نشریه فیزیولوژی محیطی گیاهی
پیاپی 63 (پاییز 1400)

In order to investigate the interaction effects of cadmium as a heavy metal and salicylic acid as an antioxidant and anti-stress substance on sunflower plants, sunflower seeds were washed with distilled water after disinfection with 1% sodium hypochlorite solution and were planted in pots containing sandy soil in a growth chamber with a temperature of 34 ℃ during the day and 25 ℃ at night, and 16/8 hours of light/dark photoperiod. This research was performed as a factorial completely randomized design with four replications under greenhouse conditions. Sunflower plants were exposed to cadmium chloride treatment (0, 50, 100, 150 and 200 µM) at two-leaf stage on a weekly basis. One week after cadmium treatment, plant leaves were sprayed with salicylic acid (0, 250 and 500 µM). After harvesting the plants, cadmium concentrations in roots and shoots were measured. Then, antioxidant enzymes were assayed. Total protein content of leaf samples was extracted and the pattern of leaf protein changes was investigated by SDS-PAGE electrophoresis. Cadmium concentration in roots and shoots increased with increasing cadmium and salicylic acid treatment. Catalase enzyme activity decreased with increasing cadmium concentration, and salicylic acid had a very small effect on its activity. The activity of superoxide dismutase, ascorbate peroxidase, and glutathione reductase enzymes increased with increasing cadmium concentration while increasing salicylic acid concentration reduced the activity of these enzymes. Leaf protein electrophoresis under cadmium and salicylic acid treatments showed differences in leaf protein intensity compared with control plants. The expression of some proteins was increased or decreased in the treated plants. Therefore, cadmium and salicylic acid treatments made changes in the amount of cadmium uptake, antioxidant enzymes activity, and the pattern of sunflower leaf proteins.

Purslane (Portulaca Oleracea L.) is a valuable medicinal plant growing in hot and dry conditions. Since drought stress is one of the most important factors limiting the production of agricultural products in these regions, this study aimed to evaluate the tolerance of different purslane landraces to drought stress in the greenhouse of Payame Noor University of Daregaz during the spring 2016. The experiment was as factorial based on completely randomized design with four levels of drought stress (field capacity, 75% FC, 50% FC and 25% FC), 5 landraces of purslane (Qom, Kalat, Sabzevar, Yazd, Gachsaran), and with three replications. The studied traits were relative water content, membrane sustainability index, photosynthetic pigment contents, chlorophyll sustainability index (the amount of chlorophylls and carotenoids), proline content, soluble carbohydrates, and fresh and dry weight of roots in two stages of vegetative and reproductive growth. Results showed that an increase in water stress level decreased the relative water content and cell membrane stability index while increasing the leaf chlorophyll index, carotenoid content, proline, and carbohydrates in different landraces of purslane. Results also indicated that the landraces of Gachsaran and Yazd had higher membrane stability index, lower RWC, and lower chlorophyll content under stress. Among the studied landraces, Qom and Kalat showed significant superiority compared to Sabzevar, Yazd and Gachsaran landraces in terms of proline and soluble carbohydrates. Also, the results showed that with increasing drought stress, fresh and dry weight of roots, leaves, and stems reduced at vegetative and generative stages of plant development such that the highest morphological and physiological traits in two stages of vegetative and reproductive growth were observed in 75% and 100% of field capacity and the minimum levels of these traits were obtained in 25% of field capacity. In general, Qom and Kalat landraces were more tolerant to drought stress compared to other landraces while Gachsaran, Yazd, and Sabzevar due to the relatively weak response to drought stress in most of the measured traits, were evaluated as susceptible landraces to drought stress.

Allelopathic effect of weeds is one of the important factors limiting the growth and yields in crops. The aim of this study was to investigate the effect of aqueous extract of shoots (leaves and stems) of wild melon (Cucumis melo L.) on growth indices and antioxidant system of rapeseed and its accompanying wild mustard (Sinapis arvensis). This study was conducted as a split-split plot in the form of a randomized complete block design with three replications at the field level. The main plot included the target plant type at two levels (rapeseed RGS cultivar and Sinapis arvensis weed), the sub-plot included the type of organ at two levels (leaf and stem extract of wild melon) and the sub-plot of extract concentration at four levels (0 (control)) 2.5, 5, and 10%). The results showed that with increasing the concentration of wild melon leaf extract, most of the growth parameters in both target plants decreased and the intensity of this decrease was higher on the growth of Sinapis arvensis compared to rapeseed, while wild melon stem extract caused a more severe decrease in rapeseed growth parameters compared with Sinapis arvensis. Also, wild melon stem extract significantly increased catalase activity in canola compared to control and decreased peroxidase while the activity of peroxidase enzyme increased in Sinapis arvensis. Also, the increasing trend of phenolic compounds and decreasing flavonoid compounds of rapeseed leaves with increasing the concentration of extract was more dramatic and intense than Sinapis arvensis. According to the results of this study, the sensitivity of rapeseed and its associated weeds to the extracts of two wild melon organs was not the same, which should be considered in managing the use of plant allelopathy as an herbicide at field level.

The aim of this study was to investigate the effects of gibberellic and salicylic acid on germination improvement and protection of Cassia angustifolia under allelopathic stress of Eucalyptus camaldulensis compounds in laboratory conditions. Treatments consisted of pretreatment with gibberellic acid (125, 250, and 500 ppm) and salicylic acid (100, 200, and 300 mg / l), and 5 concentrations of extracted allelopathic compounds of eucalyptus aerial and terrestrial organs (0, 25, 50, 75, and 100 mg / l). Each treatment had four replications and a factorial experiment in completely randomized design was performed. Results of analysis of variance indicated that the interaction effect of pretreatment and allelopathy on all measured traits was significant (p≤0.01). Means comparison showed that eucalyptus extract has allelopathic inhibitory effects on seed germination and early growth of Cassia angustifolia seedlings such that seed pre-treatment with chemical stimulants improved germination percentage and speed and also early growth of seedlings. Seed pre-treatment with gibberellic acid 500 ppm had the best effect on improvement of germination and early growth of seedlings. Overall, the results showed that Cassia angustifolia's response to seed pre-treatment with gibberellic acid was positive, and the seed pretreatment technique with gibberellic acid 500 ppm before planting decreased significantly the inhibitory effects of eucalyptus allopathic compounds at germination stage.

In order to study the effect of organic (vermicompost) and chemical (nitrogen) fertilizers on the quantitative and qualitative yield of Melissa Officinalis, a factorial experiment was conducted based on randomized complete block Design (RCBD) with three replications in the Research Field of Golestan Research and Training Center of Agriculture and Natural Resources. Experimental factors included vermicompost at four levels (0, 2.5, 5, and 7.5 tons ha-1) and urea fertilizer with 46% nitrogen at four levels (0, 50, 100, and 150 kg ha-1). Results showed that vermicompost had a significant effect on morphological characteristics and percentage of essential oil of Melissa Officinalis. The highest plant height, number of branches, leaf length and width, fresh weight, dry weight, and percentage of essential oil was obtained in application of 7.5 ton/ha vermicompost. Also, there was a significant difference between different levels of urea fertilizer so that the percentage of essential oil significantly increased when the fertilizer was applied. The highest amount of essential oil (0.49%) was obtained in simultaneous application of vermicompost (7.5 tons ha-1) and nitrogen fertilizer (100 kg ha-1) which was 38% higher than control. In general, the results showed that application of vermicompost with nitrogen increases shoot growth and dry matter production, ultimately increases the yield quantity, and significantly improves the yield of Melissa Officinalis essential oil.

This study was carried out to enhance yield and quality of Persian melon crop in a factorial experiment based on a randomized complete block design with three replications at the Research Farm of Ferdowsi University of Mashhad in 2018. The treatments consisted of foliar application of salicylic acid at three concentrations (0, 1, and 2 mM) and root drowning in the aqueous solution of silicon oxide at three concentrations (0, 0.5, and 1 g/L). The measured traits were the number of days to flowering, average fruit weight, average fruit production per plant, fruit number per plant, final yield, total phenol, antioxidant activity, proline, and soluble carbohydrate. Results showed that the highest fruit yield, total carbohydrate, and antioxidant activity were obtained in the interaction effect of 2 mM salicylic acid spray with 0.5 g/L silicon oxide application. The amount of proline and total phenol increased in 2 mM salicylic acid and 0.5 g/L silicon oxide treatment compared to control. In this experiment, foliar application of 2 mM salicylic acid with 0.5 g/L silicon oxide were superior to other treatments in the most measured traits.

Complex disease caused by the root-knot nematode, Meloidogyne javanica, and the fungus, Fusarium oxysporum f. sp. radicis-cucumerinum, has limited cucumber cultivation in Iran. Therefore, access to the nematode-resistant cultivars has a crucial role in disease control. The Assessment of plant defense compounds in the Complex disease helps understand the molecular mechanisms of resistance and the production of nematode-resistant cultivars. After inoculation of the plants in a greenhouse, the peroxidase enzyme and the phenolic compounds were measured using spectrophotometric method. The experiment was conducted based on a factorial completely randomized designed with 14 treatments, including control, fungi alone, nematode alone in four inoculations level viz. 1500, 3000, 4500, and 6000 J2s, fungus + nematode simultaneously, and fungus a week after nematode inoculation with 4 replications. Phenolic compounds increased by %54.74 and %92.34 and peroxidase enzyme activity increased by %50.64 and %63.31 in plants inoculated with fungus alone and nematode alone (6000 larvae) compared to the control, showing that these substances act as defensive compounds in cucumber. Results showed that increasing the nematode population in inoculated plants improved the defense compounds levels.  Inoculation of nematode (6000 larvae) followed by fungus led to %80 and %54.48 increases in phenolic compounds and peroxidase activity, respectively as compared with the control which might be attributed to the synergistic effects of pathogens. The fungi had a more active role than nematodes in increasing the peroxidase compared to the phenolic compounds, which indicated the complex nature of nematode parasitism in the nematode-plant interaction. Decrease in the defense compounds in Negin cultivar (susceptible to Fusarium) and increase in the level of these compounds in Khasib (tolerant to Fusarium) and Dastjerdi (tolerant to nematode) cultivars showed that the production of the defensive compounds may be related to the cucumber resistance to pathogens.

In order to evaluate genetic diversity using phenotype and phytochemical properties of sweet violet (Viola odorata), 10 regions of Mazandaran and Golestan provinces were studied. Phytochemical traits such as phenol content, flavonoid, antioxidant capacity, chlorophyll a, chlorophyll b, total chlorophyll, and morphological characters of leaf size, petiole length, pedicel length, and root length were evaluated. Sari and Kosout genotypes had the highest chlorophyll b and total chlorophyll contents and the Sari ecotype had the highest flavonoid content. The highest level of antioxidant capacity was observed in Sari and Vari ecotypes. The ecotypes of Zanglab, Aq Cheshmeh, Tangeh Chehel Chai with lower height showed the highest total phenol contents. Results of morphological evaluation showed that ecotypes of Vari, Sar,i and kosout had the longest leaves and  ecotypes of Azni and Vari had the longest roots. Also, ecotypes of Vari, kosout, Tangeh Chehel Chai, and Zanglab had the highest petiole length and Tangeh Chehel Chai ecotype had the highest leaf number. Correlation of traits showed that leaf height, leaf width, petiole length, leaf number, leaf flavonoid, and leaf phenol contents of sweet violet decreased with increasing altitude. In general, Sari, Vari, and Kosoot ecotypes from Mazandaran province had superior genotypes for most of the traits that could be used for future breeding programs.

In order to identify traits affecting sugar yield and determine cause and effect relationships between them, 13 different domestic and foreign sugar beet monogerm cultivars were evaluated at three different harvest time (7 October, 22 October, and 6 November) in a RCB design with four replications in terms of 11 important quantitative and qualitative traits in 2018 crop season in Miandoab Agricultural Research Station. The ANOVA results showed that the difference between studied cultivars was significant for all evaluated traits at 0.01 probability level. Phenotypic and genotypic coefficients of variation were high for most traits, indicating relatively high variability in the studied cultivars for evaluated traits. Genetic correlation coefficients between traits showed that the highest positive and significant correlations were observed between sugar yield trait on the one hand and white sugar yield (0.88**), impure sugar content (0.71**) and white sugar content (0.65**) traits in that order, and the highest negative and significant correlation was found between sugar yield trait on the one hand and molasses sugar (-0.62**), alkalinity coefficient (-0.58**), and root potassium (-0.52**) traits, in that order. In multiple regression analysis by stepwise method, sugar content, white sugar content, α-amino nitrogen, and root yield traits were entered into the regression model, respectively, that explained %84 of the total sugar yield variations. Based on path analysis results, sugar content (1.12) and root yield (1.03) traits had the highest positive direct effect on sugar yield and thus, selection based on these traits can help us to achieve high-yielding genotypes.

Sugarcane is cultivated in different parts of the world up to a latitude of about 32 degrees north and south. The resistance of this plant to cold is low. Considering the sensitivity of sugarcane to cold, in order to identify the pathways and genes by differential expression in sugarcane cultivars during cold stress and employ them in sugarcane plant breeding programs, 454 sugarcanes were investigated using morphological and biochemical indices, in the Research Farm of Khuzestan Sugarcane Research Institute following the incidence of -1.2 ℃ temperature in the region in December 2015. In the first stage, the cold-tolerant or sensitive cultivars were selected using morphological indices. In the second stage, biochemical indices such as proline and malondialdehyde were measured in the tolerant cultivars (selected at the first stage) after a cold stress period in 2016, which showed increases in comparison with susceptible cultivars. According to the data obtained at the two stages, two cultivars, namely BR00-01 and TUC66-107, were identified as the most tolerant and sensitive to cold, respectively. Based on the results of morphological studies, the cultivars with a higher tolerance to cold stress were also hose with higher proline and MDA levels in the biochemical study stage compared with the sensitive cultivars. There was also a high correlation between morphological traits and biochemical indicators in terms of cold resistance. Therefore, by measuring morphological and biochemical indices, it is possible to determine to a large extent the type of reaction of a sugarcane cultivar to cold stress before doing molecular analysis and spending huge sums of money, and to select superior clones when sifting sugarcane clones at different breeding stages.