Multiple invasive species affect germination, growth, and photosynthesis of native weeds and crops in experiments

Alien plant species regularly and simultaneously invade agricultural landscapes and ecosystems; however, the effects of co-invasion on crop production and native biodiversity have rarely been studied. Secondary metabolites produced by alien plants may be allelopathic; if they enter the soil, they may be transported by agricultural activities, negatively affecting crop yield and biodiversity. It is unknown whether substances from different alien species in combination have a greater impact on crops and wild plants than if they are from only one of the alien species. In this study, we used a set of common garden experiments to test the hypothesis that mixed extracts from two common invasive species have synergistic effects on crops and weeds (defined as all non-crop plants) in European agricultural fields compared to single-species extracts. We found that both the combined and individual extracts had detrimental effects on the seed germination, seedling growth, biomass, and photosynthetic performance of both crops and weeds. We found that the negative effect of mixed extracts was not additive and that crop plants were more strongly affected by invasive species extracts than the weeds. Our results are important for managing invasive species in unique ecosystems on agricultural land and preventing economic losses in yield production

Chlorophyll fluorescence imaging of cadmium-treated white cabbage plants

The chlorophyll fluorescence imaging technique is a valuable tool to study the impact of heavy metal stress in plants. The aim of this paper was to investigate the influence of Cd on photosynthetic apparatus of white cabbage (Brassica oleracea subsp. capitata f. alba) plants. Two cabbage cultivars ‘Ditmarska Najwcześniejsza’ (‘DN’; early) and ‘Amager Polana’ (‘AP’; late) were used. Cd was applied before planting seedlings (10 mg Cd kg−1 DM of soil).. Measurements were performed at the 3rd leaf after 2 weeks of planting. The level of Cd-induced stress to plants was estimated by chlorophyll (Chl) content (photometrically) and analyses of images and numeric values of the major fluorescence parameters of Chl (Chl fluorescence imaging system FluorCam). Cd negatively affected the chlorophyll content and Fv/Fm, Fv’/Fm’, Φ PSII and qP in leaves of early cultivar of white cabbage. However, in the case of late cv. we did not observe such distinct changes. It suggests that late cultivars. are more resistant to Cd than the early ones. Considering methodological aspect of the study, Chl fluorescence imaging can better reveal some alterations within the leaf, because numeric values of specific parameters, which are the averaged data collected from the whole leaf, cannot reflect the tissue specificity. Abbreviations: HM – heavy metal, Cd – cadmium, Chl – chlorophyll, Fv/Fm – photochemical efficiency of PSII in the dark-adapted state, F‘v’/F‘m’ – PSII maximum efficiency, Φ PSII – quantum efficiency of PSII electron transport, NPQ – nonphotochemical quenching of maximal Chl fluorescence, qP – photochemical quenching coefficient

Określenie bioretencji litu przez kukurydzę w warunkach kultur hydroponicznych

Irrigation of cultivated plants can be a source of toxic lithium to plants. The data on the effect of lithium uptake on plants are scant, that is why a research was undertaken with the aim to determine maize ability to bioaccumulate lithium. The research was carried out under hydroponic conditions. The experimental design comprised 10 concentrations in solution differing with lithium concentrations in the aqueous solution (ranging from 0.0 to 256.0 mg Li ∙ dm-3 of the nutrient solution). The parameters based on which lithium bioretention by maize was determined were: the yield, lithium concentration in various plant parts, uptake and utilization of this element, tolerance index (TI) and translocation factor (TF), metal concentrations in the above-ground parts index (CI) and bioaccumulation factor (BAF). Depression in yielding of maize occurred only at the highest concentrations of lithium. Lithium concentration was the highest in the roots, lower in the stems and leaves, and the lowest in the inflorescences. The values of tolerance index and EC50 indicated that roots were the most resistant organs to lithium toxicity. The values of translocation factor were indicative of intensive export of lithium from the roots mostly to the stems. The higher uptake of lithium by the above-ground parts than by the roots, which primarily results from the higher yield of these parts of the plants, supports the idea of using maize for lithium phytoremediation.Celem badań było określenie zdolności kukurydzy do bioakumulacji litu. Badania prowadzono w warunkach kultur wodnych. Schemat doświadczenia obejmował 10 obiektów różniących się stężeniem litu w roztworze wodnym, w zakresie od 0.0–256.0 mg Li∙dm-3 pożywki. Jako parametry, na podstawie których określono bioretencję litu przez kukurydzę przyjęto: plon, zawartość litu w różnych częściach rośliny, pobranie i wykorzystanie tego pierwiastka oraz indeksy: tolerancji plonu (TI), translokacji (TF), stężenia metalu w częściach nadziemnych (CI) i bioakumulacji (BAF). Depresja plonowania kukurydzy wystąpiła przy dawce 128 i 256 mg Li ∙ dm-3. Na podstawie uzyskanych wyników stwierdzono, że korzenie charakteryzowały się największymi zawartościami litu, natomiast niższymi łodygi i liście, a najmniejszymi kwiatostany. Wartości indeksu translokacji świadczą o intensywnym przemieszczaniu się litu z korzeni do części nadziemnych. Najwięcej litu pobrały łodygi, następnie korzenie, liście, a najmniej kwiatostan. Pobranie litu przez kukurydzę, w zależności od obiektu, wahało się od 2.31 do 24.36% w stosunku do ilości wprowadzonej do obiektu. Najmniejszy fi toodzysk odnotowano w obiektach, w których zastosowano największe ilości litu (3200-6400 mg Li akwarium-1), co zapewne było związane z dużymi dawkami litu oraz niskim plonowaniem i pobraniem tego pierwiastka przez kukurydzę