جستجوی مقالات مرتبط با کلیدواژه "شاخص پایداری غشاء و کارآیی فتوسیستم ιι" در نشریات گروه "زراعت"

Introduction Salinity has various effects on plant growth by affecting physiological processes. The decline in plant productivity under saline condition, frequently linked with the reduction of photosynthetic capability. It has been reported that efficiency of PSII photochemistry (Fv/Fm) of numerous plant species have been decreased due to salt stress studies have shown that salicylic acid (SA( improves resistance of plants to environmental stresses (heat, cold, drought and salt stress). In this relation, convincing data have showed that the SA-induced enhances resistance of plants to the salinity. Therefore, the present study was conducted to estimate salicylic acid effects on germination, growth and some physiological characteristics of two chickpea genotypes (Cicer arietinum L.) in salt stress condition.
Materials and MethodsIn this research we studied the effects of different concentrations of SA (0.5 and 1mM), on chickpea genotypes (MCC414, MCC789) during growth stages (germination, seedling and flowering) under salinity stress. Five levels of salinity including 0, 3, 5, 10 and 12 dsm-1 in germination stage and three levels of salinity (0, 4 and 8 dsm-1) at seedling and flowering stages) were employed separately in a factorial experiment based on Randomized Completely Block Design with three replications.
Results and DiscussionResults of means comparison showed that germination rate, significantly decreased under salt stress in both genotypes (P≤0.05). Under salt stress, increasing the osmotic pressure and the reduction seeds water absorption and the toxic effects of sodium and chlorine ions, can affect seed germination. Exogenouse application of SA concentrations (0.5 mM), under salt stress (3 and 12 dsm-1) increased rate and percentage of germination in MCC789 genotype. For MCC414 genotype, the combination of the treatment with salicylic acid (0.5 and 1 mM) and salinity (10 dsm-1) increased significantly germination rate. In same genotype, radicle and coleoptile length increased significantly after treating with SA (1mM) in salt stress (12 dsm-1). Exogenous application of SA concentration (0.5 mM), under salt stress (3 dsm-1) increased coleoptile length in MCC789 genotype (P≤0.05). Seed priming with SA leads to an activation of germination and seedling growth, while the enhancement of the division of root apical cells are important contribution to the growth stimulating effect of SA. In seedling stage, salinity decreased stem and root dry weight. SA and on some salinity levels, significantly increased stem dry weight in MCC789 and total root length in MCC414 genotype (P≤0.05). The decline in plant productivity under saline condition is frequently linked with the reduction in leaf area and stomatal conductance. Positive effects of SA on growth characteristics, in wheat, barley and maize have been reported. In both genotype, chlorophyll index, transpiration rate, membrane stability index and efficiency of PSII photochemistry significantly decreased and stomatal resistance increased under salt stress in flowering stage. Serious reduction in stomatal conductance and transpiration rate are adaptive mechanisms under salt stress. Halophytes such as Beta vulgaris and Spartina townsendi have salinity tolerance and show a combination of low photosynthesis, minimal transpiration, high stomatal resistance and low internal CO2 concentrations. Studies showed chlorophyll contents decreased under saline condition. Biochemical analysis of leaves of different maize cultivars for proline and chlorophyll contents indicated that proline accumulation increased and chlorophyll contents decreased under saline condition. SA application increased chlorophyll index and membrane stability index respectively in MCC789 and MCC414 genotypes. In both genotypes, stomatal resistance, significantly decreased and efficiency of PSII photochemistry increased with SA treatment under salt stress (12 dsm-1) (P≤0.05). Studies have shown that salicylic acid protects membranes by increasing polyamines such as putrescine, spermine, spermidine, as well as membrane sustainable complexes. In wheat, SA application improves the Fv/Fm. Szepesi et al, (2005) reported SA (10-6 and 10-7 M) could increase Fv/Fm in tomato plants under drought stress.
ConclusionThe results indicated that the modulator effects on salicylic acid on germination and other physiological processes of chickpea genotypes under salt stress.

Salicylic acid (SA), as a plant growth regulator, has an important role in alleviating the oxidative damages caused by drought stress in plant cells. In order to study the effect of different levels of SA on soluble protein content, the activity of enzymatic and non-enzymatic antioxidants including peroxidase, superoxide dismutase, ascorbate peroxidase enzymes, ascorbic acid and hydrogen peroxide and malondialdehyde levels and some physiological characteristics of two chickpea cultivars, [Kaka (MCC414) and Jam (MCC361)] under drought stress conditions, a factorial experiment was arranged based on completely randomized design with three levels of SA (0, 0.5 and 1 mM) and two moisture regimes, including drought stress (25% of field capacity) and control (100% field capacity) with three replications. Salicylic acid solutions at 0.5 and 1 mM concentrations were sprayed on leaves at intervals of 15, 25 and 35 days after sowing. Control plants were sprayed with distilled water. Results showed that at 25% field capacity, just peroxidase activity was enhanced in both cultivars. Drought stress reduced membrane stability index and PSΙΙ photochemical efficiency. Only in MCC414 cultivar, SA increased hydrogen peroxide and malondialdehyde contents under drought stress. SA significantly increased the activity of antioxidant enzymes including peroxidase and superoxide dismutase in MCC414 cultivar and ascorbate peroxidase enzyme activity in both MCC414 and MCC361. SA had not significant effect on the ascorbic acid content (P<0.05). Results suggested that SA at 0.5 and 1 mM concentrations could considerably improve membrane stability index and enhance PSΙΙ photochemical efficiency through reducing chlorophyll fluorescence under 25% field capacity.