Iranian Journal of Soil Research
Year:2007 | Volume:21 | Issue:1|Papers Count:15

Zinc deficiency, which usually appears as chlorate pattern on new growth, is considered one of the most prominent nutritional disorders in citrus trees. This study was conducted to evaluate the effects of the rates and methods of zinc application on yield and quality of citrus fruits. The experiment was conducted at Sari Kotra - Horticultural Research Station in Mazandaran province during 1999- 2002 period. A complete randomized block design was used with ten treatments and four replications. Treatments included:T0- controls, T1- 50g Zn per tree as-broadcast application, T2-100g Zn per tree as broadcast application, T3-200g Zn per tree as broad cast application, T4- 50 g Zn per tree as banding application, T5- 100g Zn per tree as banding application, T6-200g Zn per tree as banding application, T7 foliar application with concentration of 2kg ZnSO4 in 1000 lit water, T8- foliar application with concentration of 3kg ZnSO4 in 1000 lit water, T9- foliar application with concentration of 4kg ZnSO4 in 1000 lit water. Results of experiment with Satsuma mandarins showed that zinc application increase fruit yield and also leaf zinc concentration significantly and the highest yield and leaf zinc concentration was associated with treatment T9. Also, effect of the rates and methods of zinc sulfate application on the average fruit weight was significant and the highest average fruit weight was obtained from foliar application with concentration of 3kg ZnSO4 in 1000 lit water that was almost 23 percent more than the control. Application of zinc sulfate increased fruit diameter significantly compared with the control. The highest diameter of peel was obtained from treatment T5 that increased almost 17 percent over the control. The effect of zinc sulfate application on shelf life of Satsuma mandarin showed that the lowest and highest weight reduction was obtained in treatment T6 and treatment T5, respectively.

In order to evaluate the effects of plant density and nitrogen levels on grain yield and dry matter remobilization in corn, an experiment was conducted in Ardabil Agricultural Research Station in 2005, using a randomized complete block design as split plot with three replications. Three nitrogen levels (0, 75, and 150 kg.ha-1) were in the main plot, and the three plant densities (7, 9, and 11 plants.m-2) in sub plots. The result showed that dry matter remobilization increased with increasing plant density and decreased with increasing nitrogen levels. This conclusion was obtained also in dry matter remobilization from stem. The rate of remobilization contribution in grain yield was significantly affected by plant density and nitrogen levels interaction at 1% level probability. Means comparisons showed that the rate of remobilization contribution in grain yield increased with increasing plant density and decreasing nitrogen levels. Maximum the rate of remobilization contribution in grain yield occurred at the highest plant density with nitrogen at zero level. This conclusion was obtained also in dry matter remobilization from stem.

Zinc deficiency in rice has been reported from all over the world, especially in calcareous soils. One of the corrective methods is application of zinc fertilizers. Considering calcareous condition of paddy soils in Fars Province and in order to compare soil application of zinc sulfate with immersing of seedling roots in zinc oxide suspension on yield and chemical composition of rice (CV Ghasrodashti), two experiments were conducted during two years. Each test was performed in the form of RCB design with four replications.. In the first experiment, the effect of soil application of ZnSO4.7H2O was studied at the rates of 0, 5, 10 and 15 kg Zn/ha, while in the second experiment, immersing for 30 minutes of seedling roots in suspension containing 0, 1 and 2 percent zinc oxide, was tested before transplanting. The results showed that application of ZnSO4. 7H2O in the first year had significant effect (at 5% level) on the number of grain per spike, grain P Content and the Zn content of husk, but was highly significant effect (at 1% level) on grain protein content. In the second year, application of different rates of zinc sulfate had a significant effect (5%) on N, K and number of grain per spike but highly significant effect (1%) on Mn contents of rice grain. The effect of immersing in suspension of zinc oxide in the first year of experiment had significant effect (5%) on zinc and the protein content of grain but highly significant effect (1%) on N content of grain. In the second year the effect of zinc oxide on grain yield, N, K and protein content of grain was significant (5%). The ANOV of 2 years data showed that the effect of ZnSO4.7H2O on grain yield, number of grain per spike, N and P was significant (5%) but was highly significant (1%) on protein content of grain. The effect of zinc oxide on 1000 kernel weight and protein content were significant at 5 and 1% level, respectively. The final conclusion is that, application of Zn in paddy fields of Fars province is essential, but with regard to the fertilizer source and amounts, further study is needed.

The data on soils from various regions of East Azarbyjan indicates that a very low organic matter contents is the general case. On the other hand, a considerable amount of chemical fertilizers that are applied in the onion conventional farms are normally used along with sand, which not only increases production costs but also may damage soils physical properties.Organic fertilizers such as animal manure, municipal solid waste composts and vermicomposts are quite rich in plant nutrients and their application for agricultural purposes leads to sustainable food production. A randomized complete block experiment was carried out with 10 treatments in three replications at two locations, namely Khosrowshahr and Bonab during two growing seasons in 2003 and 2004 in order to evaluate the effect of various sources of organic fertilizers on the yield and quality of Azarshahr variety of red onions (Allium cepa L). Treatments were animal (domestic) manure at three levels (10, 15, and 20 t/ha), municipal compost at three levels (5, 10, and 15 t/ha), vermicompost at three rates (2,4, and 6 t/ha), and a control plot in which nitrogen, phosphorus, and potassium were used based on soil analysis and sand as seed cover. The highest yield (71.1 t/ha) was obtained with application of 6 tons of vermicompost per hectare. Also, the highest yields were obtained at Khosrowshahr location in both years. The highest nitrate concentration (155mg NO3 /kg of fresh wt.) was obtained with the control treatment and the lowest (98mg NO3 /kg of fresh wt) were in vermicompost treatments. The lowest rate of onion spoilage (12%) was obtained in different rates of animal manure. Also, the highest concentration of ascorbic acid (13.5 mg/100g of fresh onion bulbs) was obtained in vermicompost treatments. The highest level of protein (1.49%) in onions was obtained with application of6 tons vermicompost per hectare. The lowest rate of onion pungency was obtained with application of 20 tons animal manure per hectare.

The distribution of cadmium (Cd), zinc (Zn) and lead (Pb) in two clay and sandy soils were examined using soil column leaching experiments. Glass tubes, 4.8 cm diameter and 40 cm long were packed to 30 cm depth. The columns were irrigated with spiked sewage containing 8.5 mg I-1 Zn and Cd and 170 mg I-1 Pb for 30 days. Similar column was packed with sandy soil and irrigated with sewage alone. At the end of leaching experiments, soil columns were cut into three layers each being 1 cm depths. The fractionation of above elements was investigated using sequestration extraction method. The elements were fractionated into different forms: exchangeable (F1), bound to carbonate (F2), bound to Mn oxides (F3), bound to Fe oxides (F4), bound to organic matter (F5), and residual (F6). Application of spiked sewage significantly increased concentration of Cd, Zn and Pb in surface layer (0-1 cm). Results showed that in two soils Cd was mainly in F2 fraction. In two soils Zn was mainly in F6 fraction. Lead in sandy soil was mainly in F2 fraction and in clay soil was in F4 fraction. The fractionation of these elements indicated that they are mainly in nonlabile forms. Thus, in short period, the possibility of contamination of groundwater with these elements is low.

Copper (Cu) deficiency is common in calcareous soils of Fars province. Organic matter (OM) and moisture regime (MR) are among the most influential factors affecting Cu behavior in soils. The present experiment was a 2x2x20 factorial arranged in a completely randomized design with two wheat straw application rates (0 and 2%), two MR levels (20% moisture by weight and waterlogging) and 20 calcareous soils. The soils were incubated under laboratory conditions and chemical forms of Cu were determined after 60 days of incubation. Results showed that the amounts of exchangeable and water soluble Cu were not detectable. Specifically adsorbed Cu was higher in unsaturated soils than saturated treatments. Application of OM under waterlogged condition had no significant effect on the amounts of Cu bounds to carbonate, Mn-oxides, amorphous, and crystalline Fe oxides. Waterlogging increased the carbonate and amorphous Fe oxides Cu but decreased that of crystalline Fe oxides. Organic Cu was more in waterlogged soils compared to unsaturated soils. Addition of OM increased organic Cu but decreased residual Cu under waterlogging. Also, negative correlations were obtained between these two forms under waterlogging. Application of OM to waterlogged soils increased the specifically adsorbed Cu and decreased that of residual. This demonstrates that OM treatment before planting, might be considered as a useful practice for paddy fields. Due to the fact that addition of such a straw rate to soils under field condition is not economically feasible, therefore, evaluation of lower rates of OM is highly recommended.

Salinity of soil and water is a serious problem affecting the growth and performance of plants in Iran. A pot experiment was conducted to asses the physiological effects of NaCl salinity on the olive trees growth. Four rates of NaCl concentrations (0, 50, 100, 150 mM) factorially combined with three olive trees cultivars. The experiment was based on completely randomized design with four replications. The plants were cut and vegetative characteristics such as leaf area, fresh and dry weight of leaves and the concentration of Na and K were measured at the end of the experiment. The rates of both photosynthesis (Pn) and transpiration were recorded during the growth of the plants using a photosynthesis meter (IRGA). The results showed that the growth of the plants in terms of leaf area, height and leaf fresh weight reduced as the salinity increased. However, the growth reduction of Manzanilla and Zard cultivars was more pronounced as the salinity increased. The rate of Pn tended to be lower in the high salinity treatments in all cultivars. The highest (1.8 mmol.m-2s-1) and lowest (1.0 mmol.m-2s-1) photosynthesis rate at high salinity were observed in Mission and Zard, respectively. Symptoms of toxicity as marginal necrosis on the leaves caused by salinity were initiated two months after applying salinity in Manzanilla and Zard cultivars. The concentration of Na in the leaves at high salinity (150mM) was 78% (Mission) and 83% (Zard and Manzanilla) compared with their controls. A positive relationship was found between K/Na and Pn rate, suggesting that the reduction in K concentration either by low uptake or the reduction of K/Na ratiohas a remarkable effect on Pn rate. Reduction in growth of olive trees in saline conditions was a result of the reduction in leaf area, K/Na and Pn rate. It can be concluded that Mission can tolerate up to EC value of 15 dS.m-1 and 150mM NaCl in seedling stage.

Agrobacterium rhizogenes induces the formation of root hairs in dicotyledons by transferring a piece of DNA called T-DNA from its Ri plasmid into the genome of the host plant. Root hairs produced as such display two major characteristics, one being a fast rate of growth, and the other genetic stability. A very interesting characteristic of induced root hairs is their potential to synthesize growth hormones and to survive in synthetic culture media free from shoots. Such a capability has made it possible to multiply Arbescular mycorrhizal fungi, an, obligate symbiotic organism on plant roots on industrial scales. Currently, simultaneous culturing of induced root hairs and surface sterilized spores of Arbescular mycorrhizal fungi is the most successful and the most economical method of producing Arbescular mycorrhizal fungi worldwide. This investigation was carried out with the objective of developing and expanding the method of production of induced root hairs as one of the two components of in situ reproduction of Arbescular mycorrhizal fungi. Induced root hairs were prepared using two strains of Agrobacterium rhizogenes, A4V and A4S on five different plant tissues, namely, carrot slices, leaves from potato and bean plants and orange trees, and the sub-cotyledon axis of chickpea seedlings. A culture of bacteria grown on YMA medium for 48 hours was used for inoculating the subcotyledon axis of chickpea seedlings, while a bacterial suspension with population densities of 107 cells/ml prepared in LB medium followed by transferring to MS culture was used for inoculating the other four plant tissues. Induced root hairs emerged on potato and bean leaf tissues and on the sub-cotyledon axis of chickpea seedlings. In order to prevent bacterial contaminations, the induced roots were grown in an MS medium that contained 500 mg/liter of cephotaxim. The investigation indicates that the different plant tissues show different levels of response to the inoculation with Agrobacterium rhizogenes, so that the chickpea tissue appeared to be the best while the leaves of orange tree turned out to be the least effective tissue for root hair induction.

Among prokaryotes, there are some soil bacteria called Rhizobia that are very important owing to their N2 fixation ability in legumes. The sequence between two 168 and 238 fragments of rDNA genes complex is called 16S- 23S rDNA IGS. It differs by size and nucleotide order, therefore, it is very useful for grouping of rhizobial strains. In this research 16S-23S IGS PCRRFLP and Plasmid Profile (modified Eckhardt method) grouped 52 superior strains which were found as plant growth promoting Rhizobacteria (PGPR). For cluster analysis, phylip version 3.6a3 software was used. The results show that the16S-23S IGS fragments of different rhizobial strains are very diversified in terms of size (600.,1486 bp), and the number of IGS fragment differs from 1 to 3 copies. Based on 16S-23S IGS PCR-RFLP method, all 52 rhizobial strains were located in 46 groups, of which 11 groups had 70% similarity. By this method all strains (77%) except 12 strains (Bj53, Bj54; Rlv27, Rlv28; Rlv23, Rlv24; Rlp16, Rlp17; Sm10, Sm11, Sm12, and Sm13) were separated into different groups. Therefore, the mentioned method is very reliable and practical, besides being simple and having few laboratory requirements (in comparison with other molecular methods). In this research, The grouping based on Plasmid Profile of different rhizobial strains agrees with the results of IGS-RFLP to some extent, for example: Bj53, Bj54; Rlv23, Rlv24 also Rlpl6, Rlp17 and Sm11, Sm12, 5mB in both methods were completely similar and were located in separate cluster groups.

Success or failure in legume establishment is dependent on soil chemical, physical and biotic properties and also crop management. The objectives of this investigation were to evaluate the indigenous population and nodulation of Sinorhizobium meliloti and important limiting factors for nodulation of alfalfa roots in Isfahan, central Iran. Soil samples were taken from different fields of alfalfa in order to determine soil physico-chemical properties and numbers of S. meliloti. The size of these populations depend on both environmental and soil factors and generally ranges from 1.5x102 to 14.7x103 cells of S. meliloti g-1 soil. A significantly higher number of S. meliloti was present in Shahreza and Daran sites. The results also showed a significantly positive effect of soil potassium "and soil phosphorus at p£0.01 and negative effect of soil bulk density at p£0.05 on the alfalfa nodulation score and soil rhizobia numbers. Factors such as undesirable environmental condition (temperature, water supply), soil properties, improper management of alfalfa farms, excessive cutting and grazing, and lack of suitable rhizobia in soils were among the factors limiting alfalfa nodulation.

Association between AM fungi and crop species is important because of effect on growth and uptake of mineral nutrients. Limited studies have been undertaken on this association in waterlogged species in general and rice in particular. In this work, the effect of inoculation with two species of AM fungi, namely, Glomus mosseae and Glomus intraradices on growth and phosphorus and potassium uptake was investigated in two cultivars of rice (Oryza sativa L.) cv. Tarom Hashemi and Fajr. In spite of a slight reduction in above-groung growth in colonized plants, root growth and phosphorus uptake were significantly stimulated. Interestingly, the positive response of growth and phosphorus uptake to colonization was observed only in Tarom Hashemi that had higher susceptibility to phosphorus deficiency and lacked induction of root growth under -P conditions. In another experiment using rhizobox technique, it was shown that AM colonization resulted in a significant increase of weight, length and branching of roots. It was also shown that, rhizosphere pH in inoculated and P-deficient plants was lowered up to 1.68 units, could have an important role in dissolving and increasing availability of nutrients such as phosphorus and zinc in soil grown plants. It was demonstrated that, the positive effect of mycorrhizal association on growth and uptake of nutrients depends highly on AM species, plant growth and nutritional status. The positive effect of inoculation is attributable to enhancement of root surface area and reduction of rhizosphere pH.

This study was conducted on a Typic Haplocalcids, coarse-loamy over loamy skeletal carbonatic, (hyper) thermic soil (alluvium-derived) at the Gareh Bygone Plain Experiment Station, 200 km to the south-east of Shiraz, Iran. Four composite samples of surface soil (0-20 cm) were collected from: (1) a control site without floodwater spreading. (2) The first two sedimentation basins (SBs) of the Bisheh Zardl artificial recharge of groundwater (ARG) system, where Eucalyptus camaldulensis had been planted in Jan.-Feb. 1983(EUCA). (3) SB2 and SB3 of the Rahim Abad, which formed the third treatment and were under native pasture and irrigated with floodwater. (4) Farm fields located at south-west of Bisheh Zard formed the fourth treatment (AF AR). These samples were used for enumeration of total bacteria and nitrifying bacteria by the Most Probable Number (MPN) method. It was observed that, in comparison with the control, the total population of the soil bacteria increased by about 34 and 24 fold, respectively, at the sites with Eucalyptus camaldulensis and native pasture along with floodwater spreadingl. Two former sites had about 6 and 4 fold more microorganisms as compared with the farm fields. An increase in moisture and substrate supply for the biotic community at these sites, are the two major determinants. Amounts of organic matter in the site planted with E. camaldulensis, had increased by about 2-fold in comparison with control and farm fields (1.40% versus 0.63% and 0.73%, respectively). The number of ammonium oxidizers in EUCA and AFAR sites increased significantly.The number of both ammonium and nitrite oxidizers (nitrifiers) was more in the site with E. camaldulensis than the other sites. It may be concluded that cultivation of E. camaldulensis stimulates the growth and activity of nitrifier bacteria and subsequently, nitrification.

The purpose of this study was to determine optimum values of main factors affecting uniformity (i.e. water pressure, sprinklers shape and spacing) in semi-portable sprinkler irrigation system under different wind speed conditions. The standard ISO 7749/2 was taken into account to determine uniformity. The field test was conducted under single sprinkler condition in south-east region of Khouzestan Province. Results showed that uniformity decreased as wind speed and working pressure increased. According to the results of the investigations, in order to obtain acceptable uniformity (80%), the most suitable sprinkler spacing is 25 x25m with square-shaped when wind speed are higher than 2m.s-1. Uniformity decreased from 80 percent when wind speed exceeded 15 km.hr-1. Therefore, sprinkler irrigation is not recommended in this condition.

Cotton, as one of the most important industrial crops, grows in different climatic conditions. Determination of cotton water requirements (ET) is important in the light of frequent water shortage and drought in the country and inadequate precipitation during growing season. This investigation was conducted in Kashmar Research Station, Using a drainage type Lysimeter (2 * 2 * 1.5m) surrounded by 40 * 40m cotton crop to eliminate the oasis effects such as heat transfer. Before planting, soil samples were collected for chemical and physical analysis and soil moisture characteristics such as FC, PWP were determined .Fertilizers were applied according to Soil and Water Research Institute recommendations. Irrigations were done when readily available soil water was depleted. The amount of applied water was calculated according to the below equation so that 10% drainage water were collected. Inflow and drainage water were measured. Evapotranspiration was calculated based on soil water balance equation as below: ETc= I + p±dw- D, where: ETc = Evapotranspiration (mm), P = precipitation (mm), I = irrigation depth (mm), D=Drainage water depth (mm) and dw= soil moisture variations between two irrigations that was assumed (0) zero. Results showed that mean cotton evapotranspiration for four years of experiment was equal to 1183mm, while this was predicted 1000.4 mm according to Penman- Monteith equation.

The increasing demand for water has increased the awareness towards application of the artificial recharge of groundwater. Artificial recharge is a method of storing water underground in times of water surplus to meet the demand in the times of shortage. The objective of this research was to evaluate the efficiency of Bagh-e-Sorkh floodwater spreading and artificial recharge system on water table stage, and to understand the role of this system on groundwater quality in the area. For evaluation of these projects on the discharge of wells and qunats, the aquifer of the south of Shahreza Plain was selected. The area that affects of this aquifer is about 1570 km2. In this plain, data of 20 observation wells and discharge of some important qunats for 5 years before the construction (1365-1381) were analyzed. The results show very good effect on the ground water level and discharge of quants. Annual fluctuation of water level shows rise in groundwater table after storing water by these projects in spite of an increase in exploitation. The first and second time flooding occurred in 1371 and 1377 and seems to have had the highest influence on raising the groundwater level. Reduction of infiltration, evaporation from a floodwater spreading systems, overuse of groundwater resources by farmers, particularly in dry seasons, and the occurrence of recent severe drought period entails the least efficiency of this system.