Iranian Journal of Soil Research
Year:2004 | Volume:18 | Issue:2|Papers Count:19

A greenhouse experiment was conducted to study the effect of manganese (Mn) fertilizer on soybean yield and to determinate soil Mn critical level in some selected soils of Mazandaran Province. The soils were collected from 20 sites in the east of Mazandaran and had a wide range of CaCO3 (5 - 34 %) and DTPA extractable Mn of 2 to 9 mg/kg. In a randomized complete block design with three replications, 0 and 30 mg Mn/kg as manganese sulphate were applied to 10 kg soils in each pot. Soybean seeds (CV. Pershing) were planted at the rate of 7 seeds / pot and then thinned to 3 stands after 10 days. The growth period was 8 weeks. The aerial parts of plants were harvested at the end of growth period and their dry matter weight, nutrient concentrations and uptakes were used as plant responses. The results indicated that manganese sulphate application significantly increased the dry matter from 16.6 to 20.3 g/pot. Manganese application also increased Mn concentration and uptake by plants. Manganese critical level in these soils were calculated to be 3.89 and 4.1 mg/kg with Mitcherlich-Bray and Cate-Nelson methods, respectively for obtaining 85% relative yields and, 4.7 and 4.9 mg/kg for obtaining 90% relative yields. A comparison between the values obtained shows that both methods provide similar results.

This study was carried out on six-year-old date palms (c.v Piarom) in Hormozgan Province, Iran, during 1994-2001. In this study, two volumes of water and two irrigation systems were compared in a randomized complete block design (RCBD) in a factorial arrangement in three replications. Each replication consisted of four date palm trees with following four treatments: A1= drip and A2= surface irrigation method, B1= water use based on 75%, and B2= 100% evaporation from class A pan. Water use was calculated based on ETP class A pan method by following formulas: ETo= Ep ×Kp, ETc= ETo × Kc, I=ETc × S / ŋ, in which ETo = Reference evapotranspiration, Ep = Pan evaporation, Kp = Pan coefficient, Kc = crop coefficient, I = Irrigation requirement, S = surface, ETc = Crop evapotranspiration, and Ŋ= efficiency of irrigation system. Irrigation interval in drip irrigation was two days and for surface irrigation it was weekly. The results showed that there were no significant effects of treatments on the yield, and quality of fruit, such as pH, TSS, total sugar, reduced sugar, sucrose, moisture percentage, and dry matter percentage. The results of the study showed that water requirement in treatments of drip irrigation based on 75% evaporation of class A pan (Ep), drip irrigation based on 100% Ep, surface irrigation based on 75% Ep, and surface irrigation based on 100% Ep were equal to 23.7, 42.65, 57.46, 100.45 m3/tree/year, respectively. Also the results showed no significant effects of treatments on the yield and quality of fruit, except for titratable acidity that was significant (P<0.01). Therefore, due to many advantages such as more efficient use of water, low cost, easy to schedule and manage, and easy to automate, drip irrigation is recommended as the best irrigation method for date palm plantation in southern Iran.

Iron chlorosis is considered to be one of the most important nutritional disorders in citrus trees, particularly in calcareous soils that seriously reduce yield and fruit quality. Selection of Fe-efficient rootstocks is one of the important approaches to prevent this nutritional problem. A field experiment was carried out at Jahrom Agricultural Research Station, Iran, to study 4 resistant rootstocks including: Macrophylla (Citrus macrophylla wester), Volkamer lemon (Citrus volkameriana), and Sour orange (Citrus autantium) and Sour lime (Citrus aurantifolia Swing) and scions including: Valencia orange, Washington navel orange, Jahrom local orange and red pulp orange (Moro). Also the effects of Sequestrene 138 Fe in three levels 0(control), 5 and 10 g/tree were compared. The Macrophylla and Sour orange rootstocks had the best positive and significant effects in increasing the scions, leaf chlorophyll index at 1% statistical level. Macrophylla also had the highest iron absorption. The interaction between rootstocks and Sequestrene 138 Fe showed that the application of Sequestrene 138 Fe levels on Macrophylla rootstock did not have a significant effect on leaf chlorophyll index at 1% statistical level. Therefore, Macrophylla had high potential in increasing scions leaf chlorophyll index without any use of Sequestrene 138 Fe as fertilizer. Sour orange had lower iron absorption than other rootstocks, but significantly increased scions leaf chlorophyll index. In contrast, sour lime with high potential for iron absorption had little effect on scions leaf chlorophyll index. This not only clearly showed the effect of rootstocks on scions leaf iron chlorosis Paradox, but also indicated that the effectiveness of rootstock in resisting iron chlorosis is related to mechanisms other than the extent of iron absorption by the roots. Macrophylla significantly increased iron, zinc, manganese and copper absorption in comparison with other rootstocks at 1% statistical level. Moreover, it absorbed the highest rates of phosphorus and potassium and a favorable rate of nitrogen. This high absorption potential of Macrophylla put it in the group of effective rootstocks for Jahrom. The results of the experiment also demonstrated the significant difference between graft varieties on resistance against iron chlorosis, i.e., the navel and local oranges had high chlorophyll index irrespective of the rootstock varieties. In contrast, the scions like red pulp and Valencia orange had lower chlorophyll index and were affected by the rootstock varieties more than others. For example, in comparison with sour lime, the Macrophylla rootstock increased red pulps orange (Moro) leaf chlorophyll index by about 21 percent.

A major requirement in utilizing elemental sulfur to lower soil pH is the presence and activity of sulfur oxidizing bacteria (especially the Thiobacilli) in the soils. The beneficial effects of sulfur application along with Thiobacillus bacteria for soil reclamation and improvement of soil nutrient availability have been demonstrated in various fields as well as in greenhouse studies. In all such investigations, either pure cultures of Thiobacillus suspension or Thiobacillus bearing soils were utilized as inoculants, neither of which is applicable on large scale. On the other hand, the acid produced as a result of the oxidation of the sulfur material during the growth cycle or long-term maintenance phase of Thiobacillus would cause limitation on their growth and sharp declines in their population densities. The present research was aimed at the development of a carrier, suitable for a long-term maintenance of Thiobacillus bacteria as well as a source of inoculants to be used in the greenhouse and field experiments. Several easily available, inexpensive materials that are capable of sustaining the Thiobacilli were selected and some of their physical and chemical properties were measured. Then, these materials were mixed in different ratios and 6 carriers were selected. After sterilizing them, 100 ml Thiobacilli suspension was added to the carriers. The surviving abilities of the bacteria in various carriers were tested using a completely randomized split-split-plot design with 12 treatments, 8 sampling times, and 3 replications. Colony count and pH measurements were made by taking samples at 0, 14, 30, 60, 90, 120, 150 and 180 days intervals after the start of the experiment. The effect of all treatments on the carrier pH and bacterial population measured at constant time intervals during a 6-month period for different materials showed significant differences (1% level). At these time intervals, the pH values were higher at 4 oC than at 25 oC, but bacterial population were higher at 25 oC then at 4 oC. Carrier 3 contained the highest number of bacteria at 25oC while at 4oC it did not significantly differ from carriers 2, 4, and 5 in this respect. Carrier 3 maintained a large population of bacteria for a longer period of time, and, in contrast to the other carriers, it contained a larger population during the 6-month trial at 25oC than at 4oC. Therefore, it was selected as the superior carrier. Carrier 6 showed the lowest numbers of bacteria at both temperatures and, consequently had the lowest rank.

In this field research, the effect of seven rhizobium inocula on growth and yield of fababean was examined in Bayekala Station of Mazandaran Province. The design was randomized complete block design, with treatments which included a control, nitrogen fertilizer (100 and 200 kg N per ha) and seven rhizobium inocula in four replications. Four inocula included bacteria originally isolated from Mazandaran and three from Gilan, Lorestan, and Khuzestan Provinces (Rh1-Rh7). Plants were harvested in two stages, one at flowering stage and the other at the end of the growth period. The results revealed that inoculum with Khuzestan strain (Rh6) had the greatest effect on seed yield and N-uptake by increasing 17.5% and 35%, respectively, over control. All of the inocula increased nodulation score over control. It is concluded that the rhizobium isolated from Khuzestan was the best strain as inocula to be used in Mazandaran. Further experiments should be conducted in farmers fields before large scale recommendations can be made.

A randomized complete block factorial experiment was run with four replications during 2000–2001, in Neka, Mazandaran, to evaluate the combined effects of irrigation methods (drip vs. surface) with balanced fertilization on the yield and quality of citrus. The treatments included two methods of irrigation (A: drip and B: surface) and two fertilizer combinations (T1 = The control, consisting of two split applications of 0.75 kg Urea/tree each time and T2 = balanced fertilization based on the chemical analysis of the leaves of high yielding orange trees). Leaf nutrient concentration, fruit yield, average values for fruit weight and diameter, fruit juice acidity, total soluble solids, and water use per kg of the fruit were used as the response indices for the various treatments. The results showed that balanced fertilization combined with drip irrigation significantly increased the fruit yields. The average values for the fruit yield increased from 171.6 kg/tree for surface irrigation to 186.7 kg for drip irrigation. Water use efficiency increased from 5.5 kg/m3 in surface irrigation to 8.5 kg/ m3 for drip irrigation. Balanced fertilization along with drip irrigation significantly improved crop yields; and, in addition, it increased the concentrations of leaf nutrients including those of phosphorus, magnesium and manganese. The highest yield of 41.07 tons/ha was obtained with a combination of balanced fertilization and drip irrigation.

Growing commercial crops in dry continental climate and saline condition is a real challenge . Irrigation is essential if the crop is to generate an economic yield ,but irrigation combined with high evaporation during the summer can increase soil salinity. Occurrence of aridity and increasing area of saline land in arid and semiarid zone causes a lot of problems such as water deficit and plant stress. Therefore increasing of water use efficiency (WUE) in this area is necessary. An experiment was conducted with the aim of increasing water use efficiency (WUE) of saline water on maize and cotton in Varamin and Kashmar. The experiment was arranged in complete randomized block design in Varamin and strip plot design in Kashmar  with three replications and two treatments i.e. Fixed Furrow Irrigation (FFI) and Conventional Furrow Irrigation (CFI).Data showed that there was no significant difference between treatments in dry weight of stems, leaves, ear and dry weight of above ground plant parts, and in spite of decreased water use in FFI treatment, yield and its components did not decrease significantly .WUE was 0.77 kg.m-3 in (CFI) while it was 1.37 kg.m-3 in (FFI) in Varamin. As a result, the WUE in (FFI) was 1.77 times as (CFI). Data in Kashmar showed that the cotton yield was increased from 3007 kg.ha-1 to 3577 kg.ha-1 in (FFI) The amount of water used in (FFI) was 66.7 percent of (CFI) treatment. WUE in (FFI) was 1.76 times as (CFI).

Boron (B) toxicity due to the application of saline waters is one of the most important limiting factors for corn (Zea mays L.) production in southern Iran. In recent years, some nutrients such as zinc (Zn) have been used for reducing the adverse effects of B toxicity. A greenhouse experiment was conducted to determine the effect of Zn on corn resistance to B toxicity. Treatments consisted of seven levels of B (0, 2.5, 5, 10, 20, 40, and 80 µg g-1 as boric acid) and three levels of Zn (0, 5, and 10 µg Zn g-1 soil as ZnSO4). The statistical design was completely randomized factorial with three replicates. Boron application reduced plant height and shoot dry matter of corn. Low B levels increased whereas high B levels decreased uptake and apparent recovery of B. Application of B increased B concentration in plant. Low and moderate B levels increased but high B levels decreased Zn concentration and uptake. Zinc application increased plant height, shoot dry matter and Zn uptake and concentration in the plant tissue, and also decreased B concentration and affected B uptake. The results show that in soils with high levels of B, the application of zinc sulfate may reduce the adverse effects of B toxicity and, consequently, increase corn yield.

Three topsoils were selected from the different farm areas of Karaj region having CEC of 6.2, 13.6 and 18.8 cmol+/kg-1and with different textures (sand, clay loam and silty clay loam). Available potassium levels in the soils were 164, 256 and 328 mg/kg, respectively. The soils were used for a green house trial. Twenty pots were filled with 16 kg of each soil for eight potassium treatments plus one additional treatment (same three soils without K-fertilizer and without plants). The additional treatment received irrigation water similar to other pots. The experiment had a complete randomized design as factorial, plus one additional treatment, containing two factors of soils with various CEC and potassium fertilizer rates, with three replications. Two corn seeds were planted in each pot. Plants were irrigated with distilled water during ten weeks growth. Subsequently, the corn plants were cut and analyzed for potassium and magnesium. Available potassium levels were measured in samples collected from each pot after harvesting. The statistical analysis of the data showed that there was a significant difference at 5% level on the potassium concentrations in the shoots but the dry weight yields of shoots and the total potassium content of shoots were not significantly affected by the treatments. Similarly, potassium treatments did not affect magnesium uptake by the corn plants significantly. A comparison between the soil available potassium levels before planting and after harvesting showed a decline of soil available potassium for the three soils, irrespective of the fertilizer treatments. Subtracting the sum of soil available potassium after harvest plus the amount of potassium measured in the shoots of corn from the sum of the initial soil available potassium plus the added fertilizer potassium, a term ΔK was defined and used to balance the changes in the available soil potassium levels. The outputs showed the results of fitting a second order polynomial model to describe the relationship between the ΔK of different soils with various CEC and the amount of added potassium to pots. Results showed a positive statistical significant relationship between the two factors at the 1% level. The behavior of soils having low and intermediate CEC is similar but different from the soil with high CEC. A negative ΔK indicated that non-exchangeable potassium had been released during the experiment, irrespective of the fertilizer treatments. However, increasing the rates of potassium application resulted in a declining trend in ΔK values towards zero. The lighter the soil texture with lower CEC, the less potassium fertilizer was required to drive ΔK to zero.

In order to evaluate the residual amount of nitrogen, phosphorous and potassium in soil in response to different rotations and conventional and ecological cropping systems, an experiment with split-plot design based on complete randomized block design with 3 replications was conducted for 6 years. Main plots were assigned to different rotations included, wheat-wheat, and corn-wheat and sugar beet-wheat. Sub plots were assigned to different cropping systems included high-input, medium-input, low-input, integrated (with moderate input) and organic (without any chemical input). Results showed that the amount of macronutrients in surface soil layer was not consistent. The amount of residual N in soil was reduced, but the amount of residual P and K were increased in 6 years. Also soil analysis showed that the residual amount of soil minerals in organic and integrated systems was more than conventional system. The residual amount of macronutrients was affected significantly by different rotations. The electrical conductivity of saturated extract in integrated system was the highest level and high-input, medium-input and low-input systems were lower than integrated system respectively, and the organic system was the lowest one

In order to study the effects of foliar application of Zn and Mn on different safflower cultivars (Carthamus tinctorius L.), a field experiment was conducted in research facilities of Agricultural Faculty in Tarbiat Modarres University during 2002. The experimental design was factorial based on randomized complete block design with three replications. Five cultivars (Isfahan native 2819, Arak-2811, Nebraska-10, Us-10 and Jeila) and five foliar applications (Control, Water, Zinc, Manganese, Zn plus Mn) were used at 50% flowering stage in this experiment. Results showed that there were significant differences between varieties and foliar applications (for seed oil yield and protein content and leaf soluble carbohydrates. Plants with micronutrient foliar application produced more seed oil yield than the control. The effects of Zn and Mn treatment on seed oil yield were more than other treatments. Zn + Mn treatment produced 59.6 % more seed oil yield than control. Isfahan variety had the most seed oil yield. Foliar application of Zn and Mn greatly increased protein percent and leaf carbohydrate solution as compared to the control treatment. Interaction between varieties and foliar applications showed that the Arak- 2811 variety with Mn + Zn foliar application had the most seed protein with 28.2% on the average, and the maximum leaf soluble carbohydrates was measured for native Isfahan- 2819 variety with Mn + Zn foliar application.

In arid and semiarid regions of Iran most of the irrigation waters are saline. These waters are used to grow strategic crops such as wheat and barley with acceptable yields. Because of the necessities of using saline water in agriculture, research on plant tolerance to salinity has great importance. In this study, five saline irrigation water treatments were used on sunflower (Zarya cultivar) in three replicates in RCBD. Three saline water application treatments were 2.6, 6.1 and 10.5 dS/m (S1, S2 and S3) during all the season and two saline water application treatments irrigated with 2.6 dS/m water in early season (germination and establishment stages) and, for the rest of growth period, saline water of 6.1 (S4) or 10.5 dS/m (S5). The result shows that seed relative yield (Ry) in S2 and S3 were about 62 and 20 percent, respectively, compared with S1 treatment. Ry of S4 and S5 were 66.6 and 48 percent, respectively. To estimate the Ry, the best correlation was obtained with weighted average of irrigation water salinity (ECiw) in the season and was calculated from this equation (Ry=130-9.85 (ECiw)) with R2=0.67. According to the results, application of good water quality (ECiw=2.6 dS/m) (in rates of 20-25 percent of crop water consumption) during the germination and crop establishment and using water salinity of 10.5 dS/m for the rest of season had 28.4 percent yield increase compared to 10.5 dS/m (S3) in all the season. Mean electrical conductivity of soil saturation extract (ECe) during growth period and for the 40 cm soil depth were 8, 12.5, 19.4, 11.6 and 14.8 dS/m in S1 to S5, respectively. Also sodium absorption ratio (SAR) in the above mentioned treatments were 12.4, 21, 27, 20 and 25, respectively.

Exact estimation of plant transpiration is an important factor in optimal management of greenhouse in order to achieve high quality and yield. Weighing lysimeters and water balance are two most accurate methods for measuring transpiration. Beside the high costs and time consuming aspects, the methods require careful experiments to be carried out, which them make them somewhat impractical and uneconomical. Moreover, results of the measurements are only valid for the specified greenhouse and are not transferable. Since many researches have been conducted in order to relate transpiration and climatic parameters in greenhouse, efforts have been made to fit a curve on the experimental data. Usually, this relation has been assumed to be linear, an unrealistic assumption that causes errors in the estimates. The objective of this research was to establish artificial neural network for transpiration estimation of greenhouse cucumber. In this paper after defining the artificial neural network specifications, a multilayer perception network with error back-propagation training method, was developed to fit a nonlinear relation to plant transpiration and climatic parameters within greenhouse and this physiologic characteristic of the plant (transpiration) was estimated. Results showed good agreement between the estimated values by the artificial neural network and the measured data and the errors were less than the errors of the field methods.