نشریه روابط خاک و گیاه
پیاپی 9 (بهار 1391)

Land suitability evaluation is the fitness of a given tract of land based on its production potential for a defined use. This study was conducted to evaluate the land suitability of Mobarakeh-Zarrinshahr district located in west of Isfahan province using Analytical Hierarchy Process (AHP) technique. To do the evaluation, firstly the hierarchy structure was established, which consisted of objectives, criteria, sub-criteria and alternatives. The objective was determination of landuse priority in each land unit; the criteria comprised of soil suitability, climate suitability, gross income, market accessibility, water resources availability, physical environmental-impacts and chemical environmental-impacts; two alternative landuse types were chosen to be cultivation of rice and establishment of greenhouse. The questionnaires were filled out by experts and then the overall weight for each element at each level was calculated by multiplying its local weight, obtained from Expert Choice 2000 software. The results showed that climate suitability and market accessibility had the highest and least weights, respectively, for selection of the proper land use, and the inconsistency ratio was 9%. In all the land units, the greenhouse establishment had higher priority. Climate suitability and gross income were identified the major factors affecting the suitability for greenhouse establishment. In general, cultivation of rice is not recommended in the studied area, because of negative environmental impacts including soil physical-destruction, low water use efficiency, raising the groundwater levels and increasing soil salinity.

Phytophtora crown- and root- rot is one of the important soil-borne diseases of strawberry grown in hydroponic culture. Plant roots affected by root and crown rot show yellowish and decline symptoms and the plant perishes and dies gradually. To identify the factor responsible for strawberry crown rot, some samples were taken from infected plants. The samples were washed with tap water for 1-2 hr, blotted dry and plated on CMA. Phytophtora fungus was separated from infected tissue. Based on morphological characteristics and temperature requirement, the pathogen was identified as Phytophthora cactorum. Comparison of crown and root colonization and percent of dead seedlings showed that Selva, Aliso and Gavita cultivars had the most and the least resistance, respectively, but Kameroseh showed immune response to Phytophthora cactorum.

This greenhouse experiment was carried out to evaluate the effects of salinity and bacterial inoculation on some growth indices and total protein content of alfalfa (Medicago sativa) using a factorial completely randomized design with three replications. The effect of three salinity levels (0, 6 and 12 dS/m) induced by a mixture of NaCl, CaCl2 and MgCl2 salts on growth indices and protein content of three alfalfa genotypes (Hamadani, Gharahyonjeh and Gharghalogh) at three levels of inoculation with Sinorhizobium meliloti bacteria (no inoculation, inoculation with salinity-tolerant strain and inoculation with salinity-sensitive strain) was investigated. After the isolation and purification of alfalfa-symbiotic-bacteria from alfalfa fields in Tehran province, two isolates of S. meliloti, one salinity-resistant and the other one salinity-sensitive, which are effective in symbiosis with alfalfa, were selected. Analysis of the results showed that by increasing the salinity level, the shoot and root dry weight, number of active nodules, and nitrogen (N) concentration were decreased significantly (P<0.01). Inoculation with salinity-resistant strain of S. meliloti caused significant increase in shoot and root dry weight, number of active nodules, and N concentration of plants. Moreover, under saline conditions, the salinity-resistant S. meliloti strain increased significantly most alfalfa growth-indices and yield compared to control (without inoculation) and inoculation with salinity-sensitive bacteria. There was no significant difference among alfalfa genotypes in yield and other growth indices under saline conditions. In general, the R59 isolate seems to be the best isolate of S. meliloti for greenhouse-grown alfalfa in saline conditions.

Heavy metals decrease plant growth due to disorder in enzyme activities and destroying of protein structure. Since corn is an important crop in human and poultry nutrition, in this greenhouse experiment, the effect of modified polyacrylamide and montmorillonite on growth parameters and chlorophyll fluorescence of corn (Zea mays L.) grown in two polluted soils with Cd and Pb (sandy and sandy loam) was investigated. This experiment was performed using completely randomized design with four replications. Treatments were modified polyacrylamide at three levels (1, 2 and 3 gr/kg soil), modified and natural montmorillonite at two levels (5 and 10 gr/kg soil) and control (no treatment). Polyacrylamide was modified with hydrazine monohydrate and montmorillonite was modified with polyacrylamide. Plants were harvested after 45 days. Wet and dry weights of roots and shoot, stem diameter, stem length, leaf area and chlorophyll fluorescence were determined. The results showed that modified montmorillonite significantly increased dry weight of roots and shoot and leaf area. While, natural montmorillonite didn’t have any effect on the growth parameters. Modified polyacrylamide had negative effects on growth parameters and decreased stem length and chlorophyll fluorescence (Fv/Fm) of the corn plants.

Nickel (Ni) is the most recently discovered essential element for higher plants. But there is limited information about the effect of this element on yield and nitrogen (N) metabolism of different plants. In this research, the interaction of Ni supplement and N source was studied on nitrate accumulation and growth of lettuce (Lactuca sativa L. cv. Baker) in solution culture. In a greenhouse experiment, lettuce plants were exposed to two Ni levels (0 and 0.04 µM in the form of NiCl2) and three N levels (5, 10, and 20 µM in the form of urea and ammonium nitrate). The plants were harvested 6 weeks after transplanting and the fresh weight of shoots and roots, total N concentration, nitrate concentration and Fe content of shoots were determined. The results indicated that shoot and root fresh weight of nitrate-fed plants were higher than urea-fed plants. Ni nutrition significantly enhanced the yield of urea-fed plants. The shoot nitrate concentration in nitrate-fed plants was significantly greater in comparison with urea-fed plants. On the other hand, nitrate concentration in the shoots of lettuce plants decreased significantly with Ni nutrition. Ni supplementation in urea-fed plants increased the shoot Fe content. The shoot concentration of total-N in the urea-fed plants increased with the Ni supplement. While, Ni had no significant effect on shoot concentration of total-N in the nitrate-fed plants. Addition of low levels of Ni to the nutrient solution, particularly to the urea-containing solution, improved the yield of lettuce. In addition, these plant leaves are safer for human consumption because the shoot nitrate content is significantly reduced by application of Ni.

In order to reduce the growth period of Iris hollandica cv. ‘Blue Magic’ in greenhouse and to extend the vase life of its cut flowers, a factorial experiment, based on completely randomized design with three replications, was performed in the Research Glasshouse of College of Agricultural Sciences, University of Guilan, Rasht, Iran. The treatments consisted of three levels of gibberellic acid (0, 300 and 600 mg/L) and three levels of calcium nitrate (0, 5 and 10 mM). The measured parameters included sprouting time, flowering time, calcium content of shoot, anthocyanin content of petals and vase life of iris cut-flowers. The results revealed that gibberellic acid (GA3) treatments had significant effects on reduction of sprouting time, enhancing flowering time, and increasing calcium content of shoot. The anthocyanin content of petals and chlorophyll content of leaves were increased too in GA3 treatments. Calcium treatments had significant effects on calcium content of shoot and anthocyanin content of petals. In general, the interaction of GA3 and calcium had significant effects on vase life of Iris cut-flowers.

Phytic acid is the main source of organic phosphorus in grains of legumes and cereals. It has great ability of bonding with metals and minerals such as iron, zinc and calcium. As a result, the solubility of these elements and their absorption capability by human will be reduced. This greenhouse research was carried out with the aim of studying the variations of phytic acid to zinc molar ratio and evaluation of nutrients’ concentration in different varieties of red bean (Phaseolus calcaratus L.) under balanced fertilization conditions (based on soil test) in different timings after flowering stage. Treatments included: 5 varieties of red bean (Akhtar, Naz, Derakhshan, Goli and Sayyad), two levels of fertilizer (control and balanced fertilization) and 3 times of sampling (12, 22 and 32 days after flowering; T1, T2 and T3, respectively) in a factorial arrangement with complete randomized blocks design. Phosphorous, potassium, iron and zinc concentration and phytic acid to zinc molar ratio in grains of different red bean cultivars were determined. The results of analysis of variance showed that the effect of cultivar, fertilizer and sampling time on concentration of zinc, iron, potassium, phosphorous and phytic acid to zinc molar ratio in grain was significant (P<0.01). Also, the highest concentration of zinc in grain was measured in Goli cultivar at T3 timing. The phytic acid to zinc molar ratio in balanced-fertilization treatment was recorded for Goli cultivar at T1, T2 and T3 timings as 11.1, 10.49 and 7.99, respectively. In general, the results of this research showed that balanced fertilization reduced phytic acid to zinc molar ratio. This can be effective in enhancing humans’ health by improving the absorption capability of required nutrients. More investigations under field conditions are recommended.

Soil salinity may cause nutrients imbalance in plants. Addition of some nutrients to saline soils may alleviate negative effects of salinity on plant growth and yield. In order to evaluate the effect of salinity and phosphorus on growth and chemical composition of two varieties of spinach (Khardar and Virofly Duch) a greenhouse experiment was carried out in a factorial arrangement 2×3×2 in a completely randomized design with three replications. Treatments consisted of three levels of salinity (0.6, 3.8 and 8 dS/m as NaCl) and two levels of phosphorus (40 and 80 mg per kg soil as mono-calcium phosphate). Results indicated that concentration and total uptake of sodium (Na), chloride (Cl) and magnesium (Mg) were higher in Khardar than in Virofly; however, concentration and total uptake of nitrogen (N), potassium (K), iron (Fe), manganese (Mn), zinc (Zn) and copper (Cu) were lower than in Virofly. Concentration and total uptake of calcium (Ca) and phosphorus (P) were similar in two varieties of spinach. Application of 80 mg P increased dry weight of Khardar but had no significant effect on dry weight of Virofly. Addition of P, significantly increased total uptake of N, P, Ca, Mg, Zn, Cu, Na and Cl in Khardar, and total uptake of P and Cu in Virofly. Phosphorus decreased uptake of N, Ca, Mg, Na and Cl in Virofly. Application of NaCl significantly increased fresh weight of both varieties of spinach and dry weight of Virofly. Salinity decreased uptake of N in Khardar but increased it in Virofly. In both spinach varieties, salinity decreased uptake of Ca and Mg, but increased uptake of Zn, Na and Cl. Both spinach varieties are considered relatively salt-tolerant plants, due to the fact that NaCl improved their growth.

Genetic diversity is the base of plant breeding. Hence, 33 M7 soybean mutant lines, which were evolved by γ ray from cultivar L17 irradiated with doses of 150, 200 and 250 Gray (absorbed dose), with L17 cultivar and two commercial cultivars (Clark and Williams) were evaluated in view of some morphological traits (number of leaves/plant, pods/plant, seeds/pod, seeds/plant, 100-seed weight, dry weight of aerial parts, dry weight of roots, plant yield, harvest index, nodules/root and dry weight of nodules) under completely randomized design with three replications in greenhouse of Agricultural, Medical and Industrial Research School, Nuclear Science and Technology Research Institute, Atomic Energy Organization of Iran, Karaj, Iran. All traits in the studied mutant lines, except number of seeds per pod, showed a significant difference at α=1% and α=5% in comparison with L17 and commercial cultivars. Mutant line number 13 (M13) was recognized as the top line in view of the studied traits. Seed yield per plant showed the highest correlation (0.886) with harvest index (P<0.01). Cluster analysis of the studied traits along with Ward method resulted in separation of the lines into four independent groups. It can be inferred from the results that irradiation did induce significant genetic variability with regard to majority of the studied traits, such as number of nodules per plant and harvest index.

Cadmium (Cd) is one of the toxic heavy metals which can be absorbed by plants and have detrimental effects on plant growth and nutrients uptake. In order to investigate the effect of Cd on some vegetative growth parameters, nitrogen (N), phosphorus (P) and Cd uptake in aerial parts of seven rice cultivars, a pot experiment with three soil-applied Cd levels (0, 45, and 90 mg Cd/kg soil) and seven rice cultivars (Ghasrodashti, Khazar, Anbarboo, Dasht, Hassani, Taroom and Kadoos) was conducted in a completely randomized design with three replications. Results revealed that Cd addition to soil had negative effect on some growth parameters, so that application of 90 mg Cd/kg soil decreased mean relative growth (RGR), wet and dry weights, shoot height, and number of lateral, main, and total tillers of seven rice cultivars by 64.7, 65.8, 65.6, 35.4, 13.3, 88 and 40% as compared to those of control, respectively. Hassani and Ghasrodashti cultivars had the highest shoot wet and dry weights, height, and RGR, and Khazar and Tarom cultivars had the lowest ones, compared to other cultivars. Addition of Cd to soil significantly increased shoot Cd uptake, but decreased shoot N and P uptake, as compared to those of control. Hassani and Khazar cultivars had the highest and lowest N and P uptake, respectively. Our tentative conclusion is that Hasani cultivar was superior cultivar compared to other studied cultivars due to its greater performance. Therefore, Hassani and Khazar cultivars could be considered as tolerant and sensitive cultivars, respectively, to Cd toxicity.