Salinity tolerance of wild barley Hordeum vulgare ssp. spontaneum

Salinity tolerance of 47 wild barley genotypes and six barley cultivars was evaluated under control and salinity stress (300 mM NaCl) conditions. Shoot and root dry weight (DW), plant height, membrane stability index (MSI), relative water content, survival rate, leaf malondialdehyde (MDA) and proline contents, root and leaf Na, K, Ca and K/Na ratio, and chlorophyll a fluorescence were measured. Salinity stress caused significant increase in the MDA, proline content, Na and Ca concentrations of the roots and leaves, but resulted in a decrease in the other traits. H. spontaneum genotypes were considerably less affected by the salinity than the genotypes of H. vulgare. Plant survivability was negatively correlated with the Na concentration (r =−.66) but positively correlated with the leaf K/Na ratio (r = .67) and MSI (r = .68). Tolerance mechanisms such as ion exclusion (Na) were likely to be present in the wild barley causing K/Na homeostasis as well as the much lower root and shoot Na, resulting in the higher survival rate.     

Analysis of the variations in dry matter yield and resource use efficiency of maize under different rates of nitrogen,phosphorous and water supply

Abstract

Increasing resources use efficiency in intensive cultivation systems of maize (Zea mays L.) can play an important role in increasing the production and sustainability of agricultural systems. The objectives of the present study were to evaluate DM yield and the efficiency of inputs uses under different levels of water, nitrogen (N) and phosphorus (P) in maize. Therefore, three levels of irrigation including 80 (ETc₈₀), 100 (ETc₁₀₀) and 120% (ETc₁₂₀) of crop evapotranspiration were considered as the main plots, and the factorial combination of three levels of zero (N₀), 200 (N₂₀₀) and 400 (N₄₀₀) kg N ha^?1 with three levels of zero (P₀), 100(P₁₀₀) and 200 (P₂₀₀) kg P ha^?1 was considered as the sub plots. The results showed that increasing the consumption of water and P was led to the reduction of N and P utilization efficiency, while RUE increased. WUE was also increased in response to application of N and P, but decreased when ET_C increased. DM yield under ETc₈₀ treatment reduced by 11 and 12%, respectively, compared to ETc₁₀₀ and ETc₁₂₀ which was due to reduction of cumulative absorbed radiation (R_abs(cum)) and RUE. Under these conditions, changes of stomatal conductance (gs) had little effect on DM yield. It was also found that N limitation caused 11 and 20% reduction in DM yield compared to N₂₀₀ and N₄₀₀, respectively. This yield reduction was mainly the result of decrease in RUE. By decreasing R_abs(cum), P deficiency also reduced DM yield by 5 and 9%, respectively, relative to P₁₀₀ and P₂₀₀ treatments.     

Effect of soil pore size distribution on plant-available water and least limiting water range as soil physical quality indicators

Soil pore size distribution(SPSD) is one of the most important soil physical properties. This research investigated the relationships of location and shape parameters of the SPSD curves with plant-available water(PAW) and least limiting water range(LLWR) of the light-textured soils at the Torogh Agricultural Research Station in north-eastern Iran. Soil moisture release curve(SMRC), PAW and LLWR in matric heads of 100 and 330 h Pa for the field capacity and location and shape parameters of the SPSD curves of 30 soils with different texture and organic carbon contents were determined, and the variable relationships were statistically analyzed. The results showed that the median equivalent pore diameter(de), mean de, standard deviation(SD*), and skewness of the SPSD curves were significantly correlated with PAW(PAW330) and LLWR(LLWR330) measured in a matric head of 330 h Pa. Decrease in deand increase in the diversity of soil pore size(SD*) increased PAW330 and LLWR330. The SD* values of all the soil samples were lower than the optimal ranges suggested in literature. Neither PAW nor LLWR values were significantly different in the soils with the optimal modal deand those with non-optimal modal de. Optimal values of median and mean equivalent pore diameters and kurtosis of SPSD curves led to a significant improvement of PAW330 and LLWR330 as soil physical quality indicators. It was recommended to revise the optimal ranges for SD* and modal defor future studies.     

Effects of Water Hardness and Calcium: Magnesium Ratios on Reproductive Performance and Offspring Quality of Macrobrachium rosenbergii

This study evaluated the effect of specific calcium and magnesium ratios at two hardness values on reproductive performance and offspring quality of Macrobrachium rosenbergii brood‐females. Hatchery water containing 110.5 mg/L CaCO3 hardness was considered baseline as it has been used successfully to hatch and rear larvae and was used as the control treatment. At each hardness value of 150 and 190 mg/L CaCO₃, four experimental water treatments were made in triplicate. Each treatment was adjusted using soluble salts (CaCl₂·H₂O, MgSO₄·7H₂O, and MgCl₂·6H₂O) to provide the hardness and calcium to magnesium ratios of 0:20, 20:80, 50:50, and 80:20 needed. Each of the experimental tanks (140 L) were stocked with six females and one male. The results indicated that both hardness and Ca:Mg ratios affect brood‐female reproductive qualitative parameters such as intermolt period, egg hatchability, egg dry weight, and egg‐clutch somatic index (ESI) parameters (P < 0.05) but not fecundity and eggs per spawn. The results revealed that brood‐females at 150 mg/L hardness showed greater reproductive performance than at 190 and 110.5 mg/L hardness. The findings also demonstrated that the treatment 50Ca50Mg at 150 mg/L hardness with 38.8 mg/L calcium and 12.9 mg/L magnesium had optimum reproductive performance and offspring quality for M. rosenbergii brood‐females.     

Suitability of the Citrus Brown Mite,Eutetranychus orientalis (Acari, Tetranychidae) as prey for nine species of phytoseiid mites

Nine phytoseiid species were tested to evaluate their potential as predators ofEutetranychus orientalis (Klein).Typhlodromus atbiasae Porath and Swirski,Amblyseius barkeri (Hughes) andAmblyseius olivi Nasr and Abou-Awad had a shorter developmental period thanTyphlodromus transvalensis (Nesbitt).Typhlodromus athiasae andAmblyseius barkeri showed the highest oviposition rates.Amblyseius olivi showed a low rate of oviposition althoughTyphlodromus transvalensis has not able to lay any eggs. Immatures survival ofTyphlodromus talbii Athias Henriot,Typhlodromus balanites El-Badry,Amblyseius badryi. Yousef and El-Borolossy,Amblyseius cabonus (Schicha) andAmblyseius lindquisti Schuster and Pritchard were very low onEutetranychus orientalis and all failed to develop to adulthood.     

Morphological evidences for onion-induced growth inhibition of Trichophyton rubrum and Trichophyton mentagrophytes

The antifungal activity of onion (Allium cepa L.) on two important dermatophytes, Trichophyton rubrum and Trichophyton mentagrophytes, with special reference to morphological aspects was studied. Growth of both fungi was found to be strongly inhibited by aqueous onion extract (AOE) as a dose-dependent manner. The extract showed fungicidal effect for both fungi at concentrations >3.12% (v/v). The fungus T. mentagrophytes was more affected by the onion as compared to T. rubrum at all concentrations used. Morphological effects of onion exposure were examined in correlation with fungal growth. Corresponding to the growth inhibition, light and electron microscopy observations revealed morphological anomalies in hyphal compartments. The results demonstrated that AOE targets the cell membrane of the fungi as breaking down of both inner and outer membranes with consequent extrution of materials into the surrounding medium. Cytoplasmic membranes and other membranous structures of organelles, such as nuclei and mitochondria, were also disrupted. In correlation to the fungal growth, morphological alterations occurred to a less content for T. rubrum compared with T. mentagrophytes. The hyphae of T. rubrum were found to be mainly affected by converting to resistant forms, i.e., chlamidospores as a consequence of phenotype switching response to AOE. Plasmolysis accompanied by an almost complete depletion and disorganization of cytoplasmic structures were found to be the final event which led to cell death. Ultrastructural evidences obtained from this study strongly support that morphological changes of T. rubrum and T. mentagrophytes caused by AOE are associated with its fungistatic and fungicidal activities. With respect to the morphological results and the preliminary data on fungal biochemistry, a mechanism of action by interacting of AOE with thiol (-SH) groups present in essential compartments of the fungal cells was postulated.     

Surface wildfire in conifer broad-leaved forests of the Hyrcanian region of Iran: short-term effect on regeneration and damage to trees

Wildfires in recent years have resulted in degradation and damage to the Hyrcanian forest ecosystems in Northern Iran.This study was carried out to investigate fire damage to trees and changes in regeneration in early-season growth after wildfires in the Golestan Province.For this purpose,a random sampling plan was used,with 60 circular plots(each plot is 1000 m2) for each stand and 240 circular(25 m2) plots for regeneration within the burned and unburned areas,respectively.In each plot,habitat factors were recorded,including crown canopy percentage,forest stratum,herb-layer cover percentage,species,diameter at breast height,tree and regeneration quality,and quantity of seedlings and saplings.Our results showed that bark is an important factor for fire resistance in Hyrcanian forests.The Persian ironwood and European yew has the highest and lowest fire resistance;as broad leave species are more resistant than needle leaf species.Density of regeneration in unburned area was higher than burned area,and statistical analysis showed significant differences for all species between two areas.Fire effects on sapling were different among species which indicates sapling has different resistance to fire.Forest floor fuel,season,stand composition and microclimate have more effects on fire severity while environmental factors,regeneration and management practices shaping future composition stands.     

Effect of spiramycin and tulathromycin on abomasal emptying rate in milk-fed calves

Impaired abomasal motility is common in cattle with abomasal disorders. The macrolide erythromycin has been demonstrated to be an effective prokinetic agent in healthy calves and in adult cattle with abomasal volvulus or left displaced abomasum. We hypothesized that 2 structurally related macrolides, spiramycin and tulathromycin, would also be effective prokinetic agents in cattle. Six milk-fed, male, Holstein-Friesian calves were administered each of the following 4 treatments: spiramycin, 75 000 IU/kg BW, IM, this dose approximates 25 mg/kg BW, IM; tulathromycin, 2.5 mg/kg BW, SC; 2 mL of 0.9% NaCl (negative control); and erythromycin, 8.8 mg/kg BW, IM (positive control). Calves were fed 2 L of cow’s milk containing acetaminophen (50 mg/kg body weight) 30 min after each treatment was administered and jugular venous blood samples were obtained periodically after the start of sucking. Abomasal emptying rate was assessed by the time to maximal plasma acetaminophen concentration. Spiramycin, tulathromycin, and the positive control erythromycin increased abomasal emptying rate compared to the negative control. We conclude that the labeled antimicrobial dose of spiramycin and tulathromycin increases the abomasal emptying rate in healthy milk-fed calves. Additional studies investigating whether spiramycin and tulathromycin exert a prokinetic effect in adult cattle with abomasal hypomotility appear indicated.     

Interaction analysis between slenderness ratio and resin content on mechanical properties of particleboard

The interaction between particle size and resin content is one of the most important structural parameters that can influence the accuracy of predictions about wood-composite properties. We developed three kinds of equation (linear, quadratic, and exponential) for each mechanical property of particleboard based on slenderness ratio and resin content at a constant density (0.7g cm -3 ). Results from SHAZAM software (version 9) suggested that the quadratic function was not significant, but the linear and exponential functions were significant. The interaction between particle size and resin content was analyzed by Maple 9 software. The results indicated that an exponential function can better describe the simultaneous effect of slenderness and resin content than a linear equation. Under constant resin content, particles with higher slenderness ratios increased more in modulus of rupture (MOR) and modulus of elasticity (MOE) than did particles with lower slenderness ratios. Edge withdrawal resistance (SWRe) values did not increase with increasing slenderness ratio.     

Effects of NaCl salinity on some leaf nutrient concentrations,non-photochemical quenching and the efficiency of the PSII photochemistry of two Iranian pomegranate varieties under greenhouse and field conditions: Preliminary results

The present research was conducted to study the responses of ‘Malas–e–Saveh’ (M) and ‘Shishe–Kab’ (Sh) Iranian pomegranates to sodium chloride (NaCl) stress under greenhouse and field conditions. Treatments included waters electrical conductivity (EC = 1.5, 3, 6, 9 and 12 dS m^?1 for greenhouse) and (EC = 1.05 as control, 4.61 and 7.46 dS m^?1 for field studies). Interactive effects of salinity × variety indicated the highest chlorophyll and leaf potassium concentration, and the lowest leaf chloride and sodium in control under greenhouse study. Non-photochemical quenching, effective quantum yield of photochemical energy conversion in PSII reduced under the highest salinity level in field, however, basal quantum yield of non-photochemical processes in PSII increased in the highest salinity. Sodium and chloride increased with increased in salinity. Calcium, magnesium and iron significantly decreased with increased in salinity. It seems that there are differences between pomegranate cultivars and Malas-e-Saveh is more tolerant compared with Shishe Kab.