Ethylenediurea (EDU) Affects the Growth of Ozone-Sensitive and Tolerant Ash ( Fraxinus excelsior

Adult ash trees (Fraxinus excelsior L.), known to be sensitive or tolerant to ozone, determined by presence or absence of foliar symptoms in previous years, were treated with ethylenediurea (EDU) at 450 ppm by gravitational trunk infusion over the 2005 growing season (32.5 ppm h AOT40). Tree and shoot growth were recorded in May and September. Leaf area, ectomycorrhizal infection, and leaf and fine root biomass were determined in September. EDU enhanced shoot length and diameter, and the number and area of leaves, in both O3-sensitive and tolerant trees. However, no EDU effects were recorded at the fine root and tree level. Therefore, a potential for EDU protection against O3-caused growth losses of forest trees should be evaluated during longer-term experiments

Short Communication Proceedings: Impacts of Air Pollution and Climate Change on Forest Ecosystems TheScientificWorldJOURNAL

Adult ash trees (Fraxinus excelsior L.), known to be sensitive or tolerant to ozone, determined by presence or absence of foliar symptoms in previous years, were treated with ethylenediurea (EDU) at 450 ppm by gravitational trunk infusion over the 2005 growing season (32.5 ppm h AOT40). Tree and shoot growth were recorded in May and September. Leaf area, mycorrhizal infection, and leaf and fine root biomass were determined in September. EDU enhanced shoot length and diameter, and the number and area of leaves, in both O 3 -sensitive and tolerant trees. However, no EDU effects were recorded at the fine root and tree level. Therefore, a potential for EDU protection against O 3 -caused growth losses of forest trees should be evaluated during longer-term experiments. KEYWORDS: European ash, ethylenediurea, forest, growth, mycorrhizae, tropospheric ozone INTRODUCTION Much has been written about the effects of O 3 on growth of forest trees, but conclusive proof that ambient levels of O 3 affect growth of forest trees remains elusive, usually because the experimental techniques do not allow extrapolation to realistic conditions Paoletti et al.: EDU Effects on Tree Growth TheScientificWorldJOURNAL (2007) 7(S1), 128-133 129 MATERIALS AND METHODS Six O 3 -sensitive (symptomatic) and six O 3 -tolerant (asymptomatic) adult ash trees, determined by presence or absence of foliar symptoms in previous years, were gravitationally infused with 450 ppm ethylenediurea (EDU) or water at 3-week intervals from May to September, 2005. AOT40 over the period was 32.5 ppm h. The experimental site was located at the 34-ha "Millerose" park in Turin, Italy. Details about infusion methodology, site characteristics, and EDU protection from O 3 visible injury are presented elsewhere Measurements of tree and shoot growth were carried out in May and September, while biomass, leaf area, and fine root mycorrhizal infection were determined only in September. Tree diameter was measured at breast height by means of a calliper. The points of measurements were labelled to reduce the error from May to September. Tree height was measured with a clinometer (Model CM360PA, Silva, Sweden). Shoot growth was measured on one 1-year-old sun shoot per tree, from the lower crown part. The shoots were the terminal ones of a lateral branch and were randomly selected. The total number of leaves and leaflets per shoot was counted. Shoot length and base diameter were recorded by means of a ruler and a digital calliper, respectively, with 0.1-mm accuracy. In September, 3 shoots per plant were collected. Total leaflet area per shoot was determined with an AM300 area meter (ADC, BioScientific Ltd, Herts UK). Shoot biomass was determined by oven-drying at 65 °C until a constant weight was reached. Leaflet mass per unit of leaflet area (LMA) and leaflet water content (LWC = (fresh weight-dry weight)/dry weight) were calculated Fine roots (diameter<2 mm) were sampled in standard cores of soil (500 ml). Four cores per tree were collected 40 cm far from the trunk along the cardinal points and joined in a single sample. Roots were attributed to F. excelsior with the help of morphological and anatomical observations The statistical unit was the single tree. After checking for normality, data were analyzed using a twoway (EDU x tree O3-sensitivity) analysis of variance (Statistica 6.0, StatSoft, Tulsa, OK). RESULTS EDU significantly reduced the abscission of leaves and induced a larger increment of the shoot length and diameter over the growing season, compared to the water-infused trees Paoletti et al.: EDU Effects on Tree Growth TheScientificWorldJOURNAL EDU Symptomatic 8.0 ± 1.8 2.5 ± 2.5 -6.2 ± 2.3 -7.9 ± 1.7 17.5 ± 8.8 11.1 ± 2.7 EDU Asymptomatic 2.0 ± 0.8 1.1 ± 1.0 1.8 ± 0.9 2.8 ± 2.5 17.5 ± 5.5 15.3 ± 0.2 WATER Symptomatic 5.1 ± 2.7 0 -7.7 ± 1.0 -10.6 ± 1.9 6.7 ± 1.2 6.0 ± 2.0 WATER Asymptomatic 1.0 ± 0.9 2.4 ± 4.0 -2.8 ± 3.5 -6.9 ± 2.4 7.7 ± 4.4 4.6 ± 2. Paoletti et al.: EDU Effects on Tree Growth TheScientificWorldJOURNAL DISCUSSION EDU enhanced shoot length and diameter, and reduced leaf abscission. The stimulating effect of EDU on shoot growth did not translate into a stimulation of growth at the fine root and whole tree level, during one growing season. Overall, EDU effects were slight, and not enough to significantly affect the total leaf biomass. Increased growth in the EDU-treated plants over the non-EDU-treated ones has been reported in several species (Phaseolus vulgaris[18] Symptomatic trees did not show a marked reduction in growth compared to the asymptomatic trees. At the shoot level, we recorded a stimulation of leaf abscission. Part of the photosynthate may have been used to prevent or repair foliar damage rather than going toward growth In conclusion, gravitational infusion of EDU resulted in stimulation of shoot growth in both O 3 -sensitive and tolerant ash trees exposed to elevated ambient O 3 concentrations (32.5 ppm h AOT40). Ainsworth et al

Visible Foliar Injury and Physiological Responses to Ozone in Italian Provenances of Fraxinus excelsior and F. ornus

We compared leaf visible injury and physiological responses (gas exchange and chlorophyll a fluorescence) to high O3 exposure (150 nmol mol–1 h, 8 h day–1, 35–40 days) of two woody species of the same genus with different ecological features: the mesophilic green ash (Fraxinus excelsior) and the xerotolerant manna ash (F. ornus). We also studied how provenances from northern (Piedmont) and central (Tuscany) Italy, within the two species, responded to O3 exposure. Onset and extent of visible foliar injury suggested that F. excelsior was more O3 sensitive than F. ornus. The higher stomatal conductance in F. ornus than in F. excelsior suggested a larger potential O3 uptake, in disagreement to lower visible foliar injury. The higher carbon assimilation in F. ornus suggested a higher potential of O3 detoxification and/or repair. Contrasting geographical variations of ash sensitivity to O3 were recorded, as Piedmont provenances reduced gas exchange less than Tuscan provenances in F. excelsior and more in F. ornus. Visible injury was earlier and more severe in F. excelsior from Piedmont than from Tuscany, while the provenance did not affect visible injury onset and extent in F. ornus

Physiological Responses to Drought Stress in Jatropha curcas Seedlings

Aims: The aim of the study was to investigate the physiological mechanisms of Jatropha curcas seedlings exposed to drought and the possible influence of seedling age. Study Design: A pot experiment was carried out using a completely randomized design with two seedling ages (2- and 3-month-old seedlings), two treatments per age (Watered: fully irrigated, and Unwatered: Not irrigated), six replicates (24 pots). Place and Duration of Study: The experiment was performed in a greenhouse facility located at the Experimental Station “Mauro Deidda” (Department of Agriculture of University of Sassari) at Ottava (Sassari, Italy) between June and September 2011.Methodology: To investigate the responses of 2- and 3-month-old J. curcas seedlings exposed to drought stress on 4th, 8th, 12th, 19th, and 26th day from treatment’s beginning, leaf and soil water content, biometric, gas exchange, and chlorophyll a fluorescence measurements were performed; on 26th day from treatment’s beginning, biometric destructive measurements were carried out. Results: Results support the hypothesis that J. curcas is appropriate to be cultivated in areas with limited water availability or prolonged periods of drought and highlight that mechanisms of drought response are highly influenced by seedling age. J. curcas seedlings maintained a good leaf water status by means of an effective stomatal closure, associated with a reduced aboveground growth and an increased root:shoot ratio. Under drought stress, 2-month seedlings showed a higher allocation of resources to roots compared to 3-month seedlings. Drought resulted in more detrimental effects on the photosynthetic response of 3-month seedlings, inducing the reduction of stomata conductance and the loss of photosystem II integrity. 2-month seedlings were instead able to activate mechanisms of drought tolerance through the activation of excess energy dissipation mechanisms. Conclusion: In the early stage of crop establishment, the transplanting of J. curcas 2-month seedlings proved to be more effective in order to avoid water stress related consequences

State-of-the-art of the <i>Jatropha curcas</i> productive chain: from sowing to biodiesel and by-products

In the forthcoming years, 1–2 million hectares of Jatropha curcas L. are expected to be annually planted, reaching 12.8 million hectares worldwide by 2015. This considerable expansion is due to its products and byproducts multiple uses and its amazing adaptability. J. curcas oil extracted by seeds is a promising renewable feedstock for biodiesel production and, together with the oil extraction by-products, it can be used as cooking/lighting fuel, bio-pesticide, organic fertilizer, combustible fuel, and for soap making. The capability to grow on poor quality soils not suitable for food crop makes J. curcas a possible solution of all the controversies related to biodiesel production. Furthermore, J. curcas contributes to mitigate environmental problems, such as marginal land or abandoned farmland reclamation. Nevertheless, J. curcas is not a “miracle tree”: (i) the full potential of J. curcas is far from being achieved and its talents are still to be supported by scientific evidences; (ii) J. curcas capabilities are not easily exploitable and applicable simultaneously; (iii) its use is controversial and potentially unsustainable due to the current knowledge gaps about the impacts and potentials of J. curcas plantations. The aims of this review are to detail each phase of J. curcas productive chain from sowing to biodiesel and by-products, in order to logically organize the knowledge around J. curcas system, and to compare potentialities and criticalities of J. curcas, highlighting the agronomical, management, and environmental issues which should be still investigated

Physiological and biochemical responses of <i>Quercus pubescens</i> to air warming and drought on acidic and calcareous soils

The drought- and thermo-tolerant Quercus pubescens, a tree species growing on both acidic and calcareous soils in the sub-Mediterranean region, was exposed to soil drought (-60% to -80% soil water content) and air warming (+1.2 C daytime temperature), singly and in combination. The experiment was conducted on two natural forest soils with similar texture but different pH (acidic and calcareous soils). The physiological (photosynthesis) and biochemical (antioxidant system) responses of Q. pubescens were investigated. On acidic soil, Q. pubescens had a higher reactive oxygen species (ROS) content than on calcareous soil, confirming that this species is better adapted to the latter soil type. A down-regulation of ascorbate-glutathione cycle enzymes suggests that ROS were used as signalling molecules. Air warming stimulated stomatal opening, while soil drought induced stomatal closure in the late afternoon and reduced Rubisco carboxylation efficiency. Photosynthetic performance in the combined treatment was higher than under single drought stress and similar to control and air warming. Q. pubescens biochemical responses depended on soil pH. On acidic soil, Q. pubescens trees exposed to air warming used ROS as signalling molecules. On calcareous soil, these trees were able to balance both soil drought and air warming stress, avoiding ROS toxic effects by increasing antioxidant enzyme activitiy and maintaining a high enzymatic antioxidant defence. When combined, drought and air warming induced either more severe (higher oxidative pressure and impairment of the light-harvesting complex) or different responses (decline of the thermal energy dissipation capacity) relative to the single stressors. Overall, however, Q. pubescens preserved the functionality of the photosynthetic apparatus and controlled the antioxidant system response, thus confirming its drought and thermo-tolerance and therefore its potential to adapt to the ongoing climate change

Modeling bio-engineering traits of Jatropha curcas L.

The wide distribution of Jatropha curcas L. in tropical areas provides the opportunity to use this plant for improving slope stability and controlling erosion. To determine the effectiveness of Jatropha curcas L. as a bio-engineering plant we measured stem diameter and height of 1, 3, 5, 6, 18, and 36 month-old plants, and root distribution at 6, 18, and 36 months by full excavation of the root system. We also measured in the laboratory the elastic modulus and maximum tensile force of 50 roots. These data were used to calibrate a weighted log-likelihood root distribution model and a root reinforcement model. Models were coupled to estimate root reinforcement at stand scale over a three year period as a function of the plantation's tree density. Our results of root distribution indicate a rapid decrease of root diameter along the root length leading to rapidly decreasing root reinforcement with distance from the stem. Minimal root reinforcements at 0.5 m from the stem is about 1 and 11 kPa for 18 and 36-month old plants, respectively. At 1 m from the stem only 36-month old plants provide any significant root reinforcement. Despite its relatively low root reinforcement relative to other larger tree species Jatropha curcas L. is a suitable bio-engineering plant because it easily propagates, grows fast, and is resilient. Root reinforcement in the first stage of growth needs high density plantation of up to 40,000 plants per hectare. This should then be followed by thinning down to 10,000 plants per hectare to optimize root reinforcement at 3 years age

Inter- and intra-specific variability in isoprene production and photosynthesis of Central European oak species

European deciduous oaks are closely related and are known for their strong emission of volatile isoprenoids. They are chemo-taxonomically diverse, but hybridise frequently. Four-year-old oak seedlings growing together in a model ecosystem facility under near-natural conditions were studied. The leaves were morphologically classified in the three oak species Quercus robur, Q. pubescens and Q. petraea (with four provenances each) and further investigated by a molecular-genetic approach. Q. robur was morphologically and genetically clearly different from Q. pubescens and Q. petraea, whereas Q. pubescens and Q. petraea individuals used in this study were morphologically and genetically more similar. There was a minor impact of among and within species variability on isoprene synthesis, isoprene emission and photosynthesis. Isoprene emission rates normalised to 25 °C leaf temperature ranged from 5.78 to 10.66 nmol m - 2 s -1, whereas photosynthesis ranged from 12.8 to 17.6 lmol m -2 s -1. On cloudy days, among the provenances of each species, only net photosynthesis of the Q. robur provenance Hu¨nenberg was reduced and isoprene synthase activity of the Q. pubescens provenance Promotogno increased. On sunny days, photosynthesis did not differ among the provenances. Over all provenances, gas exchange on cloudy days did not differ significantly from sunny days. In the combined data of cloudy and sunny days, no differences between the studied provenances and oak species were detected in isoprene emission and photosynthesis. Thus, isoprene emission and photosynthesis rates were remarkably stable among oak species and provenances. The results indicate that taxonomic differences in the studied oak species are not reflected in isoprene emission and photosynthesis, probably because of the high plasticity of gene expression resulting in high phenotypic flexibility