SOIL AND PLANT INTERACTIONS (JOURNAL OF SCIENCE AND TECHNOLOGY OF GREENHOUSE CULTURE)
Year:2011 | Volume:1 | Issue:4|Papers Count:7

To study the effects of potassium and zinc on decreasing the cadmium (Cd) toxicity on growth and physiological parameters of tomato (Lycopersicon esculentum Mill.) a greenhouse experiment was conducted in a soilless system with complete randomized block factorial design. Zinc (Zn) was applied in three levels: 88.8, 177.6 and 355.2 mg L-1 as the first factor. The second factor was potassium (K) with three levels of 255, 510 and 1020 mg L-1. The base solution (Hoagland solution) contained 20 mM cadmium in all the treatments. The results showed that Zn treatments had significant effect on some growth indices including RGR, RLGR, LWR, LWCA, dry weight of aerial parts and soluble sugar content. Increasing the Zn level caused 7.7, 7.7, 3.3, 4 and 31.3% decrease in RGR, RLGR, LWR, LWCA and sugar content, respectively. The K treatments had significant effects on LAR, SLA, LWR, LWCA, NAR and root fresh weight. The LAR, SLA and LWR were increased 7.7, 15.3 and 6.9%, respectively. It was concluded that Zn had synergistic effect with Cd in tomato, and therefore co-existence of Zn and Cd reduced crop growth. Whereas, K application had antagonistic effect with Cd, and caused an increase in LAR and SLA. Interaction of K and Zn was not significantly effective on the measured parameters.

Water crisis is an important issue in arid and semi-arid regions like Iran. Due to drought events, the situation has become more acute in recent years. Therefore, where good quality water is not available, the use of unconventional water has increased considerably. One of these resources is municipal wastewater that can also provide some of the nutrients needed for plant nutrition. Therefore, in this research, the combined effects of treated municipal wastewater and soil texture on growth and yield of Nitraria schoberi under greenhouse conditions, was investigated. The experiment was a factorial completely randomized design with four replications. The treatments included: two types of irrigation water (wastewater and water), two soil textures (clay and sandy) and two irrigation frequencies (5 and 15 days). Analysis of the wastewater showed that concentrations of the elements were in the standard limits. The results also showed that the use of wastewater has positive effect on stem length and dry and fresh weight of the plants. Therefore, due to the problem of water supply to plant species in the arid regions, this method can have a significant role in the stability of plants, reducing costs of irrigation and fertilizers, and biological restoration.

To investigate the potential of corn (Zea Mays) for cleaning of soils polluted by cadmium and the effect of different levels of sulfur (S) element on biomass and root and concentration of some micronutrients, a greenhouse experiment was performed in Zanjan University in 2008. In the completely randomized factorial design with three replications, three levels of elemental S (0, 1 and 2 ton ha-1) and six levels of Cd (0, 50, 100, 150, 200 and 250 mg kg-1) as cadmium sulphate were added to the pots. Seeds of SC 704 corn cultivar were sown in the pots. The results showed that Cd and S levels had significant effects (P< 0.01) on Cd concentration, fresh and dry weight, concentration of Zn, Fe and Mn of aerial parts and roots of plants. As the soil Cd concentration increased, the concentration of Cd in roots and aerial parts of the corn plants increased but fresh and dry weight of these parts was decreased. Application of S increased the concentration of Cd in the roots and aerial parts of corn, but it decreased the weights of these parts. Concentration of Zn, Fe, Cu and Mn in aerial parts was decreased by application of Cd and S. It seems that application of S enhances adsorption of Cd by plant roots.

Despite of increasing request for greenhouse vegetables, there is quite limited information on their nutritional quality. This study was carried out to investigate nutritional status of macronutrients (Ca, Mg, P and K) and micronutrients (Fe, Mn, Cu and Zn) in greenhouse cucumber and bell pepper in Isfahan province. After selecting 25 greenhouses, the concentration of macronutrients and micronutrients was measured in soil and edible parts of cucumbers and bell peppers. The results showed that mean concentration of P and K in the soils was much higher than their critical deficiency level. Mean concentration of DTPA-extractable Fe, Zn, Cu and Mn of the soils was 12.0, 4.9, 1.9, and 14.5 mg kg-1. Mean fruit Mg, P and K concentrations in the cucumber and bell pepper were greater than their sufficiency level, while more than 75% of the greenhouse cucumbers were Ca deficient. Also more than half of the greenhouse cucumbers and about 20% of greenhouse bell peppers had Mn deficiency. Also more than 60% of greenhouse cucumbers were Fe and Zn deficient. According to the results, high concentration of some macronutrients such as P and K, and widespread deficiency of Ca and micronutrients in greenhouse production, is probably due to nutritional mismanagement, unbalanced fertilizer application, unstable greenhouse conditions and environmental pollution risks.

To determine the effect of application of phosphorus (P) and organic matter on soil-plant P relationship at different growth stages of spinach, an experiment was conducted at greenhouse conditions. Treatments consisted of two levels of organic matter (0 and 2% of sheep manure) and three levels of P as Ca (H2PO4)2 (0, 20 and 60 mg P kg-1soil). Soil and plant samples were collected at five growth stages (the first sampling was in the fourth week after emergence, and the other samplings were each one week after the first sampling). The results showed that crop yield increased with the increase of soil P at all growth stages, whereas it had no significant effect on plant P content. In the 4th week of growth, plant P increased with an increase of soil P, and it remained relatively unchanged in the 5th week. But it decreased significantly in the 6th to 8th week. Concentration of plant nutrients depends not only on soil nutrients concentration but also on plant age and availability of other nutrients. In some stages of the plant growth, the growth rate might be too fast such that total uptake of the nutrients is not enough to maintain the necessary concentration. Plants required adequate P at early growth stages for optimum growth. Phosphorus uptake was increased with plant growth in all samples. Soil P content was higher in all organic matter treatments (especially in the 6th week after emergence). Phosphorus uptake in samples with organic matter, and no addition of P, was more than the samples which received P. This might be due to mineralization of organic P added to the soil.

Chickpea (Cicer arietinum L.) is highly sensitive to salinity and selection of chickpea genotypes that are moderately tolerant to salinity can help to expand chickpea cultivation in saline areas. Eleven chickpea genotypes were grown in a hydroponic system containing different NaCl concentrations (8 and 12 dS m-1) and control (Hoagland solution) in order to study the effects of salt stress on physiological traits. The results showed that with increasing salinity, the concentration of photosynthetic pigments, carotenoids, proline, soluble sugars and radical scavenging activity (DPPH) in leaves and roots was increased. Among the studied genotypes, MCC674, MCC759, MCC544 and MCC783 showed superiority in most traits. Genotypes that contain higher concentration of chlorophyll, carotenoids, soluble carbohydrates, proline and DPPH in shoots were more resistant to salinity. The correlation between physiologic traits and sodium concentration in leaves was positive. Production of photosynthetic pigments, carotenoids, proline, soluble sugars and DPPH was higher in sensitive genotypes. The resistance index in 12 dS m-1 salinity stress showed that resistant genotypes to water stress (MCC760 and MCC333) were also resistant to salinity. But, in 8 dS m-1 stress level, the MCC759 sensitive to aridity, was moderately resistant to salinity.

In order to assess the effects of salt stress on some morphological traits of tolerant and sensitive cultivars of wheat (Triticum aestivum L.), a factorial experiment, based on completely randomized design in 3 replications, was conducted under greenhouse condition. The first factor was two genotypes of Sistani and Neishabour (tolerant cultivars) and two genotypes of Tajan and Bahar (sensitive cultivars) and the second factor was salinity treatments including 1.3, 5, 10 and 15 dS m-1. The salinity treatments were prepared from NaCl and CaCl2 in 10:1 ratio. Dry weight of shoots and roots, number of tillers and leaves, root volume and surface area, leaf area, specific weight of leaves and biomass were measured 10 days after anthesis. The results indicated that by increasing of salinity level, all traits, except specific weight of leaves, decreased significantly. Salinity level of 15 dS m-1 had the most negative effect. At all salinity levels, the Sistani and Neishabour cultivars, as compared with the other two cultivars, recorded significantly higher values of all measured traits. Invariability of dry root weight in Bahar cultivar at all salinity levels indicates that this cultivar has allocated less carbon to roots and this may be a reason for the sensitivity of this cultivar to salinity. This can justify the disadvantages of this cultivar in comparison to Tajan in some traits like biomass, leaf number and leaf area, shoot dry weight, root volume and root area in 10 and 15 dS m-1 salinity levels. Higher values of specific dry weight of Bahar and Tajan cultivars can be considered as a mechanism for avoiding salt stress.