نشریه فیزیولوژی محیطی گیاهی
پیاپی 72 (زمستان 1402)

Lead (Pb) not only negatively alters plant growth and yield but may also have potentially toxic risks to human health. In the present study, the effects of different concentrations of Pb (150 and 300 μM) on growth, physiological and biochemical attributes of rice under hydroponic conditions were investigated. The results showed that Pb treatments with negative effects on chlorophyll metabolism reduced photosynthetic pigments and, consequently, diminished the growth and biomass of rice plants. Pb stress induced oxidative stress and damage to bio-membranes by increasing the accumulation of hydrogen peroxide and methylglyoxal. The activity of antioxidant enzymes and glyoxalase cycle was upregulated in rice leaves under Pb toxicity. Pb treatments altered the levels of non-enzymatic antioxidant compounds (glutathione (GSH) and ascorbic acid (ASA)) in the leaves of rice plants by reducing the ratios of reduced ASA to oxidized ASA and reduced GSH to oxidized GSH compared to control plants. Therefore, concentrations of 150 and 300 μM Pb in the soil can induce negative effects on important physiological and metabolic processes of rice, which reduce plant growth and biomass.

Identifying the critical time and timing of plant irrigation based on a precise and basic plan is the key to water conservation, improvement of irrigation operations and plant tolerance to water shortage in agriculture. In recent years, vesicular arbuscular mycorrhizal fungi have been used in many plants to deal with dehydration and drought stress. In this regard, an experiment was conducted as split-plot in the form of randomized complete block design with 3 replications in the Yasuj region at years 2015 and 2016. Water stress was considered as the main factor in the form of irrigation after 30, 60, 90, 120 and 150 mm of evaporation from the evaporation pan class A and mycorrhizal fungus was considered as a secondary factor in the form of no application, application of Glomus mosseae and application of Glomus intraradices. The results showed that the interaction of irrigation and mycorrhizal fungi on flower phosphorus, flower yield, biological yield and water use efficiency of Borage was significant. In irrigation levels after 60, 90, 120 and 150 mm of water evaporation from the evaporation pan, the use of mycorrhizal fungi Glomus mosseae and Glomus intraradices compared to the absence of fungi respectively increased the yield of plant flowers (30.04% and 27.35 %), (90.2% and 90.98%), (93.21% and 94.1%) and (81.73% and 78.86%), also, at these levels of irrigation, biological yield and water use efficiency of Borage flower achieved a significant increase in the presence of mycorrhizal fungus, compared to the absence of mycorrhizal fungus application. Application of both strains of mycorrhizal fungus Glomus mosseae and Glomus intraradices in irrigation levels after 90, 120 and 150 mm of water evaporation from the evaporation pan compared to no application of mycorrhizal fungus, respectively, resulted in a significant increase in the harvest index of Borage flower (44.55% and 43.36%), (13.21% and 15.96%) and (5.6% and 5.41%) and flower phosphorus (44.69% and 20.45%), (150% and 125%) and ( 267.74% and 235.48%). Mycorrhizal fungus was able to moderate the negative effects of drought stress and increase the above-mentioned traits in those irrigation levels, and based on the results of this study, irrigation treatment after 90 mm of water evaporation from the evaporation pan + the use of Glomus mosseae mycorrhizal fungi is recommended.

Nitrogen is the most important factor limiting the growth and performance of crops, especially cereals. Therefore, with the aim of investigating the nitrogen use efficiency and its components in different cereals under the conditions of control (no use nitrogen) and optimal conditions of nitrogen, a factorial field experiment was conducted base on randomized complete block design with three replications at Gonbad Kavus University in 2017-2018. The experimental treatments included cereals at 7 levels, including bread wheat Koohdasht cultivar, durum wheat Seimareh cultivar, two rowed barley Khoram cultivar, six rowed barley Sahra cultivar, hull less barley Line 17, triticale Javanilo cultivar and oat Canadian cultivar) and the nitrogen factor were evaluated at two control (zero) and optimum levels. The result showed that cereal × nitrogen interaction was not significant on nitrogen utilization efficiency, nitrogen uptake efficiency and nitrogen use efficiency, nitrogen harvest index, nitrogen content and grain protein. But the main effect of nitrogen and cereals on nitrogen uptake efficiency, nitrogen utilization efficiency and grain protein percentage was significant at 1% level. While the nitrogen harvest index was only affected by cereals, Also, nitrogen remobilization was affected by cereals, nitrogen and cereals × nitrogen interaction. Finally, the results of this experiment showed that nitrogen use efficiency increased in all studied cereals under optimal nitrogen conditions. Nitrogen use efficiency consists of two components, nitrogen uptake efficiency and nitrogen utilization efficiency, as a result, the increase in nitrogen use efficiency is mostly due to the improvement in nitrogen uptake efficiency. Also, in all cereals under optimal nitrogen conditions, protein percentage and grain yield increased, in order to the increase in protein percentage was due to increased nitrogen remobilization. On the other hand, hull less barley had a higher nitrogen use efficiency than other cereals.

In this study the antioxidant activity and physiological properties of Clematis ispahanica from different habitats of Semnan province were investigated. Three natural habitats of this plant were identified in Semnan province (Cheshmeh Ali, Dibaj and Mojen) and leaf were sampled from plants. Chlorophyll, carotenoid, anthocyanin, proline, protein, phenol, flavonoid, reducing sugars, hydrogen peroxide, malondialdehyde, catalase and guaiacol peroxidase activities were measured. Also, the antioxidant properties of plants were investigated using DPPH radical scavenging capacity. Soil analysis of all three habitats was also done. The experiment was carried out as a completely random design with 3 repetitions and comparison of the average data using Duncan's test at a probability level of 5%. The results showed that the amount of plant metabolites, including soluble sugars, phenolic compounds and flavonoids, catalase enzyme activity and antioxidant properties was the highest in Cheshmeh Ali habitat and the lowest in Mojen habitat. On the other hand, the amount of plant defense compounds including proline, hydrogen peroxide, malondialdehyde and guaiacol peroxidase enzyme activity was the lowest in Cheshmeh Ali habitat and the highest in Mojen habitat. The amount of chlorophyll, carotenoids, anthocyanin and protein was also the lowest in the Dibaj habitat with the highest altitude above sea level. The results of this research showed that the Cheshmeh Ali habitat with the highest amount of metabolites and the lowest amount of defense compounds is the least stressful habitat, and conversely, the Mojen habitat is the most stressful habitat for C. ispahanica.

This study investigates the effect of drought stress on the morphological, physiological and biochemical parameters of Alnus subcordata C. A. Mey., an endemic wood species to Hyrcanian forests. The experimental design was completely randomized on one-year seedlings and four levels of drought stress (25% (severe stress), 50% (moderate stress), 75% (mild stress) and 100% (no stress) of crop capacity. The results showed that drought reduced the growth and biomass of seedlings. The decrease in severe stress treatment compared to the control in seedling height, basal diameter, total biomass, leaf area and specific leaf area were 41.8, 40, 72.4, 91.9 and 49.6% respectively. The root to shoot ratio showed an increase of 53.3%. With the increase of stress, total chlorophyll, chlorophyll a, chlorophyll b decreased by 50% and carotenoid decreased by 38.4%. The relative water content of the seedlings decreased by 33.50 and 24.9% in severe and moderate stress compared to the control treatment. The percentage increase of proline and malondealdehyde in the stress treatment compared to the control treatment was 169.8% and 142.7%, respectively. The activity of superoxide dismutase increased by 25% and 36% and peroxidase by 140% and 148% respectively in the mild and moderate stress treatment. The result showed that Caucasian alder seedling (a rather drought-sensitive species) could coped with drought in mild and moderate treatment by tolerance mechanisms such as reducing growth and biomass, increasing of the root to shoot ratio, reducing photosynthetic pigments and relative increasing in enzyme activities.

In order to investigate the effect of drought stress on some growth parameters and nodulation index, the symbiotic efficiency of rhizobial isolates an experiment in controlled greenhouse conditions in the form of a completely randomized design with 21 rhizobial isolates, a negative control treatment (without rhizobial bacteria) and a control treatment Positive (no bacteria with nitrogen fertilizer at the rate of 70 mg/kg from urea source) and 3 repetitions were done in 2013. Different levels of drought stress including drought in two levels S0 (100% of field capacity (control or no drought stress)), S3 (55% of field capacity (severe stress)), which by adding different concentrations of zero and 310 grams per liter of polyethylene glycol 6000 (PEG) was applied to the nutrient solution after one week of seedling germination. The results of statistical analyzes showed that drought stress had a significant reduction effect on shoot dry weight, shoot water content, nitrogen content, symbiotic efficiency of rhizobial isolates and nodulation index.

Cold is one of the most important abiotic stresses that limits crop growth and yield worldwide. In order to investigate how 20-day-old barley seedlings adapt to short-term cold stress, the present study was carried out in a factorial experiment with four replications in the seed laboratory of Karaj Seedling and Seed Breeding Research Institute. The experimental factors included barley cultivars (cold-sensitive Karon, semi-cold-tolerant Fasih, and cold-tolerant Makoi) and cold stress with three levels of 4, 8, and 22 oC (control). Temperature treatments were applied to barley seedlings for 48 hours. The results of analysis of variance showed that the interaction of cold and cultivar was significant on most of the measured traits in this study. The mean comparison also showed that the highest value of F0 was observed in Karun and Fasih cultivars at 8 oC and in Makoi cultivar at 4 oC, while in all three cultivars, Fv value and chlorophyll a content decreased with decreasing temperature. The ratio of Fm/Fv in Makoui and Fasih cultivars decreased with decreasing temperature, however no significant change was observed in Karon cultivar. In addition, with decreasing temperature, malondialdehyd (MDA) and H2O2 concentration and peroxidase (POX) activity increased in all three cultivars, especially Karon cultivar, but catalase (CAT) and super oxid dismutase (SOD) activity were not affected by the cultivar, and the highest CAT and SOD activity were obtained at 8 and 4 oC, respectively. The obtained results showed that the cultivars more tolerant than the sensitive cultivar (Karon) at low temperatures by limiting the production of compounds such as H2O2 and MDA, had higher chlorophyll content and photosynthetic efficiency, which probably reflects greater adaptation to cold.

Treated wastewater is important for plant irrigation in arid and semi-arid regions. Althaea officinalis belongs to the Malvaceae family and contains high levels of glazed compounds and mucilage. The aim of this study was to investigate the effect of different levels of ‏ ‏urban wastewater on growth and some ‎physiological characteristics of Althaea officinalis. The seeds of A. officinalis were cultured in the pots containing perlite. The plants were treated with different levels of urbane wastewater of Yasouj (0, 25, 50, 75 and 100%) in three replications. The experiment was conducted in the form of randomized complete blocks design. The plants were harvested after three weeks’ irrigation with different concentrations of wastewater for further analysis. The results have shown that wastewater treatments increased the fresh and dry weight of shoots, the leaf area, the height of plant and roots length. The highest growth rate was obtained in plants irrigated with un-diluted wastewater. In response to wastewater treatment, the amount of photosynthetic pigments including chlorophylls a, b, a+b, and carotenoids increased and the highest level of increase was observed at 100% of wastewater. Anthocyanins and flavonoids increased in response to wastewater irrigation while proteins decreased. No cadmium and lead were detected in the leaves and roots of wastewater-irrigated plants. Overall, the results of this study showed a positive response of A. officinalis to urbane-wastewater-irrigation.

Water stress is one of the most important environmental factors limiting the growth and yield of plants, especially in arid and semi-arid regions. Bio-stimulants are biological substances that stimulate metabolism and metabolic processes to increase plant efficiency. To investigate the effects of low water stress and bio-stimulants of Fosnutren and Humiforte on some morphophysiological and phytochemical traits of thyme, a factorial experiment based on a completely randomized design with 12 treatments and 3 replications in 2020 performed in greenhouse conditions. Therefore, the seedlings obtained from seed cultivation after two weeks of transfer to the pot, were exposed to dehydration stress treatments (25, 50, 75 and 100% of field capacity). Foliar application of plants with Fosnutren and Humiforte (5 ml) was performed three times and once every 15 days. The desired traits were evaluated 15 days after the last treatments. The results showed that increasing the levels of low water stress (25 and 50% of field capacity) caused a significant decrease in growth indices, chlorophyll content, total antioxidant percentage and essential oils and increase in proline content. Simultaneous treatment of drought and bio-stimulants of Fosnutren and humiforte with significantly reduced oxidative stress due to dehydration improved the evaluated traits except the amount of proline. The highest percentage of essential oil (2.34%) in Fosnutren foliar spraying and was obtained at 75% field capacity. In general, foliar application of Fosnutren and Humiforte reduced the negative effects of dehydration in thyme.

This study was conducted to investigate the effect of auxin and gibberellin on Euphorbia trigona Mill. in a randomized complete block design in 2020, and in greenhouse conditions. One minute pretreatments including auxin regulators NAA, IBA and IAA at a concentration of 500 mg / l and treatments containing GA, IAA, IBA and NAA, 250 mg / l were compared with each other and with control plants. Stems and roots fresh weight, dry weight, dry weight percentage, total photosynthetic pigments content as well as total terpenoids were measured. Fresh and dry weight and the percentage of dry weight of stem did not show sensitivity to the treatments and pretreatments, and the effects were not significant. NAA treatment had the most positive effect on roots fresh and dry weight, although the percentage of root dry weight was not significantly affected by the treatments. The highest significant increase in terpenoid content was observed in NAA treatment and NAA and IBA pretreatments. GA treatment had the most positive effects on the content of each of chlorophylls a and b, total and carotenoid content. In terms of effect on photosynthetic antenna composition, the most positive effects on the ratio of total chlorophyll to carotenoids were observed in GA, NAA, IAA and IAA pretreatments. IAA treatment also showed a significant increase in chlorophyll a to b ratio. The correlation between growth parameters with each other and also the correlation of chlorophyll content with each other and with carotenoids was positive and significant. However, the correlation of terpenoid content with none of the other traits was significant. On the other hand and from an application point of view, based on gas chromatography-mass spectrometry measurements, naphthalene-acetic-acid treatment was effective in severely increasing the content of valuable medicinal compound, bis-2-ethylhexyl phthalate, compared to the control.

In order to investigate the effect of hydrogen peroxide pretreatment and copper foliar application on some physiological traits and quantitative yield of corn under water deficit stress, a Split split plot experiment was conducted in a randomized complete block design with four replications, plants were planted in during two years (2017-19) in Baghmalek. The main plot of the irrigation regime with 4 normal levels, stopping irrigation 40, 55 and 70 days after the appearance of tassels, the sub-plot of copper foliar spraying with two control levels and 0.30 kg net per hectare from the source of copper sulfate 50% 25 days after the emergence of tassel and sub-plot of seed treatment with hydrogen peroxide with 3 control levels, 30 and 60 mM. The results showed that the triple interaction of irrigation regime, copper foliar application and hydrogen peroxide on chlorophyll a content, chlorophyll b, total carotenoid, catalase activity, plant height, number of seeds in a row and seed yield was significant at the probability level of 1%. The highest plant height and the number of seeds in the row were obtained from copper foliar spraying treatments and the application of 60 mM hydrogen peroxide under normal irrigation conditions. Also, the highest seed yield (9530.07 kg/ha) was obtained under normal irrigation conditions and copper foliar spraying and the application of 60 mM hydrogen peroxide, which showed an increase of about 42% compared to the cessation of irrigation 40 days after the emergence of tassels and the absence of copper foliar spraying and the absence of hydrogen peroxide application. The activity of catalase increased by 67% in the condition of stopping irrigation 40 days after the appearance of tassel and copper foliar application and application of 30 mM hydrogen peroxide compared to normal and control irrigation conditions. In general, the results of the experiment showed that copper foliar spraying and application of 60 mM hydrogen peroxide in suitable humidity conditions can increase chlorophyll content, grain yield and overall improvement of corn production.