یحیی امام

To evaluate the effect of sowing density (300, 400, 500, 600 and 700 plants/m2) on the growth of wheat under deficit irrigation (100, 75 and 50% crop water requirement, I100, I75 and I50, respectively), an experiment was carried out during 2009 and 2010. In both years, deficit irrigation resulted in a considerable reduction in yield, yield components, leaf area index (LAI) and leaf water potential (Ψw). In contrast, the canopy temperature (CT) significantly increased under deficit irrigation. Furthermore, increasing of sowing density from 300 to 600 plants/m2 resulted in a significant increase in grain yield under I100 and I75. Maximum grain yield as 525.9 and 564.2 g/m2 was obtained in the first and the second years, respectively in sowing density of 600 plants/m2 and I100. This sowing density was also the proper density in I75 and I50 irrigation regimes. Increasing of sowing density reduced 1000-grain weight and grain number per spike and increased spike number per square meter. In the first year, increasing of sowing density from 300 to 600 plants/m2 caused a significant increase in LAI in all irrigation regimes, while in the second year, maximum LAI was observed in 700 plants/m2 sowing density. It was found that increasing of sowing density significantly reduced the Ψw and the CT in both well-watered and deficit irrigation. In conclusion, the results suggest that 600 plants/m2 would be the optimal sowing density under different water conditions. Alleviation of water stress by the increasing sowing density was found to be associated partly with enhanced LAI and reduced CT.

This research was carried out to study the grain yield, yield components and NDVI (normalized difference vegetation index) responses of four wheat cultivars to growth retardant cycocel under terminal drought stress conditions. The experiment was laid out as a split split plot with three replicates at the experimental farm of the School of Agriculture, Shiraz University, Shiraz, Iran in 2016-2017 and 2017-2018 growing seasons. The treatments consisted of two levels of water stress (full irrigation and irrigation cut off at the beginning of flowering), exogenous cycocel in two levels (4 g ha-1 and 0) and four wheat cultivars (Sirvan, Baharan, Varedati and Ofogh). Water stress reduced the measured traits including, grain number per ear (19%), 1000-grain weight (14%), biological yield (22%), grain yield (29%), and NDVI (17%). Exogenously-applied cycocel compensated for some of such reductions including, number of spikes per square meter (18%), grain number per ear (29%), 1000-grain weight (6%), biological yield (11%), grain yield (17%), and NDVI (5%). Ofogh and Sirvan cultivars showed a better response for most of the measured traits to water stress conditions when cyclocel was used. Regarding the ameliorating role of cycocel in reducing negative impacts of terminal water stress, application of this growth regulator could be recommended for similar conditions.

Intensified salinization of water and soil resources has promoted interest for research and approaches of improving crop yield under saline conditions. Reviewing the literature showed that the records on understanding of different aspects of salt stress and enhanced salinity tolerance in the world goes back to more than a century. Different approaches have been suggested to increase crop yield under saline conditions, among which one is using plant growth regulators (PGRs). Application of PGRs has begun since 1930s and their global annual sales are about US$ 1.2 billion. Nearly 40 active ingredients og PGRs are now in use, applied either as a single or combined treatments, among which the most important are auxins, cytokinins, gibberellins, ethylene, abscisic acid, brassinosteroids, salicylic acid, chlormequat chloride, paclobutrazol, jasmonic acid, ascorbic acid, triacontanol, strigolactones, nitric oxide, polyamines and plant peptide hormones. There have been large body of reports showing quantitative and quality improvement of crops as well as salinity tolerance as the consequences of PGRs application.However, most of these studies were conducted under controlled conditions (i.e. out of field conditions), as one season experiments, and this makes the results unreliable. In this paper, with having in mind the applicability for the field conditions, crop yield improvement as the result of using PGRs has been reviewed.

The relationship between canopy temperature and soil moisture is particularly important because of using canopy temperature as an indicator of crop water stress. A field experiment was conducted to calculate crop water stress index (CWSI) of two canola cultivars including RGS and Sarigol at College of Agriculture and Natural Resources of Darab, Shiraz University, Iran during 2013-2014 growing season. Irrigation regimes consisted of well watered [Irrigation equal to 100% field capacity (FC)], light drought (75% FC), moderate drought (50% FC), and severe drought (25% FC) stresses which were arranged in a randomized complete block design (RCBD) with three replications. In RGS and Sarigol, CWSI values showed an increasing trend from March (0.066 and 0.093 in well watered) to June (0.711 and 0.821 in severe drought) respectively, as a result of higher vapor pressure deficit (VPD) and increase in canopy-air temperature differences (Tc-Ta).In both cultivars, when the air temperature increased from March to June, Tc-Ta increased. The highest monthly average value of CWSI for all treatments was obtained in June. By increasing the drought stress, the color grading score decreased from 6 to 2 sharply in May and June. An acceptable color quality (6 -5) was sustained in May, under light drought condition. Also, a negative relationship was observed between CWSI with color quality (R2=0.94**) and grain yield (R2=0.97**). It could be concluded that in semi-arid areas, light drought is the best option for canola production while mean seasonal CWSI being ranged about 0.198 to 0.294 without any loss in visual color quality of canola.

Wheat is one of the most crops and Wheat bread is the main component of Iranian nutrition patterns. A two field experiments (2013-2014) was conducted as a randomized complete block design with 3 replications at two locations (Ilam and Bushehr) to study quantitative and qualitative traits of bread wheat cultivar Kohdasht. Treatments were two levels of Cycocel (CCC) (0, 2.5 g/L), application of Zinc sulfate (Zn) at the three rates (0, 25 and 50 kg/ha) and Nitroxin, as bio-fertilizer, (seed inoculated and non-inoculated). Results showed that CCC application in both locations had significant effect on yield and its components. CCC spraying in compared to control treatment increased spike number per meter square, grain number per spike and grain yield by about 14.6, 19.6 and 28.5 percentages, respectively. The highest grain protein content (13.8%), wet Gluten (36.1%), Gliadin (53.6%) and Glutenin (31.8%) were obtained from plants treated with CCC spraying, at 50 kg/ha of zinc sulfate and Nitroxin-inoculated seeds treatment. CCC spraying at the concentration level of 2.5 g/L, application of 50 kg of Zn and inoculation of seeds with Nitroxin resulted to the highest grain yield (1710 kg/ha) and the highest amounts of lysine, Threonine and Methionine were obtained by about 510, 545 and 772 milligram per 100 gram of protein sample, respectively. Overall, it can be concluded that CCC at the concentration level of 2.5 g/L, 50 kg/ha of Zn and seed inoculation with Nitroxin might be effective in improvement of grain yield in wheat under dry land farming.

In a 2-yrs field study, growth pattern and grain yield of wheat as affected by different nitrogen levels under varied irrigation conditions were evaluated in Shiraz University during 2013-15 growing seasons. The results showed that in both years at anthesis and ripening stages in all irrigation treatments, except rainfed, 300 kg N ha-1 had the highest plant height, while the highest plant height in rainfed for all sampling stages was achieved in 225 kg N ha-1 treatment. In all irrigation treatments, except rainfed, the plots receiving more N had the higher leaf area index for all sampling stages. As water deficit was applied and intensified, the less N fertilizer was needed for achieving the higher dry matter production; so that the highest final dry matter in normal irrigation, irrigation cutting at grain filling and spike emergence and rainfed conditions for both years were obtained from 225, 225, 150 and 75 kg N ha-1, by 1195.1, 1115.2, 931.1 kg ha-1 and 517.6 at the first and by 1015.8, 957.9, 791.5 kg ha-1 and 389.9 kg N ha-1 at the second year, respectively. In both years, the highest SPAD index was observed from rainfed conditions and 375 kg N ha-1, and the highest grain yield was observed in normal irrigation with 150 kg N ha-1 by 568.1 and 515.5 kg ha-1 at the first and second years, respectively.

To evaluate the effects of different planting dates on some agronomic, physiological characteristics and yield of grain sorghum, an experiment was designed and carried out in Agricultural and Natural Resources and Education Center, Yazd province, Iran, in a split plot experiment based on Randomized Complete Block Design (RCBD) with 4 replications in 2012 & 2013 growing seasons. Five different sowing date (19 Apr, 5 May, 20 May, 5 Jun and 20 Jun) and three genotypes (Payam, Sepideh and Kimia) were allocated in main plots and subplots, respectively. Results showed that the highest amount of all measured traits were obtained from Sepideh genotype in first and second sowing dates. The highest grain yield (8424 kg/ha) was harvested from Sepideh genotype at sowing date of 19 Apr. Based on the results of the present investigation, it appeared that in similar agro-climatic conditions, earlier sowing in spring may result to a better harvest.

     Several factors affect the crop yield and weeds are among the most important factors reducing crop yields .There are high tendency to develop alternative methods of herbicides for natural control of weeds in organic products. One of the alternative methods to manage weeds is intercropping. Intercropping is growing two or more crops simultaneously in a piece of land during a growing season. The objectives of the present study were to examine the effect of cereal- legume intercropping on weeds growth. A field experiment was conducted in College of Agriculture of Darab, Shiraz University during 2014-2015.      In the experiment 16 treatments (five weed free monocultures of wheat (M1), barley (M2), triticale (M3), pea (M4), faba bean (M5), 5 weedy monocultures of wheat (WM1), barley (WM2), triticale (WM3), pea (WM4), faba bean (WM5), and six replacement intercropping treatments of wheat + pea (I1), wheat + faba bean (I2), barley + pea (I3), barley +  faba bean (I4), triticale + pea (I5) and triticale + faba bean (I6) without weed control) using a randomized complete block design (RCBD) with three replicates were studied. Cereals and legumes were planted simultaneously at 23 November 2014. Planting operation was conducted on both sides of the ridges.    Weed diversity was calculated by Shannon diversity index:     N=Total number of plants in each plot of one square meter, Ni= number of species i plants, S= total number of species, and H= Shannon diversity index. This index value ranging from zero to five, higher index value, greater diversity.      The results showed that the lowest density and biomass of weeds were obtained in both sole culture and intercropping of barley. For instance, the lowest weed biomass was observed in monoculture of weedy barley (1 g m-2), intercropping of barley + faba bean (12.67 g m-2) and intercropping of barley + pea (56 g m-2). The weed density at weed free sole culture of barley (30 plants m-2) was lowest that followed by barley + faba bean intercropping (81 plants per m-2). The lowest species weed diversity was obtained in barley + pea (zero) and weedy barley (0.007), respectively. The weed diversity of most intercropping treatments was similar or less than that of weedy sole culture. In General, pea or faba bean monoculture had greatest weeds density and biomass, because slow growth and late seedling establishment. However, cereals especially barley controlled weeds properly, due to greater growth rate, higher height and greater density than those of legumes. Intercropping of pea and faba bean with cereals reduced weeds growth and had lower weeds density and biomass than those of pea and faba bean weedy monocultures. In order to increase of legume yields, more density of legume should be intercropped with cereals.      In general, intercropping treatments caused a significant decrease in weeds density and biomass compared to the legumes monoculture. In this experiment barley and triticale due to good properties such as fast growth, high plant height and more shading could considerably control weeds in both monoculture and intercropping treatments, reducing significantly weeds density and biomass in itself sole culture and intercropping treatments. To reduce the weeds growth in faba bean and pea, which have a poor competitive ability with weeds, intercropping with cereals, especially barley and triticale, in the south of Fars province is recommended. However, intercropping is one of the ways to reduce weeds in the long term and its effects on weeds in the long period will be much more.     The authors would like to acknowledge the College of Agriculture and Natural Resources of Darab, Shiraz University, to finance the project and all those who helped us in this project.

Water stress is the most important abiotic stress in crop production. Silicium (Si) is the second most abundant element in the soil with beneficial effects on plant tolerance to biotic and abiotic stresses. In order to evaluate the effect of this element in increasing tolerance to water deficit in wheat, a factorial experiment was conducted based on a completely randomized design with three replications in the greenhouse of College of Agriculture, Shiraz University, Shiraz, Iran. Treatments included four wheat cultivars, Shiraz, Sirvan, Ofogh, Baharan, foliar silicon application in two-levels, zero (control), and 3 mM, and three levels of water deficit (field capacity, 40% and 60% of field capacity). The results showed that water deficit reduced spike length (31%), dry matter per plant (41%), grain yield (25%), greenness index (11%), flag leaf relative water content (24%), catalase (24%), peroxidase (70%) and superoxide dismutase activity (41%). Baharan and Sirvan cultivars were superior for greenness index and peroxidase activity. However, foliar silicon application at 3 mM concentration ameliorated the negative impacts of water deficit stress. Foliar application of silicon enhanced all the above parameters including antioxidants. For a majority of the measured characteristics, it was evident that Baharan and Sirvan, as water deficit tolerant cultivars, and Ofogh, were superior compared to Shiraz cultivar. The results showed that foliar application of silicon increased the activity of antioxidant enzymes and as a result ameliorated the negative impacts of water stress.

Although it has been well-known that salicylic acid (SA) can increase salinity tolerance in barley; there is no consensus on the best method and time of application. Thus, a factorial experiment based on completely randomized design under controlled conditions was conducted at College of Agriculture, Shiraz University in 2014. In this research, the effect of SA at five levels: control (No SA), seed priming, foliar application at complete establishment, double ridges and anthesis was examined on grain yield, sodium (Na+) and potassium (K+) concentration in shoot and root as well as antioxidant enzymes activities of barley cv. Reyhane under three salt stress levels: control, 6 and 12 dS m-1. The results showed that salt stress, depended to its severity reduced Na+ and increased K+ in shootand root and enhanced antioxidant enzymes including peroxidase, catalase, ascorbic peroxidase and superoxide dismutase, so that the most severe salt stress caused 147.4% increase in Na+ and 44.1% reduction in K+. Nevertheless, SA in priming and foliar application could compensate some of these changes and so increased grain yield. For example, seed priming and foliar application at complete establishment, double ridges and anthesis increased K+ by 72.7%, 77.3%, 22.7% and 18.2% and decreased Na+ by 37.8%, 40.5%, 27.0% and 13.5%, respectively. Overall, it can be concluded that the highest positive effect f SA was observed in seed priming and foliar application at establishment, which showed that SA might induce more salt stress tolerance if applied at early growth stages.

Two experiments were conducted under field and greenhouse conditions, to investigate the effect of herbal spraying chlormequat chloride (CCC) (0 and 2.5 g. L-1), soil incorporation of Zinc sulfate (Zn) at the three rates of 0, 25 and 50 kg ha-1, and pre-treatment of seeds with bio-fertilizer Nitroxin (Nit) in a randomized complete block design with a factorial arrangement and three replications. Field experiments during 2013-14 growing season were conducted under two locations, at Experimental Farm of the College of Agriculture, Ilam University at Ilam, West of Iran and Agricultural Research Station of  Bushehr, South of Iran. Root properties were studied in response to above mentioned treatments at two growth stages, anthesis and seed maturity under greenhouse condition. Results showed that spraying CCC increased spike number plant-1, grain number spike-1, grain yield and seed protein content by about 14.1%, 13.6% and 28.5%, respectively. Spraying CCC at 2.5 g L-1, application of 50 kg of Zn and inoculating seeds with Nit treatment had the greatest grain yield (1710 kg per hectare) and protein content (12.8%). Spraying 2.5 g.L-1 solution of CCC, Soil incorporation with 50 kg Zn and seeds pre-treatment with Nit at anthesis stage increased root length, root fresh weight, and root dry weight as well as ratio of root to shoot dry weight by 17.7%, 21.9%, 30.3% and 32.8% in comparison to control treatment. Overall, the greatest grain yield of wheat cultivar Kohdasht was obtained from spraying 2.5 g.L-1 of CCC, applying 50 kg of Zn as soil incorporation and pre-treatment of seeds with bio-fertilizer Nit.

In order to investigate the response of cereals to intercropping with legume in weed competition conditions, a field experiment was performed in 2014-2015 in the College of Agriculture and Natural Resources of Darab, Shiraz University. Treatments included 10 monoculture (wheat, barley, triticale, pea and bean with and without weeds) and 6 intercropping (wheat + chickpea, wheat + faba bean, barley + chickpea, barley + faba bean, triticale + chickpea and triticale + faba bean with Weeds) which laid out in a randomized complete block design (RCBD) with three replications. Results showed that grain yield, biological yield and harvest index in most intercropping treatments was similar to those in weedy monoculture and even in some cases similar to those in weed-free monoculture treatments which it shows that intercropping had a higher efficiency. For instance, grain yield in barley+ chickpea intercropping (6241 kg ha-1) and barley+ faba bean (5333 kg ha-1) was not significantly different from weedy barley monoculture (7313 kg ha-1) and weed-free barley monoculture (7621 kg h-1). Partial LER of cereals, in intercropping treatments except wheat+faba bean (0.39) based on weedy monocultures, was greater than 0.5 and also except intercropping of triticale + chickpea (0.31) and wheat + faba bean (0.41) based on weed-free monocultures was more than 0.5. Barley had a greatest grain and biological yield over all the treatments which it was because of its superior competitive ability against weeds.

In this research, the effect of concentration and time of seed priming with salicylic acid on germination and early growth and it’s application methods under salinity stress conditions on phenology characteristics of barley, variety Reyhan, was studied in two separate experiments. The effect of concentration (in five levels, control, 0.5, 0.75, 1.0 and 1.5 mM) and time (in three levels, 6, 12 and 24 h) of seed priming by salicylic acid (SA) in the first experiment and different application methods of SA (no application, priming and spraying at the stages of establishment, double ridges and anthesis) under different salinity conditions (no stress and salinity of 6 and 12 dS.m-1)in the second experiment was evaluated. Both experiments were conducted as completely randomized design with four replications at College of Agriculture, Shiraz University, Iran, in 2014. The results of the first experiment showed that SA-priming with 1.5 mM for 12 h had the highest positive effect on germination and early growth, which was selected for the second experiment. The results of the second experiment showed that salinity stress of 6 dS.m-1 reduced the planting to anthesis period as well as planting to physiological ripening and 12 dS.m-1salinity stress also reduced the planting to booting, planting to anthesis and planting to physiological ripeningperiods. Seed priming with SA prolonged the growth periods, whereas the delay in SA application decreased its positive effect. Foliar application at establishment increased planting to booting, planting to anthesis as well as planting to physiological ripening periods,however foliar application at anthesis had no significant effect on phenology of barley plants. In total, seed priming or foliar application at establishment at early growth stages ameliorated the acceleration of the developmental stages due to salinity stress and early application of SA was found to be more important with increasing salinity stress.

Wheat grain yield reduction occurs in most wheat growing regions of Iran due to post-anthesis water stress. This research was conducted to evaluate yield and yield components of wheat cultivars in normal irrigation and post anthesis irrigation cut-off conditions as a split-plot arrangement based on a randomized complete block design with three replications during 2015-16 in College of Agriculture, Shiraz University, Shiraz, Iran. The main plots included irrigation regimes (normal irrigation until the end of the growth season and irrigation cut-off from flowering to maturity) and subplots composed of 20 bread wheat cultivars. The results showed that irrigation cut-off caused a significant reduction in biological yield (46.4%), grain yield (59%), harvest index (23.7%), number of grains per spike (27.1%) and 1000 grain weight (13.8%). The highest grain yield in normal irrigation (1002 gm-2) and post anthesis irrigation cut-off conditions (485.7 gm-2) was obtained from Danesh cultivar. Among indices, stress tolerance index (STI), mean productivity (MP), and geometric mean productivity (GMP) had positive and significant correlations with grain yield in stress and non-stress conditions. Therefore, it appeared that these indices might be suitable for identification and selection of wheat cultivars that are tolerant to post anthesis irrigation cut-off. In general, the results indicated that Danesh, Sirvan, Baharan, Jones and Symonyda cultivars out–yielded the remaining ones under both stress and non-stress conditions.

Several herbicides are registered for selective weed control in sugar beet; however, no single chemical herbicide can control all weeds in beet fields. Frequently, two or more herbicides may have to be combined sequentially or as tank mixed to achieve adequate broad-spectrum weed control. In order to evaluate the effects of some combinations of broadleaf herbicides on sugar beet yield and quality, a field experiment was conducted in randomized complete block design with three replications at Miandoaab Agricultural Research Station during 2009-2010 growing season. The results showed that weed competition decreased root yield up to 84%. The maximum root yield (73.66 tha-1) was obtained from 4.5 kgha-1metamitron application at 2-to 4-leaf stage and the minimum root yield was obtained in the control (20.66tha-1). The herbicide treatments had a significant effect on white sugar content so that the highest white sugar yield was achieved from bettanal Progress Am herbicide (10.9 tha-1) and the lowest white sugar yield was found in control treatment (1.49 tha-1). The lowest sodium, potassium, amino-nitrogen as well as molasses content were obtained from phenmedipham desmedipham ethofumesate and the highest value for the above parameters was observed in control treatment. Generally, weed competition led to decreasing root yield and sugar content and treatment bettanal Progress Am herbicide was recommended to control broadleaf weeds.

Plant growth regulators (PGRs) have been used to reduce losses of wheat grain yield under limited moisture conditions. The effect of three PGRs including cycocel, salicylic acid and brassinoestroeid on growth and grain yield of four bread wheat cultivars Chamran, Shiroudi, Pishtaz and Sirvan under normal and withholding irrigation after flowering was examined. The experiment was carried out as factorial split plot arrangement in randomized complete block design with three replications in 2014-15 and 2015-16 growing seasons. The results showed that water stress significantly reduced number of grains per spike, grain weight per spike, thousand grain weight, harvest index, biological yield and grain yield. However, water stress had the least effect on thousand grain weight (11.2%) and the highest effect (25.2 %) was observed on biological yield. Furthermore, application of PGRs, especially cycocel, increased spikes.m2, grains per spike, harvest index, thousand grain weight and grain yield. Cycocel, salicylic acid and brassinoestroeid, had positive non-significant effect on grain yield components. The highest grain yield was achieved from application of cycocel in both growing seasons (3696 and 4439 kg.ha-1, respectively). Also, the highest grain yield was obtainted from Sirvan cultivar in both growing season (3608 and 4448 kg.ha-1, respectively). According to these results, although water stress reduced yield and its components, the alleviating effect of PGRs could compensate some proportions of water stress effect. The compensatory effect of PGRs was 31.3, 23.5 and 23.2 percent for cycocel, salicylic acid and brassinoestroeid, respectively. Therefore, application of PGRs can be considered as an alternative way to alleviate the effect of terminal drought stress on grain yield of bread wheat cultivars.

Remobilization of reserves from stem during maturity is important in the case of grain yield of wheat under drought stress. Annual field experiments were carried out at two sites: Ilam (52 ◦ 50 N, 1 ◦ 14 W) and Bushehr provinces (45 ◦ 46 N, 03 ◦ 09 E) during 2013-2014 growing seasons. In these experiments conducted in completely randomized block with three replications, effects of three main factors including two concentration levels of chlormequat chloride (CCC) (0, 2.5 g.lit-1), application of Zinc sulfate (Zn) at the three rates of 0, 25 and 50 kg ha-1 and Nitroxin (Nit), as biofertilizer, (inoculated and non-inoculated seed) investigated on morpho-physiological traits of bread wheat cultivar of Kohdasht. Results showed that CCC application significantly decreased plant height and amount of remobilized stem reserves. Nit inoculation increased plant height, amount of remobilized dry matter (ARDM), and contribution of stem reserves to grain yield production (REP). Zn significantly increased stem dry matter weight. CCC× Zn × Nit interaction for ARDM, REE and REP was found to be significant. The highest amounts of ARDM, REE and REP were obtained from plants of Nit-inoculated seeds applied with 50 kg ha-1 zinc sulfate and with no CCC application. Generally, it seems CCC, Zn and Nit were effectiveness in improvement and increasing grain yield of wheat under dryland farming.

To evaluate the response of 45 sorghum lines and cultivars to salinity stress, two experiments were conducted in non-stress (EC=2 dS.m-1) and salinity stress conditions (EC=12 dS.m-1) using randomized complete block design with three replications. The experiments were carried out at Ardakan research station of Agricultural and Natural Resources Research Center of Yazd, Iran, in 2014. Salinity stress significantly decreased all measured traits in lines and genotypes. Under salinity stress conditions, stem diameter, stem height, leaf number, leaf area index, fresh forage yield and dry forage yield were decreased 14.45%, 25.24%, 18.06%, 31.86%, 40.19% and 32.36%, respectively. The highest dry forage yield under non-stress and salinity stress conditions was produced by KDFGS23 (28530 kg.ha-1) and Jumbo cultivar (21042 kg.ha-1), respectively. Results of correlation coefficients among dry forage yield under non-stress and stress conditions and tolerance indices showed that GMP, HAM, MP and STI indices were the most suitable tolerance indices. Results of cluster analysis showed that Jumbo, Pegah, Sistan, Sweet sorghum, Ghalami Herat and Speedfeed (Moghan) had higher tolerance to salinity stress, while lines KDFGS23 and KDFGS26 and Nectar cultivar had greater sensitivity to salinity stress. Since line No. 1 (KDFGS1) had greater yield stability, it worth further explorations in future breeding projects.

In a 2-year field study, soil moisture and EC of soil extract (ECe) during growing season as well as grain and biological yield and water productivity of barley plant cv. Nosrat were monitored as affected by two salinity levels of irrigation water. Salinity levels of irrigation water were 2 and 12 dS.m-1. The results showed that salinity stress reduced grain, biological yield, and water productivity by, respectively, 36.0%, 52.1%, and 23.0% in the first year, and 48.4%, 69.1% and 31.7% in the second year. Higher losses in the second year were due to lower precipitation. Two-year averages of water productivity in terms of grain yields were 0.87 and 0.64 kg/m3, for 2 and 12 dS.m-1 water, respectively. In all days after imposing salinity treatment, soil moisture in control plots was significantly lower than saline plots. This difference was more distinct in the first depth and continued until the end of the growing season. On average, soil moisture levels in saline plots were higher than the control plots by 16.8% and 22.4% in the first and second years, respectively. In both years, ECe was also affected by salinity treatment, and this effect became more over time. The 2 and 12 dS m-1 salinity treatments decreased and increased ECe, respectively. The highest ECe values were observed at 160 days after planting in all three soil depths. Overall, in this condition, irrigation with saline water increased ECe about twice at the end of season compared to early growth, and increased ECe by 20% over EC of irrigation water. Greater soil moisture in saline conditions is not useful for crops because it is not easily available and has low quality, however, halophytes such as Panicum antidotale, Kochia spp., Salicornia spp. in rotation with barley might use this higher soil moisture and produce acceptable yield with less water.

IntroductionCereal-legume intercropping is one of the best ways to increase the yield per unit area (to decrease the detrimental effect caused by weeds and to reduce application of fertilizers and herbicides. Stoltz et al. (2014) in a study on corn-pea intercropping reported that crops yield in intercropped plots was significantly greater than that of monoculture. It has been reported that barley-faba bean intercropping led to an increase in total grain yield and it could cause a decrease in weed biomass. Considering the importance of intercropping to reach stability and sustainability in production, the aim of this study was to assess the changes in yield and yield components of faba bean and pea in intercropping with wheat, barley and triticale under weedy conditions in southern Fars Province.
Materials & MethodsA field experiment was performed in the College of Agriculture and Natural Resources of Darab, Shiraz University during 2014-2015. Treatments included 10 monoculture (wheat, barley, triticale, pea and faba bean with and without weeds) and 6 intercropping (wheat pea, wheat faba bean, barley pea, barley faba bean, triticale pea and triticale faba bean with weeds) which laid out based on a randomized complete block design (RCBD) with three replications. Irrigation intervals were 8 and 12 days based on environmental conditions. Weeds were hand weeded twice, at tillering and booting stages of cereals. After crop maturity, plants were hand harvested to measure yield and yield components. Additionally, partial land equivalent ratio (LER) was calculated. The partial land equivalent ratio has been defined as a measure of efficiency of an intercrop or mixture. The LER compares land areas required under single or sole cropping to give the yields obtained from the component crops of the mixture. Values greater than 0.5 indicate intercropping to be more efficient than sole cropping in terms of land use, while values less than 0.5 indicate a loss in efficiency due to intercropping. Values equal to 0.5 indicate that the components fully share the same limiting resource. The data analyzed by using MSTATC ver2.10 software (1991). Since the number of the plants was not similar in all the plots, the data was subjected to analysis of covariance.
Results & DiscussionResults showed a significant effect of treatments on 1000-seed weight of pea, number of pod per m2, number of seed per pod, grain yield, biological yield, harvest index and LER. The greatest 1000-seed weight of pea, number of pod per m2, seed yield and harvest index obtained in intercropping of wheat pea (366.7 g), weed-free pea monoculture (1317), weed-free faba bean monoculture (4149 kg/ha) and weed-free faba bean monoculture (46.46 %), respectively. The highest number of seed per pod was obtained in intercropping of barley faba bean (3.7), weed-free faba bean monoculture (3.29) and intercropping of wheat faba bean (2.93), respectively. Total and partial LER of legumes in all intercropping treatments compared to weedy monoculture was greater than 1 and 0.5, respectively. The results showed that weed-free monoculture treatments had the highest grain yield, biological yield and harvest index. However, crop yield and harvest index in intercropping treatments were similar or superior to weedy monocultures. For instance, grain yield and harvest index in intercropping of wheat faba bean was higher than those of in weedy faba bean monoculture, 102 and 93 %, respectively. In general, grain yield, biological yield and harvest index of pea and faba bean in weed-free monocultures treatments was higher than weedy monocultures and intercropping treatments. Grain yield and harvest index of intercropping was similar or higher than those of weedy monocultures.
ConclusionTotal and partial LER of legumes in all intercropping treatments compared to weedy monoculture was greater than 1 and 0.5, respectively. Since cereals are more competitive than legumes, it seems for increasing the efficiency of intercropping; a higher density of legumes should be used. Additionally, for reducing weed interference and increasing yield in pea and faba bean, the use of cereal-legume intercropping is recommended.

IntroductionDrought stress is most important abiotic stress reducing growth and production of wheat worldwide. Protective role of plant growth regulators (PGRs) against drought stress has been accepted in general, however, comparison of PGRs types to determine the optimum one is crucial. Many PGRs are known to alleviate the negative effects of drought stress in plants. However, limited research has been conducted to investigate the potential benefits of exogenous application of different PGRs in wheat plants grown under drought stress. Chlormequat chloride (CCC), salicylic acid (SA) and jasmonic acid (JA) could consider as three major PGRs using in cereals.
Materials and MethodsTo examine the effect of three PGRs consisted of CCC, SA and JA on yield components and grain yield of wheat cv. Roshan under different water stress conditions (a range of light to severe drought levels) two separated experiments were conducted at controlled and field conditions at College of Agriculture, Shiraz University during 2012-2013 growing seasons. Concentration of CCC, SA and JA were 19.0, 1.0 and 0.1 mM, respectively. Drought stress levels were 100%, 80%, 60% and 40% of field capacity in greenhouse and were 100%, 2/3 and 1/5 of field capacity in the field experiment. Field capacity was determined as 25% (g g-1) for the experimental field. Greenhouse and field researches were carried out in factorial experiment based on completely randomized design and in split plot experiment based on randomized complete block design, respectively. Four and three replications were used greenhouse and field experiments, respectively. Roshan as a bread wheat cultivar with standard height was used. Foliar application of 3 PGRs was done at double ridges stage in both experiments; however, irrigation treatments were applied at double ridges stage and early anthesis at greenhouse and field experiment, respectively. For plot irrigation a tape system was used and amount of irrigation was measured by a water meter.
Results and DiscussionThe results showed that water stress decreased flag leaf area, ear length, grain number per ear, biological yield and grain yield in the greenhouse and biological yield and grain yield in the field experiment. The maximum of flag leaf area was obtained at anthesis and after that there was no increase in green area. In the other hand, ear length and grain number per ear were fixed at anthesis and so drought stress had less negative impact on flag leaf area, ear length and grain number per ear under field conditions. Increasing the level of drought stress was considerably associated with greater reduction in grain yield and yield components. However, PGRS application improved yield components and consequently enhanced the grain yield. The higher flag leaf area in PGRs-treated plants might be due to lowering developmental rate or delaying plant maturity and senescence. So, by improving leaf area, PGR application resulted in increased photosynthetic rate leading to a higher yield. Although all PGRs had positive effect on growth and yield of wheat nevertheless, the effect of chlormequat chloride followed by salicylic acid was greater than jasmonic acid; so that foliar applications of chlormequat chloride, salicylic acid and jasmonic acid were associated with 20.7%, 13.8% and 7.24% increase in grain yield, respectively, under controlled conditions. These values were 18.3%, 12.2% and 8.1% for the field experiment. Such compensatory effects of PGRs could be due to various reasons. Chlormequat chloride can stimulate root growth, reduce transpiration, increase water use efficiency, and prevent chlorophyll destruction. Similarly, SA application may result in stomatal closure, increased WUE, increased chlorophyll content, increased respiratory-pathways and intercellular CO2 concentration, and stimulatory changes in other physiological and biochemical attributes. Jasmonic acid is also essential components for the signaling pathway triggering the expression of plant defense genes in response to abiotic stresses. This PGR had a significant role in osmotic adjustment under drought stress conditions.
ConclusionsOverall, drought stress depending on time and severity of application had several adverse effects on wheat cultivar including decreased flag leaf area, ear length and grain number which led to reduced biological yield and grain yield. However, exogenous application of SA, CCC or JA reduced at least some of the harmful impacts of drought stress and in some cases compensated losses or damages caused by the drought, resulting in purging of differences between the control and drought stress conditions. Furthermore, chlormequat chloride might have a wide scope for further investigations as an approach to increase grain yield under limited water conditions.

Drought is one of the most important factors limiting crops growth and production and use of plant growth regulators to cope with water stress is of interest to many researchers. In order to study the effects of two plant growth regulators, brassinosteroid (BR) and salicylic acid (SA) on germination and growth of two wheat cultivars in water deficit conditions, a greenhouse experiment was designed and carried out at College of Agriculture, Shiraz University, Shiraz, Iran in 2014. The experiment was factorial based on randomized complete block design, with four replications. Treatments composed of two wheat cultivars (Shiraz and Sirvan), two moisture regimes (50 and100% FC) and growth regulators (BR and SA). In this experiment water stress significantly increased greenness Index (50.58%) and significantly reduced relative water content (10.24%), spike dry weight (17.22%), one hundred seed weight (14.14%), shoot dry weight (8.74%) and seed weight per plant (19.21%). However, plant spray with 25 and 50 µg.L-1 BR and 1mM SA could offset some of the adverse effects of water stress. Furthermore seed priming with BR increased the percentage and rate of seed emergence. Sirvan as a tolerant cultivar for all of the measured traits was shown to be superior to Shiraz, as a sensitive cultivar.

This study was undertaken to better understand the probable mechanisms of salt stress tolerance induced by seed priming of salicylic acid (SA) in barley. The barley seeds were pre-soaked by SA or water and then sown under different saline watering regimes including 0.62 (tapwater), 5, 10 and 15 dS m-1 in petri dishes and trend of water absorbing, seedling growth, germination rate and percentage were measured. After 11 days, seedlings were transplanted to pots and K and Na accumulation and storage factor were determined. The results showed that salt stress reduced absorbed water (50%), germination rate (39%), seedling growth (74%) and K accumulation (38%) and increased Na accumulation (fivefold). In all hours after sowing, SA-primed seeds had greater absorbed water with higher growth rate and this trend was true for all days after sowing. SA-primed seedlings had higher germination rate (30%), as well as, shoot (17%) and root length (38%). Enhanced K and reduced Na accumulation was also found in SA-primed seedlings. Reduction in Na absorption due to SA application was found to be greater at lower salinity stress levels and this was consistent with its effect on seedling growth. Storage factor, devised for quantifying partitioning of absorbed ions, were found to be increased for K and decreased for Na at higher salt stress levels; this means that at higher salinity levels, greater Na and lower K were transported to the shoot and this was associated with greater loss in seedling growth. Indeed, SA-primed seedlings showed a greater Na storage factor i.e. they kept more Na in their roots, in non- and light salt stress treatments. Accelerated water imbibition, greater germination rate, less Na, higher K accumulation, and greater Na storage in roots might be some mechanisms for salt stress tolerance in SA-primed barley seedlings.

Optimizing the source size and its utilization by the sink is one of the main factors enhancing the yield potential and decreasing water demand in crops when exposed to drought. To investigate the effect of defoliation on leaf water relations, chlorophyll content and yield components of five triticale genotypes including Sanabad, Juanillo, ET-83-3, ET-84-5 and ET-84-8 under well-watered (100% FC) and water stress (50% FC) conditions, a controlled experiment was carried out at Shiraz University in 2013. The results showed that ET-84-8 and Sanabad genotypes had higher chlorophyll content (ranged from 49.1 to 54.6 SPAD unit) under water stress. Among the triticale cultivars, water stress caused 21 to 42% decline in rate of water loss (RWL) In all genotypes except ET-83-3 and Juanillo, the excised leaf water retention (ELWR) was slowly decreased under water stress conditions. In all triticale genotypes except ET-84-8, water stress declined main shoot yield 21-22%, while in ET-84-8 was only 9%. Interestingly, in ET-84-8, grain number per spike was not affected by moisture regimes. Sanabad cultivar, with 2.57 g/g had the highest initial water content (IWC) at defoliation of all leaves except the flag leaf and penultimate leaf treatment under water stress. Under defoliation and water stress, ET-84-8 and Sanabad genotypes showed a greater 100-grain weight ranged from 3.60 to 3.74 g. It was concluded that triticale cultivars were more sink-limited especially under water stress, and source restriction by defoliation which had less effects on main shoot yield could be used as a useful tool for lowering water consumption during grain filling.