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Ground skidding on skid trails affects the physical properties of soil. The objective of this study was to evaluate changes in soil physical properties on skid trails formed due to traffic of metal-tracked skidders with regard to soil bulk density, total porosity, water content and penetration resistance. The studies were implemented on two levels of slope – <20% (SC1) and >20% (SC2) – and three levels of traffic (one, five and nine traffic cycles). The treatment plots with three replications, consequently, were 6 m long and 4 m wide. The measurement of soil penetration resistance was carried out using a cone penetrometer. The samples were taken from 10 cm of top soil at six points in each plot. The results indicated that the skidder traffic did not significantly affect the soil physical properties measured in three levels of traffic at SC1, whereas it was significant between one and five traffic cycles in SC2. Most of the changes in the measured properties in the skid trails occurred after the first loaded skidder traffic. Within all traffic of SC2, differences in the mean values of water content and soil porosity were greater compared with the mean values at the same traffic of SC1, although these differences were not significant. The bulk density and penetration resistance at five and nine traffics of SC2 were significantly different from the same traffic of SC1.

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Background: we aimed to evaluate the effect of body weight and Body Mass Index (BMI) on Bone Mineral Density (BMD) in healthy postmenopausal Iranian women. Material and Methods: Two hundred postmenopausal women (age between 51 and 69 years) who had presented to the nuclear medicine center at Shariati Hospital in Tehran, Iran between April 2012 and August 2013 were included in this cross sectional study. Of these 46 healthy women who met the study criteria constituted for evaluation. After recording weight and height of individuals, Body Mass Index (BMI) (kg/m2) was calculated as weight (kg) divided by height square (m²). Bone Mineral Density (BMD) in Femoral Neck (FN) and lumbar spine sites (L1-L4) were measured by dual-energy X-ray absorptiometry (DEXA). Results: We observed statistically significant negative correlation between BMD measurements at femoral neck and lumbar_1-4 spine with age and significant positive correlation with weight and BMI. Stepwise multiple linear regression analysis showed that only weight and age, after adjustments to BMI determined lumbar_1-4 spine BMD (R² = 23%) and femoral neck BMD (R² = 28.6%). Conclusions: These results suggest that the relationship between body weights and BMD is Stronger than the relationship between BMI and BMD. Therefore, in comparison with body mass index, body weight alone is a better predictor of bone mineral density.

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In order to investigate the Effect of different levels of nitrogen and plant density on yield, and some morphological sunflower cultivars, experimental farm in 2009 in the College of Agriculture University researcher Ardebili A split plot factorial design based on a randomized complete block with three replicates was carried out. Nitrogen treatments included (zero, 75 and 150 kg per ha) assigned to main plots and levels of plant density (8, 10 and 12 plants per square meter) and two varieties were Urofelor and Armavirsky in sub plot. Head and stem diameter, plant height, number of kernel per disk, number of leaves at the final of harvesting and grain yield measured. Sunflower cultivars was significant difference on the stem diameter, plant height and number of kernel per disk but different levels of nitrogen and plant density were significant difference on the for all traits measured. The highest grain yield was obtained, 262 gr /m2 in 150 kg N/ha× Armavirsky. Increasing plant density by increasing the number of heads per unit area, will affect performance. Considering the excellence level of 80 thousand plant density and fertilizer level of 150 kg ha compared to other treatments in terms of grain yield, the amounts of nitrogen and planting density to achieve adequate performance in the test area and similar areas is advisable.

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In a field experiment the effect of five planting densities (100, 175. 250, 325 and 400 plants in"2 ) with or without foliar application of chlormequat chloride (2-till o methyltrimethyl uminonion chloride, CCC) on growth, development and grain yield of winter barley (cv Valfajr) was studied. The results indicated that Increasing plant density hastened the rate of apical development and stem elongation. This pattern continued up to the beginning of rapid stem elongation phase (Zadoks growth stage 32). However, during the rapid stem elongation and ear growth, the pattern was reversed i.e. it had become slightly in favor of the lower densities. Increasing plant density up to 25(1 plants in"2 increased the grain yield, however, from 250 to 400 plants m"2 there was no significant change in grain yield. It appeared that the higher planting densities, i.e. 250 to 400 plants m~- were in a range around the supposed "optimum" density. Foliar application of CCC slowed down the rate of apical development and stein elongation in all plant densities, hut without any significant effect on its spikelet initiation rate. Such retardation of development in CCC-treatecl plants was initially associated with lower dry weight accumulation. However, this trend was reversed before anthesis, as the CCC- treated plants had accumulated more dry matter by anthesis, and gave a higher grain yield. The interactive effect of CCC and plant density is worthy of further exploration.

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Life table gives the most comprehensive explanation of the survivorship, development, and reproduction of a population. The life table parameters of an aphidophagous midge, Aphidoletes aphidimyza were studied on different densities (5, 10, 20, 40, 60, 80) of third instar nymphs of Aphis gossypii as prey in a growth chamber (25 ± 1 °C, 70 ± 5% RH and a photoperiod of 16L: 8D h). The pre-ovipositional period of female A. aphidimyza was reduced as prey density increased with no significant difference. The oviposition period was 3.833 ± 0.401 and 5.5 ± 0.463 days in lowest and highest prey density, respectively. Fecundity increased significantly with increasing prey density. The lowest fecundity was obtained at density of 5 preys/day (49.667 ± 6.053 eggs) and the highest was at density of 80 preys/day (104.25 ± 7.78 eggs). Intrinsic rate of increase (r_m) ranged from 0.110 ± 0.016 to 0.166 ± 0.014 d^-1 with increasing prey density. Net reproductive rate (R₀) was positively dependent on prey density. The peak reproductive values showed that female aphidophagous midge at ages of 17, 18, 19, 22 and 25 days made the highest contribution to the population when reared on 5 to 80 preys in a day, respectively. However, mean generation time (T) ranged from 22.42 ± 0.55 to 24.47 ± 1.04 days. It was concluded that the increase in the density of third instar nymphs of A. gossypii significantly affected the demographic parameters of A. aphidimyza and it had a better reproductive performance in higher prey densities.

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Identification of intertidal echinoderms and the effect of environmental factors on their density and distribution in five stations around the Khark Island were seasonally investigated. Three transects were designated to cover the supralittoral, eulittoral and sublittoral zones within each station. The environmental factors such as temperature, salinity and total organic maters (TOM) were also recorded. Maximum and minimum water temperature were recorded in summer (35.94 ± 0.28) and in winter (18.34 ± 0.39) and the maximum and minimum salinity were recorded in winter (44.6± 0.14) and spring (37 ± 0.18), respectively. Maximum and minimum percentages of total organic maters (TOM) were observed in summer (9.63 ± 0.71) and winter (3.39±0.15), respectively.Totally four species belonging to for families were identified, viz. Asterina burtoni, Echinometra mathaei, Holothuria atra, Ophiothrix sarignyi, the highest frequency of which was encountered by E. mathaei. The maximum density and distribution were found in spring and minimum in summer and winter.

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Three stocking densities (20, 40, and 60 sheep/ha) were applied in four stocking periods (0, 2, 4, and 6 weeks) on a Medicago truncatula cv. Paraggio pasture. Treatments were arranged in a split plot system and compared through a completely randomised block design with four replications.Grazing period had a significant effect (P<0.001) on availability of both medic and other species separately. Total available forage (medic and other species) was significantly affected by both stocking density (P<0.05) and grazing period (P<0.001) and there was a significant interaction between stocking density and grazing period (P<0.001). Grazing period was the only factor affecting the cumulative forage production of medic and other species. Stocking density and grazing period both had significant effects on total cumulative pasture production. Pod production significantly decreased as grazing period increased. More seeds per pod were observed at low stocking density as compared with other densities. There was a dramatic reduction in seed production as grazing period increased (P<0.05).

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Context-dependent modeling is a well-known approach to increase modeling accuracy in continuous speech recognition. The most common way to implement this approach is via triphone modeling. Nevertheless, the large number of such models results in several problems in model training, whilst the robust training of such models is often hardly obtained. One approach to solve this problem is via parameter tying. In this paper, clustering has been carried out on HMM state parameters and the states allocated to any cluster are tied to decrease the overall number of system parameters and achieve robust training. Two types of groupings, one based on the final trained model set parameters and their inter-model distances and the other based on the training data and a decision tree, have been carried out. In the implementation of the later, a decision tree based on the acoustic properties of the Persian (Farsi) language and the phonetic similarities and differences has been designed. The results obtained have shown the usefulness of both the approaches. However, the second approach has the advantage of making the estimation of unseen model parameters possible.

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Spatial patterns of soil fertility parameters, and other extrinsic factors need to be iden-tified to develop farming practices that match agricultural inputs with local crop needs. Little is known about the spatial structure of yield and weed density across fields. In this study, geostatistics was used to describe and map spatial patterns of soil total nitrogen, available phosphorus, available potassium, grain yield and density of Sisymbrium irio L. (tumble mustard), as a common annual weed of wheat fields at Shahre Kord university. The spatial continuity of each variable was examined by variogram function. The variograms showed that the distribution of all variables is not random but spatially-dependent as their estimated variogram values increase with increasing distance. The av-erage range values were 26.5, 23.4, 31.4, 27.7, and 27.2 m for total nitrogen, available phosphorus, available potassium, grain yield and weed density, respectively. Thus, the range beyond which the property is not longer spatially dependent was almost the same for total nitrogen, grain yield and weed density. This implied close spatial interactions among these variables over the field. Applying the variogram models with the kriging al-gorithm, the values for each variable were estimated on a 55 grid. The disrribution of all variables is spatially dependent and continuous over a short distance. Furthermore, the maps illustratc a joint spatial dependence between grain yield and weed density. Spatial patterns of soil properties identified by these geostatistical techniques are of great impor-tance in the fertility management of spatially variable soils. By studying the spatial struc-ture of yield and mapping, it could be used in determining different factors controlling yield over the field. Moreover, a better knowledge of annual or perennial weed density distribution over fields might be helpful in better designing long-term field experiments in weed control programs.

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Pauesia antennata Mukerji (Hymenoptera, Braconidae) as the unique parasitoid of the giant brown peach aphid, Pterochloroides persiace Cholodkovsky (Hemiptera, Aphididae) is considered to be the most effective biological control agent of this pest. In this study, the assessment of selected biological parameters of P. antennata demonstrated that the longevity of mature parasitoid was 3.90 ± 0.22, the developmental time was 14.48 ± 1.05 and the life span was 19.46 ± 0.68 days. The maximum flight activity and oviposition were observed at the second and third days of the parasitoid lifespan. The parasitism, emergence rates and the sex ratio were affected by the variations in the number of P. persicae relative to each population of the parasitoid.

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Rearing methods for Bracon hebetor (Say) (Hym., Braconidae) were investigated in the series of laboratory experiments designed to enhance the yield of the mass rearing of this parasitoid for biological control of lepidopteran field and stored product pests. In these experiments, the effects of parasitoid and host densities on fertility and sex ratio of B. hebetor were assessed. In parasitoid densities, 50 last-instar greater wax moth (GWM) Galleria mellonella (L.) larvae were placed per container and 1, 2, 4, 8 or10 pairs of B. hebetor (one male and one female) were released in each container. In host density study two pairs B. hebetor were introduce in six different densities (10, 20, 30, 40, 50 and 60) of host, GWM per container. A density of ten male-female pairs of B. hebetor produced a higher number of progeny (205 ± 7.07 adults) on 50 last instar larvae of GWM. Similarly, in a host density experiment, a density of 60 last instars GWM larvae produced a significantly higher number of parasitoid progeny (142.0  ±  8.75 adults), followed by 50 last instar larvae (141.0 ± 8.34 adults) among the tested host densities when two pairs of B. hebetor were used. The sex ratio of progenies was male-biased in all studies and there were no significant effects on sex ratio in various parasitoid and host densities. In mass rearing experiment, total number of emerged parasitoids per 200 wax moth larvae was 1091 ± 82.38 adults with mean parasitism rate of 98 ± 0.8%.  

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Two similar field experiments were carried out at Kushkak and Fars Agricultural Ex-perimental Staties to determine the effects of plant densities and nitrogen topdressing (NT) rates on forage yield, some agronomic traits, protein and prussic acid contents of forage sorghum (Sorghum bicolor L. Moench var. Sudenense). Both experiments were conducted as spilt plots arranged in randomized complete block design with four replica-tions. Plant density consisted of 25, 33 and 50 plants m-2 in the main plots and nitrogen topdressing rates were 0, 100, 200 and 300 kg N ha-1 as urea in the sub-plots. Increasing plant density increased main stem height (MSH), leaf area index (LAI), total tiller num-ber m-2 (TTN), total fresh forage (TFF), total dry matter (TDM), leaf dry matter (LDM), and stem dry matter (SDM) yields. However, it decreased crude protein percentages (CPP) and had no effects on leaf-stem ratio at both locations. Increasing nitrogen rates in-creased MSH, LAI, TTN, TFF, TDM, CPP, forage prussic acid percentage (FPAP) and decreased leaf-stem ratio. Optimum plant densities and NT rates for these experiments were 50 plants m-2 and 200 kg N ha-1, respectively at both locations. Nitrogen applications had more effects on the second than the first out. The reaction of forage yields and most agronomic traits to the treatments were extremely similar at both locations.

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Abstract:

An experiment was conducted to evaluate the effects of stocking density on growth and survival of Nile tilapia (Oreochromisniloticus) in brackish water earthen pond. Fish with initial weight of 13 g kept in three stocking density 3, 6 and 9 fish/m₂ in duplicates and were fed on rainbow trout feed for 105 days during the light period. The results showed significant reduction in final weight, weight gain, daily growth rate, specific growth rate and survival by increasing stocking density, while feed conversion ratio enhanced in higher stocking densities (p< 0.05). Among the treatments evaluated, 3 fish/m² showed the best growth rate and survival, and the lowest feed conversion ratio. So, it seems that to achieve the highest profit, the stocking density of 3 fish/m² is suitable for culturing of tilapia in earthen pond. 

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Small walnut aphid (SWA) Chromaphis juglandicola is an economic pest of walnut trees. Population fluctuation of SWA was studied in Mamaghan walnut orchards (East Azarbaijan Province, Iran).Three factors affecting population density of SWA, including vertical divisions of canopy (upper and lower half), geographical orientations of canopy (at four levels) and elongation of branch (basal and distal ends), were investigated. Sampling unit was a cluster of five leaves. Totally 128 samples were taken weekly from all strata upon eight chosen trees, repeating 30 times during the season. Natural enemies also were counted. The first SWA individuals were observed early May, consisting of first instar larvae and alate females. A sudden population increase occurred in mid-May. Maximum 40 aphids/leaf were observed in early June with first and second instars dominant, followed by a sudden decline in late June. A small peak was observed at early October. A partial tendency was observed toward north of canopy, at basal half of downward branches. Positive linear correlation between natural enemies' and SWA populations suggests density dependence. Moreover 2-4 week delay was present between them. Trioxys pallidus (Holliday) was dominant natural enemy in the region. Contrary to previous works, overwintering stages of the SWA in the region were predominantly developed stages (third and fourth instars as well as pre-reproductive winged females).

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The effect of infestation and damage by Larger grain borer (LGB), Prostephanus truncatus (Horns) (Coleoptera: Bostrichidae) on nutrient content of some dried processed root and tuber crops (cassava, yam, sweet potato and cocoyam) were investigated in the laboratory at 25-30 ºC and 70-90% R.H. Thirty five grams each of the chips from two varieties of sweet potato, cassava, cocoyam and a variety of yam were separately placed in a 950 ml sized glass jar. The Test Host Crops (THC) were artificially infested with one, two and three pairs of adult LGB. The experiment was conducted using a completely randomized design with each treatment replicated three times and kept for 90 days. Data were taken on final population of adult LGB, weight of powder and percentage weight loss. Data on proximate analysis of LGB-infested THC after 90 days was also collected. The response of roots and tubers to infestation by LGB on the THC was significantly different. Percentage loss in quantity of root and tuber crops after 90 days of infestation showed that THC infested with two pairs of the insect had higher weight loss of the crops. The THC infested with two pairs of LGB had higher moisture content and least crude protein was recorded on the THC infested with one pair of LGB while the ones infested with three pairs of LGB had higher crude fat content. Uninfested THC had higher carbohydrate content. The findings of this study show that LGB is a serious threat to stored roots and tubers and to food security. The nutritional value of root and tuber crops was adversely affected by infestation of LGB in storage.

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Physical properties of agricultural crops are important to design of milling, planting and harvesting machines and also for reducing losses and safe quality of crops along to post harvest stage. In this study, some physical properties of three common varieties paddy rice (i. e. Khazar, Hashemy and Hybrid) including of main dimensions, geometric diameter, mathematical diameter, sphericity, area volume. weight of thousand grains, bulk density, true density, true volume, true density, angle of repose and external friction angle were determined at four level of moisture content( 10, 14, 18, 22% w. b.). Then effect of grain moisture content was investigated on them. Results showed that with increasing of moisture content of grain, main dimensions, geometric diameter, mathematical diameter, sphericity, area, volume, weight of thousand grains, bulk density and angle of repose were increased significantly (p<1%) While true volume was decreased. Also external friction angle was decreased respect to increasing moisture content of grain. At all grain moisture content levels and contact surfaces, the most external friction angle allocated to black sheet. The lowest external friction angle at Khazar and Hybrid allocated to mild contact surface. Also the lowest of this factor at Hashemy variety, obtained for galvanized contact sheet.

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There are varying patterns for growing different varieties of branched or non-branched sesame. This experiment was conducted during a two-year period (2000-2001) to identify the optimal practice for cultivation of the uni-branched sesame in the Safi-Abad Agricultural Research Center, Khuzestan Province. The statistical design was set up as strip-plot in a randomized complete block with four replications. Rows were adopted at varying spaces of 37.5, 50 and 60 cm while the plants were arranged horizontally at 5,10,15 and 20 cm. In this way, the density of the plot was surveyed over an area ranging from 83000 to 530,000 plant/ha. Combined analysis of two years, results showed a significant effect on the yield component due to an increase in row-spacing from 37.5 to 60 cm. This increase in row-spacing from 37.5 to 60 cm. could also increase the stem diameter from 16.3 to 19.4 mm, the pod number from 59 to 84 per plant, as well as the weight per thousand seeds from 3 to 3.3 grams. Moreover, an increase in plant spacing from 5 to 20 cm caused a decrease in stem height from 180.2 to 169.7 cm, an increase in stem diameter form 15.8 to 19.8 mm, a rise in pod number from 44.6 to 96.5 and in the seed content from 59.3 to 74.4 per pod. The relevance of the seed yield and row spacing obeyed a falling linear regession curve, while the seed yield and plant intervals showed a non-linear behaviour and estimated a maximum yield at 10 cm distance. Finally, the planting density reflected a non-linear fourth power equation. The maxinum seed and oil yield was then estimated at a density of 200,000–250,000 plant per hectare. In view of higher yield at the 37.5 cm row treatment and the 10 cm plant treatment, together with regressive equations, the above pattern (37.510cm) shall be recommended for uni-branched sesame growing in Khuzestan.

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