Identifying the constraining factors of production and YIELD gap is very important. Therefore; this research was performed to identify the production constraining factors of local rice cultivars. All management practices from nursery preparation to harvesting stages for 100 paddy fields of local rice cultivars were recorded through field studies, in Sari, from 2015-2016. In the CPA, the actual and calculated potential YIELD were 4495 and 5703 kg/ha, respectively and the gap was 1221 kg/ha. The YIELD gap caused by number of top-dressing variables was 324 kg/ha, equal to 27% of the total YIELD gap. The YIELD gap related to previous year of legumes cultivation was 218 kg ha-1, equal to 18% of the total YIELD variation. Among the 10 variables entered in the CPA model, the effects of top-dress fertilizer application and its application frequency and foliar application were remarkable, which could compensate a significant part of the YIELD gap (444 kg/ha, 37% of total) in the farmers’ fields by managing these variables. According to boundary line analysis (BLA) finding, actual YIELD mean on the basis of optimal limit related to 12 variables under study was 5369 kg/ha, with 881 kg/ha YIELD gap . Mean RELATIVE YIELD and RELATIVE YIELD gap for 12 variables (transplanting date, seedling age, number of seedlings per hill, planting density, nitrogen and phosphorous per hectare, nitrogen before transplanting, harvesting date, lodging problem, pest problem, diseases problem and weeds problem) were 83.64 and 16.35 kg/ha, respectively. Based on the finding, it can be stated that the model precision is appropriate and can be applied for both estimation of the quantity of YIELD gap and determining the portion of each restricting YIELD variables.

To investigate the effect of weed interference and weed-free periods on Balangu (Lallemantia royleana Benth. in Wall) and to evaluate the critical period of weed control (CPWC) in this oilseed crop, an experiment was conducted as a randomized complete block design with three replications in Naghadeh region in 2018. Experimental consisted of two groups of treatments; weed infestation treatments (infestation for 144.2, 345.9, 574, 848.2, 1147.6 and 1451.3 growing degree day (GDD) after transplanting and then plots were remained weed-free the rest of the growing season) and weed-free treatments (weeding for 144.2, 345.9, 574, 848.2, 1147.6 and 1451.3 GDD after transplanting and then plots were remained infested until harvesting time). In each block, one weed free and weed infested control was for all the growing season. Results indicated that the density and dry biomass of weeds were increased as weed removal was delayed. In contrast, density and dry biomass of weeds were decreased as weeds establishment was delayed. Height, tetrachenes fruits, ripened achenes, 1000-seed weight and biological, seed and RELATIVE YIELDs of Balangu were decreased and increased as the duration of weed-infested and weed-free period increased, respectively. Also, logistic and Gompertz curves fitted to data showed that the beginning and end of the CPWC based on a 10% YIELD LOSS of RELATIVE YIELD, was estimated to be from 11 to 108 days after transplanting (97 days weed-free period) in order to prevent a noticeable YIELD LOSS.

To evaluate the effect of plant dencity in light extinction COEFFICIENT and in performance of sorghum varieties, three level of grain sorghum varieties has been studied at research farm of Azad Islamic university, saveh-branch in 1386 year. In this experiment mention cases selects in the randomized block design and arranged in the form of factorial experiment. These are including three levels of grain sorghum varieties (Including speed feed, jumbo and kimia) at three dencities 130, 150, 190 thousand in plant/hec. Results of this experiment showed that effect of Plant dencities create a significant difference in seed numbers, 1000 seed weight, seed performance and light extinction COEFFICIENT. The best performance was 2838 kg/ha and belonged to dencity 190 thousand plant /ha. By increasing the dencity, number of seeds in panicule and 1000 seed weight decreased significantly. In case of seed number in panicule, 1000 seed weight ,seed performance and extinction COEFFICIENT sorghum varieties showed significant differences. Maximum and minimum seed number in panicule was in jumbo and kimia varieties respectively. Maximum Light extinction COEFFICIENT (K=0.55), belonged to, 190000 Plants/hectar dencity and jumbo cultivare. Minimum of light extinction COEFFICIENT (K=0.47) belonged to 130000 Plants/hectar and speed feed cultivare is. At list maximum of seed performance was belong to 190 dencity thousand plant/hec and jambo cultivare.

In order to prediction competitive effects of redroot pigweed on YIELD and YIELD components of grain sorghum by observation of RELATIVE leaf area an additive series experiment (response model) with factorial in randomized completely block design (RCBD) were conducted in 2005 growing season at farm research of khorasan Agriculture and Natural Resources Research Center (Torogh Research Station). Two factors were involved in the experiment, redroot pigweed density in four levels (0, 2, 8 and 16 plant/m2) and sorghum density in three levels (10, 15 and 30 plant/m2). kropff three parameter model was used for data analysis and predicting of competition and RELATIVE YIELD LOSS COEFFICIENT (q). Result of this study indicated that sorghum is sensitive in competition and has sever damage. The economical YIELD reducing at 10, 15 and 30 plant/m2 density due to red root pigweed competition was 0.11, 0.38 and 0.22 kg/m2 respectively, where as the biological YIELD LOSS was 0.6, 1.27 and 1 kg/m2 .Prediction of model from RELATIVE YIELD LOSS COEFFICIENT (q) indicated high competitiveness of pigweed and also faster leaf area spreading. Result showed that this model is very suitable to describe competition effects and to determine RELATIVE YIELD LOSS COEFFICIENT (q) by observation of RELATIVE leaf area.

To study the effect of salinity stress on some physiological traits in wheat cultivars (Triticum aestivum L.), a factorial experiment based on randomized complete block design with three replicates was performed at 2017 in the research greenhouse of Agronomy Department, University of Tehran. Salinity treatments at two levels; control (1.2 dS/m) and sodium chloride treatment (16 dS/m) and seven wheat cultivars, Rowshan, Inia-66, Mahdavi, Khazar-1, Karaj-2, Ghods and Shole were the experimental treatments. According to the results, RELATIVE water content, YIELD and its components and potassium/sodium ratio decreased in all genotypes while Na+ content and remobilization of carbohydrates were increased. Salt resistant varieties, Roshan and Inia-66, had the highest level of RELATIVE water content, remobilization of soluble carbohydrates and number of grains per spike. In addition, Roshan cultivar showed the highest potassium concentration and K+/Na+ in the shoots, while Ghods and Sholeh as sensitive cultivars had the highest sodium concentration in the shoots. Findings showed that the ability of a cultivar to remobilize soluble carbohydrates is one of the traits that determine salt stress tolerance, hence, this trait is suitable for evaluating salt tolerance of wheat cultivars in the future investigations.

In this paper the reflection COEFFICIENT of electromagnetic wave incidence on the walls of the buildings and obstacles that occurs in mobile communication path was modified by solving the Riccati nonlinear equations. For this purpose, the building walls are assumed inhomogeneous layers where their permittivity changes as function of the wall thickness. Using this reflection COEFFICIENT, a new propagation model based on urn and GID (uniform geometrical theory of diffraction and geometrical theory of diffraction) for multiple diffraction paths is proposed. Using this model, the diffraction LOSS as well as the path LOSS for a row of buildings with two in homogeneous faces is calculated and compared with measured data. Comparison of theoretical and measured results reveals that the modified reflection COEFFICIENT can adequately predict the reflective properties of the building walls. Moreover, results obtained with the proposed UID model are in good agreement with the measurement data. Therefore, the modified reflection COEFFICIENTs well as the new UID model can be used for estimation of multipath signals strength, diffraction LOSS and also path delay in ray tracing algorithms used in mobile communication, radar and radio links.

Background and objectives: Chickpea has the highest harvest area and production quantity among pulse crops in Iran. This crop is a poor competitor against weeds. So understanding the critical period of weed control (CPWC) is important for determining proper time of weed management and herbicide application. The objective of the experiment was to determine the CPWC of chickpea in dry-land conditions of Dehgolan plain in Kurdistan province. Material and methods: The field experiment was carried out as randomized complete block design with four replications at agricultural research station of Kurdistan University in Dehgolan plain, Kurdistan province from April 18, to July 21, 2014. The chickpea cultivar ILC 482 was used for the study. The trial had 16 treatments, including seven non-weeding (Interference) periods and seven weeding (weed-free) periods as well as whole season weed free and weed interference as control. Weed interference and weed-free treatments were set up as 12, 22, 32, 42, 52, 62, and 72 day periods after planting. The beginning and the end of CPWC was determined by curve fitting to weed interference and weed free periods respectively. RELATIVE seed YIELD of treatments was calculated as percent of weed-free control. A four parameter logistic equation was fitted to RELATIVE YIELDs of weed interference and weed-free periods and then CPWC was determined based on 2. 5, 5, and 10 percent acceptable YIELD LOSS (AYL). Results: Weed density of interference periods ranged 9. 98-17. 42 and the mean density was 14. 82 plant m-2 during growing season. Mean density of Chenopodium album, Convolvulus arvensis, Carthamus oxyacantha, and Amaranthus retroflexus were 8, 4, 1. 5, and 0. 5 plant m-2 respectively and composed the major species of weed community. Weeds dry weight increased linearly as interference period increased and reached 62. 13 gm-2 on harvest time. In contrast, weeds dry weight decreased exponentially with increasing weed-free periods and approximately approached zero at the end of growing season. Seed YIELD of weed-free and weed interference controls were 106. 38, and 68. 71gm-2 respectively. Therefore, weed interference reduced seed YIELD by 35. 5% compared to weed-free control. The beginning of CPWC was estimated 208, 292, and 426 degree days (18, 24 and 36 days after planting) equal to 3, 5, and 8 chickpea leaf stage and the end of CPWC was also determined 1234, 969, and 720 degree days (79, 67 and 54 days after planting) equal to mead seed filling, the end of podding, and early flowering according to 2. 5, 5, and 10 percent YIELD LOSS. Conclusion: The CPWC was determined 24-67 days after planting (the 5 leaf stage to the end of chickpea podding) based on 5% YIELD LOSS.

Usefulness and validity of different empirical YIELD LOSS models to predict the effect of common lambsquarters competition in corn were evaluated in a two year experiment in Karaj, Iran during 2001 and 2002 growing seasons. Experimental factors were 2, 5, 10 and 15 plants m-2 in the first experiment and 6.6, 13.3 and 20 plants m-2 in the second experiment and RELATIVE time of common lambsquarters emergence of simultaneous to, at 2-3 and 4-5 leaf stages of corn in the first experiment and simultaneous to, at 2-3 and 5-6 leaf stages of corn in the second experiment. Results indicated that the highest corn YIELD and LAI LOSSes were observed at simultaneous emergence of weed and corn resulted in 85 and 92% YIELD LOSS, and 73 and 53% LAI LOSS in the first and second years of experiments, respectively. Also, delaying common lambsquarters emergence reduced its competitive ability against corn. Comparison of different empirical models revealed that the empirical YIELD LOSS models based on density and the RELATIVE time of weed emergence, and the weed RELATIVE leaf area, also the rectangular hyperbolic YIELD LOSS model based on weed density were more reliable at predicting corn YIELD and LAI LOSSes according to their high COEFFICIENT of determination (R2). Also, results indicated that the negative effect of the RELATIVE time of common lambsquarters emergence on corn YIELD LOSS was more than weed density, so that the rectangular hyperbolic YIELD LOSS model based on weed density was more capable to predict YIELD LOSS at each of weed emergence times.

Background: Driving is a usual job with many occupational complications. Occupational hearing LOSS in track driver is not an unusual occupational problem. We studied the relation of occupational hearing LOSS and long term noise exposure in track drivers.Methods: This descriptive study was done among track driver population in Kashani and Al-Zahra hospitals in Isfahan. Taking medical history and physical examination were done by an expert otolarygologist and then, eudiometry was done. The data were analyzed by paired-t and variance regression tests via SPSS 11.5 software.Finding: In 384 track drivers, hearing threshold in left ear was more than hearing threshold in right ear (P<0.001).Conclusions: In this study, such as the other studies, a relation between persistent noise and hearing LOSS was observed. In track drivers, persistent noise can cause occupational hearing LOSS and their left ears are more susceptible than the rights in risk.