Genotype and environment: two factors related to autumn cold hardiness on Persian walnut (Juglans regia L.)

Context

J. regia timber is appreciated for high-value wood products. In new plantations, biotic or abiotic events which could affect wood quality should be monitored. Autumn frosts could affect annual shoot development, with consequent loss of timber value or even tree death. In southern Europe, climate change forecasts include erratic and severe autumn frost events.

Aims

The relationship between genotype and environment regarding susceptibility to autumn frost damage was examined in four provenances of Juglans regia L., planted at two ecologically different sites, one subject to Mediterranean and the other Atlantic weather conditions.

Methods

Annual budsticks from eight trees per provenance were collected in November 2010 from each site. The samples were then submitted to freeze–thaw cycles down to ?8, ?13 and ?18 °C, plus a control treatment (keeping samples at 5 °C). Damage to the stem was assessed using the index of freezing injury calculated from relative electrolyte leakage at each temperature considered. Frost damage to stem, apical and lateral buds was recorded by visual scoring.

Results

Differences in cold acclimation between sites were detected, with provenances exhibiting differences on senescence. A ‘provenance?×?site’ interaction was found in some of the analyses, but the same ranking of susceptibility was detected for all provenances at both sites and in all the tissues analysed. The differences between provenances could be related to their geographical origins, where an altitude gradient was observed.

Conclusions

The genetic component was important in the expression of autumn cold hardiness and, together with productive traits, should be considered in new afforestation projects.     

Effect of genotype,environment and genotype-by-environment interaction on metabolite profiling in durum wheat (Triticum durum Desf.) grain

The aim of this study was to assess the relative roles of genotype, environment and genotype-by-environment interactions in determining the metabolite profile of durum wheat grain. Four durum wheat cultivars were grown under conventional and organic farming systems over three consecutive years. The use of a high-throughput gas chromatography–mass spectrometry platform allowed the analysis of sets of different polar and non-polar compounds, including amino acids, sugars, organic acids, fatty acids (saturated and unsaturated), and sterols. Statistical analysis of the data showed a small impact of genotype and large effects of both year and genotype-by-environment interaction on the metabolite composition and quality of the wheat grain. Overall, the data from this study highlight the potential role of metabolic profiling in the analysis of durum wheat quality and production.     

Quercus ilex L. as bioaccumulator for heavy metals in urban areas: Effectiveness of leaf washing with distilled water and considerations on the trees distance from traffic

In recent years the use of plants as bioaccumulators or bioindicators has increased because enable the prediction of pollution for monitoring purposes, even in urban environments where traffic is a major source of heavy metals pollution. In this study we hypothesized holm oak (Quercus ilex L.) a valid trapping species for heavy metals. We also hypothesized that metals capture capacity by deposition on the crown is connected to the surrounding environmental characteristics and the distance of trees from the source of pollution. The study was conducted in the city of Florence. Holm oaks were selected in different sites near to heavy traffic roads. Concentrations of Zn, Pb, Cd, Cu, Fe, Mn, Cr, and Ba were analyzed through two methods: leaf washing with distilled water and leaf unwashing.One-year-old leaves (new leaves) were also compared with previous-year leaves (old leaves). Our results demonstrated the good capacity of this species to capture heavy metals (Pb, Fe, Mn, Cr, and Ba), particularly due to the presence of old leaves, which enhance the crown deposition surface. Washing was effective and it allowed testing the behaviour with regard to microelements: new leaves showed high Cu concentration, while old leaves had high Pb concentration. The dispersion of metals through the atmosphere was assessed through regression analysis, in two comparable gardens: leaves at farther distance from the traffic were richer in Zn, Pb, Mn, and Ba. The physical context of the surrounding environment was probably altering the distribution of heavy metals as barriers to dispersion, which can reach tens of metres from the source of pollution. Therefore, this work suggests that wind modelling and trees distribution and characteristics should be taken into consideration to evaluate the pollutants dispersion, especially for planning of recreational urban green areas.     

NMR characterization of saccharides in Italian honeys of different floral sources

The saccharide profiles of 5 different botanical species in 86 Italian honey samples were investigated by 1H and 1H-13C NMR spectroscopy. Nineteen saccharides were identified in the aqueous extracts, namely, fructose, glucose, gentiobiose, isomaltose, kojibiose, maltose, maltulose, melibiose, nigerose, palatinose, sucrose, turanose, erlose, isomaltotriose, kestose, maltotriose, melezitose, raffinose, and maltotetraose. PCA performed on NMR spectral regions, in particular between 4.400 and 5.700 ppm and the fructose signal at 4.050 ppm, revealed a partial sample grouping. The score contribution plots derived from PCA performed using the mean values for the buckets of the anomeric region for each floral source allowed the identification of saccharides characterizing different honeys. OPLS-DA models were further evaluated to confirm the previous findings. OPLS-DA models were also built to highlight differences between polyfloral and high mountain polyfloral honeys and between high mountain polyfloral and rhododendron honeys, both collected at high altitude; S-plots highlighted the characteristic saccharides.     

Atmospheric Deposition of Nitrogen to a Caribbean Coastal Zone (Cayo Coco,Cuba): Temporal Trends and Relative Importance as a Nitrogen Source

Nitrogen (N) deposition to the ocean is thought to be increasing worldwide, but the amount of coastal and open ocean measurements is very limited. In this paper, we assess N deposition in the coastal zone of Cayo Coco, in central Cuba, during a multi-annual period (2005–2007). Wet and dry N depositions were estimated based on the NH₄⁺ and NO_x^– concentrations in the rain. Cold fronts and troughs, coming from the west, contributed most to rain (41%) and to N deposition, followed by tropical waves and storms coming from the east, which caused 31% of the rain. Average concentrations of NH₄⁺ and NO_x^– in the rain were 8.8 and 8.3 μM. NO_x^– presented a clearly decreasing trend (0.26 μM per month), decreasing by half during 2005–2007. Total N deposition averaged 3.23 kg N ha⁻¹ year⁻¹, similar to that found in Virgin Islands and Puerto Rico, but lower than previously measured in Cuba and in nearby areas of the USA and than model predictions for the oceanic region around Cuba. These low values and the decreasing trend found are attributed to drastic reduction of fossil fuel and fertilizer use in Cuba since 1990. Because land input has decreased even more drastically, deposition seems to be nowadays the most important N source to the coastal zone of Cayo Coco. The δ¹⁵N range of seagrass (Thalassia testudinum) and macroalgae (Penicillus dumetosus) in the area (−1.83‰ to 3.02‰ and +1.02‰ to +4.17‰, respectively) sustain that atmospheric sources (deposition and N₂ fixation) comprise 70–90% of the N budget.     

Self-assembled pullulan-silica oxygen barrier hybrid coatings for food packaging applications

The scope of this study encompassed the evaluation of pullulan as a suitable biopolymer for the development of oxygen barrier coatings to be applied on poly(ethylene terephthalate) (PET), especially for food packaging applications. To enhance the oxygen barrier properties of the organic phase (pullulan) even at high relative humidity values, an inorganic phase (silica), obtained through in situ polymerization, was also utilized to obtain hybrid coatings via the sol-gel technique. Transmission electron microscopy (TEM) images and Fourier transform infrared (FT-IR) spectra showed that mixing the two phases yielded a three-dimensional hybrid network formed by self-assembly and mediated by the occurrence of new hydrogen-bond interactions at the intermolecular level, although the formation of new covalent bonds could not be excluded. The deposition of the hybrid coatings decreased the oxygen transmission rate (OTR) of the plastic substrate by up to 2 orders of magnitude under dry conditions. The best performance throughout the scanned humidity range (0%-80% relative humidity) was obtained for the formulation with the lowest amount of silica (that is, an organic/inorganic ratio equal to 3).     

Organic complexed superphosphates (CSP): physicochemical characterization and agronomical properties

A new type of superphosphate (organic complexed superphosphate (CSP)) has been developed by the introduction of organic chelating agents, preferably a humic acid (HA), into the chemical reaction of single superphosphate (SSP) production. This modification yielded a product containing monocalcium phosphate complexed by the chelating organic agent through Ca bridges. Theoretically, the presence of these monocalcium-phosphate-humic complexes (MPHC) inhibits phosphate fixation in soil, thus increasing P fertilizer efficiency. This study investigateed the structural and functional features of CSP fertilizers produced employing diverse HA with different structural features. To this end were used complementary analytical techniques: solid-phase 31P NMR, 13C NMR, laser-confocal microscopy, X-ray diffraction, and molecular modeling. Finally, the agronomical efficiency of four CSP have been compared with that of SSP as P sources for wheat plants grown in both alkaline and acidic soils in greenhouse pot trials under controlled conditions. The results obtained from the diverse analytical studies showed the formation of MPHC in CSP. Plant-soil studies showed that CSP products were more efficient than SSP in providing available phosphate for wheat plants cultivated in various soils with different physicochemical features. This fact is probably associated with the ability of CSP complexes to inhibit phosphate fixation in soil.     

Wood hydraulic and mechanical properties induced by low water availability on two ornamental species Photinia × fraseri var. Red Robin and Viburnum opulus L.

Deficit irrigation at the nursery stage induces drought acclimation through the establishment of avoiding mechanisms and hardening processes. In this experiment, we hypothesized that water deficit would affect wood hydraulic conductivity and mechanical properties with effects on the leaf water potentials of two ornamental species, Photinia × fraseri var. Red Robin and Viburnum opulus L.The experiment was conducted in a nursery (Pistoia, Italy) during summer 2011. Individuals were arranged in three plots under three watering regimes. The control plot (C) received an amount of water replacing that lost via evapotranspiration, while two plots were maintained under severe water deficit (SWD = 33% C) and moderate water deficit (MWD = 66% C).Water deficits reduced stem diameter in both species without changing wood density (D). Concerning mechanical properties, stiffness (E) and strength (YS) of Photinia resulted higher in Photinia than in Viburnum, which did not show differences between treatments in either E or YS, whereas in Photinia, E was lower in SWD (P < 0.05) than in C. Photinia was also characterized by higher k without significant differences between treatments while Viburnum showed a lower conductivity and a significant reduction of k_h under SWD (P < 0.05). Despite this, in field conditions the two species had similar behaviour concerning the leaf water status, showing a reduction of Ψ under SWD.A longer acclimation period would probably be necessary to induce major changes in wood mechanical properties, but the similarity of responses on leaf water status in MWD and C might indicate that a reduction to 66% of water need might be sufficient to maintain the level of turgor necessary for plant physiological functioning.     

A review of the roles of forest canopy gaps

Treefall gap, canopy opening caused by the death of one or more trees, is the dominant form of disturbance in many forest systems worldwide. Gaps play an important role in forest ecology helping to pre- serve bio- and pedo-diversity, influencing nutrient cycles, and maintain- ing the complex structure of the late-successional forests. Over the last 30 years, numerous reviews have been written describing gap dynamics. Here we synthesize current understanding on gap dynamics relating to tree regeneration with particular emphasis on gap characteristics consid- ered critical to develop ecologically sustainable forest management sys- tems and to conserve native biodiversity. Specifically, we addressed the question： how do gaps influence forest structure？ From the literature re- viewed, the size of gaps induces important changes in factors such as light intensity, soil humidity and soil biological properties that influence tree species regeneration and differ in gaps of different sizes. Shade- tolerant species can colonize small gaps; shade-intolerant species need large gaps for successful regeneration. Additionally, gap dynamics differ between temperate, boreal, and tropical forests, showing the importance of climate differences in driving forest regeneration. This review summa- rizes information of use to forest managers who design cutting regimes that mimic natural disturbances and who must consider forest structure, forest climate, and the role of natural disturbance in their designs.     

In vitro effect of the red alga Hydropuntia cornea (J. Agardh) on the respiratory burst activity of sole (Solea senegalensis, Kaup 1858) phagocytes

The stimulatory effect of different extracts from the red alga Hydropuntia cornea (formerly Gracilaria cornea) on the respiratory burst activity of sole phagocytes was evaluated in vitro. Aqueous and ethanolic extracts and extracellular polysaccharidic fractions from algal cultures were assayed. Phagocytes, isolated from sole kidney, were incubated in vitro with different algal fractions at concentrations of 10, 5, 2 and 1 mg mL⁻¹. As a positive control, commercial β‐glucan from the alga Euglena gracilis was used. The results obtained indicate that an ethanolic extract from H. cornea, at 10 mg mL⁻¹, is capable of enhancing superoxide anion production in sole phagocytes when the cells are incubated for 30 min with the bacterium P. damselae ssp. piscicida and the extract. On the other hand, the commercial β‐glucan leads to a significant increase at highest concentration, 10 mg mL⁻¹, after 30 min of incubation.