Iranian Journal of Field Crops Research
Year:2008 | Volume:6 | Issue:1|Papers Count:25

Salinity and drought stress can significantly affect plant growth in arid and semi-arid regions. Legume - rhizobium symbiotic relationships can also be influenced by these limiting factors. It is well known that the host plant inoculation by native strains with high efficiency has a positive effect on plant yield and biological nitrogen fixation process. The main aim of this investigation was to evaluate the salinity and drought tolerance of 49 isolates of Sinorhizobium meliloti collected from Kerman province in southern Iran. Salinity and drought tolerance of all isolates were examined in liquid TY media containing 0, 100, 200, 300, 400, 500, 600 and 650 mM NaCl and 0, 203, 298, 373, 438, 496, 548 and 573 g/L of Polyethylene glycol (PEG-6000), respectively. This experiment was carried out using a factorial arrangement in completely randomized design whith three replicants. The results showed that salinity and drought tolerance among isolates was significantly different. All isolates were grouped in three clusters: sensitive, semi-sensitive and tolerant based on their growth rate in TY media containing different concentrations of NaCl and PEG-6000. The results also showed that all tolerant isolates excreted more exopolysacharides compared to the sensitive and semi-sensitive ones. Based on salinity and drought experiments, two isolates of Sinorhizobium meliloti i.e.S27K and S36K were selected as superior in this expriment.

In order to calibrate and validate the CERES-wheat model, two experiments were carried out at Agricultural and Natural Resources Research Center of Khouzestan during 1382-83 and 1383-84 growing seasons. In addition, we used results of experiments, which were performed in previous years at this Research Center. The values of root mean square error (RMSE) for anthesis and maturity dates, grain yield and biomass production were 2.5d, 5d, 640 kg/ha and 460 kg/ha, respectively. These RMSE values were less than 10 percent of observed data means. The results indicated that the CERES-wheat model can satisfactorily predict phonological stages, grain yield and biomass of wheat. Then calibrated and validated CERES-wheat model can apply to research purposes in Ahvaz conditions.

In order to evaluate the stability and determine the highest yielding variety, 20 genotypes of hulless barley were studied in this research. The experiment was conducted in a randomized complete block design with three replication in six locations (Karaj, Esfahan, Nyshaboor, Yazd, Birjand, Zarghan) for two years (2001-2003). Simple and combined analysis of variances showed that there were significant different between genotypes, In order to evaluate interactions and determine the adaptation of genotypes study in cluding: Environment variance, Environmental coefficient of variation, Eberhart and Russell’s regression method, Lin and Binn’s years within location mean squares method, the years within location environmental coefficient of variation and Non-parametric methods of deviation from rank and yield index. The obtained results through all these methods were nearly analogous. ICNB93-328 and ALELI/4/MOLA/2 genotypes were identified as stable genotypes. GLORIA genotype was recognized specially for the unpropitious weak areas.

In order to evaluate the effect of nitrogen and herbicide management on distribution patterns of lambsquarters seed bank, an experiment was conducted in a grain corn field at the Agricultural Research Station, Ferdowsi University of Mashhad 2006 growing season. Treatments consisted of application of: 25 kg/ha nitrogen fertilizer at the time of corn planting with 2,4-D+MCPA herbicide(533 g. ai./ha 2.4.D+467 g. ai./ha MCPA), 25 kg/ha nitrogen fertilizer at the time of corn planting without herbicide, 25 kg/ha nitrogen fertilizer at the time of corn planting and six-leaf stage with herbicide, 25 kg/ha nitrogen fertilizer at the time of corn planting and six-leaf stage without herbicide, 120 kg/ha nitrogen fertilizer at the time of corn planting with herbicide, 120 kg/ha nitrogen fertilizer at the time of corn planting without herbicide 120 kg/ha nitrogen fertilizer at the time of corn planting and six-leaf stage with herbicide and 120 kg/ha nitrogen fertilizer at the time of corn planting and six-leaf stage without herbicide. Application of herbicide was useful in reducing the amount of lambsquaters seed bank. Semivariograms of seeds were fitted with spherical and exponential models. Semivariogram analysis in the levels of treatments indicated a range of influence of 0.88m to 45.12m. The highest spatial correlation was 0.093% and the lowest was 28.81%. Weed seed bank patches was obvious in maps. Although the nitrogen fertilizer had no strong effect on reducing the amount of seed bank, the application of 2,4-D+MCPA was a useful practice in reducing weed seed bank.

Common sainfoin (Onobrychis viciifolia L.) is a forage crop belonging to the legume family. The crop is characterized by numerous favorable criteria such as the capability to fix atmospheric nitrogen symbiotically. In order to study the response of various ecotypes of common sainfoin to the foliar application of nitrogen and micronutrients, such as iron and zinc, two separate field experiments were conducted using a spilt-plot design with completely randomized block replicated three times. In the first experiment, the main plots included five different ecotypes of common sainfoin, and the sub-plots included four rates of urea application (0, 15, 30 and 45 kg N/ha). In the second experiment, the main plots included seven different ecotypes of common sainfoin, and the sub-plots included four rates of micronutrients (0, 0.04 % Fe, 0.04 % Zn and 0.04 % Fe + 0.04 % Zn). The foliar application of urea, Fe and Zn with increasing nutrient concentrations had a statistically significant (p<0.01) effect on plant height (cm) and shoot dry weight (g) at the first and second harvests, and on the leaf area (mm2) only at the first harvest of different ecotypes of common sainfoin.  Results indicated that addition of 30 kg N/ha were more effective at increasing plant height, shoot dry weight and leaf surface area. Aligoodarz ecotype showed the greatest response to the foliar application of urea relative to the other ecotypes. The application of Fe and Zn simultaneously resulted in the maximum values for plant height, shoot dry weight and leaf area. Uroumia Mamish Khan ecotypes had the highest response to the foliar application of the two micronutrients compared to the other ecotypes. In general, the results of the current study show that an amount of 30 kg N/ ha as urea and 0.04 % Fe + 0.04 % Zn as the respective chelate is needed for an optimum growth and yield production of the common sainfoin in the studied area.

In order to study the effects of summer cover crops and their residues, and mechanical and chemical weed control methods, on weed density and biomass in Valencia orange orchards, an experiment based on randomized complete block design with 7 treatments and 3 replications was conducted in 2005 at Research Garden of Orangery Research Institute of Ramsar, Iran. The treatments consisted of soybean (Glycine max), alfalfa (Medicago sativa), and berseem clover (Trifolium alexandrinum) cover crops, rotivator, rice straw mulch, glyphosate herbicide, and weedy control. Cover crops were planted on first day of May month as well as rice straw mulch. Rotivator has been done each 30 days until the end of experiment. Herbicide was applied on mid-July month, simultaneously as mowing cover crop. The results of this study showed that soybean and alfalfa cover crops produced the highest and lowest biomass among cover crops, respectively. Similarly, the highest and lowest amount of LAI was observed in soybean and alfalfa, respectively. Soybean cover crop and tillage resulted in lowest weed biomass, while control and alfalfa cover crop resulted in highest weed biomass. Rice straw mulch and berseem clover cover crop have resulted the best in decreasing weed density, while alfalfa cover crop was the most inefficacious one. In conclusion, soybean cover crop and tillage were the most efficacious and alfalfa cover crop was the most inefficacious treatment for controlling weeds in studied orchard.

In order to study the effect of planting dates and nitrogen rates on yield and yield components of black cumin (Nigella sativa L.) a field experiment was conducted in spring 2006 in the Azad University of Birjand. The experiment was done as split plot based on completely randomized block design with 3 replications. Four planting dates (21 March, 4, 21 April, 5 May) were used as main plot and 3 levels of nitrogen (40, 80 and 120 kg/ha) were as sub plot. The results showed that the planting date’s effect was significant on traits such as plant height, number of main branches, number of follicles per plant, biological yield and grain yield. As, maximum plant height, number of follicles per plant and biological yield were observed in first planting date and maximum number of main branches and grain yield were observed in first and second planting dates. Planting dates had no significant effects on number of follicles in main branches, number of seed per follicles, weight of 1000 seeds and harvest index. Nitrogen rates and interaction between planting dates and nitrogen rates had no significant effect on the traits. According to the results of this experiment 40 kg/ha nitrogen is enough for black cumin. Also, planting dates in 21 March and 4 April were recognised better because of high yield production.

To evaluate the effects of different intercropping arrangements of cumin and lentil on plant growth and yield, an experiment was conducted in Agricultural Research Station of Ferdowsi University of Mashhad in the growing season of the year 2004. Treatments were A: row intercropping of cumin and lentil B: strip intercropping of cumin and lentil (three cumin rows and three lentil rows) C: strip intercropping of cumin and lentil (four cumin rows and four lentil rows) D: sole crop of cumin (six rows) E: sole crop of lentil (six rows). For this purpose a complete randomized block design with 4 replications was used. Results showed that economic and biologic yield of cumin, 1000-seeds weight, number of seeds per umbel were affected by different intercropping arrangements and there was a decreasing trend in these parameters from intercropped to the sole crop. Biological and economic yield and also harvest index for lentil were higher in sole crop compared with intercrop. There was a decreasing trend in LER from row intercropped to strip cropping and the highest LER (1.86) was obtained from treatment A and the least (1.26) was obtained in treatment C.

With respect to effect of climatic changes on crop yields, study of long term trend of yields is conducted on the basis of statistical procedures that will be a suitable way to determine contribution of climatic factors affecting yield changes. As this trend of yield changes has been studied at regional and national levels in many parts of the world, conducting these studies will be necessary for Iran. So, with respect to economical importance and social aspect of saffron for Khorasan province and Iran, evaluation of yield trend of saffron in recent years and study of relationship of its changes to climatic changes have been purpose of this research. Findings show that yield reduction of saffron in Khorasan has been affected by changes in climatic indices particularly temperature and precipitation during the past ten years, so that among main cities of saffron cultivation in Khorasan 31 to 66 percent of yield variation can be explained by these climatic variables. In this research, from meteorological parameters, effect of precipitation compared with monthly temperature has been less and results show that precipitation has been effective only in Torbat-e-heidarieh while minimum and maximum monthly temperatures are considered as the most important variables affecting saffron yield. It was also concluded that temperatures of spring season and almost the first month of summer have highest effects on saffron yield. Patterns of increasing minimum and maximum temperatures of these months during the past ten years are related to trend of yield reduction in saffron, and It seems that this decreasing trend will be continued.

In order to study the influence of inoculating two native rhizobium isolates on nodulation in Kabuli and Dessi chickpea (Cicer arietinum L.) genotypes in different soil moisture regimes, a greenhouse experiment was carried out as a completely randomized design in a factorial arrangement of treatments with three replications. Treatments included soil moisture levels, FC (Field capacity), 75%FC, 50%FC and 25%FC, variety, MCC876 and MCC180 from Dessi and Kabuli genotypes, (drought resistant and susceptible, respectively) and rhizobium inoculation, number 16 isolate, number 27 isolate and control (not inoculated). Among different moisture levels, inoculated isolates and different varieties, significant differences (p<0.01) were observed for all studied factors such as number of nodules, nodule dry weight, nodule specific weight, shoot and root biomass and chickpea shoot/root ratio. Number 16 isolate was more effective than number 27 in regard to nodulation status, while difference between number 27 isolate and control was not significant (p<0.01). Moreover, number of nodules and nodule dry weight was higher in resistant than susceptible variety, indicating less susceptibility of resistant varieties to dry conditions.

In order to investigate the effects of different levels of nitrogen, Iron and Zinc on physiological indices and forage yield maize (Sc 704) a field experiment was conducted as a split plot in a randomized complete block design with 12 treatments and four replications at jihad Agricultural Research center of Markazi province in 2003. The treatments consisted of three levels of 150, 225 and 300 kg N ha-1 as main plots and microelements at four levels including control, 4 kg ha-1 Fe sulfate, 45 kg ha-1 Zn sulfat , 4 kg ha-1  Fe sulfate + 45 kg ha-1 Zn sulfate as sub plots. physiological indices were affected by N rates. Rasing N levels from 150 to 225 and 300 kg N ha-1 increased leaf area index, crop growth rates and total dry weight at 38 days after planting that after reproductive stage were significantly. A maximum LAI of 5.7 was observed during growth season after 1100 growing degree days at level of 300 kg N ha-1  ten day after tasseling the highest TDW equal 1600 g.m-2 was observed 14 days after silking with receiving 1150 GDD in 300kgN ha-1 . Among physiological indices, the net assimilation rate was affected less by N application. Net assimilation rate declined during the growth season. The results also show that an application of microelements, particularly Zn, did not significantly increase LAI, CGR and TDW. Maximum LAI, CGR and TDW were obtained with the application of Zn Sulfate and Zn sulfate + Fe sulfate. Among nitrogen levels and microelements, maximum of forage yield equal 84.86 and 79.65 ton ha-1 obtained with the application of 300kgN ha-1 and 45 kg ha-1 Zn sulfate, respectively. The highest forage yield equal 88.66 ton ha-1 was obtained with application of 300kgN ha-1 + 45 kg ha-1 Zn sulfate. Considering the importance of LAI, CGR on foroge yield it was concluded that the magor increase in forage yield under high N and Zn sulfate was due to improvement of physiological indices.

A field experiment was conducted in Shiravan, Iran, during 2005 in order to investigate the effects of organic amendments, synthetic fertilizers and compost extracts on crop health, productivity and storability of commonly used tomato (Lycopersicon esculentum Mill.). Treatments included different fertilizers of cattle, sheep and poultry manures, house-hold compost and chemical fertilizers, and five aqueous extracts from cattle manure, poultry manures, green-waste and house-hold composts and water as control. The effect of fertilizer type on tomato yield and marketable yield was significant (P<0.05). Poultry and cattle manures and house-hold compost caused higher yields compared to control and chemical treatments. However, six weeks after storage marketable yield was highest in poultry manures and lowest in chemical fertilizers. The effect of aqueous extracts was not significant on either crop health or tomato yield and storability. Organic fertilizers also caused earlier maturity and earlier fruit productivity. Application of organic fertilizer showed higher yield in the first and second harvest than the third one, on the other hand, in treatments with chemical fertilizers, the percentage of diseased fruits was higher in the first harvest and also in total yield.

In order to investigate the effect of different levels of salinity and phosphorus on the growth and yield of berseem clover (Trifolium alexandrinum), an experiment using a factorial experiment conducted carried out based on completely randomized block design with four levels of salinity (S1=0, 12, S2=2, S3=6 and S4=10 dS/m) and two levels of phosphorus (P1=10 and P2=30ppm) with four replicates under green house conditions. Different levels of salinity have been provided from NaCl, MgCl2, Na2SO4 and MgSO4 with weight proportional respectively 2:1:1:1. The treatments of phosphorus provided from KH2PO4 sources. The traits such as growth indexes (leaf area, plant height and shoot diameter) at three different stages, shoot and root dry matters, root to shoot ratio, total length of root, nutrient elements (N, P, K and Na) in shoot and potassium to sodium ratio in shoot were measured. The salinity was applied using saline water with the above-mentioned electrical conductivities. Generally, by increasing salinity and phosphorus levels, all the measured traits were reduced and increased, respectively. Furthermore, at the high level of salinity, increased available phosphorus improves clover yield. So it seems that in saline soils, where there is no possibility for soil leaching and amending, application of phosphorus fertilizers can lead to a good growth and production in clover yield.

An experiment was conducted under field condition to evaluate the effects of pure or combinations of biofertilizers on agronomic and quality criteria of Hyssop (Hyssopus officinalis), a medicinal and aromatic plant from Lamiaceae family at Research Station of Faculty of Agriculture, Ferdowsi University of Mashhad, during years of 2006 and 2007. A complete randomized block design with three replications was used. Fertilizers containing Azospirillum/Azotobacter (Nitroxin), Azospirillum/ Bacillus subtilis/ Pseudomonas fluorescens (Super Nitro Plus), Glomus intraradices (Mycorrhizal inoculant), Pseudomonas fluorescens, Glomus intraradices / Pseudomonas fluorescens, Azospirillum/ Azotobacter/ Glomus intraradices / Pseudomonas fluorescens and control. Results indicated that in general, application of biofertilizers enhanced yield and other plant criteria in this plant. Plant performanced better with application of Super Nitro Plus and a mixture of Glomus intraradices and Pseudomonas fluorescens in terms of most plant criteria. However, in the second year plants performed better in response to biofertilizers and this is due to the nature of plant with regard to prenniality.

The Impact of climate change on irrigated wheat yield in Iran was studied using a simulation model under different climatic scenarios. SUCROS-wheat model which was adapted for the effect of CO2 concentration on photosynthetic parameters, were calibrated and validated against observed wheat yield obtained from different regions of country. Interaction effect of CO2 concentration and temperature on wheat yield was simulated at 3 CO2 concentrations including 350 (current), 550 and 700ppm (doubled) in combination with increasing mean daily temperature by 0 (unchanged), 1, 2, 3 and 4oC. In addition climatic conditions of the year 2050 were predicted by using GISS and GFDL General Circulation Models (GCM) based on IPCC scenarios for the target year. The GCMs were first calibrated by the long term (40 years) weather data from 25 stations located in different wheat production regions across the country. Predicted weather data of GCMs were used as the inputs of simulation model after statistical downscaling and generating daily weather parameters. Wheat yield at different regions was estimated for the climatic conditions of the target year with and without increased CO2 concentration. Finally adaptation strategies for improving wheat yield under future climate were evaluated by means of simulation model. The results showed that despite of some deviation between the two GCMs, average temperature will be changed in the range of 3.5-4.4oC with an increasing gradient from West to East and North to South of the country. This warming pattern will be led to the higher frequency of temperatures above 30oC during the flowering stage of wheat in the most regions. Increasing CO2 concentration without warming showed positive effects on wheat yield. However, the effect of CO2 was compensated for by temperature. Based on simulation results wheat yield was reduced when mean temperature was raised above 3oC even at doubling CO2 concentration. Predicted wheat yield for the year 2050 indicated that while the effects of higher temperatures was partly moderated by increased CO2 concentration the overall wheat yield will be decreased by 13-28% in different production regions. Changing planting dates and improvement of new cultivars with higher heat tolerance at flowering were evaluated as the most effective adaptation strategies for the future climate. Simulation results showed that wheat yield reduction at the target year could be prevented considerably with increasing temperature threshold of wheat cultivars at flowering by 2-4oC.

Salinity is one of the main problems in cereal production. For assessing the effect of salinity on seedling of the plants that had been grown in salinity conditions, an experiment with four tolerant wheat cultivars in four treatments(0, 60, 120 and 180 Mm NaCl) was conducted. The seeds of these plants were tested with distilled water using a factorial arrangement in a completely randomized design with 3 replications, and the percentage of germination, vigor, root and shoot length, root and shoot weight were measured. Analysis of variance indicated that there were significant differences between cultivars on root length, R:Sh, root and shoot weight and the biomass but these elements were not affected equally. Root length, root and shoot weight and biomass of cultivars in salinity treatments increased because of the absorption of water that is the result of reduction of osmotic potentiality of seeds. Shoot length and percentage of germination show the least amount of change among wheat species and different levels of salinity that represents the less sensitivity of these characteristics to salinity stress. However, these changes were not the same which shows the genetic difference among the cultivars.

In order to predict competitive effects of redroot pigweed on yield and yield components of grain sorghum by observation of relative leaf area an additive series experiment (response model) with factorial in randomized complete block design were conducted in 2005 growing season at Research Farm of Khorasan Agriculture and Natural Resources Research Center. Two factors were involved in the experiment, redroot pigweed density in four levels (0, 2, 8 and 16 plant/m2) and sorghum density in three levels (10, 15 and 30 plant/m2). Investigation about the pigweed growth index showed that sorghum and pigweed density was significant (p<0.01) on pigweed biomass. Pigweed seed and biomass production was affected by competition between sorghum and pigweed. The highest pigweed biomass was obtained at minimum sorghum density and with increase sorghum density pigweed biomass decreased. Maximum pigweed seed was produced at the same sorghum density where pigweed biomass was maximum. A alometric relation showed that minimum biomass pigweed needed for seed production in pigweed is 3.88 g/plant.

Allelopathic effects of barley straw and root on germination and growth of maize, sugar beet, and sunflower were investigated under glasshouse and laboratory experiments in Faculty of Agriculture, Ferdowsi University of Mashhad in 2006. The glasshouse experiment was designed based on randomized complete block design with three replications, treatments included: 0, 200, 400, 600 g/m² of grounded barley straw and also 0 and 50 g/m2 barley root. A laboratory experiment was carried out in order to study the effect of different concentrations of barley water extracts on germination and seedling characteristics of corn, sugar beet and sunflower. Treatments in laboratory trial included 0, 33, 50 and 100 percent of barley extracts. Results showed that leaf area of corn was significantly affected by barley straw treatments. Shoot dry matter and seed weight per plant in corn, leaf and tuber weight in sugar beet and leaf, stem weights , plant per plant in corn , leaf and tuber weight in sugar beet and leaf, stem weights, plant height, head diameter, head weight and seed weight in sunflower were significantly higher in treatment of 50g/m² barley roots. Crop seed germination decreased with increasing the amount of barley straw. The best germination response to barley extract was observed in corn. Maize radicle weight was significantly decreased with increasing concentration of barley water extract.

In order to evaluate phenological and morphological characteristics of chickpea (Cicer arietinum L.) cold tolerant genotypes, a field trial carried out on 2004-2005 at the experimental field of College of Agriculture, Ferdowsi University of Mashhad. In this study 152 cold tolerant accessions with 4 checks (Karaj12-60-31, ILC482, ILC3279 and FLIP84-48C) were evaluated in the Augmented preliminarily design in fall planting (9 October). There were considerable variations among genotypes with each other and with checks about phonological stages (days from sowing to emergence, emergence to flowering and flowering to ripening) and morphological characteristics (plant height, number of branches and their length per plant). The differences in all cases were significant (p£0.05). Vegetative growth period was more than 165 days in 84% of accessions and reproductive growth period was more than 29 days in 87% of them. The height of plant in 86% of accessions was more than 30cm, and total branch length per plant was more than 300cm in 82% of accessions. According to the results and regarding to the remarkable yield of some accessions, there is a suitable possibility for selecting genotypes with suitable agronomical characteristics in order to continue cold tolerance trials in replicated experiments.

A two years field experiment was conducted during 2005 and 2006 growing seasons in the Agriculture Research Station of Torogh, Mashhad to evaluate response of Canola cultivars to limited water. Experimental design was a split plot with three replications in which irrigation regimes were allocated to main plots and cultivars to subplots. Irrigation treatments including 100 (R1), 80 (R2), 65 (R3) and 50 (R4) percent of water requirement based on previously determined water requirement of Canola in Mashhad. Cultivars were Zarfam, Okapi, SLM046 and Licord. The results showed that yield and yield components were significantly affected by drought stress in two years. In R3 seed yield was decreased at first year however, at R4 decreased seed yield was observed in both years. The highest radiation use efficiency (RUE) for Zarfam, Okapi, SLM046 and Licord was obtained at R1, R4, R4 and R3, respectively. This difference was partly due to decreased leaf area index (LAI) with decreasing irrigation levels. The highest and lowest LAI was observed at control (R1) and severe stress (R4), respectively. Harvest index (HI) was affected by drought stress only in R4 treatment. These results showed considerable differences between cultivars in respect to LAI, RUE and HI under drought stress. The lowest and highest RUE of 0.95 and 2.6 g DM MJ-1 were obtained in drought stress treatments. It can be concluded that in this experiment drought resistance in Canola cultivars depends on their higher LAI and RUE.

For assessment the effects of salinity on morphophysiological traits of wheat an experiment with four caltivars (Karchia, Sorkh tokhm, Sholeh and Roshan) and one line (1-66-22) in four salt concentrations (0, 60, 120, and 180mM NaCl), were conducted by factorial analysis in a completely randomized design with three replications. The rates of leaf area were measured in four stages. In booting stage, relative chlorophyll content (SPAD meter), and in pollination phase the rate of Na+ and K+ iones in four leaves (up to down) were assessed and finally stem length and total dry matter were measured. Results showed that salinity reduced leaf area, total dry matter stem length of plants and relative chlorophyll content. With increasing of salinity the rate of Na+ were increased but the rate of K+ iones were decreased. Also the salt exclusion was observed at nodes of stem that of 1-66-22 was spot form.