جستجوی مقالات مرتبط با کلیدواژه « نشت الکترولیتی » در نشریات گروه « زیست شناسی »

Salt stress is one of the most important environmental threats that adversely affects the growth, development, and productivity of plants; therefore, suitable approaches are needed to mitigate its negative effects on plants. For this purpose, a pot experiment was carried out in a completely randomized design with two treatments include salinity (0, 25, 50, and 75 mM) and foliar application of selenium (0, 5 and 10 µM Na2SeO4), and the possible role of selenium in regulating Moldavian balm salt tolerance was investigated. Foliar applications of selenium were applied after seedlings establishment at three stages, simultaneously with the application of salinity stress, and then at weekly intervals. Results indicated that growth indices, photosynthetic pigments, and relative water content of leaves in Moldavian balm plants were decreased significantly by various levels of salinity stress. Foliar application of selenium especially at the low concentration increased all the mentioned traits in stress conditions. In contrast, high level of selenium magnified the negative effect of salinity, so that the highest value of malondialdehyde, electrolyte leakage, and water potential were obtained by 10 µM selenium under 75 mM NaCl and caused the accumulation of proline and soluble sugars. This study indicates that selenium at low concentration plays a significant role in alleviating the harmful effects of salinity through photosynthetic pigments, maintaining membrane integrity, reducing water potential, accumulation of compatible solutes, and consequently, improved the performance in Moldavian balm plants growing under salt stress.

In order to evaluate the effect of drought stress and salicylic acid on mineral content and some physiological traits of soybean genotypes (Glycine max L.) a greenhouse experiment was conducted as factorial based on completely randomized design with three replications in Mohaghegh Ardabil University in 2014. The first factor consisted of three levels of water deficit (85%, 65% and 45% field capacity), the second factor consisted of three concentration of salicylic acid (0 or distilled water, 0.4 and 0.8 mM) and the third included soybean genotypes (Williams, L17 and D42X19). The results showed that water deficit increased the amount of sodium, sodium to potassium ratio, electrolyte leakage, malondialdehyde and glycine betaine and decreased leaf relative water content and leaf area per plant. Soybean genotypes responded differently to water deficit. Williams and L17 had the highest and lowest concentrations of calcium, potassium, relative water content and leaf area per plant, respectively. Salicylic acid decreases the amount of lipid peroxidation, electrolyte leakage and increased concentrations of glycine betaine and leaf area per plant. Interaction of salicylic acid and genotype on traits was significant. Application of 0.4 mM salicylic acid exhibited afavorable effects on the accumulation of calcium, potassium, phosphorus and increasing the relative water content and maintaining the integrity of cell membranes and ameliorated the inhibitory effects of water deficit in soybean genotypes especially in Williams. Foliar application with 0.4 mM salicylic acid reduced adverse impact of water deficit stress in Williams cultivar.

Mutant genetic materials are valuable tools for understanding the physiology of remobilization and could be useful in the breeding of drought tolerant varieties. Two advanced mutant lines of bread wheat (T-67-60 and T-65-7-1) along with their wild type (Tabasi Cv.) were planted at two moisture conditions (normal and 30-40% of field capacity) as a factorial experiment in format of completely randomized design with three replications. Drought treatment initiated at full heading stage (Zadoks 60) and soluble carbohydrates were measured 5 times (0, 7, 14, 21 and 28 days after anthesis) in the stem internodes, separately. Based on the results it could be said that changes in the receiving signals for senescence phenomena under drought stress, capability of the sink, the rate of the reserves assimilated before anthesis and the use of reserves capacity over stem are the factors affecting the differences of genotypes in remobilization of stem soluble carbohydrates under drought stress. It seems that under drought stress mutant line T-65-7-1 was significantly better than wild type cultivar in terms of remobilization and its efficiency and also for faster receiving signals of senescence (as a stimulating factor of remobilization), higher capability of the sink (more grain yield) and higher reserve capacity (higher maximum soluble carbohydrate concentration and specific content). Also, mutant line T-65-7-1 has utilized full ability of all parts of the stem for remobilizing soluble carbohydrates during grain filling.

The paclobutrazol is one of plant growth regulators from triazoles group that is able to protect plants against environmental stress conditions. This experiment was carried out to investigate paclobutrazol (0، 25 and 50 mg/L) effects on reduction of injuries caused by low temperature (5±1ºC) stress in two cultivars of Phaseolus vulgaris [Daneshkadeh cv. (white bean) and Sayyad cv. (red bean)]. The results showed that low temperature stress، reduced fresh weight and dry matter and also reduced length of shoots and roots and leaf chlorophyll contents but increased electrolyte leakage percentage. Paclobutrazol treatment reduced fresh weight and dry matter and length of shoots but increased root dry weight and root development. Moreover، paclobutrazol-treated plants، when exposed to the cold stress condition، showed electrolyte leakage percentage less than control plants. Treatment of seedlings with paclobutrazol led to an increase in chlorophyll contents، either in stress or non stress conditions. White bean was more sensitive to cold than red bean and paclobutrazol affected white bean more than red bean. Therefore، it could be concluded that paclobutrazol treatment improved ability of plant responses to the cold stress and this effect was more remarkable in cold sensitive cultivars.

In this study, the role of salicylic acid in cadmium induced physiological changes was investigated in solid hydroponic culture in soybean plantlets. After presoaking soybean sterilized seeds in 0.5 mM SA solution for 6 hrs, seeds were transferred to pots containing perlite and then they were irrigated with Hoagland nutrient solution (full strength) containing 200 µM CdCl2 for 20 days. After harvesting the plantlets and calculation of growth parameters (root and shoot dry and fresh weight and length), photosynthetic pigments contents (chl a and b), electrolyte leakage in leaves, and cadmium content (in the roots and the shoots) as well as Ca and K content in shoots, it came to our knowledge that salicylic acid had little effect on this parameters in the absence of cadmium, but in the presence of cadmium, SA increased growth parameters, photosynthetic pigments contents, Ca and K content in shoots, against decreased electrolyte leakage in leaves and cadmium content in arial parts of plant. Therefore, SA could reduce cadmium toxicity and protect growth potential of plant by changing plant strategy in translocation of elements to aerial parts of plant and inhibition of electrolyte leakage and protection of photosynthetic pigments.