جستجوی مقالات مرتبط با کلیدواژه « Relative leaf water content » در نشریات گروه « زراعت »

Phaseolus vulgaris L., commonly known as the common bean, is an important legume crop, responsible for 85% of global bean production. Nevertheless, soil salinity represents a significant challenge that severely impairs its productivity. Soil salinity represents one of the most detrimental constraints on crop growth and production. Conversely, beans are regarded as one of the most susceptible crops to salinity stress. However, the detrimental effects of salinity on crops can be significantly mitigated by the use of certain substances. Salinity exerts a significant negative influence on the primary plant processes, including photosynthesis and the production of photoassimilates, which ultimately results in a reduction in plant production. The application of an appropriate quantity of salicylic acid (SA) enhances the plant's tolerance to abiotic stresses, thereby reducing the destructive effects of stress and increasing tolerance to abiotic stresses. It has been demonstrated that the external application of salicylic acid can induce the tolerance of crop plants to a range of abiotic stresses, including salt, drought, heat, cold, and heavy metals. Furthermore, SA can be an effective substance against plant abiotic stresses, as it can regulate a variety of phytohormones, and it may play a key role in free radical scavenging and nutrient uptake. Furthermore, the utilization of biochar represents an efficacious approach to mitigating the consequences of abiotic stresses, such as salinity. Biochar, a carbon-rich material, is employed to enhance soil carbon sequestration, reduce CO₂ emissions, and augment soil microbial diversity and activity. It has been postulated that biochar has the capacity to adsorb some of the toxic ions, such as Na and Cl, thereby reducing the toxic effects of salinity.

A two-year glasshouse study was conducted using a randomized complete block design, with four replicates in each treatment. The study was conducted at the Faculty of Agriculture, University of Mohaghegh Ardabili, Iran over two consecutive years (2022-2023). The experiment included three levels of salicylic acid (SA): SA0 (0 mM), SA0.5 (0.5 mM) and SA1 (1 mM), four levels of biochar, including no biochar application as the control treatment (B0), recommended biochar (Rb) by application of 2.5% biochar. The treatments included 5% (w/w) of modified biochar with phosphoric acid (PA), 1.25% of modified biochar with sulfuric acid (Sb), and salt stress (SS) using NaCl in three levels: SS0 (distilled water), SS4 (4 dS m-1), and SS8 (8 dS m-1). In this experiment, the salinity treatment was applied in two stages: at the planting time and when the seedlings had fully established themselves in the soil. Salicylic acid was applied foliarly at two stages: early and late flowering, according to the predetermined levels.

Salinity had a detrimental impact on the biochemical attributes of bean plants, yet this effect was alleviated by the application of the SA treatment. Furthermore, salt stress resulted in a reduction in relative water content, membrane stability index, leaf area and photosynthetic pigments, which in turn led to a reduction in current photosynthesis and remobilisation of photoassimilates. Nevertheless, the application of biochar and the use of SA were found to alleviate the negative effects, resulting in a higher grain yield compared with the control plants, i.e. at the absence of biochar and SA application at the end of the experiment. The combined application of biochar and SA resulted in a higher relative water content, photosynthetic pigments and an enhanced rate of photosynthesis. The greatest accumulation of chlorophyll-a and carotenoids was observed in response to the application of SA1 without biochar in non-stress conditions. Furthermore, the lowest photosynthetic rate was observed in response to SS8. Moreover, the greatest anthocyanin accumulation was observed in response to the addition of biochar to the soil in the absence of SA under salt stress conditions.
Our research has demonstrated that the combined application of biochar and SA can significantly mitigate the adverse effects of salinity stress on common beans. Furthermore, the results demonstrated that SA significantly enhanced grain yield of plants under both saline and non-saline soils. The results indicate that the excessive use of biochar and SA may lower the mentioned effectiveness, as the biochar increases soil porosity, which negatively impacts water availability. Furthermore, application of high doses of SA has been shown to have a negative impact on the biochemical and enzymatic attributes of the plant under salinity conditions.

Although the study on the effects of biochar and SA on common beans under salinity stress provides valuable insights, it is important to consider the limitations of the study. Consequently, the findings may not be directly extrapolated to the natural agricultural settings, where multiple environmental factors interact.

Barley is one of the most important crops in cereals, which shows the wide range of adaptation to different environments. Plant growth is severely influenced by environmental stresses such as drought, high salinity and extreme temperatures. Environmental stresses trigger a wide range of plant responses, like change in the gene expression to variability in cellular metabolism and growth. One of the most important harmful factors is the production of crops in different areas of salinity, which has a negative impact on all aspects of plant growth and production. Also, in the plants exposed to salinity the photosynthetic apparatus activities were damaged or impaired, leading to a decrease of photosynthetic capacity and lipid oxidation is increased in these conditions and on the other hand Cause disturbance of the balance between production of reactive oxygen species and antioxidant defense and thereby causing oxidative stress. Due to the increase in water salinity and its damages on plant production, evaluation of salinity effects on crop plants, is very important. The study of biochemical and physiological variations under salinity stress is a suitable solution that can help to identify the effective factors in tolerating this stress and selecting resistant cultivars. Therefore the aim of the present study was, investigate and compare photosynthetic pigments, the changes in water status, osmotic regulators and activity of antioxidant enzymes in leaf tissue of two native barley cultivars of Sistan region under Salinity stress.

Two native barley cultivars of Sistan region (Nomar and Nimroz) were examined in a factorial experiment (the first factor of cultivar in two levels and the second factor of drought stress in three levels) in a completely randomized design with three replications. The seeds of Numar and Nimroz varieties were prepared from Zabol Agricultural Research Center. 10 seeds were planted in each pot and the thinning was performed after the plants reached the 4-leaf stage and 5 identical plants were kept in each pot. After cultivation and complete establishment of plants in the seedling stage (four leaves), Salinity stress treatment was applied at different levels (Control (0), 150 and 300 mm NaCl) for two weeks. Sampling of all plant leaves was performed at a specific time and then the studied traits were measured. The studied traits were included the activity of antioxidant enzymes (catalase (CAT), polyphenol oxidase (PPO), ascorbate peroxidase (APX)), photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll and carotenoids), protein content, relative leaf water content (RWC) and some regulators Osmotic (proline and carbohydrate). After measuring the traits, the obtained data were analyzed by Duncan's method.

Analysis of variance showed that the effect of cultivar, drought stress and cultivar interaction and drought stress were significant at 1% probability levels, on all studied traits. According to the results of interactions, it was found that salinity stress in both barley cultivars reduced physiological traits such as photosynthetic pigments, relative leaf water content, protein and increased content of carbohydrates and proline, carotenoids and the activity of catalase, ascorbate Peroxidase and polyphenol oxidase. In normal conditions, Nomar cultivar compared to Nimroz cultivar had the highest amount of chlorophyll a, b, total and carotenoids, relative content of leaf water, protein and proline. Also, at salinity of 300 mM, the highest activity of antioxidant enzymes of ascorbate, peroxidase, polyphenol oxidase, catalase, protein, photosynthetic pigments was related to Nomar cultivar, while the highest amount of carbohydrates and carotenoids was related to Nimroz cultivar at salinity of 300 mM.

In generally, according to the results of this study, it can be said that among the cultivars under study, in vegetative phase, Nomar cultivar had higher capacity and function to salt stress tolerate than another cultivar.

In order to study the effects of late-season drought stress and foliar application of potassium silicate on yield and yield components of spring genotypes of canola, a factorial split-plot experiment is conducted in Karaj, Iran in a randomized complete block configuration with three replications for two years of cultivation (2016-2018). The irrigation is performed at two levels in this study, including routine irrigation (control) and interruption of irrigation from the pod formation stage. Potassium silicate foliar application at two levels is comprised of 0 and 4 g liter-1 in factorial status in main plots and five Brassica napus L. genotypes including OG×AL, RGS×SLM, DALGAN, RGS003 and RGS×Okapi in subplots.  The results show that the measured properties are affected by the applied treatments. Full irrigation with foliar application in OG×AL genotype results in highest seed yield (5620 Kg/ha) and total chlorophyll content (1.71 mg/g.FW) increase stomatal resistance, leaf proline, leaf soluble and carbohydrates, decreasing total chlorophyll content and relative leaf water content. Under drought stress conditions, DALGAN and RGS× SLM genotypes have higher yield, which indicates its better performance under stress conditions. Finally, our research demonstrates Potassium Silicate's beneficial effects in improving the drought tolerance of canola plants, particularly at the end of the season. Our study will act as a foundation for any attempt in new approaches to mitigate drought damage, establishing a functional connection between the position of potassium silicate, physiological response, and drought stress tolerance in canola plants.

Drought is one of the most important stresses that inhibit growth of plants and due to mainly disturbance of the balance between the production of reactive oxygen species and antioxidant defense, causes oxidative stress and different biochemical and physiological responses in plants. So, the evaluation of plants for drought tolerance to cultivate in dry regions is very important.In this way, the present study aimed to investigate and compare two native barley cultivars of Sistan region (Nimroz and Nomar) based on measurement of some defense mechanisms and physiological properties including Antioxidant enzymes activity (Catalase (CAT), Ascorbate Peroxidase (APX), Polyphenol oxidase (PPO)) photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll and carotenoids), protein content, relative leaf water content (RWC) and some Osmotic regulators (proline and carbohydrate) were under drought stress. This experiment was performed as a factorial in a completely randomized design with three replications, conducted at the Institute for Biotechnological Research in the University of Zabol. Experimental treatments included drought stress (50%, 75% and 100% of the field capacity (control)) and two cultivars native to Sistan region (Nimroz and Nomar). Analysis of variance showed that the effect of cultivar, drought stress and interaction of cultivar and drought stress were significant at 1% probability levels, on all studied traits. Results indicated that with increasing drought stress levels compared to normal levels, the amount of photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll and carotenoids), protein content and relative leaf water content (RWC) decreased. However, proline and carbohydrate concentration, carotenoid content, the activity of antioxidant enzymes CAT, PPO and APX were increased. Based on the results of the interaction, it was identified that Nimroz cultivar had a better reaction than Nomar cultivar in terms of protein, relative leaf water content, carotenoids, osmotic regulators and antioxidant enzymes (catalase and ascorbate peroxidase) during drought stress. While the Nomar cultivar was the highest average in terms of chlorophyll a, chlorophyll b, total chlorophyll, protein and enzyme polyphenol oxidase compared to the Nimroz cultivar during drought stress.

Water stress is the most important abiotic stress in crop production. Silicium (Si) is the second most abundant element in the soil with beneficial effects on plant tolerance to biotic and abiotic stresses. In order to evaluate the effect of this element in increasing tolerance to water deficit in wheat, a factorial experiment was conducted based on a completely randomized design with three replications in the greenhouse of College of Agriculture, Shiraz University, Shiraz, Iran. Treatments included four wheat cultivars, Shiraz, Sirvan, Ofogh, Baharan, foliar silicon application in two-levels, zero (control), and 3 mM, and three levels of water deficit (field capacity, 40% and 60% of field capacity). The results showed that water deficit reduced spike length (31%), dry matter per plant (41%), grain yield (25%), greenness index (11%), flag leaf relative water content (24%), catalase (24%), peroxidase (70%) and superoxide dismutase activity (41%). Baharan and Sirvan cultivars were superior for greenness index and peroxidase activity. However, foliar silicon application at 3 mM concentration ameliorated the negative impacts of water deficit stress. Foliar application of silicon enhanced all the above parameters including antioxidants. For a majority of the measured characteristics, it was evident that Baharan and Sirvan, as water deficit tolerant cultivars, and Ofogh, were superior compared to Shiraz cultivar. The results showed that foliar application of silicon increased the activity of antioxidant enzymes and as a result ameliorated the negative impacts of water stress.