Barbara Hawrylak-Nowak

Ameliorative effect of selenium on tomato plants grown under salinity stress

ABSTRACT The ability of selenium (Se) to counteract salt inhibitory effects in crop plants, especially in tomato, is still poorly documented. In order to examine the impact of Se addition on the growth, some biochemical parameters related to osmotic adjustment and antioxidant defense of salt-stressed tomato, a two-factorial experiment was conducted in a greenhouse. The plants were supplied with NaCl (0, 25, or 50 mM) and Se (0, 5, or 10 μM), individually or simultaneously. The results showed that salinity had a deleterious impact on plant biomass and physiological parameters studied. The application of Se alleviated this adverse effect by improving the integrity of cell membranes and by increasing leaf relative water content under stress conditions. Moreover, the application of 10 μM Se significantly increased the photosynthetic pigments concentration under salt stress. Salt stress also caused an inhibition of catalase activity, but its activity was restored in the presence of Se. The free radical scavenging activity significantly increased in plants subjected to 25 mM NaCl and supplied with 5 µM Se, compared to NaCl-alone treatment. Both physiological and biochemical results indicate that 10 µM Se treatment can increase plant performance under salt stress, especially under high NaCl concentration. Abbreviations: CAT: catalase; Chl: chlorophyll; DPPH: 2,2-diphenyl-1-picrylhydrazyl; DW: dry weight; FW: fresh weight; POD: peroxidase; REL: relative electrolyte leakage; RWC: relative water content; free radical scavenging activity (FRSA); TW: turgid weight

Growth and mineral composition of nickel-stressed plants under conditions of supplementation with excessive amounts of calcium and iron.

This study investigated the effectiveness of excessive calcium (Ca) and iron (Fe) supplement nutrition in spinach Markiza F1 cv. and sweet corn Zlota Karlowa cv. to alleviate nickel (Ni)-induced phytotoxicity. The following doses of the pollutant Ni were introduced: 0 (control), 40, or 60 mg Ni/kg growth medium. Two levels of calcium (Ca), 270 (basic) and 400 mg/kg (intensive), as well as two levels of iron (Fe), 10 (basic) and 20 mg/kg (intensive), respectively, were used. Intensive nutrition supplementation of Ni-stressed test plants species with Ca or Fe was beneficial as manifested by significantly increased maize shoots and roots biomass, lowered content of Ni in spinach and maize in above-ground parts, and decreased concentration of the pollutant in roots of intensive Ca-supplied maize plants grown in the environment containing 60 mg Ni/kg. Moreover there was significantly elevated Fe content in highly fertilized with iron spinach plants grown in the presence of 60 mg Ni/kg and in shoots of Ni-treated maize plants intensively supplied with Ca or Fe. Generally, high content of Ca or Fe in the growth medium significantly raised the content of free and bound Ca in shoots of Ni-stressed spinach plants. The same phenomenon was found in roots, but only in the presence of 60 mg Ni. Intensive nutrition supplementation of Ni-treated maize plants with Fe or Ca generally did not change the concentration of free Ca in plant organs, but elevated bound Ca levels in roots was observed. Increased bound Ca content was also found in leaves of maize plants intensive supplied with Ca. Thus, intensive Ca or Fe nutrition presents a promising potential for use in the conditions of Ni contamination by increasing plant growth, reducing Ni translocation from roots to shoots and raising the nutritive value of above-ground parts of spinach and maize plants.

Selenium improves physiological responses and nutrient absorption in wheat (Triticum aestivum L.) grown under salinity

Abstract Salinity is a serious limiting factor for crop growth and production. The present study was conducted to investigate the response of wheat grown at salinities of 0.12, 0.30 and 0.60 S m−1 on soil supplemented with 0, 0.5, 1 and 4 mg kg−1 Se as selenite. Chlorophyll a and b, carotenoid contents, Fe, Zn and Se in shoots as well as shoot dry weight were negatively affected by increased salinity. Se had a dual effect: at 0.5 mg kg−1, chlorophyll b, proline, and shoot Fe content were increased, catalase activity was stimulated; there was no effect on Zn content and shoot dry weight. At the two higher concentrations, Se led to decreases in chlorophyll content, nutrient concentration, and shoot dry weight. Thus, moderate addition of Se to soil could be a strategy to improve physiological responses and micronutrient status in wheat under salinity stress.

Selenium biofortification enhances the growth and alters the physiological response of lamb's lettuce grown under high temperature stress

We examined the possibility to enhance the growth and the physiological tolerance of lambs lettuce (Valerianella locusta L.) grown under heat stress (HS) by biofortification with selenium (Se). The plants were grown at optimal (22/19 °C; day/night) or high (35/22 °C; day/night) temperature and Se was applied via foliar or soil treatment. The HS reduced plant biomass and photosynthetic pigment concentration and impaired some parameters of chlorophyll a fluorescence. The lambs lettuce grown under HS accumulated large amounts of H2O2 in the leaves, especially in younger ones. The Se fertilization (both foliar and soil) at HS was beneficial to plant growth, whilst the concentration of photosynthetic pigments and the analysed parameters of chlorophyll a fluorescence were unaffected by the Se supply. The application of Se enhanced the thermo-tolerance of plants through cooperative action of antioxidant enzymes, such as guaiacol peroxidase (GPOX; EC 1.11.1.7) and catalase (CAT; EC 1.11.1.6), and reduced glutathione (GSH) among low-molecular-weight non-enzymatic antioxidants, in removal of excess of H2O2. Although under HS the content of different phenolic compounds in the leaves was higher than under normal temperature (NT), the application of Se did not affect their concentration at stress conditions. On the other hand, at NT the Se-biofortified plants accumulated significantly more phenolic compounds with health-promoting properties than Se-untreated plants. Therefore, biofortification of lambs lettuce with Se can be beneficial in terms of plants yield and their nutritional value under both NT and HS.

Mechanisms of Selenium-Induced Enhancement of Abiotic Stress Tolerance in Plants

Selenium (Se), an essential micronutrient for humans, animals, and some microorganisms, has been found to be a beneficial trace element for many plant species, especially Se hyperaccumulators. Selenium accumulation in plants profoundly affects many biochemical reactions in cells. There is a growing interest in understanding the plant reaction to Se enrichment, both to ensure adequate dietary Se intakes for humans and animals, which often needs Se biofortification using edible crops, and to achieve increased tolerance of plants to some environmental stress. In recent years, many investigations have shown that Se-enriched plants exhibited enhanced tolerance to some abiotic stresses, e.g. cold, high temperature, drought, salinity, UV radiation, and excess of some trace metals/metalloids. In plants exposed to environmental stresses, the protective role of Se ions, used in relatively low concentrations, has often been attributed to stimulation of antioxidative protection systems, but the associated mechanisms are complicated and not fully elucidated. To obtain positive effects of Se phytofortification, the possibility of accumulation of this element in given plant species, the chemical form of Se applied, the way of the application thereof, as well as the probability of its interaction with other elements should be taken under consideration. In this chapter, we will focus on reviewing the effects of Se biofortification on plants growing under different abiotic stress conditions. Changes in the physiological and biochemical characteristics of Se-supplied plants, with particular emphasis on the influence of Se on the changes in enzymatic and non-enzymatic antioxidant defence mechanisms under abiotic stress, will be summarised in this review.

Macronutrient Balance of Nickel-Stressed Lettuce Plants Grown under Different Sulfur Levels

ABSTRACT This study investigated whether intensive nutrition with sulfur–sulfate (S-SO4) (2, 6, or 9 mM S) of nickel-stressed (0, 0.0004, 0.04, or 0.08 mM Ni) butterhead lettuce cv. Justyna may improve macronutrient balance and reduce Ni bioaccumulation. Nickel exposure resulted in various unfavorable changes in the macronutrient content together with increase of Ni accumulation in the biomass. Intensive S nutrition of Ni-treated lettuce seems to have no beneficial effect on macronutrient balance. In general, it significantly reduced the root and foliar phosphorus (P), potassium (K), calcium (Ca), and S content and simultaneously did not affect the magnesium (Mg) content in the biomass. At the same time, the nitrogen (N) content was reduced in roots and elevated in shoots. Supplementation of Ni-exposed lettuce with high S doses raised in roots and reduced foliar Ni accumulation; however, Ni content in useable parts exceeded the acceptable limits established for consumption.

Assessment of Chosen Reproductive Cycle Processes and Genetic Diversity of Salix myrtilloides L. in Wetlands of Polesie Lubelskie: The Prospects of Its Survival in the Region

ABSTRACT Salix myrtilloides L. is an endangered species whose western limit of range runs through Poland. The main aim of the study was to increase the knowledge on the ecology and biology of S. myrtilloides populations in the Polesie Lubelskie region (Eastern Poland) in order to create an effective protection program. An 80% decrease in its population was found in this area. Our study was conducted to identify the mechanisms responsible for the process of withdrawal of this species from its natural stands by determining whether the processes of generative reproduction (pollen viability and germinability, seed germination ability and dynamics) in the populations occur properly and by characterizing within- and among-population genetic diversity of S. myrtilloides, using ISSR (Inter-Simple Sequence Repeat) primers. The results confirmed that S. myrtilloides pollen viability was high (84.17±8.67), and so were the seed germination ability (76% of the total number of sown seeds/24 h) and dynamics. The within-population genetic diversity was quite high for this species and the inter-population genetic variation was of medium value (&PHgr;PT=0.148). The condition of two populations, their genetic diversity and sex ratio as well as the correctness of the investigated reproductive cycle stages altogether give prospects for their survival. It seems to be very important to start conservation involving the reintroduction and reconstruction of S. myrtilloides populations in the Polesie Lubelskie region. The proposed method for restoration of S. myrtilloides resources would be possible if ex situ cultivation and in vitro methods were used.

Estimation of the macro- and micronutrient status of raspberries grown in the Lublin region

Abstract Environmental monitoring was conducted in the Lublin region in 2009-2012 aimed at the assessment of the supply of several macro- and micronutrients in raspberries plants. The plantations studied were located in eight main regions for the growing of raspberries (Bełżyce, Chodel, Godziszów, Kraśnik, Lublin, Międzyrzec Podlaski, Opole Lubelskie and Urzędów). The contents of nitrogen (N), potassium (K), phosphorus (P), magnesium (Mg), calcium (Ca), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu) and boron (B) were determined in raspberry leaves. Furthermore, the impact of select soil properties on the content of essential elements in the leaves was assessed. The results obtained revealed the suitable N, P, K, Mg, B, Zn and Cu supplies in the plants. However, the mean content of Mn greatly exceeded the optimal level recommended for this species. Also, the content of Fe in some regions was above the optimal value. The calculated correlation coefficients between soil properties and the content of the elements in raspberry leaves suggest that these variables were interdependent in only a few cases.