Betula platyphylla var. japonica (white birch) has heterophyllous leaves (i.e., early and late leaves) and is a typical pioneer tree species in northern Japan. Seedlings of white birch were exposed to ozone during two growing seasons, and measurements were carried out in the second year. Early leaves did not show an ozone-induced reduction in photosynthesis because of lower stomatal conductance resulting in higher avoidance capacity for ozone-induced stress. Also, an ozone-related increase in leaf nitrogen content may partly contribute to maintain the photosynthetic capacity in early leaves under elevated ozone in autumn. On the other hand, late leaves showed an ozone-induced decline of photosynthesis and early defoliation of leaves occurred. Also, smaller leaf size and higher stomatal density in late leaves were observed under elevated ozone. Differences in stress resistance to ozone may be related to differing functional roles of early and late leaves for birch species.

The effects of the ionic liquid 1-octyl-3-methylimidazolium chloride ([OMIM]Cl) was studied in hydroponically grown rice seedlings. Observed effects included increased root length and weight at concentrations of 0.1 mg/L [OMIM]Cl, however, as concentrations increased a reversed response was observed where roots and stems grew shorter and the weight decreased. The inhibitory concentration 50 (IC50,5d) values for root length and stem length were 0.59 mg/L and 0.70 mg/L, respectively. The Hill reaction activity and root system activity in [OMIM]Cl-treated rice seedlings were observed to be lower than the controls, however, root membrane permeability increased. The antioxidant enzyme activity in roots decreased, while in leaves there was an initial stimulation followed by a decrease. Malondialdehyde (MDA) content was found to be greater in seedlings subjected to [OMIM]Cl treatment. The cellular structures, such as chloroplasts, mitochondria and rough endoplasmic reticulum in rice root and leaf cells were affected at concentrations of 0.6 mg/L [OMIM]Cl.

Historic emissions from two zinc smelters have injured the forest on Blue Mountain near Palmerton, Pennsylvania, USA. Seedlings of soybeans and five tree species were grown in a greenhouse in a series of mixtures of smelter-contaminated and reference soils and then phytotoxic thresholds were calculated. As little as 10% Palmerton soil mixed with reference soil killed or greatly stunted seedlings of most species. Zinc was the principal cause of the phytotoxicity to the tree seedlings, although Mn and Cd may also have been phytotoxic in the most contaminated soil mixtures. Calcium deficiency seemed to play a role in the observed phytotoxicity. Exposed soybeans showed symptoms of Mn toxicity. A test of the effect of liming on remediation of the Zn and Mn phytotoxicity caused a striking decrease in Sr-nitrate extractable metals in soils and demonstrated that liming was critical to remediation and restoration.

Anaerobically digested and composted sewage sludge (CSS) has been suggested to be a slow-release fertilizer in forestry and an alternative to quick-release inorganic fertilizers. The effects of CSS with or without added carbohydrate on inorganic nitrogen availability and on soil animals were tested in two Norway spruce plantations. Half of the seedlings were individually fertilized with CSS, and the rest were left as controls. Solid sucrose was added to half of the fertilized and untreated seedlings. Soil samples were taken in the autumn in the first and the second year after the treatments. CSS increased soil NH4–N (2100%), the proportion of soil NO3–N, and the N concentration of spruce needles. CSS greatly reduced the abundances of enchytraeids, tardigrades and collembolans, but increased the proportion and abundance of bacterial-feeding nematodes irrespective of carbohydrate addition. A better stabilization method needs to be developed before CSS can be used as a forest fertilizer.

The influence of different concentrations (10–2000μM) of heavy metals (Cu, Mn, Ni, Zn) was analysed in Atriplex halimus and Salicornia ramosissima germination pattern and seedling size. They are two halophyte species that grow in the Estuary of Huelva (Southwest Iberian Peninsula, Spain), one of the most heavy metal-polluted environments in the world.All of the metals tested affected the final germination percentage in A. halimus and only Ni reduced germination in S. ramosissima. The germination rate was unaffected in both species.The study of seedling development shows that S. ramosissima, an intertidal annual species, has a higher tolerance of metals than A. halimus, a bush that inhabits the upper part of the marshes.Taking into account the metal concentrations in the estuary and the effects of these on the seedling development of the species analysed, we conclude that metals might limit plant colonisation in some parts of the marshes.

The effects of Si on growth, the anatomy of the roots, radial oxygen loss (ROL) and Fe/Mn plaque on the root surface were investigated in Avicennia marina (Forsk.) Vierh. seedlings under Cd stress. Si prompted the growth of seedlings and reduced the Cd concentration in the root, stem and leaf of A. marina. Si prompted the development of the apoplastic barrier in the roots, which may be related to the reduction of Cd uptake. The higher amount of ROL and Mn plaque on the root surface due to Si were also related to the promotion of Cd tolerance in A. marina seedlings. Therefore, it is concluded that the alteration of the anatomy of the roots, the increase of ROL and Mn plaque of A. marina seedlings play an important role in alleviation of Cd toxicity due to Si.

Petroleum hydrocarbon contamination of soil is an emerging environmental threat on the Earth due to possible toxic impact on different ecological receptors. The present study was mainly carried out to evaluate the phytotoxicity of long-term total petroleum hydrocarbon-contaminated soils by the toxicity end points obtained from three plant species Zea mays, Lactuca sativa L., and Cucumis sativus. The tested soil exerted phytotoxicity for all the evaluated end points of plants with dose-dependent relationship. The determined IC₅₀ indicates inhibition in root elongation as the most sensitive toxicity end point for L. sativa L., while inhibition in cross-section area of meristematic zone as the most susceptible and inhibition in seed germination as the least susceptible end points for both Z. mays and C. sativus. The tested root morphometric parameters confirm their applicability as novel toxicity end points. In addition, microcalorimetric analysis confirmed the applicability of inhibition in metabolic heat emission rate as a toxicity end point. Microcalorimetry can be applied to determine the exerted phytotoxic effect on seedlings. The present combined approach concludes that the phytotoxicity of the tested soil is species-specific and varies as follows: Z. mays < C. sativus < L. sativa L. The findings of this study may have implications in planning comprehensive phytotoxicity assessment for hydrocarbon-contaminated soils or screening plant species for phytoremediation program.

Many airborne and soil-borne nanoparticles (NPs) can enter plants, which are the primary producers in the food chain; recently, studies on the genotoxic effects of NPs on plants are emerging. In the present study, the phytotoxic and genotoxic effects of ZnO and CuO NPs on buckwheat (Fagopyrum esculentum) seedlings were estimated. The inhibition of root growth and biomass at the tested concentrations of NP suspensions and dissolved free ion suspensions were compared. Changes in root morphological features and localization of NPs inside the root epidermis cells were observed. Growth of root treated with ZnO NPs (84.9 and 89.6 %) and CuO NPs (75.4 and 80.1 %) at 2,000 and 4,000 mg L -1, respectively, was decreased significantly than control. The root morphological features and NP incorporation into the root epidermal cells at a high dose of NP showed completely different patterns compared to those for the controls. Through random amplified polymorphic DNA assays for comparison of the effect of ZnO and CuO NPs on DNA stability, it was shown as different DNA polymorphisms at 2,000 and 4,000 mg L-1 of ZnO and CuO NPs, compared to those for controls. Our results provide the first clue to the genotoxic effects of ZnO and CuO NPs on early growth of edible plants such as buckwheat. © 2013 Springer Science+Business Media Dordrecht.

Being predominant inorganic arsenicals, methylarsenicals also occur in anaerobic paddy soils. Therefore, this study investigated the influence of Fe concentrations and arsenic speciation [arsenate (As(V)) and dimethylarsinate (DMA)] in paddy soils on arsenic uptake in rice plant. Rice seedlings were grown in soil irrigated with a Murashige and Skoog (MS) growth solution containing As(V) or DMA with or without 1.8 mM Fe in excess to the background concentration of total iron (0.03 mM) in the soil. Arsenic concentration in rice roots increased initially and then decreased gradually when the seedlings were grown with excess Fe and As(V). In contrast, arsenic concentration in the roots increased steadily ( P < 0.01) when the seedlings were grown without excess Fe and As(V). When the form of the arsenic was DMA, total arsenic (tAs) concentration in rice roots increased gradually ( P < 0.01) and was not affected by the addition of excess Fe in the soil. When rice seedlings were grown with As(V), tAs concentration in rice roots and shoots increased steadily ( P < 0.01) for gradual increase of Fe concentrations in soil. However, tAs concentration in roots and shoots was independent of Fe concentrations in soil when the form of arsenic was DMA. The tAs concentrations in rice shoots also increased significantly ( P < 0.01) with increasing exposure time for both As(V) and DMA. Thus, Fe concentrations in soil affect arsenic uptake in rice plant depending on the speciation of arsenic.

Two mine soils in southeastern Ohio do not support a luxurious vegetation growth probably because of soil-related constraints. Thus, a laboratory study was conducted to improve the mine soil quality using amendments of zeolite (two grain sizes), flue gas desulfurization gypsum (FGD), fly ash, and biosolids at an application rate of 10 % by weight. The results showed that FGD was the best amendment for increasing soil pH and improving seed germination of lettuce (Lactuca sativa) while biosolids significantly enhanced soil aggregate stability and saturated-water-holding capacity. Specifically, FGD increased soil pH from 3.1 to 5.0, and 4.2 to above 7.0, respectively. Elongation of the lettuce seedlings (shoots) in mine soil solutions was also enhanced by the amendment, from an initial length of 0-1.5 cm to 4.5-9.6 cm. Application of biosolids, on the other hand, increased the mean weight diameter of soil water-stable aggregates by two to four times from initial 0.5-1.6 mm to 2.0-2.9 mm. Saturated-water-holding capacity of both soils was also significantly improved by biosolids. But biosolids did not enhance soil plant-available-water-holding capacity. Neither zeolite nor fly ash significantly improved the mine soil qualities measured in our study. Soil chemical analyses showed that these mine soils neither contained high concentrations of heavy metals nor other toxins in solids or in solutions, suggesting that soil acidity is the only chemical constraint limiting the vegetation establishment and growth besides the nutrients deficiency. © 2013 Springer Science+Business Media Dordrecht.