Linking morphological and ecophysiological leaf traits to canopy dieback in Persian oak trees from central Zagros

Intraspecific variability in morphological and ecophysiological leaf traits might be theorized to be present in declining populations,since they seem to be exposed to stress and plasticity could be advantageous.Here we focused on declining Persian oaks(Quercus brantii Lindl.var.persica(Jaub and Spach)Zohary)in the Zagros Mountains of western Iran,representing the most important tree species of this region.We selected trees with contrasting crown dieback,from healthy to severely defoliated,to investigate the relationships between canopy dieback and leaf morphology,water content and pigments.We also measured esterase and peroxidase,as enzymatic antioxidants and indicators of contrasting genotypes.Trees showing moderate to severe defoliation showed higher leaf mass area(LMA),reduced relative water content(RWC),and lower stomatal density(SD).Increasing LMA indicates a more sclerophyllic structure,according to drier conditions.We did not find significant differences in leaf pigments(chlorophyll a and b,and carotenoids)among crown dieback classes,suggesting that Persian oak trees are able to maintain accurate photochemical efficiency,while reduced RWC and SD suggest hydraulic limitations.Our results do not provide a consistent pattern as regards enzymatic antioxidant defense in Persian oak.Morphological leaf traits would be important drivers of future adaptive evolution in Persian oak,leading to smaller and thicker leaves,which have fitness benefits in dry environments.Nonetheless,drought responses may be critically affecting carbon uptake,as photosynthetic compounds are less effectively used in leaves with higher sclerophylly.     

Growth and yield of 5 years old teak and flueggea in single and mixed species forestry systems in the Solomon Islands

New Forests - Mixed species plantings of teak (Tectona grandis) and flueggea (Flueggea flexuosa) were introduced as a method for overcoming the reluctance of local growers to thin their teak....     

Nitrogen and carbon cycling associated with litterfall production in monoculture teak and mixed species teak and flueggea stands

Purpose

High demand for teak (Tectona grandis L.f.), a species of economic importance, was the reason Solomon Islands experienced a surge in community-wide planting of monoculture teak stands in the last two decades. Mixed species planting of teak and flueggea (Flueggea flexuosa Muell. Arg.) was introduced to overcome the reluctance of growers to thin their stands. However, there is lack of information on the effect of changing from monoculture to mixed species plantings on the cycling of nutrients especially carbon (C) and nitrogen (N).

Materials and methods

This study assessed litter quantity and quality, total C (TC), total N (TN), C:N ratio and C and N isotope compositions (δ¹³C and δ¹⁵N) over 18 months at two sites (Ringgi and Poitete). The treatments included teak planted at 833 stems per hectare (sph) (T1), teak planted in rows with two rows of flueggea at 833 sph (T2), 625 sph (T3) and 416 sph (T4), and teak planted in alternating rows with flueggea at 833 sph (T5).

Results and discussion

Treatment 1 (T1) produced significantly higher total litter than T4 at Ringgi. However, based on individual tree litterfall production, teak in T4 (lowest stocking rate) at both trials produced higher litter per tree than the teak in T3, T2, T5 and T1 while there was no significant difference with litter production of flueggea. An enrichment of litter δ¹⁵N was observed over time in either species, which suggested an increased N loss and transformations in both experimental sites. When comparing each treatment and using individual tree productivity, T4 significantly produced and returned higher litter TC and TN than T3, T2, T5 and T1.

Conclusions

Overall, individual tree productivity demonstrated that mixed species stands had a significant potential for cycling higher rates of C and N than monoculture teak stands. Therefore, establishment of mixed species stands, especially T4 and T3, was recommended as a practical measure to address the widely experienced problem of reluctance by growers to thin high value trees while preserving the balance of C and N inputs into the ground.

     

Measuring the migration of silver from silver nanocomposite polyethylene packaging based on (TiO<Subscript>2</Subscript>) into <Emphasis Type="Italic">Penaeus semisulcatus</Emphasis> using titration comparison with migration methods

We have employed both common and novel methods to measure the amount of silver released from nanoparticle composite packaging. Forty-eight packages of green tiger prawns (Penaeus semisulcatus) were prepared: 24 packages with nanoparticle packaging and 24 packages without nanoparticle packaging. The normal shelf life of P. semisulcatus in the refrigerator is 1–2 days, and we therefore we tested the packages after 0, 1, 2, 3, 4, 5 and 6 days. We measured the diameter of the inhibition zone of the targeted microorganisms (Escherichia coli and Staphylococcus aureus) and examined scanning electron microscopy (SEM) images, using both titration and migration methods, to measure the amounts of silver nanoparticles released. Compared to the standard amount allowed by standard 13737-3 of the National Information Standards Organization, our results indicated the superior sensitivity of the titration method over the migration method in terms of determining the remaining amount of nanoparticles (P < 0.05). The evaluation of SEM images indicated the homogeneity of the surface of the silver nanoparticle packaging and the even exchange capacity of titanium dioxide. The average size of the nanoparticles in the packaging films was determined to be 30–48 nm. The diameter of the inhibition zone in the silver nanoparticle, measured at the six time points, was significantly larger than that seen with other packaging, except for the phosphomycin and penicillin antibiogram disks (P < 0.01). The sensitivity of the titration method using the titration equipment was significantly higher than that of the migration method (P < 0.05). The findings indicate that nanoparticle packaging decreased the microbial count and enhanced the shelf life of P. semisulcatus, leading us to recommend the utilization of silver nanoparticle packaging.     

Changes in δ15N in a soil–plant system under different biochar feedstocks and application rates

The application of biochar in soils has been hypothesised to improve soil quality whilst enhancing carbon (C) sequestration. However, its effect on nitrogen (N) dynamics in the soil–plant system is still not fully understood. In the present work, N isotope composition (δ¹⁵N) was used to facilitate the understanding of the processes involved in the N cycling when biochar is applied. We evaluated, through a wheat pot trial, the effect of different application rates of two types of biochar produced from jarrah and pine woodchips on the wheat biomass at harvest and on the soil and plant C and N contents and δ¹⁵N. In addition, the potential benefit of using nutrient-saturated biochar for the soil–plant system was also investigated. Whilst biochar produced from different feedstocks had similar effects on soil and plant nutrient contents, they induced differences in wheat grain biomass and plant δ¹⁵N. The effect of the biochar application rate was more pronounced, and at rates higher than 29 t ha^?1, the application of biochar decreased grain biomass by up to 39 % and potentially increased N losses. Isotopic analyses indicated that this acceleration of N dynamics had probably occurred before the stage of wheat grain formation. The application of nutrient-enriched biochar resulted in an improved wheat grain production, most likely due to the enhanced nutrient availability, and in reduced N cycling rates in the plant–soil system, which could offset the competition between biochar and plants for nutrients and could decrease adverse environmental impacts due to N losses.     

Effect of Fish Gelatin Coating Enriched with Oregano Essential Oil on the Quality of Refrigerated Rainbow Trout Fillet

ABSTRACT

In the present study, the effect of fish gelatin coating (FG; 4%, w/v) containing oregano (Origanum vulgare L.) essential oil (OEO; 1.2% w/v) on shelf-life extension of rainbow trout (Oncorhynchus mykiss) fillet stored under refrigerated storage (4 ± 1ºC) was investigated. The control and the treated fish samples were analyzed periodically for chemical (pH; total volatile basic nitrogen, TVB-N; peroxide value, PV; thiobarbituric acid, TBA) and microbiological (total viable count, TVC; psychrotrophic count) characteristics. The FG + OEO treatment produced significantly lower (p < 0.05) TVB-N values as compared to control and FG-coated samples after Day 6 and until the end of the storage period. The TBA values remained low and were found to fluctuate during storage. Results showed that TVC exceeded 6 log CFU g^?1 on Day 8 of storage for control and FG-coated samples and Day 12 for samples coated with FG + OEO. The reduction of 1.05 and 0.83 log CFU g^?1 of psychrotrophic counts was achieved by FG + OEO coating in trout fillet (p < 0.05) as compared with control and FG-coated samples, respectively. Therefore, the incorporation of OEO into FG coating may be a promising method of maintaining the storage quality of the rainbow trout fillet stored at refrigerated temperature.     

Time-Varying Markov Models for Binary Temperature Series in Agrorisk Management

This paper uses high-order categorical non-stationary Markov chains to model the occurrence of extreme temperature events, in particular frost days. These models can be applied to estimate: the probability that a given day in the future is a frost day (below zero); the probability that a given period is frost-free; the distribution of the length of the frost-free period. These quantities then can be used for pricing of weather derivatives. Several stationary and non-stationary high-order (yet parsimonious) Markov models are proposed and compared using AIC and BIC. Partial likelihood theory is used to estimate the parameters of these models. We show that optimal (in terms of AIC/BIC) non-stationary Markov models that have constant ??Markov coefficients?? (across the year) are not adequate to estimate the aforementioned probabilities. Therefore this paper develops Markov models with a time-varying periodic structure across the year. A challenge in fitting these models (by maximizing the partial likelihood) is the large number of parameters. The paper presents a method for overcoming this challenge; one that uses parametric fits to the logit of the nonparametric estimates of the seasonal transition probability curves to initialize the optim function in the R package. Satisfactory results are shown to obtain from this approach. The work is applied to temperature records for the Province of Alberta, Canada.     

Effect of Food Deprivation on Formalin-Induced Nociceptive Behaviors and Beta-Endorphin and Sex Hormones Concentration in Rats

Background: The present study examined the possible role of endogenous opioidergic system in effect of food deprivation on formalin-induced nociceptive behaviors in male and female rats. Also, we investigated the effect of food deprivation on the plasma level of beta-endorphin and sex hormones. Methods: Food was withdrawn 48 h prior to performing the formalin test, but water continued to be available ad libitum. The formalin was injected into hind plantar paw. Results: There is significant difference between male and female control rats during phase 2B. Following 48-h food deprivation, both male and female rats exhibited enhanced nociceptive behavior in response to formalin. Food deprivation for 12 and 24 h increased and for 48 h decreased beta-endorphin level in male and female rats. Food deprivation for 24 h decreased testosterone level in male, while it had no significant effect on female rats and food deprivation for 48 h decreased testosterone level in both sexes. Food deprivation for 24 h increased estradiol level in female and that for 48 h had no significant effect on male and female rats. Conclusions: The present study demonstrates the existence of food deprivation for 48 h causes enhancement of nociception in the formalin test in male and female rats that has correlation with decrease in plasma beta-endorphin and testosterone levels. Key Words: Rat, Food Deprivation, beta-endorphin, Naloxone     

The impact of land afforestation on carbon stocks surrounding Tehran,Iran

The city of Tehran,like many polluted metropolises of the world,has higher emissions of greenhouse gases than other cities in Iran,due to heavy consumption of fossil fuel and landuse changes.To estimate carbon sequestration in two 40 year-old stands of planted Cupressus arizonica and Fraxinus rotundifolia in degraded lands surrounding Tehran,sampling of above-and below-ground biomass,soil(at two depths of 0-15 and 15-30 cm),and leaf litter was done by systematic random sampling.The total carbon stocks of C.arizonica and F.rotundifolia stands were respectively 328.20 and 150.69 Mg·ha-1.The aboveground biomass with 233.16(71%)Mg·ha-1 in C.arizonica and88.16(58.50%)Mg·ha-1 in F.rotundifolia contributed the most shares to carbon sequestration.The diameter at breast height,total height,basal area,total volume,and biomass of C.arizonica were significantly(p0.01)higher than those of F.rotundifolia.Also the depth of 0-30 cm of soil contributed between 18.29%and 32.15%of total ecosystem carbon,respectively.The economic value of carbon sequestration in the two stands in 2011 was calculated at 3.5 and 2.5 million dollars,respectively.Our results indicate that afforestation of the degraded land surrounding Tehran would sequester more carbon than would continuously degraded land,the current status quo.These stands can absorb atmospheric CO2 at different rates,thus tree species selection and stand development should be considered in planning future afforestation projects.