Iranian Journal of Field Crops Research
Year:2012 | Volume:10 | Issue:1|Papers Count:34

Drought and salinity are two important environmental stresses limiting the crop production. In order to study the influence of drought and salinity stresses on germination characteristics of Marshmallow plant seeds, two separate experiments were conducted based on completely randomized design with four replications in controlled conditions. Drought stress levels were 0, -2, -4, -6 and -8 bar in the first experiment and salinity stress levels were 0, -2, -4, -6, -8 and -10 bar in the second experiment which were accomplished using PEG 6000 and sodium chloride, respectively. The results indicated a decrease in germination rate and percentage, as well as in lengths and fresh and dry weights of both plumules and radicles, as the osmotic potential was reduced in both experiments. Marshmallow seeds showed an overall higher tolerance against salinity stress compared to drought stress, with germination occurring at as low osmotic potentials as -10 bars in salinity treatments, while only until -8 bar drought stress. In osmotic potentials of -2 and -4 bar the decrease in germination percentage was more sever in the salinity stress compared to drought stress; whereas in higher levels of stress (-6 and -8 bar) drought stress brought about a higher decrease in germination percentage than did the salinity stress; illustrated by the percentage of germination decrease at -6 bar, i.e. 63% for drought and 80% for salinity treatments. At the treatments of higher potential (-2, -4 and -6 bar) the decrease in radicle length was greater in response to salinity than to drought stress, but the length of plumule was more influenced by drought stress and also showed the highest sensitivity to drought, among all measured characteristics.

In order to compare effect of magnetic field and frigate surfactant to enhance the efficacy of Iodosulfuron-methyl-sodium plus Mesosulfuron-methyl (chevalier) to control wild oat, a greenhouse experiment of dose-response was conducted. Treatments were 0, 3, 6, 12, 18 and 24 doses g a.i. ha-1 of chevalier (i) without treatment, (ii) with Frigate % 0.1 v/v, (iii) with magnetic field, and (iv) Frigate % 0.1 v/v plus magnetic field with four replications. Besides, the effect of treatments on surface tension was evaluated. Magnetic field and Frigate reduced the surface tension of water and chevalier spray solution significantly. But Frigate as compared to the magnetic field was more effective in reducing surface tension of water and chevalier spray solution. Furthermore, magnetic field and Frigate increased the efficacy of chevalier remarkably. Applying magnetic field when chevalier mixed with Frigate showed more efficacy than applying the magnetic field and/or Frigate alone.

To evaluate interaction of salinity stress and nitrogen use methods on yield and yield components, in experiment was conducted in split plot in randomized complete block with 3 replications. Treatments included: salinity of irrigation water levels 1.5, 4.4 and 7.9 ds/m as main plots, and nitrogen treatments 1. using N fertilizer at 3 stage in soil, 2. using two third N fertilizer in soil at planting and tillering and heading and one third in form of foliar application of N at tillering, 4. using and one third in form of foliar application at heading, 3. Using two third of N fertilizer in soil at planting one third of N fertilizer in soil at planting and two third in form of foliar application at tillering and heading, as sub plots. Results this study showed that increased in salt stress significant decreased total yield components such that showed decrease 41.5 kg/h in yield with increase in per unite salinity. Also methods of nitrogen application in salinity condition, have significant effects on total yield components. At the tillering, one stage of foliar with soil application of urea could increase spike no. m-2 and kernels of spike compared with other treatments. Foliar application of urea at heading stage increased kernels weight.

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Both poor germination and crop establishment due to water stress and salinity are among the most important limitations for production in semi-arid regions such as Iran. To evaluate the response of four genotypes of triticale (ET-82-15, ET-82-8, ET-79-17 and Juanillo-92) to different water potentials caused by salinity and/or drought and recognizing the germination and seedling establishment, a study was carried out based on factorial completely randomized design with three replications in 2008.Salt treatments consisted of 0, 0.5, 1, 1.5 and 2 percent of NaCl solution(equal to 0, -3.8, -8.5, -11.6, and -14.8 bar, respectively) and drought treatments consisted of 6 levels of 50, 100, 150, 200, 250 and 300 gr PEG per 1 liter distilled water(equal to -0.5, -1.48, -2.95, -4.91, -7.36 and -10.3 bar, respectively). Results showed that negative water potential caused by salinity and drought treatments had significant effect on percentage of germination. With decreasing the water potential, percent of germination was reduced similarly in same water potential until -7 bar, reduction of germination percentage was lower in drought rather than salinity. Cultivar Juanillo-92had the highest and genotype ET-82-8 the lowest germination under drought and salinity conditions. Similarly, rate of germination was reduced with decreasing water potential, and in the same water potential until -7 bar rate of germination in drought condition was higher than salinity. In lower water potential (-10 bar) in drought treatment, seed germination of triticale was halted, while this trend in salinity treatments was continued until -15 bar. Differences between percent of germination in genotypes under salinity at 0.01 % probability level were significant, but under drought stress was not significant. Finally, based on ranking of genotype with measurement characteristics, salinity tolerance was: ET-82-8 < ET-79-17< ET-82-15< Juanillo-92.Also, despite of similar drought tolerance of genotypes, cultivar Juanillo-92 was relatively more tolerant to drought under these conditions.

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Weed spread and diversity were studied both chemical and non-chemical treated fields of cotton (Gossipium hirsutum L.) in Esfarayen. In this study frequency, uniformity, density and evenness parameters in three sampling dates (30 days after sowing, flowering and harvesting stages of cotton) were determined and analyzed by "Cluster analysis". The results showed that from 29 weed species belonged to 5 plant families in cotton fields, poaceae family with 6 species was the most frequent family. Application of herbicide had significant effects on frequency, uniformity, density and evenness parameters in the first sampling date. Dominance distribution, species richness and uniformity in herbicide treated fields were lower than non-herbicide plots. Species richness in non-herbicide was higher than herbicide treated plots and it was similar for three sampling dates. At first sampling date, species diversity in sprayed and non-sprayed fields was significantly different, and herbicide application decreased species diversity. Dominance index in fields with herbicide was higher than fields without herbicide.

Five genotypes of chickpea as a half diallel crossed with each other, in 2008, 5 parents and 10 progenies were planted as randomized complete block design and some traits including days to podding, basal pod height, number of pods per plant, number of double seed pods per plant, number of single seed pods per plant, number of empty pods per plant, seeds per plant and seed yield per plant were evaluated. According to diallel variance analysis, for the traits the basal pod height and number of empty pods per plant, only additive genetic effects was significant. For number of double seed pods per plant only non-additive genetic effects were significant and for other traits, both of additive and non-additive genetic effects were significant. The degree of dominance average for the basal pod height was lower than one and for other traits was more than one. Narrow sense heritability exception of basal pod height (0.47) that relatively high, in the other traits was low, which shows the inheritance of these traits is quantitative and complex. Therefore, probably of successful selection these traits in early generations are low. Direction of dominance were negative for days to podding, number of double seed pods per plant, seed number and seed yield per plant that indicating amplifier effects of dominant genes for these traits, while the positive direction of dominance for basal pod height, number of pod, number of single seed pods per plant and number of empty pods per plant illustrates the effect of reducing dominant genes.

In order to evaluate intercropping of summer savory (Satureja hortensis L.) and persian clover (Trifolium resupinatum L.), an experiment was conducted at Agricultural Research Station of Ferdowsi University of Mashhad in 2004 growing season. Treatments were sole cropping of persian clover (eight rows), double-row intercropping of persian clover and summer savory with 27, 40 and 80 plants.m-2 (eight rows) and sole cropping of summer savory with 27, 40 and 80 plants.m-2 (eight rows). For this purpose a complete randomized block design with 4 replications was used. Results showed that leaf area index (LAI), crop growth rate (CGR) and total dry matter (TDM) of summer savory in sole cropping were much higher than the intercrop. In sole cropping, these indices decreased by increasing plant density. In intercrops, these parameters increased by increasing plant density. In the first harvest of persian clover, all growth indices in double-row intercropping of persian clover and summer savory with 27 plants.m-2 treatment were highest and by increasing summer savory density, these parameters decreased. However, in the second and third harvests a reversed pattern was observed.

In order to study the effect of water hardness on sinosulforun efficacy an experiment was carried out under controlled conditions in 2010 at the College of Agriculture, Ferdowsi University of Mashhad. Treatments included herbicides doses at 6 levels (0, 200, 250, 300, 350 and 400 g.a.i ha-1), calcium carbonate concentration at 6 levels (0, 100, 300, 600, 1000 and 1500 ppm) and weeds at 2 levels (redroot pigweed and common lambsquart), were evaluated as a completely randomized design in a factorial arrangement with three replications. Spray was done at 6-8 weeds leaf stag. 2 weeks after spray weeds survival and shoot dry matter measured. For results analysis, data analysis of variance was done and plants response to sinosulforun doses on deferent water hardness level was fitted with sigmoid 4 parametric equations to the shoot biomass data as a function of the herbicide doses and was used to calculate the herbicide dose for 50% inhibition of plants shoot growth (ID50). Results showed herbicide rate and water hardness had significant effect (P<0.01) On both weeds growth and survival. Increasing of herbicide rate decreased survival. Increasing of herbicides rate decreased survival and growth on both weeds in pure water spraying. Increasing water hardness decreased sinosulforun efficacy in both weeds control. Maximum and minimum weeds biomass production was obtained at 1500 and 0 ppm of calcuim carbonate respectively in eachrate of sinosulforun. Common lambsquarter and redroot pigweed did not respond differently to increasing of herbicide doses. But by increasing of water hardness, common lambsquarter tolerance to sinosulforun was more than redroot pigweed. Increasing water hardness, increased ID50 parameter in both weeds. Maximum (1485.5, 917.75 g ha-1) and minimum (1302, 768.8 g ha-1) of sinosulforun ID50 indicated for common lambsquart and redroot pigweed at the highest level of water hardness and pure water respectively.

The role of sesame oil in human nutrition is clear and water limitation decreases production and oil yield of sesame. This study was conducted to evaluate the effects of seed treatment and irrigation regimes on sesame yield, yield component and oil percentage. A split-plot arrangement was used in a randomized complete block design with three replications. Main-plot consisted of four irrigation regimes (50, 60, 70 and 80% soil moisture depletions of available water) and sub-plot consisted of two seed treatments (osmopriming with solution -2 bar PEG and untreated seed as control). The studied characteristics were number of days from planting to emergence, 50% flowering, capsule formation, physiological ripening, plan height, LAI, number of capsule per plant, number of seed per capsule, 1000-grain weight, grain yield, biological yield, harvest index and oil yield. The results showed that irrigation regime had no significant effect on number of days from planting to seed emergence, 50% flowering, number of seed per capsule, seed weight and biological yield. Seed treatment had significant effect on all studied traits except number of days from planting to 50% flowering, seed per capsule, seed weight, biological yield and harvest index. Also, interaction between irrigation regimes and priming was significant on 1000-grain weight and oil yield. The highest grain and oil yield obtained from 50% soil moisture depletions and the lowest obtained from 80% soil moisture depletions. The highest grain and oil yield obtained from osmopreming and the lowest grain and oil yield was obtained under control (unprimed). The 50% soil moisture depletions with osmopriming had the highest seed weight and oil yield while irrigation regime 80% soil moisture depletions with control had the lowest oil yield. Based on overall results, osmopriming with -2 bar PEG under70% was the most suitable treatment.

Tobacco (Nicotiana tabaccum) is one of the valuable agricultural and industrial crops that there is little information about its variation. For studying genetic variation on the basis of morphological characteristics, a number of 100 exotic and endemic oriental tobacco genotypes were obtained from the germplasm collection of the Urmia Tobacco Research Center, Urmia, Iran, using simple lattice design with 2 replications. Eight traits include: stem height and diameter, leaf number per plot, leaf length and width, fresh and dry leaf weight and day to 50% flowering were examined. Principal component analysis could reduce the studied morphological traits to 5 components having 96% accumulative variance. In the first component, all traits (except stem height) showed positive significant correlations with. Cluster analysis using UPGMA method distinguished genotypes in 4 different groups. Maximum distance was between groups 1 and 4. Mean comparison revealed that genotypes (Trimph and Ohdaruma) belong to group 4 had the maximum value of most examined traits, therefore, they could be utilized as parents of crosses in breeding programs.

Study of genotype by environment interaction (GEI) has assumed great importance in genotype testing programs due to yield performance of a genotype is a result of interaction between genotype and environment. GEI occurs when the performance of the genotypes is not consistent from one environment to another. Therefor, 17 barley genotypes with three check cultivars (WA 2196-68/NY6005-18, F1//Scotia l, Bereke-54 and Makouee) were growen in seven cold regions (Hamedan, Miandoaab, Karaj, Arak, Urmia, JolgeRokh and Mashhad) during two years (2008-2009) and two cold regions (Tabriz and Ardabil) during one year (2009). These trials were conducted as a randomized complete block design (RCBD) with three replications. Simple analysis of variance showed that there were significant differences among genotypes. Moreover combined analysis of variances differences among genotypes revealed that the GEI were significant at the 1% probability level. For determining of yield stability, different stability parameters were used. Considering seed mean yield, G9 and G17 genotypes had a minimum environmental variance and environmental coefficient of variation while genotypes G9 and G11 had a minimum of Wricke’s ecovalence, stability variance, Plaistad’s interaction variation and Plaisted and Peterson’s average interaction variance. Based on Hernandez’s Desirable index, genotypes G9 and G19 with maximum amount of this index were identified as a more stable genotypes. The results of most of stability methods introduce genotype G9 as the most stable genotypes and G14 for the propitious rich areas.

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The reduction of herbicide applications is a main research priority in recent years for herbicide reducing the risk of side-effects and costs from herbicides. Therefore To predicting additive, synergism or antagonism effects mesosulfuron + iodosulfuron and clodinafop-propargyl two herbicides mixture on wild oat with isobole curvatures, greenhouse experimental in completely randomized design with 36 treatments (in dose-response arrangements) and four replicates for each experiment treatments were conducted at Ferdowsi University of Mashhad. Treatments included mesosulfuron + iodosulfuron alone at doses of 0, 2.4, 6, 12, 18 and 24 g ai ha-1, clodinafop alone at doses of 0, 6.4, 16, 32, 48 and 64 g ai ha-1 and six mixtures ratio of doses of two herbicides above mentioned as 100:0%, 75:25%, 50:50%, 25:75%, 10:90% and 0:100%. The results showed mesosulfuron + iodosulfuron and clodinafop-propargyl at high dose rates showed complete control of wild oat. In addition Concentration Addition (CA) model describe Fitted the data better than Hewlett and Voelund models. On the other hand, herbicides combination with each other showed additive effects on wild oat control, As by increasing the clodinafop-propargyl ratio in mixtures (90% clodinafop-propargyl + 10% mesosulfuron + iodosulfuron) increased wild oat control compared with other mixing ratios remarkably.

Increasing atmospheric CO2 concentrations and nutrients supply are generally expected to enhance photosynthesis and growth of crops as a result considerably increase yields. The present study aims to investigate effects of elevated CO2 and different fertilizer conditions on physiological traits in Lemon balm. A factorial experiment was conducted based on completely randomized design with three replications and nine treatments at the greenhouse in 2010. The experiment factors were included three CO2 concentrations (380, 700 and 1050 ppm) and three kinds of conditions fertilizer (no fertilizer, manure fertilizer and nitrogen fertilizer). The results indicated that increasing of CO2 from 380 to 1050 ppm led to improve in leaf area, plant height, relative growth ratio, total dry matter and final yield of individual plant. The highest and the lowest amount of measured traits related to with and without nitrogen fertilizer, respectively. Impact of elevated CO2 in conjunction with nitrogen and manure fertilizers increased. These effects were more on total dry matter and final yield than other growth indices. Therefore, it can be concluded that, whereas increase of temperature caused by rising CO2 is not considered or there is not any limitation for resources, CO2 enrichment will be improved lemon balm production.

GBSS protein, that is the product of Waxy gene (Wx) is one of the major enzyme in starch biosynthesis that controls the proportion of amylose to amylopechtine and its absence leads to production of starch with low amylose and higher amylopechtine content, called Waxy starch.Wx-A1, Wx-B1, Wx-D1 are three locuses in bread wheat (Triticum aestivum) genome that encodes GBSS protein and waxy starch is produced when all of them are null. In this project the polymorphism of Wx-A1 and Wx-B1 genes in 20 Tetraploid and Hexaploid Iranian wheat cultivars was studied by PCR-RFLP and Direct Sequencing techniques. Result showed any polymorphism in Wx-B1 genes of studied population But PCR-RFLP demonstrated the polymorphism in the second part of Wx-A1 gene of Hamoun and Alvand cultivars. According to sequencing and in silico studies of the mutation effects on GBSS features, the two selected cultivars can be assumed as a donor for Wx-A1 null allele.

In order to providing selection indices using heritability and correlation effective traits on yield and multiple regression an experiment was conducted by 265 F3 families as well as parents and F1 related to Gharib × Khazar population in 2009 at Gonbad High Education Center fields. Days to repining (0.97) and panicle number and flag leaf length (0.66) had maximum and minimum heritability, respectively. Positive and significant correlations were detected between plant yield and flag leaf width (0.265**), plant height (0.193**), panicle number (0.734**) and biomass (0.828**). Biomass, days to heading and plant height were explained about 98% of total variation of yield and inserted to model respectively. Phenotypic and genotypic correlations, genetic and phenotypic direct effect in path analysis, heritability were used for construct selection vectors. According to this study, increasing of traits is not result of relative efficiency and compares parameter. Selection indices were showed that yield, significant genetic correlation with yield and high heritability are three important part of selection index. Fifth, Sixth and fourteenth are the most important between discussed indices.

One of the basic principles of an experiment is the repetition of its treatments so that treatments cannot be statistically compared without repetition. Using enough replications has a great impact on scientific validity, but in most cases, not enough attention is paid. Generally, selecting the number of replications is done according to previous experiments at similar conditions, regarding the number of replications is specifically depended on the experiment conditions. In this study effort has been made to investigate the number of treatment replications effect on the validity of experimental results by considering agricultural experiments. The results have shown that by increasing test error fluctuations and reducing the difference between the treatments that must be found to achieve a minimum level of significance and an acceptable test power, a minimum number of replications will be required. And the minimum number of required replications declines by controlling test error fluctuations. Therefore, under the same conditions, fewer replications are required for experiments under controlled conditions such as growth chamber experiments. Fewer replications will reduce test power and only through increasing the number of replications, significance level and test power can be simultaneously maintained at high level.

In order to study on adaptability and grain yield stability of eight bread wheat cultivars (Alvand, Alamout, Zarrin, Navid, Azar 2, Sabalan, Omid and Bezostiya), a RCBD experiment was conducted during three cropping seasons (2007-2010) at six locations (Sanandaj, Gorveh, Marivan, Divandarreh, Saggez and Baneh). Simple analysis of variance (ANOVA) and combined ANOVA for three years in each location and combined ANOVA for eighteen environments were implemented. Lin and Binns parameter, environmental coefficient of variations, Rick ecovalance method and Shukla stability variance, environmental variance and rank method were used for determination of stable cultivars. Combined ANOVA (three years x six locations) results showed that the genotype, year x genotype and year x location x genotype had significantly effects on grain yield. The highest grain yield belonged to Alvand (3.74 tha 1). Results of stability analysis with Lin and Binns method showed that Sabalan, Navid and Zarrin, cultivars had the lowest inside location variance and also Zarrin and Sabalan had the lowest environmental coefficient of variations, respectively. Azar 2 the lowest environmental variance among the genotypes. Results of Riclk ecovalance method showed that Zarrin and Sabalan cultivars had the lowest amount of ecovalance. Stability analysis based on Shukla method showed that Zarrin and Sabalan cultivars had the most stablest grain yield, respectively. Also stability analysis based on rank method showed that Alvand and Sabalan cultivars had the most stablest grain yield, respectively. Based on methods that used in this study, it can be concluded that Zarrin and Sabalan cultivars could be produce stable grain yield in cold areas of Kurdestan and their could be recommended for planting at these regions.

Drought and salinity are the most important limiting factors of plant growth and development in many regions of the world. In this regard, using of species that are able to have higher production in this condition is a suitable strategy. In order to study the effect of drought and salinity stresses on morphophysiological properties of kallar grass (Leptochloa fusca L. kunth), a factorial experiment based on completely randomized design with 4 replications was conducted under greenhouse conditions in 2009. The treatments were drought (100, 50 and 25 percent of field capacity equal -0.33, -3.4, and -11.2 bar, respectively) and salinity (electrical conductivity equal 0, 5, 10 and 20 dS/m). The results showed that electrolyte leakage was increased by reduce of soil water content in the cells and it reached the highest value 57% in severe drought stress (25% FC). Whereas, the different levels of salinity stress didn't increase it. The lowest of value of relative water content, root and shoot dry weight also were found in severe drought and salinity stress. However, the value of reduction of them in drought was more than salinity stress. Study on stomatal conductivity showed that it was increased 60 percent in combined stress (50% FC + 5 dS/m) in comparison with control. In total, kallar grass showed more tolerance salinity than drought stress, therefore, it is recommended for planting at saline water conditions.

In order to investigate the effects of supplementary calcium chloride and potassium nitrate on plant growth of Ammi (Carum copticum L.) in different salinity levels and nutrient solutions (NS), an experiment based on randomized complete block design (RCBD) with factorial arrangement was conducted under greenhouse condition in the faculty of agriculture, Vali-e-Asr university of Rafsanjan, during September to December 2009. The treatments were three levels of salinity levels (0, 5 and 100 mmol) and five different nutrition solution including: Control: Hoagland solution only (N1); Hoagland solution plus 40 mM CaCl2 in nutrition solution (N2); Hoagland solution plus 40 mM CaCl2 as spray (N3); (4) Nutrient solution plus 40 mM KNO3 in nutrition solution (N4) and Hoagland solution plus 40 mM KNO3 as spray (N5). Results showed that relative water content of leaf did not affected by salinity, type of nutrient solutions and the interaction of salinity and nutrient solution. The lowest and the highest sodium content were observed in the control and 100 Mm NaCl treatments, respectively. K, Ca and Mg content significantly reduced in Ammi shoot with increasing salinity. Salinity increased soluble sugars in plant while type of nutrient solution and interaction of salinity and nutrient solution were not significantly affected soluble sugars. The Highest and lowest protein content of plant organs were observed in the control and 100 Mm NaCl, respectively. Type of nutrient solution also influenced protein content. The highest protein content related to N3 and the lowest related to N5.

In order to investigate the indices of drought tolerance, correlation coefficient and path analysis at deficit irrigation and nitrogen experiment, this experiment was conducted as split plot arranged in a randomized complete block design (RCBD) with three replications during 2000-2003 for wheat at Maragheh agricultural research station of DARI. The treatments were included four levels of deficit irrigation (Rainfed, 100, 160 and 220mm of water use) as main plots and five nitrogen rates (0, 30, 60, 90 and 120 kg.N.ha-1) as sub plots. Grain, straw and biological yield, harvest index, productivity degree, plant height, kernel number per spike, Spike number per square meter and TKW determined from the middle of each plot. There were positive significant correlations due to grain yield with all variables: harvest index (r=0.969**), Productivity degree (r=0.952**), straw yield (r=0.904**), plant height (r=0.904**), biological yield (r=0.824**), Spike number per square meter (r=0.817**), kernel number per spike (r=0.773**) and TKW (r=0.612**) respectively. Results of path analysis showed that increase in grain yield was due to increase spike number per square meter and kernel number per spike respectively. On based of indices of drought tolerance (Tolerance Index, Mean Productivity, Geometric Mean Productivity and Harmonic Mean), treatment of %66full irrigation combined with 90KgN.ha-1 was substantially increased water productivity.

Two study the effects of urea foliar spray at different plant growth stages on grain yield and protein percentage of two dryland wheat varieties of sardari and azar 2, an experiment was conducted in East M ngor agricultural station of mahabad in 2007-2008. The experiment design was split plot based on randomized complete block design with three replications. Treatments were 50 gr´10 m-2 N urea foliar spray at tillering, tillering +1.5 lit´ha-1 of 2, 4-D herbicide, jointing, heading stages and control (without urea spray) for varieties of sardari and azar 2. Results showed that the grain yield of azar 2 (2270.8 kg/ha) was greater then sardari (1932.5 kg/ha). Urea foliar spray treatments affected the length of spike, grain yield and its components, biological yield and protein percentage. The greatest grain yield belonged to urea foliar spray at tillering +1.5 lit´ha-1 of 2, 4-D herbicide treatment (2371 kg/ha) that had greater grain yield rather than control by 17%. The greatest protein percentage (16.05%) belonged to urea spray at flag leaf stage and sardari variety treatment. Its be seemed that application of N as foliar urea spray instead of urea fertilizing will increase grain yield and protein percentage, and application of urea foliar spray accompanist with 2, 4-D herbicide is the most effective time.

In order to evaluate the effect of balanced application of chemical phosphorus fertilizer and seed inoculation with phosphate solubilizing bacterium and arbuscular mycorrhizal fungus and on the yield and yield components of maize (Zea mays L.) under normal and limited irrigation conditions, a split-split plots arrangement based on randomized complete block design with three replications was conducted. Treatments consisted of two levels of irrigation including: irrigation of 60 (normal irrigation) and 120 (limited irrigation) mm evaporation from class A pan evaporation; combination of phosphate solubilizing microorganisms (arbuscular mycorrhiza fungus and phosphate solubilizing bacterium) at four levels; and phosphate chemical fertilizer at three levels includes: no consumption of phosphate chemical fertilizer (control), consumption of 50% triple superphosphate fertilizer needed based on soil-test results and consumption of rock phosphate (based on the quantity of consumed phosphate of triple superphosphate source). The results showed that the irrigation levels had significant affect on all traits except harvest index, and the phosphate solubilizing microorganisms had significantly affected all traits except harvest index and number of row in ear. The results of mean comparison indicated that the maximum of amount most traits related to normal irrigation treatment, and co-application of phosphate solubilizing bacterium-arbuscular mycorrhizal fungus. The effect of phosphate chemical fertilizer on all traits was significant. Results of interactions between irrigation and phosphate solubilizing microorganisms in both normal irrigation and limited irrigation conditions showed that the co-application of phosphate solubilizing bacterium-arbuscular mycorrhizal fungus increased grain yield more than other treatments; Also, the result of balanced application of phosphate chemical fertilizer with phosphate solubilizing microorganisms showed that effect of balanced application of triple superphosphate fertilizer along with phosphate solubilizing microorganisms on investigated traits was more than rock phosphate.

In order to evaluate of yield, water and radiation use efficiencies in wheat genotypes, a field experiment was conducted using a split split plot design based on a randomized complete block design with three replications at Khorasan Razavi Agricultural and Natural Resources Research Centre (Mashhad, Iran) in 2006-2008. Main plots were assigned to two levels of water stress treatments; D1: optimum irrigation, and D2: cessation of watering from anthesis to maturity stages. Sub plots were assigned to eight bread wheat genotypes: 9103, 9116, 9203, 9205, 9207, 9212, C-81-10 and Cross Shahi (control); and photosynthetic conditions with two levels: P1: using of current photosynthesis and P2: inhibition of current photosynthesis were in sub-sub plots. Grain yield were significantly influenced by irrigation treatments and source limitation. Grain yield significantly decreased by 35% and 68% under D2 (2976 kg ha-1) and P2 (1830 kg ha-1) treatments, respectively compared with D1 (4577 kg ha-1) and P1 (5722 kg ha-1) treatments. Moisture stress decreased WUEG and RUE. WUEG significantly decreased by 18.31% and 64.42% under D2 (0.687 kg m-3) and P2 (0.401 kg m-3) treatments, respectively compared with D1 (0.841 kg m-3) and P1 (1.127 kg m-3) treatments. WUEG decrease due to water deficit was attributed to grain yield reduction. Genotypic differences exist in related to mentioned traits, as at optimum irrigation and cessation of watering conditions, the highest WUEG achieved from 9103 and C-81-10 genotypes, respectively; and the less WUEG at D1 and D2 conditions was obtained from Cross Shahi variety. According to results of this experiment, C-81-10, 9103 and 9116 genotypes could be introduced as promising genotypes and desirable for cessation of watering condition, and used them in breeding programs.

In order to study the effects of integrated application of bio-fertilizer and chemical fertilizers on yield and yield components of corn, an experiment was conducted in 2008 in Dezful city, (Khoozestan province) in a factorial arrangement based on complete randomized block design with four replications. Treatments were integrated application of biological and chemical fertilizers in four levels (100% chemical fertilizer, 50% chemical fertilizer+ bio-fertilizer, 25% chemical fertilizer + bio-fertilizer and bio-fertilizer) and bio-fertilizer application method in three levels (seed inoculation, fertigation, seed inoculation+fertigation). The results showed that highest and the lowest grain yield was obtained by application of 50% chemical fertilizer+ bio-fertilizer (10.7 t/ha) and bio-fertilizer (5.2 t/ha), respectively. The greatest and the lowest harvest indices were recorded in chemical (0.59) and bio-fertilizer (0.45) treatments, respectively. Number of grain per row and row in ear had not significant differences in integrated and chemical treatments. Methods of bio-fertilizer application had not significant effect on maize yield and yield components. The results of soil analysis showed that bio-fertilizers increased P, K as well as other macro elements availability rather than N. The results revealed that although replacing chemical fertilizers by bio-fertilizers reduced maize growth, but integrated application of these sources produced highest grain yield, nitration elements availability and reduced substantially consumption of fertilizer. The results also indicated that non-chemical sources of crop nutrients can be considered as a reliable alternative for chemical fertilization in ecological production of crops in agro-ecosystems of Iran.

Now a day winter cover crops planting has been attended to reduce herbicide application. An experiment was carried out at the Research Farm of Agriculture Faculty, Bu- Ali Sina, University, in 2009. The experiment was a randomized complete block design with three replications. The trial included of five treatments consists of no cover crop, rye, winter oilseed rape, barley and triticale. The results showed that winter cereals were produced more biomass than winter oilseed rape. living mulch of rye, barley, oilseed rape and triticale reduced winter weeds biomass 89, 86, 82 and 70 percent respectively, in compare to control. Cover crop treatments showed significant different weeds control of potato at 3 time (15, 45 and 75 DAPG) compare to control treatment. Residues mixed to soil of oilseed rape and rye had the most inhibition affects on summer weeds. These treatments, average weeds biomass decreased 61 and 57 percent respectively, in compare to control. Oilseed rape and rye in compare to control reduced weeds density in potato 36 and 35 percent, respectively. Significant negation correlations of weeds plant population, weeds dry matter with average tuber weight and potato yield. The treatments, oilseed rape and rye in compare to control increased tuber yield of potato 54 and 50 percent, respectively. These treatments, the average tuber weight increased 74 and 38 percent in compare with control, respectively.