Lolium Perenne Seedlings Research Articles

Biometric indicators of growth and development of Lolium perenne and Trifolium repens in terms of recultivation of soil contaminated with petroleum

The aim of the research was to determine the factors defining the growth and development of Lolium perenne and Trifolium repens upon petroleum contamination. The top layer of clay soil contaminated with petroleum products resulting from an oil pipeline failure was collected for the tests. The control was the same type of uncontaminated soil with the addition of, under laboratory conditions, tissue paper. The research was conducted in two stages. The first concerned the germination process and seedlings parameters (Petri dishes). The germination energy ( GE) and the germination capacity ( GC) of seeds were determined. The seedling’s development was also evaluated based on ‘WinRhizo PRO 2009’ software. Then, in the second stage, pot tests were carried out, where the growth and development of species in the first year after sowing were temporarily measured. The parameters studied were the number, height, green and dry masses of the plants. A Gompertz regression model describing seed species germination and number species as time dependent dynamic was applied. The data were analysed statistically using variance analysis (ANOVA) and the PCA (principal component analysis) method. The results of our study indicated that admixture of petroleum into the soil does not seriously affect the development dynamics of Lolium perenne seedlings. The diesel oil contamination mostly affects the germination of the Trifolium repens by a statistically significant increase of the maximum value of germination and increasing the maximum growth rate.

Labdane-Type Diterpenoids from Leonurus japonicus and Their Plant-Growth Regulatory Activity.

Thirteen new labdane-type diterpenoids 1-6, 9-11, 13, 14, 18, and 19 and seven known ones were isolated from the aerial parts of Leonurus japonicus. Compounds 1-5 represent rare examples of labdane-type diterpenoids, of which compounds 1-4 carry an N-chain linked at C-7 in their B-ring and compound 5 featured an α,β-unsaturated-γ-lactam moiety. The structures and absolute configurations of these new diterpenoids were characterized by a combination of spectroscopic techniques, X-ray crystallography, electronic circular dichroism, and calculated specific rotations. The plant-growth regulatory activity of these compounds on the growth of the roots and shoots of Lactuca sativa and Lolium perenne seedlings were evaluated. Compound 3 showed a broad-spectrum inhibitory activity with the inhibition rates ranging from 60 to 83.5% at a concentration of 200 μg/mL, which were as active as those of glyphosate. Compound 8 had a selective inhibitory activity against the growth of the roots of L. perenne seedlings with an inhibition rate of 81.7%. However, compounds 11 and 16 exhibited significant stimulation effects on the roots of L. sativa with stimulation rates of 59.8 and 65.3%, respectively. In addition, compounds 3 and 8 exhibited inhibitory effects on the germination of L. perenne seeds.

Effects of elevated CO 2 concentration on rhizodeposition from Lolium perenne grown on soil exposed to 9 years of CO 2 enrichment

The effects of enriched CO 2 atmosphere on partitioning of recently assimilated carbon were investigated in a plant-soil-microorganism system in which Lolium perenne seedlings were planted into cores inserted into the resident soil within a sward that had been treated with elevated CO 2 for 9 consecutive years, under two N fertilisation levels (Swiss FACE experiment). The planted cores were excavated from the ambient (35 Pa pCO 2) and enriched (60 Pa pCO 2) rings at two dates, in spring and autumn, during the growing season. The cores were brought back to the laboratory for 14C labelling of shoots in order to trace the transfer of recently assimilated C both within the plant and to the soil and microbial biomass. At the spring sampling, high N supply stimulated shoot and total dry matter production. Consistently, high N enhanced the allocation of recently fixed C to shoots, and reduced it to belowground compartments. Elevated CO 2 had no consequences for DM or the pattern of C allocation. At the autumn sampling, at high N plot, yield of L. perenne was stimulated by elevated CO 2. Consistently, 14C was preferentially allocated aboveground and, consequently belowground recent C allocation was depressed and rhizodeposition reduced. At both experimental periods, total soil C content was similar in all treatments, providing no evidence for soil carbon sequestration in the Swiss Free Air CO 2 Enrichment experiment (FACE) after 9 years of enrichment. Recently assimilated C and soil C were mineralised faster in soils from enriched rings, suggesting a CO 2-induced shift in the microbial biomass characteristics (structure, diversity, activity) and/or in the quality of the root-released organic compounds.

Glomus intraradices Enhances Growth and Gas Exchange of Lolium perenne Seedlings in Petroleum-contaminated Soil

Arbuscular mycorhizal fungi (AMF) have been used in phytoremediation and can increase tolerance and growth of plants in contaminated environments. However, little is known about the influence AMF on plant growth to organic contaminants in soils. A greenhouse experiment was conducted to study the response of seedlings of annual ryegrass (Lolium perenne L.) var. Passerel Plus inoculated with Glomus intraradices Schenck & Smith in soil contaminated with sweet Arabian median crude oil. Inoculated (AMF) and non-inoculated (Non-AMF) plants were established in an pasteurized and artificially contaminated sandy loam soil with 0; 3000; 15,000; or 45,000 mg of petroleum kg-1 soil (n = 20). Plants were inoculated with 500 spores of G. intraradices (Mycorise® ASP, PremierTech Biotechnologies, Canada). After 90 days, plant growth of AMF or Non-AMF plants, was drastically affected at all petroleum concentrations. However, G. intraradices enhanced plant growth, chlorophyll content, and gas exchange of plants grown at 3,000 mg kg-1 compared to Non-AMF plants. Total leaf area, chlorophyll, and net photosynthesis were also higher (+380%, +63%, and +81%, respectively) at this concentration. Water use efficiency (net photosynthesis/stomatal conductance) of AMF-plants was three times greater than Non-AMF at 3,000 mg·kg-1. At concentrations of 15,000 and 45,000 mg kg-1 AMF did not have effect, but colonization was observed (11.8% and 18.6%, respectively). These values of colonization were significantly lower than those observed in AMF-plants at 0 (42.5%) and 3,000 mg·kg-1 (55.6%). Studies are currently being conducted to understand the physiological role of AMF on plants exposed to organic contaminants.

Forum

In a recent Forum article, Tibbett (2000) argued that mycorrhizal symbionts are more important than root proliferation for the exploitation of nutrient-rich zones or ‘patches’ in soil. There is little doubt that mycorrhizal fungi can enhance nutrient capture for their host. Both ecto- and ericoid mycorrhizal fungi can access nutrients (e.g. organic N) that would otherwise be unavailable to the plant, and through enzymatic production may enhance organic matter degradation. But this paper addresses the role of arbuscular mycorrhizas (AMs) in patch exploitation, as AMs are the most common of mycorrhizal associations, occurring in two-thirds of all land plant species. Tibbett’s case for mycorrhizas competing better than roots for nutrients needs critical examination. He stated that ‘we may come to perceive the role of roots, in terms of acquiring nutrients from organic patches, as relatively inert structures from which symbiotic organs, that can better compete with the wider microbiota are dispatched.’ Thus fungal, not root, proliferation would be expected. In support of this view, Tibbett (2000) cited experiments where root proliferation took a long time to occur in complex organic patches of a high C : N ratio. Other studies however, reveal that: • Plant N capture from N-rich patches of lower C : N ratio (<4) can be substantial (45–54%) even if root proliferation occurs only after c. 25 days (Hodge, Robinson & Fitter 2000). • Mycorrhizal colonization had little effect on the root foraging responses of seven co-occurring herbaceous species, and only one (Oxalis acetosella) showed a nutritional benefit from colonization (Farley & Fitter 1999). • Root responses are demonstrably more important for plant N capture than those of AM fungi. Lolium perenne seedlings supplied with l-lysine patches had the same slight (<20%) AM colonization that did not vary among treatments nor differ from controls (Hodge et al. 1999a). By contrast, roots responded strongly to the treatments. Duke et al. (1994) concluded that ‘increased plant root proliferation and uptake capacity are likely to be more important for the exploitation of temporary nutrient pulses or patches than is increased mycorrhizal activity.’ In contrast, Tibbett (2000) stated that ‘current emphasis on plant roots may have over estimated their significance in patch exploitation.’ Which view is correct? It is not yet possible to give a definitive answer. More experiments must be carried out on the ecology of AM fungi, in particular on the role of the external mycelium, before we can determine their importance in patch exploitation and their influence on root proliferation. Furthermore, AM fungi are multifunctional, and it cannot be assumed that all will necessarily enhance nutrient capture equally. Meanwhile, it should be remembered that the context in which roots proliferate may be as important as the response itself, for example, proliferation is relatively unimportant for nitrate capture by isolated individuals, but is important when individuals compete for nitrate (Hodge et al. 1999b). This context dependency may also apply to AM fungi. For example, inoculation of Plantago lanceolata seedlings with an AM fungus did not increase N capture from an organic patch, but it did increase root production, most pronouncedly within the patch zone (Hodge et al. 2000). Had the plants been grown in competition, however, the AM-related increase in root production may have enhanced their N capture. Root proliferation in N-rich patches would still give a plant a competitive advantage over its neighbours, whatever their mycorrhizal status.

Characterisation and microbial utilisation of exudate material from the rhizosphere of Lolium perenne grown under CO 2 enrichment

The effects of elevated atmospheric CO 2 concentration on alterations, both qualitatively and quantitatively, of exuded compounds from the roots of Lolium perenne seedlings were investigated by growing plants in a sterilised sand microcosm unit. In addition, the effect of CO 2 treatment on carbon substrate utilisation of microbial populations extracted from the rhizosphere of L. perenne seedlings grown in soil microcosm units was examined and alterations on microbial activity and diversity assessed using a commercially-available redox-based sole C source utilisation test (Biolog®) including additional exudate compounds. Both types of microcosm units (sand and soil) were maintained at specific growth conditions under two CO 2 regimes (450 and 720 μmol mol −1). Growth of L. perenne seedlings from both types of microcosm units was enhanced under elevated atmospheric CO 2 although the root-to-shoot ratios were not significantly altered, indicating no gross change in dry matter partitioning. Cumulative total organic carbon (TOC) release in the exudate material over the duration of the experiment was significantly ( P≤0.05) higher from ambient-grown seedlings despite a significant ( P≤0.05) increase in the dry weight of roots of the elevated CO 2 grown seedlings as determined at harvest. Over the individual sampling periods TOC release was significantly ( P≤0.05) higher from elevated CO 2 grown seedlings on only one occasion (21 d). Qualitative differences, measured between d 1–6 and 14–18, also occurred with elevated CO 2 treatment decreasing the amount of phenolic acids and total sugars at the latter sampling period compared to ambient CO 2 seedlings. Total numbers of bacteria were significantly ( P≤0.05) decreased under elevated CO 2 although culturable numbers significantly ( P≤0.05) increased. This increase in culturable microorganisms may explain the faster carbon source utilisation rates of the elevated CO 2 treatment. No change in morphotypes of microbial colonies were observed suggesting a quantitative difference due to elevated CO 2 treatment only.

Ultrastructural evidence of damage to leaf stromal protein four hours after treatment with paraquat

An ultrastructural investigation of paraquat-treated leaf tissue of Lolium perenne seedlings using negative staining techniques alongside conventional ultrathin sectioning methods revealed extensive damage to the Rubisco molecules after only 4 h in light. The early involvement of hydroxyl radicals in chloroplast stroma destruction is discussed

The use of experimental design and response surfaces in a study of the influence of copper, arsenic and chromium on Lolium perenne seedlings

The present investigation uses response surface methodology (RSM) in the study of the effects of Cu, As and Cr on Lolium perenne seedlings and reports the interactions that may occur between these elements.

The effect of copper on Lolium perenne seedlings

The present study looks at the effects of copper on perenial ryegrass seedlings that have been grown in hydroponic solutions and the uptake of some essential elements.

Uptake of selenium, tellurium and interaction with some essential metals (Mn, Fe, Cu and Zn) by Lolium perenne

Two experiments involving the growth of Lolium perenne seedlings were carried out by adding Se(VI) (as sodium selenate) or Te(VI) (as telluric acid) to the nutrient solutions and the plants allowed to grow for a further period of time. Se and Te concentrations in the shoots follow closely the level of Se or Te supplied in the nutrient solution. The uptake of Se and Te by shoots is higher thanin the corresponding root samples. Se and Te reduce the dry weight of both shoots and roots of this particular species. The significant effects of Se and Te which were observed on the uptake of some essential metals (Mn, Fe, Cu and Zn) into the roots did not extend to the shoots.

Paraquat tolerant and susceptible perennial ryegrasses: effects of paraquat treatment on carbon dioxide uptake and ultrastructure of photosynthetic cells

Abstract. Paraquat treatment of susceptible Lolium perenne seedlings (cultivar Kent Indigenous) rapidly inhibited CO2 uptake and after 1 h chloroplasts exhibited abnormal fusions of the thylakoid membranes. Further ultrastructural changes occurred within the chloroplasts until 8 h after treatment, when cytoplasmic damage also became evident. The localization of primary damage within the chloroplast differs from previous reports of paraquat toxicity in other species. Paraquat treatment of tolerant L. perenne seedlings (line PRP IX) resulted in little change in CO2 uptake and ultrastructural effects were generally confined to the gradual development of deposits in the chloroplast stroma. These observations are discussed in relation to the mechanism of action of the herbicide and the proposed mechanism of paraquat tolerance in L. perenne.