نشریه روابط خاک و گیاه
پیاپی 29 (بهار 1396)

In an experiment the effective dose and the time of application of phenamiphos (Nemacur 10G) for control of the root knot nematode, Meloidogyne javanica, infecting cucumber, was found out to be 22.5 g/m2 of commercial product and the best time of its application was one week prior to sowing of seeds. However, the results revealed that in concomitant and sequential (one week before) treatment, highest yield were obtained. For the determination of Nemacur residue of the most effective dose of 22.5 gr/m2 the products of the treatment blocks were harvested for six times. The samples were transferred to the laboratory and then prepared for extraction, purification and finally measurement of the residues by GC-NPD. The results were compared with the Codex Alimentarius MRL for Nemacur on a vegetable which is 0.5 ppm and the best timing for pesticide application which was estimated to be one week before sowing of seeds was chosen. It is therefore suggested that the cucumbers produced up to 4th stage of harvesting be used by the consumers, because the products harvested up to this stage possess residues which are closed to the MRL shown by codex Alimentarius.Keywords:

The present study was aimed to investigate the response of the growth and physiological parameters of stevia (Stevia rebaudiana Bertoni) medicinal plant to salinity stress using a pot experiment in 2014. Ten levels of salt stress (0, 30, 60, 90, 120, 150, 180, 210, 240 and 270 mM of NaCl) were arranged in randomized complete block design with three replicates. Regression analysis of data indicated that some measured parameters such as stem diameter, plant height, green leaf number in plant, relative water content (RWC), chlorophyll a, b, leaf greening (SPAD value), leaf fresh weight, root and shoot dry weights linearly decreased when NaCl amount increased in the growing media. Green leaf number in plant and leaf greening (SPAD value) were more sensitive than other mentioned parameters. However, the response of some determined parameters such as electrolyte leakage, chlorophyll a/b ratio, stem, root, shoot and total fresh weights along with leaf, stem and shoot fresh weights were described by a segmented model. In conclusion, stevia plant could tolerate salt stress up to 80 mM and then its growth and physiological parameters significantly and adversely affected. Results, also, revealed that physiological parameters were more sensitive to salt stress than morphological parameters.

Iron is an essential element for plant growth which is involved in many plant processes such as photosynthesis and activating enzymes involved in mitochondrial and photosynthetic electron transfer. In order to compare the effect of different sources of iron on yield and physiological characteristics of two varieties of lettuce in hydroponic culture, a complete random factorial experiment was done in Nutrition Film Technique (NFT system). The factors involved cultivar in two levels (Leaf lettuce and head gardesco) and iron fertilizer in three levels (Ferrous sulfate, Fe-EDDHA and Nano Fe-chelate, all with the 20 micro-molar concentration). The results indicated that the maximum yield and physiological parameters (Fv/Fm, PI, soluble sugars, proline, chlorophyll a, b, total and carotenoids) were obtained for the treatment of Fe-EDDHA and leaf lettuce gardesco cultivars, but the highest absorption of nutrients (iron, copper, manganese, nitrogen and phosphorus) belonged to the treatment of Fe-EDDHA and head lettuce gardesco cultivar. According to the results, it is recommended to use Fe-EDDHA chelate to increase the yield of lettuce in hydroponic systems.

In order to determine the best source of iron fertilizer for green pepper under alkaline conditions, the experiment was conducted as factorial with three factors include of iron fertilizer (control, Fe-EDDHA and nano iron chelate), sodium bicarbonate (0 and 10 mM) and two cultivars (Bonanza and Griffaton) with three replications. Plants were treated with bicarbonate 45 days after planting for 2 month. The results indicated that the maximum vegetative parameters (root and shoot fresh and dry weight), reproductive parameters (number of fruits, fruit length, fruit weight and fruit diameter) and physiological paramneters (RWC, PI and Fv/Fm) were found in control treatment. Under the alkaline condition maximum and the minimum chlorophyll a and b and carotenoid contents were obtained in control and Fe-EDDHA treatment, respectively. Sodium bicarbonate significantly decreased the Fe concentration in root and shoot of pepper. According the results obtained from this work, Fe-EDDHA was the best iron fertilizer under the alkaline conditions and nano chelate iron was next in this situation.

Silicon is one of the beneficial nutrient elements for the most of the plants. This element improve the growth and yield of plants. The aim of this study was to evaluate the effect of foliar spray and root application of Micro- and Nano-SiO2 on concentration of macro- and micro elements and content of silicon in canopy of strawberry. Strawberry plants in the 4-5 leaves growth stage and two weeks later were affected by different concentration (0, 20, 40 and 80 mg L-1) of Micro- and Nano-silicon. At the end of the growth period of 4 months concentration of nutrient elements in canopy of plants measured, and finally the data were statistically analyzed. The results showed that Application of micro- and nano-silicon in high concentrations reduced the amounts of nitrogen and phosphorus. Application of micro- and nano-silicon increased the concentrations of potassium, calcium, magnesium, iron, manganese and silicon significantly, but on zinc and copper amounts not significant effect. The concentration of 60 mg L-1 Nano-SiO2 in root-applied method showed the better results on the most studied traits than the other treatments as well as the control and it can be a good option for recommendations to be considered in the soilless culture of strawberry in greenhouse. Overall, the application of Nano-SiO2 than Micro-SiO2 as well as root-application than foliar-application methods has shown better results.

Root-knot nematodes cause physiological and anatomical disorders in plants. The present study contains the results of an investigation of the effect of Meloidogyne incognita race2 on the growth of roots and aerial organs of tomato under greenhouse conditions. The experiment in a completely randomized design split split plot on two susceptible (Falat Y) and tolerante (Gina VF) tomatoes variety with four nematode population levels, 0 (control), 500, 1000 and 2000 second stage juveniles in four termination times (20, 40, 60 and 80 days after inoculation) and four replications was carried out. The species and race of nematode were determined after sampling and purification. Inoculum densities were obtained by reproduction of pure population on tomato Rutgers cultivar. Nematode population levels were inoculated at four-leaf stage and characteristics were measured at mentioned time. The results showed that increasing nematode populations levels, increased the number of galls, egg sacs and second stage juvenile in both cultivars, which changing were far more in the susceptible variety. But the reproduction factor decreased. Stress of nematodes affected plant morphological traits and growth indices. In high population levels, plant growth characters such as chlorophyll, leaf relative water content, stem diameter, leaf area, plant height, stem dry and fresh weight, root length/root volume, leaf area/ root level, root density and root dry weight/soil volume were decreased. But root fresh and dry weight, root area, root fresh weight/soil volume, root diameter, root volume and root area density were increased.

Root-knot nematodes (Meloidogyne spp.) are the limiting factors of agriculture crops including pepper. The M. incognita has widely distributed in pepper fields of Gilan Province. In this study, eleven pepper cultivars including AA pepper (Hyb. Coyame- Petoseed, Hyb. Aziz- Petoseed, Hyb. Bounty- Petoseed) and Bell peppers (California Wonder 301- Petoseed, Hyb. Camelot- Petoseed, Hyb. King Arthur- Petoseed, Hyb. Wizard- Petoseed, Hyb. Aristotle (SQ-R)- Petoseed, Hyb. Plato (SQ-R)- Petoseed, Mercury- Petoseed, California Wonder 301- Canyon) were evaluated against M. incognita race 2. Experiments conducted in a completely randomized design with four replications in greenhouse conditions with range of 22 to 28 Celsius degrees. Seedlings with six leaves were inoculated with 2000 second-stage juveniles/kg soils. Eight weeks after inoculation, growth indexes cultivars (Chlorophyll content of leaves, fresh and dry weight of shoot and root, root length and volume, length and diameter of shoot and number of healthy leaves) and nematode reproductive traits (Number of galls, egg masses, juveniles in the soil and nematode reproduction factor) were evaluated. In the final reaction of cultivars were determined based on reproduction factor gall and egg masses and resistance indices. The results revealed that pepper cultivars showed different ranges of sensitivity to the nematode. Based on the growth factors, hybrid wizard, California Wonder 301, Bavnty Hybrid, Mercury and Camelot hybrid cultivars were less sensitive than others cultivars. Among cultivars, California Wonder 301, Bavnty Hybrid, Mercury and Camelot hybrid showed less sensitivity in reproductive. The assessment of gall, egg masses and resistance indices revealed that Mercury and Camelot hybrid were evaluated as tolerant cultivars and King Arthur's hybrid and aziz hybrids as the most sensitive cultivars.

This research was carried out to evaluate the effect of two mycorrhiza species on growth, yield and oil content of geranium under salinity stress. The experiment was done at research greenhouse of Faculty of Agriculture, Lorestan University, Iran, in 2014. Four levels of substrate (sterilised and non-sterilised control soil and sterilised soil inoculated with Glomus mosseae or G. intraradices), and three levels of salinity (0, 30 and 60 mmol NaCl) were combined factorially based on a completely randomized design with three replications. Results showed significant differences at 0.05 probabilty level for plant height, stem diameter, number of lateral shoots, number of leaves, leaf area, root length, root volume, leaf fresh and dry weights, stem, root and shoot fresh weights, essential oil content and yield, relative water content and electrolyte leakage and at 0.01 probability level for number of nodes, root diameter, stem and root dry weights. The results showed that as salinity level increased, plant height, stem diameter, number of lateral shoots and leaves/plant, leaf area, leaf, stem and root fresh and dry weight, and oil yield decreased, while, oil content increased. Inoculation with both mycorrhiza species increased leaf relative water content, decreased electrilyte leackage and improved shoot yield, oil content and oil yield under salinity stress, so that, oil yield in plants treated with Glomus mosseae and G. intraradices were 41.9 and 56.8 percent hiegher compared with control, respectively. According to these results and due to environmental sustainability, application of mycorrhiza in substrate could be recommended to decrease the detrimental effects of salinity stress and increase plant yield in geranium.

To study the effects of drought stress and soil application of beet bagasse on biochemical characteristics, photosynthetic pigments content and antioxidant activity of peppermint (Mentha piperita L.) leaf, a pot experiment was conducted in 2015 at Ferdowsi University of Mashhad. The experiment was carried out as a factorial experiment based on completely randomized design with four treatments of drought stress (30, 50, 70 and 90% of field capacity) and three levels of soil application of beet bagasse (0, 10, 20% by volume) in 3 replications. The results showed that the highest amounts of chlorophyll a, chlorophyll index, ratio of chlorophyll a/b, carotenoid and relative water content were obtained in 90% stress of field capacity and 20% application of beet bagasse, so that increasing stress levels reduced the aforementioned characteristics. Furthermore, the application of bagasse created significant changes in the above characteristics. The highest contents of chlorophyll b, total chlorophyll, antioxidant activity and electrolyte leakage were obtained in 30% drought stress of field capacity and without use of sugar beet bagasse treatment, so that was equal to 47/19, 49/48 mg/kg fresh weight, 91/2% and 75/93%, respectively. Application of beet bagasse at this level of drought stress caused a significant reduction in these traits. Based on the results obtained, it is clear that application of beet bagasse in the medium due to high water absorption and retention, improves biochemical traits and photosynthetic pigments in the peppermint.