JWSS - Journal of Water and Soil Science

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Knowledge of the vegetative and reproductive characteristics of soybean cultivars with different growth habits and maturity groups is essential for the selection of a suitable variety as well as for providing optimum conditions for their growth. In 1994 in a field located in Kholenjan of Isfahan, Iran, nine indeterminate type cultivars belonging to different maturity groups, namely Williams, Wood Worth, Hack, Zane, Black Hawk, Bonus, Steel, S.R.F. and Harcor and one determinate cultivar belonging to maturity group III namely Hobbit, in a complete block design with four replications were evaluated. Indeterminate cultivars and higher maturity group cultivars produced more dry matter. On the whole, indeterminate cultivars with later maturity had longer main stem with more nodes, pods and grains. The determinate cultivar had more lateral branches, and more pods and grains in them but these traits did not show any specific trend in different maturity groups. Height of the first pod from ground surface in indeterminate cultivars was more than that of determinate cultivars. Number of pods per each node of main stem, number of grains per each pod of lateral branch and number of nodes per lateral branch showed no significant difference among cultivars. Classification of these cultivars based on the above characteristics showed that cultivars with different growth habits had basic differences and also that some cultivars showed some similarity to maturity groups which did not exist in the present study.

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Twenty-two surface soil samples (0-20 cm) from Fars province were extracted by five extractants (i.e., DTPA, 1.5 M NH₄H2PO₄, 0.1 NH₃PO₄, 0.05 MNa2EDTA, and 1% Na₂EDTA) and used in a 7-week greenhouse experiment which was a 22 × 3 factorial with 22 soils (clay 16-63% pH 7.8-8.2 electrical conductivity 0.32-1.78 dS m^-1 calcium carbonate equivalent 28-63% organic matter 1.1-4.9% cation exchange capacity 9-27 cmol kg^-1 and DTPA-extractable Mn 4-24 mgkg^-1), 3 levels of applied Mn (0, 10, 20 mg Mn kg^-1 as manganese sulfate), 3 replications, and soybean [Glycine max (L.) Merr., cv. Williams]. Application of Mn significantly increased top dry weight by 4 to 104%, averaging to about 12% over the control. But the increase in Mn concentration was not significant. Total Mn uptake also significantly increased but the apparent recovery of the applied Mn was very low (i.e., 0.05%). Soil pH, calcium carbonate equivalent, and clay content were found to be the properties influencing the extractability of Mn. The DTPA-extractable Mn, alone (with a critical level of 13 mg Mn kg^-1) or along with some soil properties, was the only form of Mn that could reasonably predict the plant responses.

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The esterification process causes some desirable changes in physicochemical properties of fat by exchanging the acyl groups in triglyceride molecules. The aim of this study was to produce a suitable edible fat for industrial and home uses. In this study a mixture of 60 percent soybean oil and 40 percent edible tallow were inter-esterified, using 0.5 percent sodium methylate or ethylate as catalyst. The results obtained for solid fat contents and melting points indicated that the process of inter-esterification was accomplished in 30 minutes at 90°C. It was also observed that sodium methylate and. ethylate had similar effects on physical and chemical characteristics of the esterified blend. Iodine and saponification values indicated that the esterification process did not have any considerable effect on the degree of unsaturation or molecular weight of fatty acids. The peroxide values showed that the processing condition did not produce any peroxide. The esterified blend contained 1.10 percent trans fatty acids, which were originally present in the tallow. It is concluded that interesterification of soybean oil and edible beef tallow can be used as an alternative method to hydrogenation to produce a suitable plastic fat with low levels of trans fatty acids for the manufacture of different types of margarines and fats for home uses.

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To determine the relationships between yield and its components, and to find the direct and indirect effects of yield-related traits on soybean yield, 240 genotypes were grown in the Research Station, College of Agriculture, Karaj, Iran, in 1997-98 using an augmented design. The study of correlation analysis showed that number of seeds per plant and seed yield per plant had the highest significant correlation coefficient (r=0.92). Other significant correlation coefficients were found between biomass per plant and yield (r=0.86) and between number of pods per plant and yield (r=0.67). Results of stepwise regression analysis revealed that number of seeds per plant, seed weight, and number of seeds per pod were the three major traits affecting seed yield in soybean. However, path analysis showed that only two of the three above-mentioned traits, namely, number of seeds per plant and seed weight, are quite important for soybean selection programs. Stepwise regression analysis was used again, omitting number of seeds per plant, which showed that number of pods per plant, seed weight, plant height and number of days to 90% maturity, are important contributors to yield. Path analysis, this time, revealed that the correlation effects to plant height and number of days to 90% maturity on yield is due to the indirect effects exerted through other traits. It is concluded that three traits, namely, number of seeds per plant, seed weight and number of pods per plant have notable effects on soybean seed yield.

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Iron (Fe) availability is low in calcareous soils of Iran due to high pH levels and presence of excessive amounts of CaCO₃. Overfertilization by phosphorus (P) fertilizers may also decrease Fe availability. The objective of this study was to evaluate the effects of P, Fe and their interactions on the growth and chemical composition of soybean [Glycine max (L.) Merrill] under greenhouse conditions. Treatments consisted of a factorial arrangement of P rates (0, 40, 80, 120 and 160 mg kg^-1 as KH₂PO₄) and Fe rates (0, 2.5, 5 and 10 mg kg^-1 as FeEDDHA) in a completely randomized design with four replications. Plants were grown for 8 weeks in a loamy soil, classified as Chitgar series (fine-loamy, carbonatic, thermic, Typic Calcixerepts). Results showed that P application up to 80 and Fe at 2.5 mg kg^-1 increased shoot dry matter. Phosphorus concentration, total uptake and P:Fe ratio in soybean increased by P application but decreased by Fe application. Application of Fe up to 2.5 mg kg^-1 increased dry matter but decreased it at higher rates. Concentration and total uptake of Fe increased by Fe application but decreased by P application. Interaction of P and Fe had no effect on shoot dry matter. Zinc (Zn) and copper (Cu) concentrations decreased significantly when P was added and manganese (Mn) concentration increased up to 40 mg P kg^-1 but decreased at higher rates. Iron application had no effect on soybean Zn and Cu concentrations but decreased Mn concentration at all rates. Prior to any fertilizer recommendations, it is necessary to study the effects of P, Fe and their interactions on soybean under field conditions.

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This study was conducted to evaluate the effects of four levels of irrigation (irrigation of plants after I₁ = 40, I₂ =60, I₃ = 80 , and I₄ = 100mm of evaporation from class A pan) and four plant densities(D₁ = 30, D₂ = 40, D₃ = 50 and D₄ = 60 plants/m²) on the seed yield and seed quality in three soybean cultivars(V₁=Hobit, V₂=Williams and V₃=Hill) in a split factorial design, based on the completely randomized blocks, with three replication for two years(2001 and 2002). The Irrigation treatments were assigned to the main plots, and the plant densities and cultivars to the sub plots. Results indicated that soybean seed yield was influenced by the different irrigation and plant density levels in the both years. Irrigation levels I₂ produced the highest and I₄ the lowest seed yield. It was also revealed that the plant density D₃ produced the highest and D₁ the lowest seed yields. Among the cultivars under investigation, V₂ produced the highest and V₃ the lowest seed yield . Seed oil and its protein contents both were affected significantly by the irrigation levels, plant densities and cultivars in both years. The plants receiving I₁ treatment had the highest and those having I₄, the lowest percentages of seed oil. Changes in the plant densities also affected seed oil and protein content. The plant density of D₁ caused the seeds to have the highest oil and lowest protein percentages. However, D₄ decreased oil and increased protein percentages. The highest water use efficiency was obtained from I₃ and that of the lowest value from I₁. The results also indicated that D₄ had the highest and D₁ the lowest water use efficiencies. Therefore, it could be concluded that the water use efficiency can be increased by increasing the plant density per unit area. The highest efficiency for biological and grain yield belonged to V₂ and V₁ respectively where as the lowest efficiency for those two mentioned characters belonged to V₁ and V₃, respectively. However, the treatment I₂V₂D₂ is recommended for higer the seed yield production per unit area.

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In order to investigate mineral manganese forms and their relations with plant responses, 22 soil samples from Fars province (0-20 cm) were in a greenhouse experiment filled in 3 liter pots, and soybean (Glycine max (L.) merr.,CV.Williams) was grown for 7 weeks. Chemical forms of manganese were determined in soils by warden and Reisenauer sequential extraction method (readily soluble, weakly adsorbed, carbonate bound and oxide bound extracted with Ca(No₃)₂, Ca DTPA +Na₂B₄O₇, HNO₃ and NH₂OH. HCl, respectively) after harvesting the plants. Results showed that the amount of Mn in different forms was in the following order: Carbonatic Mn >Mn Oxides >Weakly adsorbed Mn > Soluble Mn. Regression equations between soil properties and Mn forms showed a significant correlation between calcium carbonate equivalent and carbonate bound Mn. Significant correlation between Carbonate bound Mn and concentration of Mn in the aerial part of soybean showed that this fraction plays an important role in plant nutrition.

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Certain microorganisms in soil have phosphate solubilizing ability. Phosphorus has an important role in plant nutrition and N₂ fixation in legumes. The interactive effect of three phosphate solubilizing bacteria (PSB) and Bradyrhizobium japonicum on yield and N, P, K uptake and nodulation of soybean root (Glycin max L. CV. Harcor) was studied under greenhouse conditions. In greenhouse experiment treatments consisted of a factorial combination of four levels of PSB (without PSB M₀ ,Pseudomonas putida M₁ , Aeromonas hydrophila M₂ , Pseudomonas fluorescens M₃) and two levels of B.japonicum (without bacterium B₀ and with bacterium B₁) and three levels of P(P₀ = 0 , P₁=29, P₂ = 58 mg triple superphosphate/Kg soil) in a randomized complete block design with four replications. At harvest, shoot dry weight, seed weight, nodule number, dry and fresh weight of nodules and concentrations of N, P, K in shoot dry matter were measured. PSB significantly increased shoot dry weight, N, P, K concentrations in shoot, fresh and dry weight and number of root nodules. B.japonicum had positive significant effect on these parameters as well as on seed weight. Dual inoculation of plants with PSB and B.japonicum had significant effect on shoot dry weight, P and N concentrations in shoot. Increasing phosphorus levels significantly increased plant dry weight, shoot P concentration and seed weight. Highest P concentration in shoot was obtained at P₂ level but in plants inoculated with P.putida, dry weight at P₁ level was not significantly different from P₂ level.

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Thirty soybean cultivars from different maturity groups were evaluated in a randomized complete block design with four replications in Research Station of College of Agriculture at Tehran University in Karaj in 2004. The purpose was to determine genetic relationship of some important agronomic traits related to seed yield. Analysis of variance showed that there were significant differences among varieties for the traits under study, indicating the existence of genetic variation among varieties. Number of pods/plant, number of seeds/plant and 100-seed weight, all of which are considered yield components, had the highest genotypic correlation with seed yield. Using stepwise regression analysis, 85.6 % of seed yield variation was attributed to four traits, including harvest index, biological yield, protein precent and number of seeds /plant. Harvest index was more important for predicting seed yield compared to other traits based on standardized ßs. Results of path analysis showed that the harvest index and protein precentage had the highest and lowest direct and positive effect (p=0.536), (p=0.008), respectively. Therefore, harvest index may be considered as a selection criteria to improve seed yield in breeding programs. Results of factor analysis showed five independent factors accounted for 80.2 % of total variations in data. The first principle determined 28.2 % of total variation and was designated as phenologic factor.

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  A factorial experiment, based on RCB design, with three replications was conducted to evaluate the effects of rhizobial inoculation, urea, and weeds on soybean performance in the field. The factors under study consisted of inoculation and non-inoculation, three levels of 0, 150, and 300 kg/ha urea, and weed-control and weed-infestation. Results showed that weed-control, inoculation and urea application increased biological and seed yield. The highest effect on yield was due to weed control, followed by inoculation and urea application. Inoculation, weed-control and urea application of 300 kg/ha enhanced protein percentage in soybean grains. In this case, inoculation had the highest effect on protein percentage, followed by urea application and weed control. In contrast, only weed-control significantly increased seed oil percentage. Seed filling rate increased as a result of inoculation, but, seed filling duration was not affected by inoculation. Weed-control improved seed filling rate and duration. Urea application induced seed filling duration, but had not any effect on seed filling rate.

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Concerning the effects of increasing the species number on the maintenance of ecological stability and agricultural ecosystems sustainability, two field studies were conducted in 2002 and 2003 to evaluate the effects of plant population densities on soybean and sorghum intercropping at the Research Center, the Faculty of Agriculture, Tabriz University, Tabriz, Iran. Cultural pattern was an additive series. The factorial set of treatments was arranged within a randomized complete block design with three replications. The first factor comprised soybean densities of 20, 30, 40, and 50 plants/m², and the second factor consisted of sorghum densities of 0, 4, 8, and 12 plants/m². The results indicated that both soybean and sorghum yields were significantly affected by soybean and sorghum densities. Soybean yield increased as density increased up to 40 plants/m², and then decreased with increasing soybean density from 40 to 50 plants/m². With increasing soybean density, sorghum yield was decreased. Sorghum and soybean yields, respectively, increased and decreased as sorghum density increased. On the other hand, Soybean and sorghum densities of 20:4 (1.6) and 50:12 (0.8) had the highest and the lowest LER (Land Equivalent Ratio), respectively. It was, therefore, concluded that intercropping of Soybean and sorghum, is more advantageous, compared to their pure cultivation in the same conditions.

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Somatic embryogenesis is affected by several factors. In this research project, we studied the effect of explant size, wounding and desiccation treatments on somatic embryogenesis and their conversion into plantlet among three genotypes of soybean. The explants were sampled from immature embryos of soybean in three different sizes (3, 5 & 7 mm) with wounding treatment on half of each, and then were cultured on the somatic embryogenesis medium. In order to determine desiccation effect on conversion amount of embryos into plantlets, the produced embryos were affected by three levels of desiccation treatments (2, 4 & 6 days). The increase ratio of callus mean weight, percentage of embryogenic calli, embryo number per explant and percentage of embryo conversion to plantlet were used for treatment evaluation. Variance analysis of the data showed significant differences (P<0.01) between treatments regarding the variables. The results indicated that BP was a superior genotype with embryogenic capability (24.19 %) and the best explant size for somatic embryogenesis was immature embryo with 3 mm length. The six day desiccation treatment caused highest percentage of embryo conversion into plantlet (74.7 %). Wounding increased callus production on explants and number of embryos per explant (20.28), but it did not show any significant effect on percentage of embryogenic calli. Germinated somatic embryos were transferred to pots containing peat-moss. Somatic embryogenesis is an efficient method for the plant regeneration and genetic transformation. However, this method still offers low percentages of plant regeneration, and is perhaps related to the maturation process and high morphological abnormalities of the matured embryos. This study aimed to find some solutions for soybean somatic embryogenesis problems.

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Deficit irrigation is one of the irrigation management methods that is used to increase Water Use Efficiency. Considering the internal plant adaptability characteristic to water shortage, Partial Root Drying method has been introduced in recent years. In this field research improvement of Water Use Efficiency for Soybean was determined. This experiment which was conducted at four furrow irrigation treatments at the Research Field of Tehran University in Karaj in 2008, consists of full irrigation (100% soil moisture deficit compensation), conventional deficit irrigation at 50 and 75 percent soil moisture deficit compensation and Partial Root Drying at 50 percent soil moisture deficit compensation with three replications. The amounts of irrigation used were exactly compensation level (negligible loss). Results indicated that Water Use Efficiency according to Duncan's Multiple Range Test at the five percent level of probability there was a significant difference between partial root drying treatment (PRD50%) and conventional deficit irrigation treatment at fifty percent soil moisture deficit compensation (DI50%),. Water Use Efficiency in PRD50% compared with DI50%, DI75% and full irrigation increased by 48.3%, 61.9% and 70.1% respectively.

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Modification of irrigation scheduling and management improvement of irrigation systems are two essential factors that have significant impact on agricultural water use efficiency. Therefore, a field experiment was conducted to evaluate the effect of tape drip irrigation (T) and furrow irrigation systems (S) under different irrigation regimes on yield and yield components of soybean in growing season of 2006-2007 at Gorgan Agricultural Research Station in north part of Iran. The experiment was laid out in a split plot design in a randomized complete form where each treatment was replicated three times. The main plots were irrigation systems of tape and furrow, and three irrigation regimes 100 (I100) , 75 (I75) and 50 (I50) percent of total irrigation requirement were chosen as secondary plots. Results showed that thousandgrain weight (gr) and plant height (cm) in furrow irrigation were significantly more than the tape drip irrigation method. Also significant differences between different irrigation regimes in terms of plant height, node numbers and yield were observed. So, I100 and I50 had highest and lowest values, respectively. In terms of irrigation system, 63 percent of water consumption was reduced in tape drip irrigation method. Also, the results indicated that higher and lower water use efficiencies were obtained from tape drip irrigation method with I50 treatment (1.09 kg m-3) and furrow irrigation with I100 treatment (0.50 kg m3), respectively.

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The pattern of root distribution in layered soils is one of the significant issues in the calculations of soil water and irrigation management and planning. The objective of this study was to determine the pattern of root distribution of soybean in layered soils and its effect on water uptake. The research was conducted in a completely randomized design with 15 treatments consisting of three different textures of soil (light, heavy, and medium) in four replications. The pattern of root distribution was monitored by the sampling of columns at the end of the growth period of the soybean. It was observed that the presence of the layer with medium texture has led to better plant development and growth after comparing the treatments in terms of plant growth. In general, root length density decreased with increasing soil depth, except in cases where there were different layers of soil, and root length density takes place in the following order: root length density in layers with medium texture≥ heavy texture≥ light texture. The rate of root water uptake rate was highest in the sandy layers, intermediate in clay, and lowest in loamy texture. Also, the rate of root water uptake rate increased significantly with increasing depth regardless of treatments. It can be concluded that the pattern of root distribution and plant growth is significantly affected by soil texture and its stratification.