3 . For soilless culture fertigation in an open system, the maximum ion concentrations in water cannot exceed the recommended ones in the nutrient solution for the given plant. Also, the EC value should be taken into consideration.

In recent decades, increasing human pressure has caused the gradual deterioration of the physical and chemical properties of water and soil. Salinity is an important factor influencing the quality of water. The aim of this comprehensive research was to determine the effect of increasing concentrations of sodium chloride, which is a salinity inducer, on the yield, photosynthesis efficiency (expressed with chlorophyll fluorescence measurement) and content of selected nutrients in the leaves of hydroponically grown lettuce (Lactuca sativa L.). Experiments were conducted at the following concentrations of NaCl: 0 (control treatment), 10, 20, 40, and 60 mmol L−1. Studies were conducted in two independent seasons: spring and autumn. The plants exposed to NaCl stress modified their chemical composition by lowering the uptake of (for 60 mmol L−1 NaCl in relation to control): N (−11%), K (−35.7%), and Mg (−24.5%), while increasing the sodium content (+2400%). The Na:K ratio was significantly narrowed (from 76:1 to 2.6:1). The increase in the Cl level in the lettuce leaves may also have caused a decrease in the content of nitrates. As a result of disturbed ionic balance, the RWC was significantly reduced (−6.2%). As a result of these changes, the yield of the biomass of the aerial parts decreased (more than two-fold for the highest NaCl concentration in relation to control) whereas the dry matter content increased (+32%). The measurement of fluorescence showed significant changes at the PSII level. Salinity modified the energy flow rate (F0, FM, FV, FV/FM) as well as the specific energy flows through the reaction centre (ABS/RC, TR0/RC, ET0/RC, DI0/RC). The PSII functioning index, calculated on the basis of energy absorption (PIAbs), also changed. The salinity induced with NaCl significantly worsened the physiological reactions of the plants in the PSII, changed the ionic balance, which resulted in a significantly lower yield of the plants. Due to increasing water quality problems, it will be necessary to use, in agriculture on a much larger scale than before, saline water treatment systems (e.g., highly effective nanofiltration and/or reverse osmosis).

`Buttercrunch', `Grand Rapids', and `Summer Bibb' lettuce (Lactuca sativa L.) seedlings were grown with the nutrient film technique (NIT). The influence of two K concentrations (150 and 225 mg·liter-1) and four solution pH levels (5.0, 5.5, 6.0, and 6.5) on lettuce tipburn was investigated in four experiments. Additionally, the influence of pH on foliar nutrient concentration was examined. Even though tipburn was observed in `Buttercrunch' and `Summer Bibb' lettuce, neither K nor pH level consistently affected tipburn incidence. No tipburn was observed in `Grand Rapids'. Solution pH generally did not affect concentration of total N and NO3-N in lettuce tissue. Increasing the pH increased K concentration and resulted in increased proportions of K compared to Mg or Ca. Although the influence of solution pH on P, Ca, and Mg concentration was significant, nutrient accumulation differences were not reflected in lettuce fresh-weight differences. The influence of K solution concentration and pH on lettuce yield was not significant. Tipburn incidence in NIT-produced lettuce appears to be primarily affected by environmental conditions maintained during greenhouse growth.

Heavily urbanised areas are not a favourable habitat for plant growth and development. On the other hand, urbanised areas can be a favourable habitat for harmful fauna. Tin our study, those trees growing along the roadside were more heavily infested by pests than trees growing in parks. Three orders of insects, mites and lugs were identified on the Norway maple. The dominant insect species was Periphyllus aceris. On small-leaved lime four insect orders (the dominant species was and Eucallipterus tiliae) and mites were found. An overall visual inspection confirmed that of maple and lime growing in city parks were in better condition than those growing by roads.

The aim of the study has been to assess the efficiency of choline-stabilized orthosilic acid (ch-O-SA; bioavailabile form of silicon) application under increasing intensity of manganese stress on the chemical composition of plants and yielding of tomato (Lycopersicon esculentum Mill. cv. Alboney F 1 and cv. Emotion F 1). Plants were grown in rockwool with the application of a nutrient solution of the following chemical composition (mg dm-3): N-NH 4 2.2, N-NO 3 230,