Leaf biomass and leaf area equations for three planted trees in Iran

Leaf area (LA) and leaf biomass (LB) are important variables for most physiological, horticultural and agronomic studies involving plant growth, development rate, radiation use efficiency, and water or nutrient use. Measuring these variables need destructive and aggressive sampling. Fortunately, evolving allometric equations can help for low cost and non-destructive estimation of such variables. The aims of this study are Estimate, compare and develop allometric models of LA and LB per tree and per stand for Alnus subcordata (AS), Populus deltoides (PD) and Taxodium distichum (TD) plantations. We selected 12 sample trees in each stand. Leaf Fresh weight of randomly selected branches was weighted in the field. Branch-level LA was modeled as a function of branch diameter (R2 > 0.8) and total fresh weight of LB has been calculated for each sampled tree. For each species, 100 leaves from all canopy directions of trees were randomly selected and transported to the laboratory. At the lab, leaf area has been measured using leaf area meter. Allometric equations were derived using regression analysis. For all species, derived equations showed high accuracy (R2 ranged from 0.837 to 0.947). However, with respect to mean square error, power regression equations (individual leaf area = a(L×W)b and LA or LB = a DBHb) are best models to estimate Individual Leaf Area, LA, and LB of AS, PD, and PD. The highest LAI was in the order of 16.9 > 5.5 > 4.5 for AS, PD, and TD, respectively. DOI: http://dx.doi.org/10.5281/zenodo.26791

THE SUBLETHAL EFFECTS OF FIVE COMMERCIAL INSECTICIDES ON THE AMYLOLYTIC AND PROTEOLYTIC ACTIVITY OF THE BIOCONTROL AGENT, HABROBRACON HEBETOR SAY (HYMENOPTERA: BRACONIDAE)

Habrobracon hebetor Say is an important biological control agent that has a wide range of lepidopteran hosts, especially from the Noctuidae and Pyralidae families. Nutrition is a very important element in the efficiency of natural enemies in integrated pest management (IPM). In the presented research, the sublethal effects of five selected chemical and botanical insecticides, fenvalerate, propargite, buprofezin, dayabon and palizin, on the activity of amylase and protease enzymes in the midgut of this important ectoparasitoid wasp were studied under laboratory conditions. Changes in the activity of enzymes were investigated by LC30 treatment of the female wasps, which were 0.14, 7.01, 3.04, 9.58 and   2.53 mg a.i./mL, respectively. The obtained results showed that this parasitoid wasp has a long midgut in its digestive tract. Also, there were significant differences among the enzymatic treatments (F5,12 =14.695 and 99.278) except protein concentration (F5,12 = 0.670). Regarding the amylase enzyme, the highest and lowest activities were obtained in the control and fenvalerate treatment (0.0435±0.0023 mU/mg vs. 0.0277±0.0010 mU/mg). In addition, the highest proteolytic activity was observed in the control (4.9817±0.0268 U/mg) and the lowest in the propargite treatment (3.2231±0.0917 U/mg). By closely investigating the results, dayabon and palizin showed the lowest negative effects on the enzymes and could be applied together with this parasitoid wasp in IPM designs

Population density and spatial distribution pattern of Hypera postica (Coleoptera: Curculionidae) in Ardabil, Iran

The alfalfa weevil, Hypera postica (Gyllenhal), feeds almost exclusively on alfalfa, Medicago saliva L. in most region of the world where forage crop is grown. It has been investigated the population density and spatial distribution of alfalfa weevil on alfalfa in Ardabil during 2010. Using a 0.25 m(2) quadrate sample unit a reliable sample size was 65, with maximum relative variation of 15%. The relative variation (RV) of the primary sampling data was 13.6. The highest population density of the alfalfa weevil was recorded on 17(th) April. To estimate the spatial distribution pattern of this pest, data were analyzed through index of dispersion. Lloyd's mean crowding. Morisita's index and two regression models (Taylor's Power Law and Iwao's Patchiness Regression). Taylor's model showed an aggregated distribution pattern for all life stages. Iwao's patchiness regression indicated that larvae, adult and total life cycle had aggregated spatial distribution (t(c

Insecticidal activity of isolated essential oils from three medicinal plants on the biological control agent, Habrobracon hebetor Say - Hymenoptera : Braconidae

The effects of Allium sativum L. (Alliaceae), Piper nigrum L. (Piperaceae) and Glycyrrhiza glabra L. (Fabaceae) essential oils were investigated on the biological control agent, Habrobracon hebetor Say. The female wasps of H. hebetor were treated by LC30 concentrations of the tested essential oils for 24 h and their demography was investigated. Results indicated that the adult longevity, survival, fecundity, fertility, hatch rate, offspring sex ratio and the other demographic parameters negatively were affected by these essential oils. At the same time, our findings indicated that G. glabra essential oil has the less severe effect on H. hebetor. Accordingly, G. glabra essential oil seems to be a compatible botanical compound with H. hebetor for applying in integrated pest management programs

Effect of grafting time and scion diameter on grafting success in Larch (Larix decidua)

Extreme grazing, illegal logging, fire and irregular harvesting are factors of forest degradation and boundaries change particularly in the upper parts of Caspian forests. Planting of exotic species such as Larix with good adaptability in these areas due to cattle’s avoidance of grazing and immunity due to psychical effects on forest residents for it’s unknown identity, can help considerably to reestablishment of forest cover in upland degraded areas. Since there isn’t enough seed for seedling production in the country and it’s high prices of seeds and currency need for procurement from foreign countries using of techniques that reduce the time to obtain enough seeds in the country is necessary. Grafted trees in comparison to non-grafted trees produce seeds in shorter time. Therefore, obtaining success in grafting was due to two factors: grafting time and scion diameter. According to the obtained results grafting time and scion diameter in prob., level of 1% and interaction between two factors in prob., level of 5% were significant. Therefore, the best time for grafting according to vegetative activity of stock and scion was the time that stock buds started swelling and scion buds were dormant (March) and the best scion diameter was more than 2 m

Digestive proteolytic and amylolytic activities in Helicoverpa armigera (Lep.: Noctuidae) larvae fed on five host plants

Abstract: The cotton bollworm, Helicoverpa armigera (Hübner), is a serious pest on a wide range of economic crops in many parts of the world. In this study, digestive proteolytic and amylolytic activities of H. armigera larvae (3 rd to 5 th instars) were evaluated on five main host plants including chickpea (cv Hashem), cowpea (cv Mashhad), soybean (cv 033), navybean (cv Dehghan), and corn (cv SC 704) at 25 ± 1 °C, relative humidity of 65 ± 5% and a photoperiod of 16: 8 (L: D) hours. The results indicated that the highest enzyme activity was in 5 th instar. The highest general protease activity of 3 rd , 4 th and 5 th instar larvae was found on corn. The larvae fed on corn had the lowest trypsin activity. This leads to hyperproduction of chymotrypsin and elastase-like enzymes to compensate the inhibition of trypsin. The larvae of H. armigera reared on cowpea had the highest level of amylase activity, and the lowest activity was in the larvae fed on corn. The results revealed that among host plants tested, corn was more resistant (unsuitable) to H. armigera. Study on digestive proteolytic and amylolytic activities of H. armigera can be used in identifying the antidigestive or antifeedent compounds, which will help us to design appropriate management programs

Central composite design for the optimization of removal of the azo dye, methyl orange, from waste water using fenton reaction

In this study the degradation of Methyl Orange, using Fenton reaction was studied and optimized using central composite design as a response surface methodology. The effects of various experimental parameters in this reaction were investigated using central composite design. 28 experiments, with 4 factors and 5 levels for each factor were designed. These factors (or variables) were: initial concentration of Fe (II), initial concentration of H2O2, initial concentration of oxalate and the reaction time. A full-quadratic polynomial equation between the percentage of dye degradation (as a response) and the studied parameters was established. After removing the non-significant variables from the model, response surface method was used to obtain the optimum conditions. The optimum ranges of variables were: 0.25 - 0.35 mM for initial concentration of Fe (II), 5-17 mM for initial concentration of H2O2, 4-9 mM for initial concentration of oxalate, and 50-80 min for the reaction time. Also the results of extra experiments showed that these optimized values can be used for real samples and yield to a high value for the response

Analyzing the Effects of Power Plant Fuel Price Reform on Iran Electricity Market by Using Agent-Based Simulation

This paper examines the impacts of fuel price reform on the technology mix of power plants and other outputs of the Iran electricity market. In this regard, Iran electricity market has been simulated by using an agent-based model for a long-term period. Then, as a result of fuel price reform, the changes in the outputs of the electricity market, including the average price, average efficiency, capacity and technology mix of generation has been studied and analyzed. The results show that, the current situation of technology mix of power plants is far from optimum conditions. Accordingly, the reform of fuel prices may change the returns and incentives of investment in different technologies so that, technology mix of power plants would face major changes, and by increasing share of more efficient power plants like combined cycle power plants, the average efficiency of electricity production increase from current 36% to more than 55%