نشریه روابط خاک و گیاه
پیاپی 18 (تابستان 1393)

Beneficial effects of arbuscular mycorrhizal fungi (AMF) on plant growth have been widely reported. But there is a lack of information on the effect of this symbiosis in soil-less culture systems. Therefore، this experiment was aimed to investigate the effect of mycorrhizal symbiosis on leaf chlorophyll index of sorghum plants grown in perlite media under micronutrients deficiency conditions. The experiment was laid out in factorial randomized complete blocks design with three replications. In pots with sterile and washed perlite، sorghum plants (Sorghum bicolor L.) were inoculated with either Glomus etunicatum or G. intraradices، or left un-inoculated as control. Three levels of micronutrients (zero، half and full strength) in Rorison’s nutrient solution were applied to the pots during vegetative growth period. Results showed that plant fresh weight in non-mycorrhizal and plants inoculated with G. etunicatum and G. intraradices were 90، 14 and 11 gr/pot، respectively. Mycorrhizal root colonization for G. etunicatum and G. intraradices treated plants was 43 and 37%، respectively. Chlorophyll index was significantly lower in mycorrhizal than non-mycorrhizal plants، and it was markedly declined with decreasing micronutrients concentration in the nutrient solution. With increasing plants age and approaching the reproductive stage، chlorophyll index was significantly increased. According to the obtained results، reduction in growth of mycorrhizal plants in comparison with non-mycorrhizal plants seems to be due to decreased chlorophyll content and thus reduced photosynthetic power in the presence of mycorrhizal fungi. Further research is needed for more careful evaluation of the effect of symbiosis fungi on growth and yield of plants in the soil-less culture systems.

Evaluation of certain biochemical and physiological changes under stress can provide an appropriate approach for the study of hereditary factors influencing salt stress tolerance. In this greenhouse study، the changes in water status، osmotic regulators and activity of antioxidant enzymes in leaf tissue of panic blue grass (Panicum antidotale Retz) exposed to salinity were evaluated over five consecutive weeks. Five levels of salinity (0، 70، 140، 210 and 280 mM NaCl) were applied at the 4-leaf stage. Results showed that the highest leaf relative water content (RWC) in non-saline (control) treatment، as compared with the lowest RWC in 280 mM salinity treatment، was 8. 67، 31، 25، 28 and 27% in the 1st to the 5th wee، respectively. Average leaf osmotic potential showed a decreasing trend in different salinity treatments over time and was reduced from -0. 717 MP in the first week to -1. 26 MP in the 5th week after exposure to salinity. Total soluble carbohydrates content of the leaves was reduced with increasing the salinity level. After 28 days of exposure to salinity، the activity of ascorbate peroxidase enzyme in non-saline treatment was 40% more than the 280 mM treatment; although the highest activity of ascorbate peroxidase enzyme was observed in the 70 mM treatment. Leaf RWC (r=0. 62**) and membrane stability index (r=0. 52**) had the most positive correlation with dry matter production of blue panic grass. In addition، increasing the DPPH radical scavenging activity (r=-0. 61**) and total phenol concentration (r=-0. 69**) had effective role in survival of this salt-tolerant plant. The data analysis، using stepwise regression، indicated that total phenol concentration (β= -0. 722) and leaf proline concentration (β= -0. 265) were the main components of salinity tolerance of blue panic grass.

Chrysanthemum is one of the most important ornamental and medicinal plants in the world. In this study، diversity among 50 genotypes of chrysanthemum morifolium was analyzed using phenologic and morphologic traits. The variation between studied genotypes showed a significant difference for all traits and coefficient of genetic variations for most traits was greater than 40%. The highest general heritability belonged to days to bud coloring (h2=90. 59%) and post-production longevity (h2=88. 3%). The lowest heritability (h2=6. 05%) was related to disc floret opening. In multiple linear stepwise regression for flower longevity as the dependent variable، such traits as number of days to bud coloring، days to full bloom and pollen shed entered the model. Therefore، vegetative growth period and behavior of florets affect post-production longevity. On the other hand، cluster analysis according to the morphological traits using Ward method classified all the studied genotypes into six groups. In this classification، two genotypes of “Afrooz” and ‘Unknown1’، with short vegetative period، late pollen shed and high post-production longevity were classified into a separate cluster. The findings of this research showed that the studied Chrysanthemum genotypes have desirable genetic potential، and depending on the objectives، most of them could be used in breeding programs to improve different traits.

To evaluate the relationship of various P fractions and alkaline phosphatase activity with bean indices growing in 10 calcareous soils، amended with municipal sewage sludge from Chaharmahal-Va-Bakhtiari province، a greenhouse research was carried out. Soil samples were incubated for one month with sludge at a rate equivalent to 1% (w/w). Then، the P fractions، including P adsorbed by Fe and Al oxides (]NaOH+CB]-P)، occluded P (CBD-P) and P absorbed by Ca (HCl-P)، were determined by Olsen and Summers'' sequential fractionation procedure. Furthermore، total P، organic P and residual P were determined. Also، alkaline phosphatase activity was measured. A pot experiment in a completely randomized design with three replications in the ten soils was done to evaluate the bean plant indices. The results showed that the amount of P fractions decreased in the following order: HCl-P>residual-P>]NaOH+CB]-P > OP>CBD-P. The results also indicated that alkaline phosphatase activity was significantly correlated with CBD-P fraction، organic P and total P. In addition، significant correlations were found between ([NaOH+CB] -P) and HCl-P and plant shoots. In general، the results of this research showed that P fractionation method appears to be a powerful tool to identify the P status and availability in the soils amended with sewage sludge.

In order to study of quantitative and qualitative yield، chlorophyll content and some growth indices of wheart (Triticum aestivum L.) in response to seed inoculation with plant growth promoting rhizobacteria (PGPR) at different levels of soil salinity، a factorial experiment based on randomized complete block design with three replications was conducted at Research Greenhouse of Faculty of Agriculture، University of Mohaghegh Ardabili، Ardabil، in 2011. Experimental factors were soil salinity at four levels (0، 15، 30 and 60 Mm as Nacl) and seed inoculation with PGPR in four levels (no inoculation as control، seed inoculation with Azotobacter chrocoocum strain 5، Azospirillum lipoferum strain OF، Pseudomonas putida strain 186). Comparison of means showed that in soil salinity conditions، grain yield per plant، number of grain per spike، grain 100 weight، spike length and root weight increased due to seed inoculation with PGPR compared to without seed inoculation. Investigation of total dry matter accumulation indicated that in all treatment combinations، it increased rapidly until 85 days after sowing. From 85 days after sowing till harvest time، it decreased due to increasing of competition، shedding and aging of leaves. In all treatment combinations، the highest grain yield and total dry matter accumulation per unit area was obtained in treatment combination of seed inoculation with Azosperilium × no soil salinity and the lowest amount was in the highest level of soil salinity × no seed inoculation. Similar trend was obtained in crop growth rate and relative growth rate. Hence، the results of this study showed that in order to increase the quantitative and qualitative yield، chlorophyll content and some other growth indices such as total biomass، crop growth rate and relative growth rate of wheat in soil salinity conditions، it could be suggested that wheat seed inoculation with Azospirillum be applied

In drought stress conditions، besides the inhibition of water uptake، the plant nutrients availability and uptake are also limited. Proper nutrition is known as a management procedure for plant production under different environmental-stress conditions. Generally، the combined effects of drought and deficiency of potassium and zinc on plant water content and some physiological parameters reduce yield quantity and quality. This investigation was conducted to assess the interactive effect of different levels of potassium as KNO3 (0. 6، 3 and 6 mM) and zinc as ZnSO4 (0، 1 and 2 μM)، under drought stress conditions induced with PEG 6000 (0، 55 and 110 g/L PEG 6000) on some water status indices and physiological parameters of tomato in hydroponic culture. The results showed that interaction of drought، potassium and zinc on shoot and root dry weight، leaf chlorophyll and proline content and percentage of root ion leakage was significant. Both potassium and zinc improved water status of the plants; however the effect of zinc on leaf water potential was not significant. Drought stress increased the chlorophyll content and decreased the sulfhydryl groups. Application of a high level of potassium in the nutrient solution increased root ion leakage.

In medicinal plants، secondary metabolites are very important and factors influencing their quantity and quality are considered. Iranian borage (Echium amoenum Fisch. & C. A. Mey.) belonging to Boraginaceae family is a long-day، biennial، herbaceous plant، with a lot of rough trichomes، is found in northern Iran. In the present work، effects of silicon on some morphological، anatomical and physiological characteristics of this plant were investigated. For this purpose، borage plants، cultivated in hydroponic system in greenhouse، were treated with silicon (as sodium silicate) at 3 concentration levels (0، 0. 2 and 0. 7 mM). The experiment was carried out as completely randomized design. Some morphological and anatomical characteristics such as length of trichomes، number of trichomes، number of stomatal cells، cuticle thickness، stomatal index and palisade parenchyma cells density of treated plants and control were measured and anthocyanin and flavonoids content was also evaluated. Based on the results، in silicon-treated plants، compared to control، the stomatal index was decreased. The cuticle thickness، palisade parenchyma cells density، trichomes length، and anthocyanin and flavonoids content in silicon-treated plants were increased significantly. But، there was no significant difference in number of trichomes in the treated plants.

Pepper (Capsicum annuum) is generally propagated from seeds. In Iran، imported hybrid seeds are used for this purpose. Germination of the greenhouse pepper seeds and stabilization of their seedlings takes a long time. But، tissue culture technique could rapidly propagate this plant with a homogeneous genetic structure in a large scale. An attempt was made in this study to evaluate the effects of different genotypes، explants and growth regulators on callus production and regeneration and introduce the appropriate protocol for micropropagation of commercial varieties of pepper in Iran. Analysis of variance indicated that effect of different genotypes، interaction of various explants and combination of hormones and interaction between genotypes، explants and hormones were significant on the evaluated traits at 1% level. Based on the results، for micropropagation of pepper with leaves and cotyledons، combination of 1 mg/l IAA and 5 mg/l BAP was selected. It seems that using leaf explants for micropropagation of pepper in large scale in greenhouses would be suitable.

Growing media could affect quality and shelf life of strawberry fruits. In the present study، effect of seven growing media including a control medium (50% cocopeat + 50% perlite v/v)، and media supplemented with either 10، 20 and 40% of vermicompost or cattle manure in a completely randomized design with three replications was studied on postharvest quality and shelf life extension of Camarosa strawberry fruits. Freshly picked strawberry fruits were submerged in 1 mM putrescine solution for 5 minutes and after being air-dried at room temperature، were kept in plastic containers at 4 ºC refrigerator. After 15 days، total soluble solids (TSS)، total acidity (TA)، TSS/TA ratio، fruit firmness and the percentage of fruit weight loss were determined. The results of analysis of variance showed that growing media had significant effect on fruit firmness، TA، TSS، TSS/TA ratio and percentage of fruit weight loss. The lowest fruit weight loss (16. 2%) belonged to 10% cattle manure medium and the highest weight loss (36%) was observed in control medium. The highest fruit TSS content (19. 13%) was observed in the growing medium containing 40% vermicompost. Since soilless culture growing media of strawberry are pathogen-free، no fruit was rotted before or after the harvest. Therefore، by using organic fertilizers in growing media، not only there is no need to use chemical fungicides، but also it would be possible to increase postharvest shelf life of strawberry fruits.

Nowadays، various training systems are utilized to grow greenhouse roses. Some of the training systems permit high canopy light penetration and hence increase canopy photosynthesis rate. The aim of this investigation was to evaluate the response of arching and traditional training systems to shading (0 (no shading/control)، 25، 50 and 65%) and their effects on marketing quality of cut roses (Rosa hybrid. cv. ‘Avalanche’)، in the greenhouse condition. The experiment was carried out as split plots، based on completely randomized blocks design، with four replications and two plants assigned to each experimental unit. Results showed that training systems affected some qualitative traits. Plants trained with arching method produced longer flowering stems with higher fresh and dry weight and also higher leaf area over decapitated shoots. In both training systems، no significant difference was observed in time of sprouting، flower shoot diameter and specific leaf area. Increased shading significantly reduced shoot diameter and shoot fresh and dry weight; while it increased specific leaf area. However، shading had no significant effect on shoot length and leaf area. Based on the results of this experiment، application of arching training method could lead to improvement in qualitative properties of cut roses compared to traditional method under low light intensity and/or shade stress.

To evaluate the effect of plant density on yield and quantitative characteristics of two greenhouse cucumber cultivars، this experiment was planned as factorial، based on completely randomized blocks design with three replications، during two years in the greenhouse of Jiroft Agricultural Research Center، Jiroft، Iran. The experimental factors were width of planting strip (15، 30 and 45 cm)، each strip consisted of two planted rows، three levels of within-row spacing (25، 40 and 55 cm)، and two cultivars (Royal sluis 198 and California Ayat). The results showed that different densities had significant effect on yield traits. In this experiment، fruit weight، number of fruits per plant، and fruit yield per plant were decreased with increasing plant density; but، number of fruits and fruit yield per m2 increased significantly. Moreover، the highest fruit length to diameter ratio، number of fruits per m2، yield of single plant، and yield per m2 were obtained in planting strip width of 30 cm. However، cultivars didn’t show significant yield difference. Based on the results of this experiment، planting spacing of 25×30 cm was the best treatment for maximizing yield for greenhouse cucumber.

Humic acid (HA) with pseudo-hormonal activity has an important effect on nutrients uptake، yield and quality of crop products. Therefore، this experiment was conducted in soilless condition to evaluate the best HA concentration (0، 250، 500، 750 and 1000 MG/l) of nutrition solution and its effects on morphological traits، nutrients uptake، and postharvest vase life of pot marigold. Based on the results، HA showed significant effects on physio-morphological traits of pot marigold. Accordingly، as compared with control plants، the leaf area and chlorophyll content (a، b and total) as plant photosynthetic capacity، flower number and total phenol concentration were significantly affected by HA application. Also، as compared with control plants (without HA application)، HA showed a significant effect on P and Ca uptake. Flower longevity، as an important postharvest quality index، was increased 20% higher than control plants، in 250 mg/L concentration of HA. The results of the current investigation revealed that application of HA with 250 and 500 mg/L concentrations in soilless culture of pot marigold ‘cv. Crysantha’ could be recommended.

Lettuce is one of the major leafy vegetables that is consumed as fresh and salads crops. Although، today، the tendency is to grow lettuce as hydroponic crop، there is not an optimal nutrient solution and growers use different nutrient solutions for growing lettuce. Therefore، an experiment was conducted to find an optimal nutrient solution to grow lettuce. In this experiment، the effect of various important nutrient solutions including، NSHog، NSKnop، NSUK، and NSU. T on two cultivars of lettuce (Siahoo and Conquistador) was investigated. The experiment was arranged in the randomized completely block design with four replicates and traits i. e.، chlorophyll index، photosynthetic efficiency، tip burn، fresh and dry weight، leaf area، and number of edible leaves were assessed. Plants were sown in the media containing perlite and then irrigated with nutrient solution manually. The results showed that nutrient solution had significant effect on the yield and some of the growth characteristic of lettuce. Plants grown in the UK solution had the highest fresh and dry mass، leaf area، and the number of edible leaves. The lowest fresh and dry weight، leaf area and the number of edible leaves was obtained in plants supplied with UT solution. Results also showed significant variation between two cultivars. Siahoo had higher fresh weight، leaf area، and the number of edible leaves than conquistador. Interaction between cultivar and nutrient solution had significant effect on chlorophyll index. According to the results obtained، UK nutrient solution was the best nutrient solution for lettuce production.

To investigate the effect of cadmium (Cd) on some physiological parameters of safflower genotypes a 3-replicate factorial randomized complete blocks experiment was conducted under hydroponics culture in greenhouse facilities of the Isfahan University of Technology in 2012. Four levels of Cd (control (0)، 1. 5، 3. 0 and 4. 5 mg/L) were tested on six safflower genotypes (Arak2811، Kouseh، Nebraska-10، C111، K12 and S149). Physiological characteristics such as leaf number/plant، leaf fresh weight، shoot fresh weight، root volume، shoot dry weight، root dry weight and Cd concentration in plant roots and shoot were measured. Results indicated that in higher Cd concentrations in the solution، negative effects of Cd on different plant traits were more visible. Safflower plants showed 61. 2، 37. 5 and 71. 8 percent decrease in their root length، leaf number/plant and root volume، respectively، and 52- and 156-fold increase in their shoot and root Cd concentration، respectively، when grown under the 4. 5 mg/L of Cd in the solution، compared to the control. Cd concentration of plant shoot was profoundly lesser than that of plant roots for all studied genotypes. It was concluded that while Cd leads to considerable changes in growth and physiological attributes of safflower، but some differences exist among safflower genotypes.