Effects of ingested diflubenzuron on the longevity and the peritrophic membrane of adult mealworms (Tenebrio molitor L.)

When fed to adults of Tenebrio molitor, diflubenzuron reduced the longevity, the weight of the adults and the thickness of the post-ecdysial adult cuticle. It also affected the production of the peritrophic membrane. The loss of weight and the decrease of longevity of the treated adults may have been because of alterations to the peritrophic membrane, caused by the inhibition of chitin biosynthesis by diflubenzuron.     

Comparison of the responses to NaCl stress of two pea cultivars using split-root system

Two pea (Pisum sativum L.) cultivars were compared: cv Lincoln and cv Douce de Provence. Seedlings grown for 14 d on standard medium were challenged for 21 d with salt using a split-root system. This protocol allowed salt-treated plants to absorb nutrients through a part of their root system maintained in control medium (C), the other part of the root system being placed in medium added with 75 mM NaCl (S). Full salt treatment (S/S) resulted in severe but non-lethal growth inhibition, high concentration of Na⁺ and Cl⁻ in leaves, and decrease in leaf K⁺ and chlorophyll contents. The two latter effects were more pronounced in Lincoln than in D. Provence. Growth inhibition was partially (Lincoln) or totally (D. Provence) alleviated in S/C configuration, and K⁺ content was less diminished than in full salt treatment. S/C treatment mitigated Na⁺ and Cl⁻ accumulation in Lincoln, but not in D. Provence. Thus, in the latter cultivar, growth inhibition by salt in S/S condition likely did not result from excessive Na⁺ and Cl⁻ accumulation in leaves. Increased electrolyte leakage from leaf tissues evidenced damages to leaf cell plasma membrane of both cultivars in S/S condition. However, damages to chloroplasts, as inferred from chlorophyll loss, were much pronounced in Lincoln than in D. Provence. Antioxidant enzymic activities in leaves were measured as proxies for oxidative stress. Catalase activity was stimulated by S/S treatment in both cultivars, but superoxide dismutase (Fe and Cu/Zn isoforms) and gaiacol peroxidase activities were augmented only in Lincoln. The absence of superoxide dismutase activity stimulation by salt in D. Provence could signify either that constitutive activity was sufficient to ensure protection against oxidative stress, or that intrinsic salt tolerance of this cultivar mitigated cellular oxidative stress. Thus, intraspecific variability for salt response exists between pea cultivars presenting similar growth sensitivity to salt.     

Application of nanosilver-coated zeolite as water filter media for fungal disinfection of rainbow trout (Oncorhynchus mykiss) eggs

This study investigated the indirect use of silver nanoparticles (AgNPs) for reduction of fungal infections during incubation period of fertilized rainbow trout eggs. Different concentrations of nanosilver-coated zeolite (0.5, 1, and 1.5 % AgNPs) were compared with unmodified zeolite as water filter media in semi-recirculation systems. For testing the effect of AgNPs on reduction of fungal infection, fertilized eggs were transferred in incubators receiving water from filters coated with nanosilver. The eggs in each incubator were inoculated with Saprolegnia-infected trout eggs. Any dead or infected eggs and embryos were periodically removed, while the performance of the filters was assessed by calculating the survival rates from fertilization up to completion of the yolk–sac absorption stage. The results showed that the filters containing 0.5 % AgNPs increased the survival rate by 4.56 % from fertilization to the swim up stage compared to the control (p < 0.05). Also, the additional application of activated carbon (as absorbent media) along with AgNP-coated media in filters caused an increase of about 11.24 % in the survival rate for the larval stage (p < 0.05). In contrast to the control group with about 6 % fungal infection, no infections were observed during the incubation period in the incubators containing nanosilver-coated filters. Therefore, the final results confirmed that the indirect use of AgNPs in the aforementioned filters were significantly effective for preventing fungal infections in semi-recirculation systems for rainbow trout, making them a candidate for replacing the chemical fungicides currently used during egg incubation in hatchery systems.     

Effects of olive pomace on growth performance,digestibility, body composition and fatty acid profile in yearling Siberian sturgeon,Acipenser baerii (Brandt 1896)

Replacement of olive pomace (OP) with wheat flour in diet was studied in diet of yearling Siberian sturgeon (Acipenser baerii). Fish (165 ± 6.8 g) were randomly allocated to 15 fibreglass tanks (15 fish/tank, in triplicate). Fish were assigned to one of five dietary treatments at 19.1 ± 1.5°C for 8 weeks: control diet (crude protein and crude lipid at 514.6 and 188 g/kg_, respectively) and four experimental diets with 20, 50, 75 and 100 g/kg OP to replace wheat flour in the experimental diets. No significant difference was observed in the final weight, feed conversion ratio, specific growth rate, hepatosomatic index, viscera‐somatic index and survival rate among the treatments (p > 0.05). No change was seen in digestibility of protein and lipid in diets containing 20 g/kg and 50 g/kg OP compared to control group, while these values decreased with increasing in OP above 50 g/kg. Digestibility of dry matter and gross energy among the treatments demonstrated no significant difference (p > 0.05). Polyunsaturated fatty acids, especially C22:6n3 (DHA), in the muscle of the fish fed 75 g/kg and 100 g/kg OP in diets were significantly higher than control group (p < 0.05). These data show that OP could be recommended as a substitute for wheat flour in diet of S. sturgeon but its utilization for other species warranted future works.     

Bacillus pumilus and Stenotrophomonas maltophilia as two potentially causative agents involved in Persian oak decline in Zagros forests (Iran)

The oak decline is known as one of the most destructive complex diseases causing high economic losses around the world, especially in Iran. The main objective of the present study was to investigate the possible role of bacteria as causative agents of oak decline in the Zagros forests of Iran. To do this, stem, root and leaf samples were taken from symptomatic Persian oak trees (Quercus brantii) in different zones of Zagros forests (Ilam Province, Iran). From 150 bacterial isolates, 20 showed pathogenicity against Geranium seedlings. Among 20 hypersensitivity test positive strains, four strains showed pathogenicity against oak saplings. Based on morphological and 16S rRNA gene sequence analysis, three strains were identified as Bacillus pumilus and one strain as non‐sporulating Gram‐negative Stenotrophomonas maltophilia. Pathogenicity studies of different B. pumilus and S. maltophilia strains revealed that they have potential to cause the disease in oak saplings and symptoms of disorder in Persian oak trees. To our knowledge, there are no previous records of B. pumilus and S. maltophilia causing decline on Fagaceous trees like Q. brantii. More detailed field and molecular studies are required to confirm the absolute role of such bacteria in occurrence of oak decline in Zagros forests.     

Genetic analysis of yield and fruit traits in cantaloupe cultivars

The purpose of this research was to evaluate the combining ability of six local Iranian and one imported cantaloupe cultivar. Heritability of traits was estimated using a half‐diallel mating design. Seven parents and their crosses were evaluated in 2013 and 2014. The greatest general combining ability (GCA) for yield and fruit number was for “Rish‐baba” (0.53 kg/plant and 0.3, respectively). The cultivar “Ananasi” had the highest GCA for fruit weight and soluble solids content (SSC) (0.088 kg and 1.4, respectively). “Ananasi” presented the highest GCA values for fruit firmness, chlorophyll a and b and carotenoid content, as well as the highest total chlorophyll content. The cross Garmak × Rish‐baba showed the highest specific combining ability (SCA) for yield with heterosis value of 99%. High heritability estimates for SSC (0.52), flesh thickness (0.61) and concentration of chlorophyll a (0.7) were obtained. Although there were significant SCAs for yield, the parents are suggested to be improved prior to hybrid development. The parent “Ananasi” appears to be a suitable donor in breeding programmes.     

Removal of Chromium by Coagulation-Dissolved Air Flotation System Using Ferric Chloride and Poly Aluminum Chloride (PAC) as Coagulants

In this study, dissolved air flotation (DAF) was examined as a possible treatment method for the removal of chromium from aqueous solution and plating wastewater. Two coagulants, ferric chloride and poly aluminum chloride (PAC), were used for pretreatment of wastewater. Maximum removal of chromium was achieved for poly aluminum chloride (98 %). Artificial neural network was used for the prediction of the DAF system. The best neuron used for the prediction of chromium removal percentage of interpolated wastewater was 6 %. The mean score error and the coefficient correlation were 0.0007542 and 0.997, respectively.     

Evaluation of forage maize yield gap using an integrated crop simulation model-satellite imagery method (Case study: four watershed basins in Golestan Province)

The yield gap provides a guide for prioritization of crop management options (such as optimized sowing date, seeding rate, irrigation schedule, soil fertility, fertilizer application, weed and pest control) in a studied area. This study aimed to determine the maize yield gap in four major watersheds in Golestan Province, Iran, using an integrated crop simulation model-satellite imagery method. The actual yield estimated by the NDVI (as the selected index) was between 8.89 and 20.40 t ha^?1, while the potential yield is between 19.03 and 22.35 t ha^?1. About 91.76% of the studied area had a yield less than 85% of the potential yield. The lowest actual yield was in the south, southeast, and north of the study area. The yield gap was estimated between 0 to 11.76 t ha^?1 and 66.66% of maize farms yield gap was between 3.5 to 5.5 t ha^?1. The yield gap fraction changed between 0 and 0.57. The results showed that soil-dependent variables, slope, and fluctuation in farm management factors (plant density, planting, irrigation, and various methods of weed control) caused the yield gap. High yield gap indicates that there is an opportunity to increase production through managerial optimization or excluding maize from cropping patterns.     

Physiological and biochemical responses of Melissa officinalis L. to nickel stress and the protective role of salicylic acid

The present study investigated the mediatory effects of salicylic acid (SA) in alleviating nickel (Ni) toxicity in Melissa officinalis L. One-month-old plants were exposed to different levels of Ni and SA concentrations in sand culture under greenhouse conditions. Excess Ni significantly inhibited the growth indices and dramatically increased accumulation of Ni in the leaves and roots. Exogenously SA applications (1.0 mM) led to a substantial improvement in the shoot and root fresh and dry weights. Foliar application of SA mitigated the deleterious effects of Ni and decreased its transport to the shoots. The results showed a significant loss in chlorophylls and carotenoids contents only at 500 µM of Ni. The impact of SA was not significant in terms of chlorophyll contents, while carotenoid contents of the Ni-stressed plants were significantly affected by SA. Exposure to Ni did not modify proline accumulation. Hydrogen peroxide accumulation was observed under Ni stress, while lipid peroxidation significantly decreased at the same conditions. Application of SA caused a significant decrease in electrolyte leakage of Ni-stressed plants. Due to the high potential for Ni accumulation in the roots and translocation factor values lower than 1, M. officinalis could be introduced as an excluder medicinal plant.