This experiment was conducted with 12 genotypes of durum wheat originating from Iran and Azerbaijan Republic in both stressed and non-stressed conditions in Agricultural Research Station, Islamic Azad University of Ardabil in a randomized complete blocks design with 4 replications and in two years, 2008 to 2009 and 2009 to 2010 agricultural years. In this experiment, in addition to physiological traits, traits like leaf chlorophyll content, initial fluorescence (F0), maximum fluorescence (FM), variable fluorescence (FV), efficiency potential (FV/FM) and the amount of superoxide dismutase enzyme (SOD) had been measured. The results showed that stress tolerant varieties had higher chlorophyll content and it is increased by stress operations of amount of superoxide dismutase enzyme in varieties to overwhelming stress. In this study, genotypes 8, 10 and 11 had stress tolerance, chlorophyll fluorescence levels as desirable, appropriate chlorophyll amount and ultimately optimized yield in stressed conditions. Also, the higher amount of superoxide dismutase enzyme (SOD) in these varieties, this represents these varieties can cope desirably with drought stress conditions. It is probably that genotypes 10 and 11 are consistent with regional conditions. Also high and meaningful correlation between chlorophyll content and yield (r = 0.56*) showed that by increasing the amount of chlorophyll, the yield rate will be increased. Finally, it was found stress tolerant and high-yield varieties had higher superoxide dismutase, as well as high amount of chlorophyll.
This study investigates the impacts of drought-induced stress on the responses of ten bread (common) wheat genotypes to the physiological parameters and activities of POX, catalase CAT, and SOD under irrigation and stress conditions. The results of variance and mean comparison analysis indicated that the drought stress increased the activity of CAT while significantly decreased POX and SOD levels. In comparison with the irrigated plants, the photochemical efficiency of photosystem II (Fv/Fm) didn't change significantly; however, the concentration of chlorophyll and the relative water content in the flag leaves decreased in response to harsh environmental conditions. The observations included a significant enzyme activity in cultivar's interactions with the environment, which indicates various biochemical reactions of bread wheat plants under stress and non-stress environmental conditions.
The most critical issue regarding plants production is drought stress. Due to the near dating amongst leaves chlorophyll content within the plant achievement prices for photosynthesis and their resistance against the environmental strain, it may be beneficial to decide on varieties (cultivars) associated with superfluous chlorophyll content in the breeding (Revisory) programs. Thus, to assess the relationship between chlorophyll strain resistances in the experimental maize cultivars, we used 4 replications of five Maize genotypes with both irrigation and dry farming using the randomized entire block layout in 2016-17 agricultural year in Ardabil. We used Fernandez strain tolerance indices to calculate the strain tolerance of different genotypes. Besides, we used CCI-2 hundred tool to measure the leaves chlorophyll content. The results showed that strain-resistant genotypes which provided superior capability yield as well as 1.2 fold chlorophyll content compared with the resistant cultivars. Accordingly, genotypes 1 and 5 had the maximum chlorophyll content and the highest quantity of yield and thus, these genotypes are the maximum resistant genotypes against the drought. Moreover, further studies are required to choose genotypes compatible with dry situations.
To investigation the effects of salt stress levels (0, 50, 100, 150, 200 and 250 mM NaCl) on five maize (Zea mays L.) cultivars at germination stage, this study was performed at Ardabil, Iran in 2011. The results showed that in all cultivars, as the salt concentration increased, both germination percentage and germination index decreased significantly. Increasing salt concentration affected the early seedling growth in all cultivars. There were differences in responses of cultivars to salt stress. For all salt concentrations, Golden west had the highest germination percentage and germination index. Salt concentration decreased shoot and root dry weight. BC678 and Golden west had the lowest reduction of shoot and root dry weight, respectively. OS 499 had the highest reduction of shoot and root dry weight in this study; Golden west showed better results than the other cultivars in respect to salt tolerance index. The results show that Golden west was the cultivar to be recommended for saline soils. OS499 was more sensitive to salinity in this study.
To evaluate durum wheat (Triticum durum Desf.) tolerance to osmotic stress at the water potential levels induced by polyethylene glycol 6000 and NaCl solutions at an early stage of plant growth. Each, on germination and early seedling stages, were investigated for two durum wheat genotypes differing in drought tolerance (boefi and leucurum) at laboratory, in Iran in 2010. This investigation was performed as factorial experiment under complete randomized design with four replications. Daily and final germination as well as germination and seedling emergence rate, and seedling fresh and dry weight were measured in the study under controlled conditions. Results showed those germination rate was delayed by both solutions in both varieties, with differences between genotypes among growth stages, given that boefi genotype showed a higher germination rate than leucurum genotype in NaCl. NaCl had a lesser effect on genotypes in terms of germination rate and the final germination than did polyethylene glycol (PEG). This conclusively proves that the adverse effect of PEG on germination and early seedling growth was due to the osmotic effect rather than the specific ion. Seedling growth was reduced by both stresses. But NaCl usually caused less damage than PEG to durum wheat seedlings, suggesting that NaCl and PEG acted through different mechanisms. This difference in cultivar's behavior according to the growth conditions is discussed. It was concluded that inhibition in germination at equivalent water potential levels of NaCl and PEG was mainly due to an osmotic effect rather than did salt toxicity. Finally boefi genotype showed that resistance to both NaCl and PEG stress than leucurum genotype.
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