جستجوی مقالات مرتبط با کلیدواژه « وزن خشک » در نشریات گروه « اکولوژی »

 Drought is one of the most important environmental stressors that adversely affects agricultural products, especially in arid and semi-arid regions. Using Trichoderma fungus along with biopolymers such as chitosan is one of the ways to reduce drought stress. Trichoderma fungus as plant growth-promoting fungus is the most common fungal and soil-modifying species that are able to directly with plant roots in the rhizosphere and improve growth as well as biological control of living stresses such as pathogenic fungi and non-living stresses such as drought, salinity and heavy metals. On the other hand, one of the effective ways to protect the plant in conditions of low irrigation is the use of anti-transpirants, including the biostimulant of chitosan, which markedly limits transpiration from the plant surface. The anti-transipirants action of chitosan can be attributed to the involvement of chitosan in the abscisic acid pathways, which closes the stomata and thus reduces transpiration. Chitosan is readily soluble in water and organic acids. Therefore, it can be used in various methods such as mixing with soil, foliar spraying and impregnation with seeds in agriculture.

 This research was conducted in a split factorial arrangement based on randomized complete block design. The main plot factor was irrigation interval in three levels (two days as normal irrigation and three and four days as deficit irrigation conditions) and sub-plots were inoculated with T. longibrachiatum at two levels (inoculation and uninoculated control) and chitosan at three levels (0, 0.2 and 0.4 g/L). Each experimental plot consisted of three planting lines two and a half meters long and one meter wide .T. longibrachiatum was obtained from Tabarestan Agricultural Genetics and Biotechnology Research Institute. The first irrigation was done simultaneously with planting basil. Up to one month after sowing the seeds (six to eight leaf stage of plants), the plots were irrigated evenly with tubes and from this stage onwards, irrigation treatments were applied. Pesticides and herbicides were not used during the experiment and weed control was done manually. Chitosan was prepared from Sarina Teb store and prepared in three levels of zero, 0.2 and 0.4 g/l and sprayed in three stages: vegetative, before flowering and 50% flowering.

 The results showed that with increasing the irrigation period from two to four days, the morphological traits of basil, such as root length and stem length, leaf dry weight, root, stem and dry matter yield decreased. Also, physiological traits of basil such as carotenoids and chlorophyll meter increased while chlorophyll a, b and total chlorophyll decreased. Application of 0.2 g/L of chitosan inoculated plants increased chlorophyll b content by 68%. The highest percentage and yield of essential oil in both normal and irrigation deficit conditions were obtained when plants inoculated with Trichoderma and foliary sprayed by chitosan. The highest percentage and yield of essential oil were observed with an average of 0.88 and 42.87% in normal irrigation conditions, application of Trichoderma and zero level of chitosan, respectively. According to the results, increasing the irrigation cycle along with chitosan application and fungal inoculation increased the percentage and yield of essential oil. However, by increasing the irrigation cycle, chitosan alone decreased the percentage and yield of essential oil and only in the three-day irrigation cycle, it increased the percentage of essential oil compared to the control.

 Overall, the findings showed the positive effect of concomitant use of Trichoderma fungus and chitosan on improving the growth of sweet basil and increasing drought resistance.

This study was performed to investigate the response of three rice cultivars in competition with barnyard grass densities and to select a suitable cultivar with the ability to more competitive. The experiment was conducted as a factorial arrangement based on randomized complete block design (RCBD) with three replications in Babol, Iran, in 2018. Factors included rice cultivar (Tarom Hashemi, Fajr, and Neda) and barnyard grass density (0, 10, 20, 30, and 40 plants m-2). The results showed that the Biomass of barnyard grass and rice yield were affected only by the simple effects of rice cultivar and barnyard grass density. The Biomass of barnyard grass in Fajr and Neda cultivars compared to the Tarom Hashemi cultivar decreased by 28 and 35%, respectively. The amount of barnyard grass biomass increased by 18, 49 and 67% at densities of 20, 30 and 40 plants compared to the density of 10 plants m-2 of barnyard grass. The highest and lowest rice grain yield was obtained in Neda (779 g m-2) and Tarom Hashemi (297 g m-2) cultivars, respectively. The amount of increase in rice grain yield in Fajr and Neda varieties compared to Tarom Hashemi cultivar was 133 and 162%, respectively. Also, grain yield decreased up to 2, 7, 12, and 24%, respectively, at 10, 20, 30, and 40 barnyard grass m-2 with 493 g m-2.

To determine the critical period of weed control in transplanted tomato in Kermanshah, in order to reduce the weed control costs.

a field experiment was conducted in a randomized complete block design with three replications. Treatments were divided in to two series. The first one consisted of six weed interference until 0, 15, 30, 45, 60 and 75 days after transplanting and then weeds were removed until the end of the growth period, and the second one consisted of six weed control until 0, 15, 30, 45, 60 and 75 days after transplanting and then permit to weeds to complete to crop until the end of growth season.

The results showed that full weed interference reduced total dry matter, maximum leaf area index and fresh fruit yield of tomato by 67.2, 36.5 and 83.5 percentages, respectively. The critical period for weed control was determined using logistic and gompertz functions. Critical period of weed control based on 5 and 10 percent acceptable yield loss was determined from 14 to 89 and from 19 to 78 days after transplanting, respectively, that was equal to from 103 to 1189 and from 144 to 1003 growth degree days after transplanting, respectively.

Generally due to the low planting density and the non-complete canopy closure, it is necessary to weed control be started from two to three weeks after tomato transplanting and continued for five to six weeks.

The aim of this study was to compare the effect of fertilizer types on growth characteristics, essential oil content and element uptake of two savory species and to identify savory species compatible with regional conditions.

field experiment as a factorial study based on a randomized complete block design with three replications in the north of Lorestan, Iran in 2017-2019. The first factor was assigned to three mycorrhizal fungi (Funneliformis mosseae, Rhizophagus irregularis, and G. fasciculatum), phosphate biofertilizer (Baravar-2), fish manure (800 kg ha-1), cattle manure (20 t ha-1), vermicompost (5 t ha-1), and control (no fertilization) and the second factor was assigned to two savory species including Satureja khuzestanica and S. rechingeri.

The results of the combined analysis of variance for the second and third years showed that the simple effects of fertilizers and species were significant on all recorded traits. The highest plant height (39.16 cm), number of lateral branches (29.58), leaf area index (0.79), plant dry weight (4.15 t ha-1), essential oil content (5.53%), essential oil yield (22.92 kg ha-1), leaf N, P, K and Fe contents (3.78, 1.91, 4.18, and 466.25 mg kg-1), were obtained from the foliar application of vermicompost.

Except for essential oil content and yield. According to the results, the foliar application of vermicompost at a rate of 5 t ha-1 can contribute to the sustainable production of both savory species and improving their growth and essential oil yield.

In order to study of morpho-physiological attributes in corn under influence of weed, an experiment based on randomized complete block design with four replications was performed at the Moghan climate during 2020 growing season.

The experiment was included 14 treatments; seven weed-infested and seven weed free treatments were applied at regular intervals as 0, 10, 20, 30, 40, 50 and 60 days after corn emergence in which weeds were allowed to grow until harvest, and weeds were removed, respectively. Total dry weight of weeds, plant height, length of ear, total biomass, leaf area index (LAI), crop growth rate (CGR), relative growth rate (RGR), net assimilation rate (NAR), leaf area duration (LAD), and yield of corn were measured.

The results showed that all measured traits were affected by weed interference duration and weed control period. Weed interference duration increased total dry weight of weeds and weed-free duration reduced total dry weight of weeds. Also, increase in weeds interference duration significantly reduced, plant height, length of ear, total biomass, LAI CGR, RGR, NAR, LAD, and grain yield of corn. On the other hand, total biomass, LAI, CGR, RGR, NAR, LAD, and grain of corn increased by rising weed-free duration.

The weed interference duration had a significant effect on the final yield of corn and with interference of the all weed season, grain yield of corn decreased. Weed interference duration increased total dry weight of weeds and weed-free duration reduced total dry weight of weeds.

This research was conducted in order to study the possibility of increasing yield, yield components and chlorophyll content of artichoke (Cynara scolymus L.) by mycorrhizal inoculation and living and non-living mulches.

Experiment was conducted during 2017 and 2018 at the research farm of the University of Zanjan. A three-replicate split plot design based on randomized complete block design (RCBD) was conducted. Two levels of inoculation (inoculation with Rhizophagus irregularis and non- inoculation) were considered as main plots and a variety of living mulches (Trifolium alexandrinum, Lathyrus sativus), non-living mulches (plastic mulch (silver external side and black internal one), wheat straw) and Complete handweeding, one-hand weeding and no-weeding were considered as sub plots.

The highest of fresh weight (336.01 ton/ha) and dry weight (34.21 ton/ha) were recorded in plastic mulch treatment under mycorrhizal inoculation conditions. Mycorrhizal colonization increased plant height, Leaf Area Index (LAI), chlorophyll a and chlorophyll (a+b) by 2.1%, 9.1%, 6.6% and 5.2%, respectively. Highest plant height (167 cm), leaf area index (122.18), number of leaves per plant (43), chlorophyll a, b and )a+b( (0.697, 0.388 and 1.085 mg g -1 FW) were obtained in plastic mulch treatment.

Generally, mycorrhizal inoculation and the use of living and non-living mulches can be suggested as a solution to increase the yield of artichoke.

The aim of this study was investigated the effect of weed interference on some growth indices and grain yield of corn (Zea mays L.), an experiment was carried out in a randomized complete block design with four replications during 2019 growing seasons at the Moghan region.

The experiment was included fourteen treatments; seven weed-infested and seven weed free treatments were applied at regular intervals (0, 10, 20, 30, 40, 50 and 60 days) after corn emergence in which weeds were allowed to grow until harvest and weeds were removed, respectively. Total dry weight of weeds, total dry matter (TDM), leaf area index (LAI), crop growth rate (CGR) and yield of corn were measured.

The results showed that all measured traits were affected by weed interference duration and weedcontrol period. Weed interference duration increased total dry weight of weeds and weed-free duration reduced total dry weight of weeds. Also, increase in weeds interference duration significantly reduced TDM, LAI, and CGR and grain yield of corn. On the other hand, TDM, LAI CGR and grain of corn increased by rising weed-free duration.

Considering of 10% yield loss, the critical period of weed control was 3 and 52 days after corn emergence, respectively. The weed interference duration had a significant effect on grain yield of corn and weed interference at the whole season. Weed interference reduced grain yield of corn.

Salt stress is one of the main environmental factors restricting horticultural crop production. Exogenous salicylic acid (SA) can alleviate salt stress in plants. The objective of this study was to improving growth and physiological chracteristics in salt stressed Lantana camara Linn. by application of exogenous salicylic acid. 

In a factorial experiment and completely randomized design (CRD), three levels of SA (0, 0.5 and 1 mM) and five levels of salinity (0.5, 3, 5, 7 and 9 dS.m-1) with three replications per treatments were applied. 

The results showed that by increasing salinity levels, growth characteristics, chlorophyll a and b and potassium concentration significantly decreased, while the number of necrotic leaves, Sodium and the ratio of sodium to potassium increased. At high salinity levels, application of salicylic acid improved the growth characteristics of the plant such as height, final diameter of the main branch and shoot dry weight and relative water content of the leaves and reduced sodium content in compared to the control. Maximum number of plant branches (4.66), final diameter of main branch (6.11 mm), final diameter of cuttings (9.92 mm), number of leaves (28.66) and fresh and dry weight of shoots (14.80 and 7.46 g) were obtained in plants treated by 0.5 mM salicylic acid and in salinity of 0.5 dS. m-1. 

The use of 0.5 mM salicylic acid at high salinity levels significantly improved the growth and flowering characteristics of the lantana plant. Therefore, the use of 0.5 mM salicylic acid can significantly reduce the damage caused by the negative effects of salinity stress.

Nowadays, with increasing tendency to monoculture of medicinal and horticultural plants, the range of genetic diversity in agricultural ecosystems has decreased. Conventional agricultural activities with simplification of ecosystems makes ecosystems more unstable and more sensitive to environmental hazards. Therefore, the promotion of biodiversity in these systems is effective for their recovery and sustainability. The purpose of designing sustainable agricultural ecosystems is to integrate ecosystem components in such a way that maintains and strengthens the biodiversity, productivity and self-regulatory capacity of the agricultural ecosystem. Functional diversity is achieved by using different functional species with different roles in agroecosystems. The role of weeds in increasing diversity in agroecosystems is very important because they are closely associated with many of the crops and genetic exchange between them. The presence of weeds in the crop ecosystem reduces genetic vulnerability through strategy of environmental diversification as well as the occurrence of resistance mechanisms.

In order to investigate the effect of some medicinal plants on weed density and diversity, an experiment was conducted based on a complete randomized block design with three replications at the agricultural research station, Ferdowsi University of Mashhad, Iran, during 2012 and 2013. Treatments included 13 medicinal species (Origanum vulgar, Hyssopus officinalis, Tanacetum parthenium, Echinacea purpurea, Ruta graveolens, Althea officinalis, Hypericum perforatum,Trigonella foenum-graecum, Oenothera erythrosepala, Malva sylvestris, Securigera securidaca, Achillea millefolium and Digitalis purpurea).After tillage, land preparation and leveling, each plant was cultivated in strips of 10*3 meters. After complete establishment of the plants in order to achieve the desired density, thinning operations were performed on each strip. The distance between the test strips was 0.5 m. Seeds of all studied plants were sown in April 2012. In both cropping years to study the diversity of weeds, a part of each plot with dimensions of 0.5 m was separated and remained without weeding and in all plots of medicinal plants, density and dry weight of weeds was determined at two stages of vegetative and reproductive growth of medicinal plants. Also, physiological and morphological characteristics such as height, leaf area and dry weight of plants in each plot were measured. In order to calculate the diversity of weeds, the type of weed species and their density were determined in quadrates with dimensions of 40*40 cm. Then the weeds in each plot were harvested separately and transferred to the laboratory and were placed at 70 °C for 48 hours to determine the dry weight. Shannon, Margalf and Simpson diversity indices were used to quantify weed diversity.

The results indicated that the effect of medicinal species on total weed density and weight was significant. The highest and the lowest dry weed weight was obtained in Digitalis purpurea (39.4 g.m-2) and Tanacetum parthenium (3.2 g.m-2), respectively. The highest total weed density was observed in Malva sylvestris, Securigera securidaca, Digitalis purpurea and Hyssopus officinalis. Malva sylvestris had the highest weed richness (four species) that it was not significantly different with Securigera securidaca and Achillea millefolium. During different sampling years and stages, the highest Shannon index was obtained in Achillea millefolium (0.48) that it was not different with Malva sylvestris, Securigera securidaca, Hyssopus officinalis, Hypericum perforatum, Digitalis purpurea and Echinacea purpurea, significantly. Also, the highest margalof index was obtained in Malva sylvestris, Achillea millefolium and Hyssopus officinalis (4.05, 4.03 and 3.33, respectively). Studied medicinal species for weed diversity divided to 5 groups in 75% similarity level.Despite the importance of biodiversity for the stability of natural ecosystems and agroecosystems, increasing species and functional diversity, simultaneously, is necessary to improve agroecosystem’s function. Keep the limited weed population in field increase functional diversity of agricultural landscapes but, this profit must reach equilibrium with the risk of decreasing crop production due to competition with weeds.

In order to investigate the weed interference duration on some growth parameters and yield of potato (Solanum tuberosum L.), an experiment was carried out in a randomized complete block design with four replications during 2017 in Ardabil region.  

The experiment was included twelve treatments; six weed-infested and six weed-free treatments were applied at regular intervals (0, 10, 20, 30, 40 and 50 days) after potato emergence in which weeds were allowed to grow until harvest and weeds were removed, respectively. Total dry matter (TDM),leaf area index (LAI), leaf area index duration, number of branches, mean tuber weight and tuberyield of potato (Solanum tuberosum L.) were measured.  

The results showed that all measured traits were affected by weed interference duration and weed control period. Weed interference duration increased total dry weight of weeds and weed-free duration reduced total dry weight of weeds and mean tuber weight. Also, increase in weeds interference duration significantly reduced total dry matter, leaf area index, leaf area index duration, number of branches, mean tuber weight and tuber yield of potato. On the other hand, total dry matter, leaf area index, leaf area index duration, number of branches and tuber yield of potato increased by increased weed-free duration.  

Considering of 10% yield loss, the critical period of weed control was 18 and 57 days after potato emergence, respectively. The weed interference duration had a significant effect on the final yield of potato tubers and the interference duration through whole season caused 59.7% yield loss as compared to the control.

The purpose of this experiment, evaluating hetrotoxicity potential of aqueous extract of various organs of medicinal plant of Malva sylvestrisa L. on morphological, physiological characteristics and biochemical of total phenols of Cichorium intybus L. and Echinochloa crus-galli L. under hydroponic culture as two separated experiments in completely randomized design in botanical laboratory of Gonbad Kavous University in 2017. For experiment, aerial parts of M. sylvestrisa were collected in flowering stage from Ramian fields and then various organs such as stem, leaf and flower was divided and finally were powdered. At the end, 5% suspension from each organ and a mixture of organs were supplied and added to hydroponic culture containing 7 days old seedlings of C. intybus and E. crus-galli. The results showed different responses C. intybus and E. crus-galli to aqueous extract of various organs of M. sylvestrisa. So that studied treatments had a different additive effect on morphological characteristics, photosynthesis pigments and total phenols.  The highest additive effect on root length, plant height, leaf area, dry weight per plant, content of chlorophyll b and total chlorophyll were obtained for extract of flower organ. In case of chlorophyll a, carotenoids and total phenols content, the most of this amount were found for extract of leaf, leaf and mixture of organs respectively. Although had no significant difference with some other treatments. In case of C. intybus, aqueous extract of M. sylvestrisa leaf only had a significant inhibition effect on leaf area, dry weight per plant, content of chlorophyll a, total

Because Iran is in an arid and semi-arid area¡ lack of water is considered as a serious crisis in the country; so using agronomic techniques such as irrigation¡ use of low quality water resources (brackish and saline) and the use of dry-friendly herbs and halophytic herbs is of great importance in agricultural production. Deficit irrigation is an optimal solution for agricultural production whereby the removal of excess irrigation and reduction in water use at every turn has no negative effect on net profit but increases water use efficiency (Sohrabi et al.¡ 2006). Currently¡ an alternative crop resistant to drought compared with conventional forage plants has been kochia whose rapid deployment in the soil¡ in addition to creating a short lived protective cover¡ can be used as an alternative forage especially in areas that are confronted with lack of forage production (Jami Ahmadi et al.¡ 2004). Kochia is a drought resistant annual plant and can be a valuable source of forage in ecosystems under drought conditions. Its rapid growth of kochia and drought resistance shows that this plant has a high potential for designation as an important forage crop in arid and semi-arid areas (Jami Ahmadi and Kafi¡ 2007).
In order to investigate the effect of plant density¡ height of harvest and consumption of nitrogen fertilizer on yield of dry matter and some agronomic traits of Kochia¡ an experiment was conducted in a factorial arrangement based on a randomized complete block design with three replications in spring and summer of 2011 in a research field at Neishabour city. The treatments consisted of plant density at three levels (20¡ 30 and 40 plants in 1 m2)¡ height of harvest at two levels (10 and 20 cm from level of soil) and nitrogen fertilizer at two levels (consumption of 150 kg ha-1 Urea after the first cutting and non consumption nitrogen fertilizer).
The results indicated that the effect of plant density was not significant on the leaf dry weight and the ratio of the leaf dry weight to stem in the first and second cutting¡ while its effect on the yield¡ stem dry weight and the leaf area index in the first and second cuttings was significant; also¡ by increasing the plant density¡ these traits increased significantly. The effect of the height of harvest on studied traits¡ also the consumption of Urea after the first cutting on the yield of dry matter¡ stem dry weight and the leaf area index in the second cutting was not significant¡ but its effect on leaf dry weight and the ratio of the leaf dry weight to stem in the second cutting was significant.
Generally¡ it seems that the plant density of 30 plants per m2¡ the height of harvest of 20 cm from level of soil and the consumption nitrogen fertilizer after harvest of the first cutting are effective factors to obtain desirable yield and quality in produced forage of Kochia.

Drought stress reduces plant growth by affecting various physiological and biochemical processes, such as photosynthesis, respiration, translocation, ion uptake, carbohydrates, nutrient metabolism and growth promoters.
Garlic (Allium sativum L.) is an annual bulb crop that has been cultivated since ancient times and was used as a spice and condiment for many centuries. Garlic is an important plant because of its pharmaceutical properties. The optimum yield of this bulb crop depends on well-managed irrigation, fertilization and cultivation practices. In the final and middle stages of growth, garlic is sensitive to water stress and low irrigation is unsuitable in these stages.
This experiment was established to study the influence of drought stress and planting density on yield and its components and the non-enzymatic anti-oxidant content of two different garlic ecotypes.
This study was conducted in 2011-2012 in a farmland at the south east of Semnan city. The experimental layout was a split-plot factorial with a randomized complete block design with three replications.
The treatments were comprised of three factors: irrigation rates (60%, 80% and 100% of estimated crop evapotranspiration (ETC)) as the main plot and the factorial combination of three levels of planting density (30, 40 and 50 plants.m-2) and two ecotypes (Tabas and Toroud) as the sub-plots.
To estimate the crop water requirement, different meteorological parameters were collected from Semnan weather station and were used based on FAO-56 water irrigation calculation instructions.
After harvesting, ten garlic plants were sampled randomly in each plot and bulb yield components were measured. To calculate the leaves anti-oxidant content, DPPH method was used. The statistical significances of mean values were assessed by analysis of variance and LSD tests at p≤0.05. All calculations were performed using SAS and Mstat-C softwares.
Drought stress decreased bulb yield and dry matter percentage significantly.
Planting density had significant effects on bulb yield and the yield of planting density of 50 plants m-2 were significantly higher than two other densities.
The interaction of drought stress and ecotype factors affected the dry matter percentage.
Drought stress decreased fresh and dry weight, length of bulbs and the bulb diameter significantly.
Drought stress decreased fresh and dry weight, diameter, length and number of cloves significantly as well.
Drought stress is an important limiting factor at the initial phase of plant growth and establishment. It affects both elongation and expansion growth (Shao et al., 2008).
Fresh and dry weight and length of cloves were significantly higher in Toroud ecotype. In contrast, the number of cloves in the bulb was significantly higher in Tabas.
Studying the correlation coefficients showed that the bulb yield per unit area was significantly and positively correlated with diameter, weight and length of cloves and bulbs and also the dry matter percentage at P≤0.001. The maximum correlation belonged to yield at the unit area and weight of the bulb (r=0.72). In other words, any bulb-weight-increasing factor did have the highest effect on increasing the yield per unit area as well.
Drought stress, increased leaf non-enzymatic anti-oxidant significantly.
Anti-oxidants plays significant roles in ROS scavenging and influences cellular ROS balance. Activation of antioxidant system helps the plants to tolerate stress form induced damage.
The effect of ecotype was significant on anti-oxidant content and the value were significantly higher in Toroud ecotype. Toroud ecotype showed resisting reactions against higher levels of drought stress by increasing the non-enzymatic anti-oxidant content and created tolerating mechanisms versus stress.
Drought stress reduced yield and yield parameters and increased non-enzymatic anti-oxidant content of garlic. The increment of anti-oxidant content showed the tolerance of garlic to drought stress. The maximum bulb yield was obtained at the highest planting density.

In order to investigate the effects of soil texture and density on corm and flower yield of Saffron (Crocus sativus L.) an experiment was conducted as a factorial layout based on complete randomized block design with three replications at the Faculty of Agriculture، Ferdowsi University of Mashhad during two growing seasons of 2009-2010 and 2010-2011. Treatment included 6 soil textures (clay loam، silty loam، loam، sandy loam، loamy sand and silt) with 2 plant densities (100 and 150 corms. m-2). Results indicated that the corm number and dry weight were affected by soil texture، significantly (p≤0. 01). The highest number and dry weight of corms were observed in loamy sand texture. Loamy sand، sandy loam and silty texture had the maximum flower number. The highest stigma yield was obtained in silty texture (1. 22 g. m-2)، but with no significant difference with sandy loam. The lowest stigma yield was obtained in clay loam، loam and silty loam textures. A negative significant correlation was observed between clay percentage of soil and corm number and dry weight، flower number and flower and stigma yield. In two growing seasons، plant density didn’t have significant effect on flower number، flower and stigma dry weight.

This study was performed to evaluate the efficacy of some previous or recently registered herbicides for chemical weed control on forage sorghum in Mashhad (Iran) during 2010. The experiment was conducted in RCBD with four replications. Treatments were consisted of Mesotrion+S-Metolacholor+Terbuthlazine (Lumax 3 and 4 l ha-1 post and pre-emergence), Cinosulfuron (Setoff 250 and 375 g ha-1, pre-emergence), Oxadiagyl (Topstar 3 and 4 l ha-1, pre-emergence), Trifluralin (Treflan 1 l ha-1), Trifluralin+Atrazin (2 l ha-1+1.5 Kg ha-1), 2,4-D+Banvel+Atrazine (Dialant 1 l ha-1+Atrazine 1kg ha-1), along with weed free and weed infested controls. The results showed that Lumax, Treflan, Treflan+Atrazine and Atrazine+Dialan with 85-95 percent reduction were the most successful in weed suppression while Setoff and Topstar with35% reduction were relatively unsuccessful. Also, the mention treatments were the most efficient to saving forage yield of sorghum while it was decreased in post emergence application of Setoff 375 gr ha-1 and Lumax 4 l ha-1. Application of Lumax caused a temporary injury symptoms early season in sorghum.The most important weeds were Amaranthus retroflexus, Chenopodium album, Portulaca oleracea, Convolvulus arvensis and Solanum nigrum.

In order to study the weed populations in wheat, under different crop rotations an experiment was carried out at Agricultural Research Station of Jolgeh Rokh, Iran. During growing season this project was done in five years, based on Randomized Complete Bloch Design with three replications, on Crop rotations included: wheat monoculture for the whole period (WWWWW), wheat- wheat- wheat- canola- wheat (WWWCW), wheat- sugar beet- wheat-sugar beet- wheat (WSWSW), wheat- potato- wheat- potato- wheat (WPWPW), wheat- potato- wheat- canola- wheat (WPWCW), wheat- sugar beet- wheat- potato- wheat (WSWPW), wheat- maize- wheat- potato- wheat (WMWPW), wheat- maize- wheat- sugar beet- wheat (WMWSW). Data analysis was done in fifth year. Weed sampling was done at four growth stages of wheat, including tillering, shooting, heading and soft dough stage of grains. Density, dry and fresh weight of each weed species per unit area, besides wheat grain yield were determined. All analysis of variances for traits related to weed were statistically significant (p≤0.01). The highest weed biomass was obtained in heading stage of wheat, and the greatest weed dry matter in all four growth stages was achieved in WWWWW rotation and the least one in WMWSW rotation. The highest weed density in different growth stages was achieved in rotations 7, 3, and 6. Wheat grain yield in all crop rotation treatments had a significant increase compared to monoculture. It seems that, yield reduction of wheat monoculture is related to weed density, its population and higher weed biomass in this treatment.

In order to Investigation some soil characteristics and filed age effects on flower and corm yield of saffron, an experiment was conducted as factorial based on complete randomized design with five replications in two regions of Neyshabur during growing season 2009-2010. Treatments were included different filed ages (2, 4 and 6 years) and two geographical regions (Eshagh abad and Soltan abad). Different characteristics such as fresh and dry weight of corm, corm number, number of corm sprout and flower and stigma yield of saffron were determined. Soil physical and chemical characteristics such as soil texture, pH and EC were measured. Results showed that effect of filed age on all characteristics was statistically significant. Flower and stigma yield were affected by region and filed age and region interaction significantly. Positive significant regression was shown between field age and parameters such as fresh and dry weight of corm, number of corm sprout and corm number. With increasing field age to 4 years, saffron yield increased and then decreased. Results showed that changes in stigma and flower yield was significantly related to physical and chemical soil criteria (soil texture, EC, pH) characteristics. Significant negative correlations were observed between clay percentage of soil with corm number, corm dry weight, flower and stigma in.

In order to evaluation of freezing tolerance in viola (Viola gracilis L.) under controlled conditions, a trial carried out in completely randomized design with six replications at college of agriculture, Ferdowsi University of Mashhad, Iran, during 2008-2009. Seeds were planted in bed and seedlings were acclimated during natural conditions in autumn and at 5-7 leaves stage plants transferred to the thermo-gradient freezer to apply 12 freezing temperatures (0, -2, -4, -6, -8, -10, -12, -14, -16, -18, -20 and -22°C). Leaf cell’s membrane integrity was measured through electrolyte leakage (EL) after the freezing and survival percentage and plant recovery (e.g. plant height and dry weight, number of branches and flowers and flower’s diameter) were determined after three weeks of plant re-growth in the cold frame. As temperature decreased, EL% increased significantly and reached to the maximum in -20oC. Survival percentage did not affected by temperatures between 0oC to -18oC but all plants killed in -22oC. LT50el and LT50su were -20.0°C and -19.4°C, respectively. Decreasing the temperature lower than -18 oC reduced plant dry matter severely and RDMT50 was -19.2°C.