فهرست مطالب hamidreza mohammaddoust chamanabad

AbstractConsidering the effect of stresses on photosynthesis, the investigation of chlorophyll fluorescence in plants is very important to evaluate the effect of herbicides on plants. This experiment was also conducted in order to study the effects of Dylan, Atlantis and Total herbicides on the dandelion fluorescence system in the green space of the Faculty of Agriculture and Natural Resources of Mohaghegh Ardabili University in 2021 For this purpose, different doses (0, 0.5, 1 and 2 times the recommended dose) of the herbicides Dylan, Atlantis and Total were applied. Fluorescence of dandelion was measured.1, 2, 3, 5, 7, 10 and 14 days after treatment with herbicides with a portable fluorometer. The results showed that Dylan and Atlantis reduced maximum fluorescence more severe than Total and irreversible. The application of high dose of Atlantis reduced the variable fluorescence of dandelion by 46% compared to the control. Also, the dry weight of dandelion decreased under the influence of different herbicide treatments compared to the control. The amount of reduction in the herbicide treatment of Dylan and Atlantis was more than total. In these herbicides, the dry weight of dandelion was 50% less than the control.IntroductionHerbicides are one of the most effective agricultural tools in the fight against weeds, and the use of these chemicals has increased significantly in recent years, especially in developed countries in the field of agriculture. It is necessary to use non-destructive and high-speed methods to accurately and quickly investigate the effects of herbicides on plants and identify their mechanisms of action. Evaluation of chlorophyll a fluorescence is a quick and non-destructive method to determine the state of the plant's photosynthetic system in response to various stresses, such as herbicide stress. Chlorophyll a transfers the energy received from the light photon to the reaction center and these interactions cause the electron transfer chain to start in the chloroplast. Considering the effect of stresses on photosynthesis, the investigation of chlorophyll a fluorescence in plants is very important to evaluate the effect of herbicides on plants.Materials and methodsThis experiment was also conducted in order to study the effects of Dylan, Atlantis and Total herbicides on the dandelion fluorescence system in the green space of the Faculty of Agriculture and Natural Resources of Mohaghegh Ardabili University in 2020  in the form of a basic randomized complete block design with 3 replications. Different doses (0, 0.5, 1 and 2 times the recommended dose) of Dylan, Atlantis and Total herbicides were evaluated. Chlorophyll a fluorescence of dandelion was measured 1, 2, 3, 5, 7, 10 and 14 days after treatment with different herbicides with a portable fluorometer. For this purpose, fully developed leaves on the top of the plant were selected. The selected leaves were placed in the dark for 20 minutes using special clips so that all reaction centers of the photosynthetic apparatus were open and ready to transfer electrons. Then, a light pulse at a wavelength of 650 nm with an intensity of 3000 μmolphotons per square meter per second was irradiated to these leaves for four seconds, and parameters such as minimum fluorescence (F0), maximum fluorescence (Fm), variable fluorescence (Fv), maximum photochemical efficiency of photosystem II (Fv/Fm), efficiency of the water-decomposing complex as an electron donor of photosystem II (Fv/Fo), and heat loss (Fo/Fm) ) were studied. One month after application of different weed control treatments, in each plot dandelion were colected using a 25×25 cm square and then placed in an oven at a temperature of 72°C for 48 hours and their dry weight was measured.Results and discussionResults showed that application of herbicides decreased maximum fluorescence of Fm, variable fluorescence of Fv, maximum photochemical efficiency of photosystem II (Fv/Fm) and efficiency of water splitting complex as an electron donor to photosystem II (Fv/Fo) of dandelion and increased minimum fluorescence and Fo/Fm. Also, dry weight of dandelion weed decreased under the influence of different herbicide treatments compared to control (no herbicide). Results showed that maximum fluorescence reduction in Dylan and Atlantis was more severe and irreversible than Total. Application of a dose of 2 times recommended amount of Atlantis reduced variable fluorescence of dandelion by 46% compared to control. Also, dry weight of dandelion weed decreased under the influence of different herbicide treatments compared to control. The amount of reduction in Dylan and Atlantis herbicide treatment was more than total. In these herbicides, the dry weight of dandelion was 50% less than the control. The results of the effect of herbicides on dry weight were consistent with their effect on the fluorescence parameters of chlorophyll a. Total herbicide did not have much effect on chlorophyll a and dry weight parameters, on the contrary, Atlantis and Dylan herbicides increased Fo and Fo/Fm and decreased Fm, Fv and Fv/Fo, and as a result decreased dry weight of dandelion.ConchusionOverall, results showed that Atlantis herbicide had the greatest effect on fluorescence parameters of chlorophyll a and dry weight. Based on results obtained from the evaluation of chlorophyll a fluorescence parameters and the existence of a relationship between chlorophyll a fluorescence parameters and dandelion weed biomass calculated one month after the application of herbicide treatments, it can be concluded that chlorophyll a fluorescence is a quick method to study the effectiveness of herbicides and reduces the time required to study the plants response to herbicides.

Urban landscapes are considered as one of the main elements of beauty in cities. In order to investigate the effect of different herbicides on the control of dandelion in the lawn, an experiment was conducted in the greenhouse and natural landscape of University of Mohaghegh Ardabili in 2021. For this purpose, first, in the screening test, nine broad-leaved and dual-purpose herbicides were tested at 0.25, 0.5 x , 1 x and 2 x recommended dose with a control (no herbicide application) in the greenhouse environment on dandelion seedlings. After the statistical analysis of the data from this stage, six herbicides bromoxynil, U46, Otello, Dylan, Atlantis and Total were selected and tested at 0.5, 1 and 2 of recommended dose with the control in natural conditions. It was used in three replications in the landscape infected with dandelions in plots of 1 square meter (1x1). In natural condition, applied of bromoxynil and U46 reduced dandelion dry weight by more than 50% compared to control, which had significantly different with other treatments (except Total). In this case, level of visual scoring on lawn was less than 20% in U46, Bromoxynil, Dylan, Atlantis and Total herbicides and had no significant difference between them. Application of 2x recommended dose of bromoxynil, U46 and Atlantis herbicides had the lowest density of dandelion, which was 37, 50 and 37% less compared with control (dose 0), respectively.

The aim of this study was conducted to investigate the effect of row spacing and cover crops on weed control and yield and components yield of corn (TWC647). This experiment was carried out factorial based on a randomized complete block design with three replications in the farm of Moghan Agriculture and Natural Resources Research Station in 2021. The treatments consisted of row spacing at two levels (75 and 65 cm), cover crops at five levels (rye, hairy vetch, clover, and no cover crop and Maister power herbicide). In the condition without cover crop, the highest total biomass of weeds was obtained at the row spacing of 75 cm. Also, the highest biomass of cover crops in the row spacing of 75 cm was obtained from rye cover crop. The number of grain rows per ear, grain yield, biological yield and harvest index were affected by the interaction row spacing ×cover crop; So that the maximum number of grain rows per ear was observed at a row spacing of 75 cm and clover. The highest biological yield of corn was obtained at the row spacing of 65 cm and rye cover crop. highest grain yield (8.05 tons per hectare) was obtained from the row spacing of 65 cm and the rye cover crop treatment and also the highest control percentage of the total biomass of corn weeds (47.47%) was related to the rye cover crop and row spacing of 65 cm.

The most effective tool to prevent and delay resistance to herbicides, and increase weed control spectrum is herbicide tank mixtures. In order to evaluate the effects of binary mixtures of metribuzin:halosulfuron and metribuzin:flumioxazin on potato weeds, a field experiments was conducted in factorial experiments in a randomized complete block design in Ardabil in 2019 .The doses of metribuzin were 10.93, 21.87, 43.75, 87.5, 175, 350 and 700 g ai. ha-1 and halosulfuron doses were 0.78, 1.562, 3.125, 6.25, 12.5, 25 and 50 g ai. ha-1. The metribuzin:halosulfuron uses (100:0), (98:2), (93:7), (82:18) and (0:100)% mixture ratios with three replications. On the other hand, the doses of metribuzin were 10.93, 21.87, 43.75, 87.5, 175, 350 and 700 g ai. ha-1 and flumioxazin were 0.97, 1.95, 3.9, 7.81, 15.62, 31.25 and 62.5 g ai. ha-1. The metribuzin:f1umioxazin mixtures ratios were (100:0), (97:3),  (92:8), (79:21) and (0:100)% with three replications. The experiments were carried out on two-time levels: pre-emergence (7 days after planting) and post-emergence (75% potato emergence, 35 days after planting). The ED50 and ED90 values indicated (0:100)% metribuzin:halosulfuron and metribuzin:flumioxazin had the most effective treatment on total weed, convolvulus arvensis and setaria viridis biomass. Dose-effect curves demonstrated metribuzin:halosulfuron and metribuzin:flumioxazin followed an antagonistic effect based on the additive dose model (ADM) reference model.

To evaluate the effect of row spacing, planting pattern and density on weed control and morpho physiological characteristics of corn (Zea may L.), the experimental was carried out factorial based on a randomized complete block design with three replications in the farm of Moghan Agriculture and Natural Resources Research Station in 2022. The first factor included row spacing in two levels (75 and 65 cm), the second factor was planting pattern in two levels (single row and zigzag twin row) and the third factor was planting density in two levels (75,000 and 85,000 plants per hectare). The results showed that the highest grain yield and leaf area belonged to the density of 75000 plants per hectare and the row spacing of 75 cm. The highest density and total biomass of weed was observed at density of 75,000 plants per hectare and row spacing of 75 cm, But the lowest density and total biomass of weed was obtained from the density of 85,000 plants per hectare and row spacing of 65 cm. The maximum cob diameter, cob wood diameter and leaf chlorophyll index were obtained at the density of 75,000 plants per hectare with the row spacing of 75 cm and the single row planting pattern. Correlation coefficients between traits showed that the correlation between grain yield with total weed biomass, cob diameter, cob wood diameter, seed depth and leaf chlorophyll index is positive and significant. Generally, the results of this research showed that with extending of twin row patterns with increased density of corn, it is possible to control weed through the competitive ability of the plant, it achieved an acceptable performance.

Barley is one of the most important crops after wheat, corn, and rice. Barley is an excellent source of food for humans and is also used to feed livestock. The purpose of this study was to evaluate and select superior genotypes with high grain yield and desirable agronomic characteristics and also to investigate the application of MGIDI in selecting superior genotypes based on morpho-phenological different traits in the warm and dry region of southern Fars.

To select the best barley genotypes in the southern regions of Fars using the MGIDI index, 108 pure lines in the non-repeating Augment design with four controls (Nowruz, Auxin, Nobahar, and WB-97-11) in the Fars Agricultural and Natural Resources Research and Education Center (Darab station) were evaluated during the cropping year 2020-2021. MGIDI index was calculated to select superior genotypes using 13 morpho-phenological traits. These traits include grain yield, number of spikes per square meter, number of grain per spike, weight of spikes, 1000-grain weight, spike density, filling period length, peduncle length, awning length and spike length, plant height, days to flowering and days until the maturity.

According to the results of variance analysis, a significant difference was observed between the studied lines for all traits (except awning length and 1000-grain weight) at the probability levels of 5 and 1%. Also, the results showed that there was a significant difference between the lines and experimental controls in all traits (except peduncle length). The results of factor analysis for the 13 studied traits identified five hidden factors that explained 80.2% of the total variance of the data. Based on the MGIDI index, L110, L99, L88, L51, L56, L108, L63, L33, L50, L112, L52, L36, L20, L69, L68, L94 and L35 genotypes, respectively, with the lowest value of this index were superior genotypes. The highest and lowest values ​​of differential selection percentage of MGIDI index were related to grain yield (11.5%) and 1000-grain weight (-3.62%), respectively. The results showed that low values ​​of the number of grain per spike and weight of spikes and high values of the number of spikes per square meter were effective factors in selecting superior genotypes using the first factor. Based on this factor, L20, L94, L110 and L88 were superior. In the second factor, high values of the number of days to maturity, grain yield, and grain filling period were the main factors in selecting genotypes, and based on this factor, L112 genotype was top. Third factor selected genotypes based on high values ​​of both trait plant height and peduncle length. L88 and L94 genotypes were ideal based on the third factor. Fourth factor selected genotypes based on high awning length and spike length (L33 genotype was superior), and fifth factor selected genotypes with low values ​​of spike emergence length and 1000-grain weight and based on this factor L50, L35 and L51 genotypes were ideal.

Overall, the results showed that none of the factors could classify the superior genotypes based on the ideal value of all their internal traits. Therefore, genotypes are selected that have the lowest MGIDI value, and also their grain yield is higher than the average grain yield of unselected genotypes. So the results showed that among the selected genotypes using the MGIDI index, L99, L88, L51, L56, L108, L63, L20, L69 and L94 genotypes ​​were the top genotypes in this study. On the other hand, proving the efficiency and development of a new index such as MGIDI requires more research in other plants.

To evaluate 38 maize hybrids, an experiment based on randomized complete block design with three replications at the Moghan Agriculture Research Station during the 2020 growing season. The results indicated that a significant difference had among maize hybrids for ear yield, plant height, ear height, leaf temperature, chlorophyll index, maximum fluorescence (Fm), variable fluorescence (Fv) and maximum quantum yield of PSII (Fv/Fm). K74/2-2-1-4-1-1-1 × K3640/3 hybrid (No. 9) with high ear yield and photosynthetic system introduced the best hybrid to comparing with other hybrids. The range of heritability was from 3% for minimum fluorescence (Fo) to 71 % for ear height. Path analysis revealed that minimum fluorescence (Fo) and leaf temperature had the highest and positive direct effects on ear yield. The cluster analysis, with ear yield, plant height, ear height, leaf temperature, chlorophyll index, and quantum yield, was classified 38 maize hybrids in three different groups, and the third group with 9 (K74/2-2-1-4-1-1-1 × K3640/3) was the most desirable.

In order to evaluate the drought stress tolerance of durum wheat genotypes, an experiment was conducted at Gachsaran Dryland Research Center, Iran during 2017-18. A total of 18 durum wheat genotypes were studied in a randomized complete block design with four replications under rainfed and supplementary irrigation conditions. The results of combined analysis of variance showed that supplementary irrigation significantly increased grain yield. In supplementary irrigation condition, the genotypes 16, 17 and 18 and in rain fed condition the genotypes 4, 16 and 17 had the highest grain yield per hectare. The stress tolerance indices were calculated based on yield of genotypes in rain fed and supplementary irrigation conditions. With considering of significant positive correlation between grain yield in the rain fed condition (YS) with relative drought index (RDI), mean productivity index (MP), stress tolerance index (STI), yield index (YI), geometric mean productivity index (GMP), new drought resistance index (DI), improved stress tolerance index (MSTI), non-Stress Environmental Stress Index (SNPI) and harmonic Mean Index (HARM), these indices are suitable for identification of stress tolerant lines. Stress susceptibility index (SSI), yield stability index (YSI), abiotic stress tolerance index (ATI) and stress sensitivity percentage index (SSPI) did not play a significant role in the differentiation of genotypes. On the other hand, there was a significant positive correlation between grain yield in supplemental irrigation with TOL, MP, YI, MSTI, SSPI, ATI, SSI and STI. Grouping of genotypes using cluster analysis method showed that the genotypes were classified into four distinct groups and genotypes 4, 16 and 17 were in the fourth group with the highest tolerance indices compared to the other. Genotypes 7, 8 and 10, which had the lowest yield and also the lowest amount for the most indices, were identified as the most susceptible to drought stress. The results of factor analysis confirmed the above results.

Drought tolerance of 18 advanced lines durum wheat were evaluated in a randomized complete block design with four replications under dryland and complementary irrigation conditions in GachsaranAgriculturalResearchCenter at 2016-2017. In this study, traits like days to spike formation, days to maturity, plant height, peduncle length, spike length, 1000 seed weight, seed yield, spike number, spike number per m2, canopy temperature reduction of two stages of spike and seed filling, rate of greenness at two stages of spike and grain filling, were measured. Analysis of variance showed that there were significant differences among lines under study for days to spike formation, plant height, peduncle length, spike length, 1000 seed weight, seed yield, crop score, number of seeds per spike, temperature reductions of canopy at two spike stages seed and greenery content in two stages of spike and grain filling were significantly different. Mean comparisons showed that lines 4, 9, 13, 15, 16 and 17 were better than other lines in most traits. Evaluation of sensitive and tolerant lines according to tolerance index (Ti) showed that lines 1, 2, 4, 6, 9, 15 and 17, had high Ti index in most traits, were tolerant. Selection for superior lines, based on SIIG and selection of ideal genotype (SIIG) index, were performed. The results of variance analysis of traits based on Ti index showed that difference among lines in terms of 1000 seed weight, reduction of canopy temperature at grain filling stage, seed yield, grain filling period, chlorophyll content at both clustering and grain filling stage, days to reach and number of days to clustering were significant at 1% probability level. Lines 4, 5, 9 and 15 were the highest values of this index and were suitable for growing under dryland conditions. Lines 7, 8, 10 and 14 having lowest value of the SIIG index were sensitive to rainfed condition. The results of this ranking are similar to the results of cluster decomposition based on Ti index.

Purple nutsedge is one of the most problematic weeds of onion fields. To investigate the management practices of this weed, an experiment was conducted in the Agricultural and Natural Resources Center in Southern Kerman in 2017-2018 as a randomized complete block design with three replications. Treatments included twice disk + glyphosate, heavy plow + disk, metribiuzin, pendimethalin (Stomp), hand weeding, soil solarization, soil solarization + glyphosate, Control (no control), pendimethalin (Prowl), three times plowing, and twice disk + two times glyphosate. The results showed that the effect of different treatments was significant on shoot and underground dry weight and density, neck diameter, number of leaves and yield of onion. Twice disk + twice glyphosate decreased shoot and underground dry weight and density by 86, 87, and 87.2 %, respectively, and yield of onion increased 83 %. Therefore, combination of disk and glyphosate was desired in purple nutsedge control and this treatment is recommended.

The culture of man and rice have historical and profound relationships. Rice (Oryza sativa L.) has an inescapable role in providing food, economy, religion and civilization in many countries of the world. Weeds are among the most important factors affecting crops such as rice. Successful weed control is essential for rice production. Grasses, broad-leaved, sedges, ferns and algae are the weeds of Guilan rice fields. Infestation of weeds in a field can be described by three characteristics of the number of available weed species, the density of each species and the distribution of species in the field. The species in a field are almost constant from year to year, but the other two factors vary greatly in response to the environment, agronomic plans and weed management practices. However, detailed information on the presence, composition, abundance, importance and ranking of weed species depends on weed management strategies with average yield of rice. The objective of this study was to investigate rice weed community richness and composition in the Guilan province, Iran during 2014 and 2016 and their relationships with management. The study was conducted in Guilan province (between 36° 34' to 38° 27' latitudes and 48° 53' to 50° 34' longitudes), northern Iran, with 14044 kilometer square of area. 481 fields were selected from 10 days after transplantation to the end of panicle formation. Taking the area of each field into consideration, 0.25 m2 quadrats were done for sampling using a W-shaped sampling pattern. The weeds at each quadrat were counted and their genera and species were identified. The Frequency, field uniformity over all fields, density of the weeds in each field, the mean weed density of the visited fields, and dominance of the various species in each region were determined. The Simpson index (D) gives more importance to the common species, but the Shannon-Wiener index (H) puts greater importance on rare species. After collecting the data and making the calculations required for determining the population indices, this information created the main layer in the project, and was then designed in the format of a databank. 66 weed species were identified in rice fields of Guilan province, which belonged to 29 families. According to the dominance index of weed, Echinochloa crussgalli was the highest among 66 identified species in Astaneasharafyeh, Amlash, Anzali, Rasht, Roudsar, Siahkal, Fouman, Lahijan and Langroud. Alisma plantago-aquatica had the highest prevalence index in Rezvanshahr. Paspalum distichum was one of the dominant species in shaft, Talesh and Masal regions, having the highest dominance index. Cyperus difformis had the highest dominance index in Somesara. Bolbosoenus maritimus was one of the most important weeds in rice fields located in Roudbar with dominance index equal to 9.9. Azolla filiculoides in 11 regions of Guilan had the highest frequency among floating and submerged weeds in 16 regions. The green algae were the dominant weeds at Astaneasharafyeh and Masal. In the both of regions of Somesara and Lahijan, Lemna minor was the most abundant aquatic weeds. Najas marina is the herbaceous plant having the highest abundance among floating and submerged species in Roudbar. The Shannon-Weiner and Simpson indices were the highest in Talesh (2.85 and 11.93, respectively) and the lowest in Roudbar (1.97 and 3.99, respectively). Uniformity index in Rezvanshahr had the largest quantity equal to 0.806. Identification of weeds is the most important action for weed management. Weed flora composition in rice fields of 16 areas at Guilan Province consisted of 66 species belonging to 29 families. Roudsar and Langaroud regions were the most dominant sites with a total of 47 weed species followed by Rasht and Lahijan (46 sp.), Astaneasharafyeh (42 sp.), Amlash (37 sp.), Talesh (36 sp.), Fouman and Siahkal (34 sp.), Roudbar (32 sp.), Rezvanshahr and Somesara (30 sp.), Masal (28 sp.), Astara (27 sp.) and Shaft and Anzali (25 sp.). Ten species, three grass (narrowleaf) species (E. crussgalli, P. distichum, and E. oryzoides), three sedge species (C. esculentus, C. serotinus, and C. difformis), four broad-leaved species (E. prostrata, S. trifolia and A. plantago-aquatica), and one fern species (A. filiculoides) were the most widespread and of the highest abundance. Frequency, density and dominance of weeds according to the rice ecosystem in different regions can be changed. Due to lack of knowledge on identification and effective weed control factors, the weeds population is growing. Therefore, assessing the management role in changing the weed communities structure of species diversity can be useful to improve weed control.

In sustainable agricultural systems and healthy crop production, using of high-competitiveness cultivars is an easy and inexpensive method for weed management. Therefore, in order to study of competitive ability of 25 wheat varieties against weeds and identification and introduction of wheat cultivars with high competitiveness to use in crop breeding, an experiment was conducted using randomized complete block design with three replications in natural conditions in the university of Mohaghegh Ardabili field. The results showed that there was a difference more than 10 and 7 times between the lowest and the highest initial dry weight and the initial cover of wheat cultivars, respectively. The lowest (162.3 plant.m-2) and the highest (683.3 plant.m-2) weed density were observed in Ofogh and Orum cultivars, respectively. The difference between the lowest and the highest weed dry weight was more than 3 times. The results showed that weed dry weight had a negative correlation with the initial wheat dry weight (R2= -0.55**) and the initial wheat cover (R2= -0.70**). In competition with weeds, yield loss of wheat cultivars was between 3.22% in Sivand cultivar to 68.98% in Shiraz cultivar, which had a close relationship with weed dry weight. Cultivars showing high tolerance and competition index showed lower yield loss. This finding showed that wheat cultivars have a difference in CI (competitive ability) and WITI (weed interference tolerance index) and this feature can be used for non-chemical weed management programs.

Machine vision technology can be used to detect the location of weeds around the main crop in a field as the machine moves, in order to decrease the losses of using herbicides. The purpose of this research is to determine the accuracy of image processing method in discriminating weeds from potato crop according to color features. Therefore, by performing a research which conducted in university of Mohaghegh Ardabili research field, three factors including: environmental light condition, type of weed (Shalambig, Pichack and Wheat), and level of crop growth, were investigated on discrimination accuracy. The results of this research were showed that there are no significant differences between two types of environmental light conditions. However, the main and interactive effects of two factors of type of weeds and level of crop growth was significant on discriminating system performance. According to this study, the first stage of crop growth is the best time for the visual tests (middle of the June) and among the three types of popular weed in the region, it is possible to discriminate the wheat from potato leaves with a reasonable accuracy according to RGB color model. By this method, it is possible to determine the location of weeds around the main crop by maximum accuracy of 95% dependent to different condition of treatments.

Basically, the most important limiting factor in plant growth is the lack of water. More lands in Iran are located in arid and semi-arid region and so identifying of ghenotype that can produce acceptable yield under drought conditions is essential. In order to identification of drought stress tolerant varieties, 20 wheat cultivars were evaluated at three stress levels (control, -0.6 and -1.2 MPa) and in aquaculture medium as a factorial experiment based on completely randomized block design with three replications in the green house of Mohaghegh Ardabili University based on root length, root and shoot fresh weight, root and shoot dry weight and root/shoot dry weight ratio. Stress levels were induced by using polyethylene glycol 6000. Results of ANOVA showed that the stress levels had significant effect on all traits. Also, Cultivars had significant differeces in all traits. The cultivars×stress interaction was significant in all studied traits. The drought tolerance indices of HARM, GMP, MP and STI were calculated based on yield in control (Yp) and stress levels (Ys). Results of ANOVA for indices showed significant difference between cultivars that showed different response of cultivars to drought stress. Comparisons of means were carried out by Duncan's method at one percent probability level. In all of traits the means of cultivars reduced by increasing of stress levels. According to cluster analysis results based on morphological traits in control level, the cultivars of Arta, BC Roshan, Tajan, Gascozen and shiroodi were beter than other cultivars. In -0.6 MPa stress level, the Arta, Shiriidi, Tajan, Kavir and Gascozen cultivars wre tolerant and Moghan2, Rasul and Mihan had partial tolerant to drought stress. In -1.2 MPa stress level, the Kavir, Rasul, Mihan were tolerant to stress. Totally, according to cluster analysis based on morphological traits and tolerance indices, the Rasul and Mihan cultivars were identified as tolerant cultivars.

This study was conducted to evaluate the effect of osmotic stress on physiological characters of wheat cultivars as a factorial experiment based on completely randomized design with three replications in 2012 at the Mohaghegh Ardabili University. Twenty wheat cultivars studied in three stress levels (control, -6 and -12 Bars). Analysis of variance showed that the stress had significant effect on all traits, except of carotenoids, chlorophyll b and quantum yield. Comparisons of means by Duncan method at one percent probability level showed that increasing of osmotic stress increased averages of soluble sugar, proline and chlorophyll a in most cultivars. But, the average of chlorophyll fluorescence, maximum fluorescence (Fm), variable fluorescence (Fv) and carotenoids were decreased in more varieties such as Tajan, Gascogen, Mihan, Rasool, Gaspard and ­Roshan (­winter type back­ cross) in compared with control level. Also, mean of quantum yield and chlorophyll b were greate in most varieties such as Arta and ­Roshan in -6 bar osmotic stress level. According to cluster analysis results based on physiological traits in control level, the varieties of Zarrin, Inia, Arta, Moghan1, Tajan and Shiroodi had high deviation from total mean for most of traits. In -6 bar osmotic stress, the varieties of Mihan, Shiroodi, Arg, Tous, Orum, Kavir, Moghan3 and ­Roshan (­winter type back­ cross) and in -12 bar osmotic stress, the varieties of Mihan, Gascogen, Mihan, Moghan2 and Rasool categorized in tolerant varieties groups.

Environmental stresses are the most important factors that reduce plant growth in stages of development. The presence of aluminum in acidic soils as an environmental stress has an impact on different parts of the plant and reduces root growth, water absorption and nutrients and increases susceptibility to drought. In order to evaluate the effect of aluminum stress levels on wheat at germination stage, an experiment was conducted as factorial based on completely randomized design with three replications. The root and shoot characters of four wheat cultivars (Arta, Gascozen, Moghan3, Mihan) at seedling stage were studied at eight stress levels (control, 0.5, 1, 1.5, 2, 2.5, 5 and 10 mM Al
3
). The root and shoot fresh weight, root and shoot length, root volume and area, root number and Root/Shoot ratio were measured. Results showed that stress level had significant effects on all studied traits. Also, wheat cultivars were significantly different for number, volume, weight and area of root and also shoot length. Interaction between cultivars and stress levels was significant for root number. The Mogha3 variety had higher root number at 2.5 mM Al
3
stress level. In all of varieties, the root number increased by increasing of Al
3
concentration. Comparison of means showed that Al
3
stress caused significant reduction in all studied traits except root number. The Moghan3 variety had higher means for studied traits as compare with other varieties.

Cover crops are an effective tool in the non- chemical weed management in sustainable agriculture. In order to evaluate the effect of type and time planting of cover crops on weed control in tomato، a factorial experiment was established using a randomized complete block design with three replications at 2013 on personal farm located about 65 kilometers from Shiraz province. The factors were included the type of cover crop at four levels (rye، red clover، rapeseed and control (no mulch)) and time of planting in three levels (one month before tomato transplanting، at the same time and one month after transplanting). The results showed that the type and time of planting of cover crops had a significant effect on the weed density and weed dry weight and tomato yield. Planting cover crops decreased weed density up to 35% and the weed dry weight of 67% compared with control. Also، cover crops reduced density of Convolvulus arvensis، Portulaca oleraceae and Echinochloa crus-galli as 8، 4 and 6 times compared with control. Tomato yield increased 60/42% with cover crop. The results showed that cover crops are appropriate tool for weed management in sustainable agricultural systems and can be used in integrated weed management.

Choosing varieties with high weed competitiveness is important in integrated weed management (IWM). This experiment was carried out in order to study weed tolerance and competition indices of 18 wheat genotypes under natural weed interference or without interference at the research field of agricultural faculty, University of Mohaghegh Ardabili, during 2010-2011 growing season. Significant differences were found in the indexes of wheat genotypes. Stress tolerance index of genotypes was between 110.3 to 915.0 kg ha-1. More tolerance indices such as Mean Productivity, Harmonic index and Weed Interference Tolerance Index were higher for N-80-19 and Alvand genotypes and lower for Dabira and Toos than others. Among the tolerance indices, weed interference tolerance index (WITI) and ability of weed competition (AWC) were more efficient to classify wheat genotypes to weed tolerance. Alvand and C-85-9 genotypes had the highest competitive index (CI). This finding can be used for non-chemical weed management programs.