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Salinity impacts on crop production is further increasing as the global demand for food means agriculture extends into naturally salt-affected lands. Chlorophyll retention and the low sodium traits were associated with salt tolerance in wheat and barley under salinity conditions. Saline soils limit plant growth due to osmotic stress, ionic toxicity, and a reduced ability to take up essential minerals. Barley and wheat have different salt tolerances capacities and are grown as major grain crops in both saline and non-saline soils. The net sodium uptake for a plant growing in 150mM NaCl with perfect osmotic adjustment is similar to actual rates measured for wheat and barley. Our hypothesis is that salinity reduces the growth of wheat more than barley by reducing chlorophyll content. The aims of this study were to analyse the effects of salinity on the growth and yield of barley and wheat cultivars to explore the links between the sodium accumulation and chlorophyll content.

Tow bread wheat cultivars differing in salt tolerance (Arg and Tajan) and a barley cultivar (Nik) were used to assess the change in the chlorophyll content and sodium accumulation over time under saline conditions. Two levels of NaCl (0 and 150 mM NaCl) were imposed as the salinity treatments when the leaf 4 was fully expanded. At 21 days after salt treatment plants were harvested and shoot and root dry weight, root length and sodium root were measured. Sodium accumulation rates and chlorophyll content examined between days 14 and 42 after salt added. Na+ and K+ flag leaf were measured in days 49 after salt treatment started.

Results showed that the rate of sodium accumulation initially was the same for both wheat cultivars in leaf. After 30 days of salinity, the rate of sodium accumulation rose in Arg compared with Tajan. In Nik barley cultivar, shoot sodium concentration was higher than bread whit cultivars. Salinity caused degradation in chlorophyll content in both bread wheat cultivars and at the determination of this experiment Tajan had lower chlorophyll content than Arg cultivar. Nik barley cultivar showed much longer chlorophyll retention than tow bread wheat cultivars. Salinity decrease K+ flag leaf, K+/Na+ flag leaf, shoot and root dry weight, seminal root length, yield and increase Na+ flag leaf and Na+ roots compared to control. Flag leaf K+/Na+ ratio was higher in salt tolerance cultivar (Arg) compared to Tajan and Nik, despite the similar roots sodium concentration. Flag leaf Na+ concentration was the same in tow wheat cultivars and barley under salinity stress and there was no relationship between Na+ exclusion and salt tolerance in cultivars in our experiment. Yield loss of 35 percentages was found in wheat cultivars on average and in barley did not observed remarkable decrease in seed yield. There was may be no beneficial effect of the low Na+ trait at 150 mM NaCl (high salinity level) in all cultivars. Root length reduction in cultivars was due to osmotic stress of salt solution out of the roots. A significant correlation between shoot dry weight and sodium flag leaf showed that sodium concentration in leaf can be used as an index for evaluating salt tolerance.

Given the effect of salinity on shoot growth, it seems that other factors may have influenced net carbon gain before any reduction in the concentration of chlorophyll. It implies that osmotic and tissue tolerance in bread wheat and barley contributed to the salt tolerance in tolerant cultivars and preferential sodium accumulation and maintains in roots and old leave relative to young leaves can caused an increase in salt tolerant. The low shoot sodium concentration was not associated with chlorophyll content in wheat cultivars.

Faster and more extensive root growth is important for good plant growth and such a root system is expected to extract more available soil water in salt conditions. In order to examine root system and some physiological characteristics of four bread wheat contrasting in salt tolerance (Arg, Ofoq, Tajan and Morvarid) and two durum wheat cultivars (Behrang and Shabrang), a greenhouse experiment was conducted with two salinity levels (0 and 13.5 dS/m NaCl) growing in PVC tube. Salt stress decreased root dry weight, shoot dry weight, seminal root length, total root length, root and shoot K+, shoot K+/Na+, root K+/Na+ and tillers and increased root Na+,shoot K+ leaf temperature and chlorophyll content compared to control. Seminal root growth did not affect by salinity stress in Arg andno significant differences was observed between Arg and Shabrang in this aspect. Although, reduction in seminal root length was less in Arg (5%) and Shabrang (32%), but these cultivars had more reduction in total root length by 64% and 68% respectively under saline conditions. Root growth reduction in cultivars was due to osmotic stress of salt solution out of the roots and the values for total root length in bread wheat cultivars was more under salt stress. Finding of this study on root lentgh identify it as one of the valuable index for improved adaptation to osmotic stress in wheat.

In order to examine root system and some physiological characteristics of four bread wheat contrasting in salt tolerance (Arg, Ofoq, Tajan and Morvarid) and two durum wheat cultivars (Behrang and Shabrang), a greenhouse experiment was conducted with two salinity levels (0 and 150mM NaCl) growing in PVC tube. Treatments were imposed when the leaf 2 was fully expanded. Leaf temperature of plants was acquired in the greenhouse 5 days after imposing the salt treatments. At 21 days after salt treatment plants were harvested and traits were measured. Seminal root length, total root length, Chlorophyll content, K+ and Na+ root, root and shoot dry weight in all cultivars were investigated.

Salt stress decreased root dry weight, shoot dry weight, seminal root length, total root length and increased root Na+, leaf temperature and chlorophyll content compared to control. Seminal root growth did not affect by salinity stress in Arg and no significant differences was observed between Arg and Shabrang in this aspect. Although, reduction in seminal root length was less in Arg (5%) and Shabrang (32%), but these cultivars had more reduction in total root length by 64% and 68% respectively under saline conditions. Differences in root Na+ concentration between some wheat cultivars were less obvious in 21 days after salt treatments and it seems the roots exposed to salinity were reduced in growth mainly because of the osmotic effect of the salt, rather than a salt-specific or toxic effect. Seminal root length reduction in cultivars was due to osmotic stress of salt solution out of the roots and the values for total root length in bread wheat cultivars was more under salt stress. Shabrang showed the highest and significant increase in leaf temperature among cultivars and the most reduction in shoot dry weigh was observed in this cultivar under salt conditions. In more extended studies, shoot growth was more inhibited than root growth in saline and dry soils, however, in this study, there was little effect on shoot growth. Thus, assimilate supply was not limiting root growth.

The ability of wheat to retain seminal and total root length improved osmotic tolerance and extending root system in salt tolerant cultivars would allow water acquisition from deeper in the soil profile, thus helping to overcome osmotic stress. Results showed that osmotic tolerance may be in bread wheat to the same extent as in durum wheat cultivars and the finding of this study on root traits identify it as one of the valuable index for improved adaptation to osmotic stress in wheat. Under salt conditions or in some wheat cultivars, modification of root water uptake capacity plays a more important role compared with stomatal closure in avoiding stress-induced growth reduction.

In this study, response of two bread wheat cultivars (Arg and Tajan) to different irrigation regimes (full irrigation and 85 percent of water requirement) and different salinity levels (0, 50, 100 and 150 mM NaCl) in a greenhouse using a factorial experiment based on a randomized complete block designe with three replications was evaluated. Treatments were imposed when the leaf 4 was fully expanded. 150 mM level of  salinity significantly decreased  shoot dry weight, root dry weigh, and water use efficeiny in grain and shoot dry weight. Although, water use efficeiny in grain and shoot dry weight of tolerant Arg cultivar (3.9 and 0.97 g/L per plant respectively) was more than sensitive Tajan cultivar (2.8 and 0.85 g/L per plant respectively), but both cultivars had the same reduction in shoot dry weight. Deficit irrigation decreased the rate of roots Na+, shoot Na+ and flag leaf Na+, and increased flag leaf K+/ Na+ ratio from 4.73 to 5.33 and water use efficeiny in shoot dry weight from 3.1 to 3.5 g/L per plant respectively. The yield of both cultivars did not affect by 50 and 100 mM NaCl. At last, 150 mM NaCl caused a same reduction in yield at full irrigation and 85 percent of water requirement in Tjan, but in Arg cultivar, the yield did not affect by this level of salinity. Because grain yield of both cultivars did not affect by deficit irrigation under salinity levels, thus they had a similar resistance to osmotic stress.

The understanding of salt tolerant mechanisms is crucial for development of varieties with high salinity tolerance. Crop growth is being limited by the osmotic effect of the salt around the root and the toxic effect of the salt within the plant. The osmotic stress has a greater effect on growth rate than the ionic stress. The osmotic stress immediately reduces stomatal conductance with the onset of salinity and is one of the initial causes of a decline in crop growth. As leaf temperature correlate with stomatal conductance, this can be used to asses osmotic stress tolerance in plants. Much of the recent experiment to improve the salt tolerance in wheat has focused on sodium exclusion in plant tissue as a criterion for salinity tolerance but in some work there was no significant relationship between sodium exclusion and salt tolerance. However, pattern of sodium accumulation in shoot is different in wheat cultivar through time. The aim of this study was to evaluate the potential use of leaf temperature in screening for salt tolerance and pattern of sodium accumulation through time and its relationship with some physiological characters and salt tolerance.

In this greenhouse experiment, two bread (Arg and Tajan) and a durum (Behrang) wheat cultivars were evaluated in terms of leaf temperature and patterns of Na+ accumulation under three salinity levels (Control, 100 and 200 mM NaCl). Treatments were imposed when the leaf 2 was fully expanded. Leaf temperature of plants were acquired in the greenhouse 6 days after imposing the salt treatments. Plants were harvested after salt treatment every 15 days for 60 days and sodium concentration was measured at each harvest. Chlorophyll content, K+ and Na+ root and shoot and shoot dry weight, 45 days after salt treatment, were measured.

Shoot and root Na+ concentration was increased in response to increasing salinity but in roots this increase was greater than shoots. Salt stress decreased shoot dry weight in bread wheat cultivars (32%) and durum wheat (63%). In the highest salinity level, after 45 days exposure to salt, shoot K+/Na+ ratio was reduced in all genotypes to a similar extent (about 60%) and in this level of salinity higher reduction in chlorophyll content occurred in Behrang (75%) cultivar. Shoot K+/Na+ ratio showed the most reaction to salinity. Differences in leaf Na+ concentration between two bread wheat cultivars was more obvious in 45 days after salt treatments but in other growth stages were less obvious. Results showed that differences between sodium concentrations in two bread wheat cultivar through time, was remarkable 45 days after treatments. At 200 mM NaCl, Arg showed the lowest and non significant increased in leaf temperature (0.87◦ C) but in Tajan (1.74◦ C) and Behrang (4.30◦ C) this increased were significant. Salt concentration of 100 mM NaCl had no effect on leaf temperature in cultivars.

Different patterns of Na+ accumulation may be exist in wheat cultivars through time. Differences in sodium transport rates from roots to shoots may cause different patterns of sodium accumulation through time in wheat. This preferential in early growth stages, stomatal factors is more important than chlorophyll content and as leaf temperature is largely a function of stomatal conductance, this can be used to assess osmotic stress tolerance. Thermography could be acquire accurate technique to distinguish differences in salt tolerance in wheat cultivars. The shoot K+/Na+ ratio, cannot be used as a reliable indicator of salt tolerance in wheat. Greater tissue tolerance in wheat cultivars was associated with prolonged retention of chlorophyll in leaves and this resulted in less reduction in shoot growth.

Background and Objectives Plants are often subjected to water deficit and soil salinity in arid and semiarid regins. Water deficit and salinity threaten crop productivity as both stresses reduced the soil water potential. In the natural invironment drought and salinity frequently combined. Understanding how plants responds to water deficit, salt and co-occurring stresses can play a major role to improving the toleranc of crops to both water deficit and salinity. Salinity may cause ions imbalances, due to the competition of Na+ with nutritons such as K+. Reduced transpiration rates due to water deficit reduces the nutrient uptake and transport. Deficit irrigation with fresh water can increase water use efficiency without significantly decreasing yield. Several studies have focused on effect of water deficit and salinity on nutrients uptake but there is still no information on the effect of these conditions on ions relations and water use efficiency. The aim of this study was to investigate the effects of salinity and water deficit on ion distribution in different tissues and water use efficiency of bread wheat cultivars with contrasting of sodium concentration.   Materials and methods In this study, ions distribution and grain water use efficiency (WUE) of two bread wheat cultivars (Arg and Tajan) with contrasting of sodium concentration to different irrigation regimes (full irrigation, 80 and 70 percent of water requirement) and different salinity levels (0 and 150 mM NaCl) in a greenhouse experiment with three replications were evaluated. Treatments were imposed when the leaf 4 was fully expanded. For sodium and potassium analysis, at 7 weeks after treatments, plants were completely harvested from pots, washed and divided into required parts. Roots, flag leaf sheath, flag leaf blade and leaf 3 blade used for determining Na+ and K+ concentrations. The remaining plants were left to grow until physiological maturity. Plants were harvested after 16 weeks to measure yield and root biomass. Results and discussion Whole plant sodium concentration of cultivars was significantly increased under salt stress. In salt treatment, the tissues Na+ and K+ concentration was significantly higher in Arg than Tajan. Under salt stress, water deficit caused a reduction in Na+ concentration in all tissues. Sodium uptake by root was similar in cultivars but Tajan maintained lower Na+ concentration in shoot tissues under salinity. Differences in sodium concentration were found in flag leaf blade in cultivars. Genotypic differences in the rate of sodium transfer from the root to shoot are caused to occure genotypic differences in leaves Na+ concentration. Tajan had more control of ion transport from root to shoot. Under salt stress, K+ concentration was not affected by water deficit in tissues. Arg maintained higher K+ concentration with K+/Na+ ratios in flag leaf blade than Tajan cultivare. Root biomass decreased in cultivars at 150 mM NaCl whereas don’t affected by deficit irrigation. An NaCl concentration of 150 mM was found suitable to identify genetic variation in root wheat genotypes. NaCl decreased grain yield and grain WUE in salt stress conditions and Tajan showed more decreases from this aspect. It seems that, a lower decrease in grain WUE in Arg, is due to greater tissue tolerance. Differences in Na+ concentration under salinity and drought, mainly occur in the youngest leaf blade between cultivars and lower sodium transfer from the root to shoot, lower sodium accumulation in younger leaves and higher K+/Na+ ratios can be important in stabilizing wheat yield and grain water productivity. Tajan have a more resistance to osmotic stress than Arg and tissue tolerance in Arg was greater than Tajan cultivare. Cultivars that maintained low concentration of Na+ in shoots and have a greater degree of tissue tolerance, in regions with poorer quality irrigation water, have more water productivity and thus this is an imperative to develop cultivars with above mentioned characteristics in soils with higher salt and limited water.

To assess the effects of sodium exclusion on leaf chlorophyll content and biomass production, three bread wheat cultivars with contrasting of sodium concentration and different salt tolerance were grown at 2 salinity levels (0 and 150 mM NaCl) under hydroponics and greenhouse conditions in 2017 year. Salinity decreased yield, shoot dry weight, shoot K+/Na+ ratio and chlorophyll content and increased shoot Na+ compared to control. In this experiment, shoot K+ was not affected by salinity. Shoot Na+ concentration was more in salt tolerant cultivar (Kavir) than Mahdavi and Tajan under salinity stress and there was no relationship between Na+ exclusion and salt tolerance in cultivars. Leaf Na+ concentration were much lower in Mahdavi than two other cultivars. Chlorophyll content showed the most decreases in Tajan (75%) than Kavir and Mahdavi under salinity stress. Yield and shoot dry weight was reduced to the same extent (40% and 37% respectively) by 150 mM NaCl in each cultivar, despite greater chlorophyll content by Kavir cultivar. Results showed that Kavir had the highest ability to tolerate high leaf tissue concentrations of Na+. Despite different sodium concentration, the reduction in shoot biomass under salt stress was the same for all cultivars. It seems that the major effect of salinity on shoot biomass and yield was due to the osmotic effect of salt, not due to Na+-specific effect within the plant.

An understanding of physiological mechanisms of salt tolerance is necessary for breeding programs, in order to select the desired trait in different wheat genotypes. Three bread wheat genotype differing in salt tolerance were employed to assess ion distribution and growth responses under saline conditions. To evaluate ion distribution in plant, sodium and potassium concentrations as well as Kﳖ ratios in different tissues including root, leaf 3 blade, flag leaf sheath and flag leaf blade were assessed in a pot experiment in the glasshouse using a factorial experiment based on a randomized complete block design with three replications . Four levels of NaCl (0, 50, 100 and 150 mM NaCl) were imposed as the salinity treatments when the leaf 4 was fully expanded. Salinity had a similar effect on shoot biomass of all genotypes at 150 mM NaCl. Root biomass decreased in all genotypes with increasing salinity and this decrease was more in sensitive one (Tajan) at 150 mM NaCl. The genotypes did not differ significantly in root uptake of sodium. Sodium contents reduced from root to shoot and Salt tolerance in wheat genotypes was related to lower sodium accumulation in leaves. The major differences of salt tolerant genotypes (Arg and Mahdavi) and sensitive one in sodium transport to the younger leaf were due to the rate of transfer from the root to the shoot, which was much lower in Arg and the capacity of the leaf sheath to extract and sequester sodium as it entered the flag leaf blade in Mahdavi. Salt tolerant genotypes maintained higher Kﳖ ratios in flag leaf blade than in salt sensitive one. Its likely that reduction in sodium transfer from the root to the shoot and leaf sheath sequestration specially in flag leaf are the traits that interact to control leaf blade sodium and would appear to be the most important mechanisms contributing to the improved salt tolerance in tolerant genotypes.