EFFECTS OF ANTHROPOGENIC IMPACT ON SEXUAL DIFFERENTIATION OF CERTAIN SPECIES OF THE GENUS SALIX

Plant organisms actively respond to changes in the natural components of their environment. A sensitive indicator of the adaptation of the plant organism to the environment is the state of the reproductive system. The article discusses the results of a study of the sex composition of populations and the quality of pollen grains of two species of the genus Salix. The peculiarities of the sexual sphere Salix fragilis and Salix dasyclados revealed during the work show the feminizing effect on the sexual structure of the populations of these types of anthropogenic factors. During the increase of stress conditions the level of vitality and fertilizing ability of pollen grains decreases. The results of the study confirm the possibility of using these plants as bioindicators of the environment.

Особливості лінійного приросту однорічних пагонів верби шерстистопагінцевої (Salix dasyclados Wimm.)

Різні форми і гібриди верби шерстистопагінцевої масово вирощуються на спеціальних плантаціях для отримання енергетичної біомаси. Однак останнім часом інтерес до верб як джерела біоенергетичної сировини помітно знизився. Однією з головних причин цього є нестабільність врожайності плантацій. Водночас відомо, що стабільний урожай фітомаси може бути забезпечений шляхом створення поліклональних насаджень з використанням клонів з різними ритмами розвитку. За результатами проведених досліджень вивчено типи динаміки наростання лідерських пагонів верби шерстистопагінцевої на відносно вирівняному одновіковому матеріалі, в однорідних едафо-фітоценотичних умовах. Встановлено, що динаміка росту пагонів верби шерстистопагінцевої характеризується наявністю трьох чітко виражених максимумів. Перший максимум в усіх пагонів припадає на кінець травня, у першій декаді липня спостерігається другий максимум, а у другій половині літа проявляються індивідуальні особливості в динаміці наростання пагонів: у особини da 2 третій максимум припадає на кінець липня, а у da 5 – на першу декаду серпня. Довгоперіодичними компонентами динаміки середньодобового приросту характеризуються не різні особини, а різні пагони. Усі короткоперіодичні компоненти характеризуються наявністю чотирьох максимумів, які загалом збігаються з фактичними максимумами. Довгоперіодичні компоненти визначають загальний тренд розвитку пагонів, а короткоперіодичні – спричиняють модуляційний вплив на динаміку наростання пагонів. Саме короткоперіодичні компоненти визначають індивідуальні відмінності в динаміці наростання пагонів.

The investigation of morphological characteristics of willow species in different environmental conditions

Alternative or renewable energy is a modern strategy with a good per?spective in the nearest future. There are several directions of renewable energy development that depend on climatic, economic and technological opportunities of a region. The perspective choice for areas with moderate climate is bioenergy. One of the bioenergy directions is agro forestry based on short rotation coppice plantations (SRC) of trees, like willow, poplar and others. The goal of experiments was the assessment of the potential of different willow species for the obtaining of energy in two climatic zones and on two types of soils of Belarus. For this purpose several morphological characteristics were metered: height of plants, biomass, diameter and number of sprouts. The field experiments were conducted on two types of soils: post-mining peaty soils in Grodno region and on degraded peaty soils in Brest region of Belarus. The same soils are very problematic for growing of traditional agricultural crops, thus willow production is a good alternative for biomass production of energy as well as for the reclamation of these soils. In our experiments the following species of willow were tested (Salix alba, Salix viminalis, Salix dasyclados, Salix aurita) that may grow on peaty soils at the natural conditions. The most popular species for modern selection of SRC of willow is Salix viminalis. Nevertheless, the most suitable morphological characteristics on post-mining peaty soils were established for plants of Salix dasyclados and on degraded peaty soils for the plants of Salix alba. The unfavorable parameters at the both type of soils were identified for the plants of Salix aurita. However, it is necessary to take into account that the used species are more popular for natural wetlands and in our experiments plants have best results of survival of cutting and rates of growth at the beginning of vegetation. In accordance with these facts Salix aurita may not be used for energy plantation directly, but it is interesting for hybridization with other species. Our results have shown that perspective hybrids for peaty soils may be for instance Salix aurita x Salix dasyclados and Salix aurita x Salix alba.

The application of diffusive gradient technique (DGT) for assessment of changes in Cd, Pb, and Zn mobility in rhizosphere

Diffusive Gradient in Thin Films (DGT) technique was applied to determine Cd, Pb and Zn concentrations in rhizosphere of four different plant species: hyperaccumulator Penny-cress (Thlaspi caerulescens J. et C. Presl), trees with a good accumulation capacity willow (Salix dasyclados Vimm.) and poplar (Populus nigra L.) and crop maize (Zea mays L.). Moreover, the effect of two chelating agents (ethylendiaminetetraacetic acid – EDTA, and S,S-ethylendiaminedisuccinic acid – EDDS) on element mobility in rhizosphere like soil was investigated. DGT was able to register even small changes in heavy metal concentrations in rhizosphere according to individual crop and/or soil treatments. A particularly significant effect of EDTA application to enhance solubility of metals bound to solid phase into the soil solution was observed resulting in increased concentrations of mobile metals in rhizosphere. The suitability of DGT technique for evaluation of heavy metal behavior in the environment was demonstrated with reasonable results.

Effects of co-cropping on bioaccumulation of trace elements in Thlaspi caerulescens and Salix dasyclados

Most phytoremediation technologies are based on the use of selected plant species cropped as in monoculture. Separated (monoculture) and combined (simultaneous) cropping of hyperaccumulator <i>Thlaspi caerulescens</i> and accumulator tree <i>Salix dasyclados</i> were tested in our experiment. We used moderately and highly contaminated soil. Extremely contaminated soil caused progressive mortality of willows planted separately. Combined cropping with <i>T. caerulescens</i> enabled willows to survive. Generally, we determined decreased bioaccumulation of As, Cd, and Pb in both tested species and Zn in willow plants. Combined cropping enhanced bioaccumulation of Zn in <i>T. caerulescens</i> shoots. The remediation efficiency of the individual species in the co-cropping system did not differ from those obtained in separate cropping mode. For As and Pb the negligible effectiveness of phytoextraction was confirmed for both separate and combined cropping of the tested plant species.

Variation in the uptake of Arsenic, Cadmium, Lead, and Zinc by different species of willows Salix spp. grown in contaminated soils

The experiment assessed the variability of in seven clones of willow plants of high biomass production (Salix smithiana S-218, Salix smithiana S-150, Salix viminalis S-519, Salix alba S-464, Salix ’Pyramidalis’ S-141, Salix dasyclados S-406, Salix rubens S-391). They were planted in a pots for three vegetation periods in three soils differing in the total content of risk elements. Comparing the calculated relative decrease of total metal contents in soils, the phytoextraction potential of willows was obtained for cadmium (Cd) and zinc (Zn), moderately contaminated Cambisol and uncontaminated Chernozem, where aboveground biomass removed about 30% Cd and 5% Zn of the total element content, respectively. The clones showed variability in removing Cd and Zn, depending on soil type and contamination level: S. smithiana (S-150) and S. rubens (S-391) demonstrated the highest phytoextraction effect for Cd and Zn. For lead (Pb) and arsenic (As), the ability to accumulate the aboveground biomass of willows was found to be negligible in both soils. The results confirmed that willow plants show promising results for several elements, mainly for mobile ones like cadmium and zinc in moderate levels of contamination. The differences in accumulation among the clones seemed to be affected more by the properties of clones, not by the soil element concentrations or soil properties. However, confirmation and verification of the results in field conditions as well as more detailed investigation of the mechanisms of cadmium uptake in rhizosphere of willow plants will be determined by further research.