Effect Of Moderate Salinity Research Articles

Effect of moderate salinity on Golden Thistle (Scolymus hispanicus L.) grown in a soilless cropping system

• Soilless cultivation of S. hispanicus l. improved plant growth and yield characteristics. • S. hispanicus L. was resilient to moderate salinity until 90 days after transplant. • Salinity level of 10.0 and 15.0 mM improved functional quality characteristics. • Physiological indicators significantly declined at salinity levels of 10 and 15 mM NaCl. Selecting salt-tolerant crop species for cultivation might be a feasible option to maintain crop productivity in arable lands affected by salinity. In this context, here we examine the responses of the wild edible green golden thistle ( Scolymus hispanicus L.) to moderate levels of salinity when grown in a soilless system for culinary use. Treatments were obtained by establishing four NaCl concentrations (0.5, 5.0, 10.0, and 15.0 mM) in a standard nutrient solution, resulting in initial solution electrical conductivities (EC) of 2.2, 2.8, 3.2, and 3.8 dS m − 1 , respectively. By the end of the experiment, 120 days after transplanting (DAT) drainage EC reached 2.65, 3.33, 3.96, and 4.51 dS m − 1 , respectively. At the first harvest, 90 DAT, the increase of the NaCl concentration had no significant impact on the number of leaves per plant, leaf fresh and dry weight [g plant −1 ], and root dry weight [g plant −1 ]. At the second harvest (120 DAT), 15.0 mM NaCl significantly decreased root and leaf fresh and dry weight without affecting the number of leaves per plant compared to 0.5 and 5.0 mM NaCl, while 10 mM NaCl had no impact on any of these parameters. The concentrations of K + , Ca 2+ , Mg 2+ , and P in the leaves were not influenced by the tested salinity levels, while those of organic-N and NO 3 − -N were significantly reduced by 10 and 15 mM NaCl, 90 DAT. Furthermore, 10 and 15 mM NaCl significantly increased the Cl − and Na + concentrations in leaves, but not in the roots. In the root tissues, only the K concentration was reduced by salinity while P increased at the highest salinity level (15 mM NaCl). Based on these results, we conclude that S. hispanicus L. is resilient to moderate salinity levels and can be considered a promising candidate plant for introduction to soilless cropping systems.

Iodine Enhances the Nutritional Value but Not the Tolerance of Lettuce to NaCl

Positive stress or essential and nonessential elements can improve nutritive values (biofortification) of edible plants. In the present study, we evaluate (i) the effect of moderate salinity on lettuce biofortification, evaluated as nutritional bioactive compound accumulation, and (ii) the role of iodine in enhancing salt tolerance by increasing photorespiration and the content of antioxidants in lettuce. Physiological (gas exchange and chlorophyll fluorescence emission) and biochemical (photosynthetic pigment and bioactive compound) analyses were performed on lettuce plants grown under moderate salinity (50 mM NaCl alone or 50 mM NaCl in combination with iodine, KIO3). Our results show that NaCl + iodine treatment improves the nutritional value of lettuce in terms of bioactive compounds acting as antioxidants. More specifically, iodine enhances the accumulation of photosynthetic pigments and polyphenols, such as anthocyanins, under salt but does not improve the salt tolerance. Our findings indicate that iodine application under moderate salinity could be a valid strategy in plant biofortification by improving nutritional bioactive compound accumulation, thus exercising functional effects on human health.

Salinity and phosphorus availability differentially affect plant growth, leaf morphology, water relations, solutes accumulation and antioxidant capacity in Aeluropus littoralis

In this study, we examined the combined effect of moderate salinity (100 mM NaCl) and three phosphorus (P) levels: low, moderate and high (5 µM, 60 µM and 180 µM KH2PO4, respectively) on several physiological parameters in the facultative halophyte Aeluropus littoralis. Our results showed that plants cultivated under low P availability exhibited higher leaf hair and trichome densities, root length, and shoot soluble sugars concentrations. The response of plants to combined salinity and P deficiency was similar to that of plants cultivated under P deficiency only. Furthermore, in the absence of salt, A. littoralis plants reached maximum biomass at 180 µMP. However, in the presence of 100 mM NaCl, plants exhibited maximum growth from 60 µMP which suggests that salt supply decreased P requirements of A. littoralis plants. Moreover, salinity has no significant effect on biomass production, shoot water content and shoot potassium (K+) content when combined with 5 µMP and it significantly decreased gradually these parameters when combined with 60 µMP and 180 µMP. This was associated with higher values of P and K use efficiencies, leaf hair and trichome densities, total polyphenol content, and total antioxidant capacity in plants cultivated under combined effects of salinity and P deficiency.

Moderate salt treatment alleviates ultraviolet-B radiation caused impairment in poplar plants.

The effects of moderate salinity on the responses of woody plants to UV-B radiation were investigated using two Populus species (Populus alba and Populus russkii). Under UV-B radiation, moderate salinity reduced the oxidation pressure in both species, as indicated by lower levels of cellular H2O2 and membrane peroxidation, and weakened the inhibition of photochemical efficiency expressed by O-J-I-P changes. UV-B-induced DNA lesions in chloroplast and nucleus were alleviated by salinity, which could be explained by the higher expression levels of DNA repair system genes under UV-B&salt condition, such as the PHR, DDB2, and MutSα genes. The salt-induced increase in organic osmolytes proline and glycine betaine, afforded more efficient protection against UV-B radiation. Therefore moderate salinity induced cross-tolerance to UV-B stress in poplar plants. It is thus suggested that woody plants growing in moderate salted condition would be less affected by enhanced UV-B radiation than plants growing in the absence of salt. Our results also showed that UV-B signal genes in poplar plants PaCOP1, PaSTO and PaSTH2 were quickly responding to UV-B radiation, but not to salt. The transcripts of PaHY5 and its downstream pathway genes (PaCHS1, PaCHS4, PaFLS1 and PaFLS2) were differently up-regulated by these treatments, but the flavonoid compounds were not involved in the cross-tolerance since their concentration increased to the same extent in both UV-B and combined stresses.

Salt Tolerance is Associated with Differences in Ion Accumulation, Biomass Allocation and Photosynthesis in Cowpea Cultivars

AbstractCowpea is widely cultivated in arid and semi‐arid regions of the world where salinity is a major environmental stress that limits crop productivity. The effects of moderate salinity on growth and photosynthesis were examined during the vegetative phase of two cowpea cultivars previously classified as salt‐tolerant (Pitiúba) and salt‐sensitive (TVu). Two salt treatments (0 and 75 mm NaCl) were applied to 10‐day‐old plants grown in nutrient solution for 24 days. Salt stress caused decreases (59 % in Pitiúba and 72 % in TVu) in biomass accumulation at the end of the experiment. Photosynthetic rates per unit leaf mass, but not per unit leaf area, were remarkably impaired, particularly in TVu. This response was unlikely to have resulted from stomatal or photochemical constraints. Differences in salt tolerance between cultivars were unrelated to (i) variant patterns of Cl− and K+ tissue concentration, (ii) contrasting leaf water relations, or (iii) changes in relative growth rate and net assimilation rate. The relative advantage of Pitiúba over TVu under salt stress was primarily associated with (i) restricted Na+ accumulation in leaves paralleling an absolute increase in Na+ concentration in roots at early stages of salt treatment and (ii) improved leaf area (resulting from a larger leaf area ratio coupled with a larger leaf mass fraction and larger specific leaf area) and photosynthetic rates per unit leaf mass. Overall, these responses would allow greater whole‐plant carbon gain, thus contributing to a better agronomic performance of salt‐tolerant cowpea cultivars in salinity‐prone regions.

Differential effect of moderate salinity on growth and ion contents in the mainstem and subtillers of two wheat genotypes

To understand the differential effect of moderate salinity on the growth and ion contents in mainstem and subtillers of wheat plants, two spring wheat (Triticum aestivum L.) genotypes (Sakha 8 and Thasos) were grown in a greenhouse in soil with or without salinity. Both the above-ground dry weight and the leaf area at day 55 after sowing, as well as the grain yield, grain number, spikelet number, straw dry weight and above-ground dry weight at plant maturity, were determined. Inorganic ion content in young leaves at day 55 after sowing was also analyzed. The results showed that the above-ground dry weight and leaf area in the subtillers (T1 and T2) at day 55 after sowing were greatly reduced by salinity. Compared with the effect of salinity on subtiller growth, the mainstem was much less affected during the vegetative growth stages, whereas there was a similar effect of salinity on the grain yield between the mainstem and subtillers. The reduction in the grain yield of Sakha 8 by moderate salinity mainly resulted from a decrease in the number of tillers, whereas in addition to a reduction in the number of tillers in the salt-sensitive genotype Thasos, the grain yield in mainstem and subtillers was further reduced during the grain filling. Both wheat genotypes are more sensitive to salt stress during the vegetative growth stages than in the reproductive stages. The salt-tolerant genotype Sakha 8 is characterized by the exclusion of Na+ in the leaves. Thus, under moderate saline conditions the greater reduction in subtillers may result from an ion imbalance in the salt-tolerant genotype Sakha 8 and from Na+ toxicity in the salt-sensitive genotype Thasos.

The Effect of Moderate Salinity on Nitrate Leaching from Bermudagrass Turf: A Lysimeter Study

A column lysimeter study was conducted under greenhouse conditions to determine the impact of moderately saline irrigation water on NO3 leaching from turfgrass. Bermudagrass (Cynodon dactylon L. ‘NuMex Sahara’) was fertilized at three N levels (25, 50 and 75 kg NH4NO3-N ha−1 month−1) and irrigated with saline water (0, 3.0 and 6.0 dS m−1) in a factorial arrangement. Leachate was analyzed for salinity and NO3, and clippings were collected and analyzed for total N. Nitrate leaching was not affected by either N level or salinity. Nitrate concentrations in the leachate were low, averaging approximately 0.3 mg N L−1; less than 1% of the applied N leached. Longer-term N allocation to leaf growth accounted for up to 98% of applied N, whereas short-term allocation, determined using 15N, ranged from 46–67%. Salinity had no affect on clipping yield, the biomass of root and verdure, or root distribution. These data indicate the potential for moderately saline irrigation water to be used on bermudagrass turf without increasing NO3 contamination of groundwater, as long as leaching is adequate to prevent rootzone salinity reaching damaging levels.

The Effect of Moderate Salinity on Nitrate Leaching from Bermudagrass Turf: A Lysimeter Study

The Effect of Moderate Salinity on Nitrate Leaching from Bermudagrass Turf: A Lysimeter Study

Effect of moderate salinity on patterns of potassium, sodium and chloride accumulation in cells near the root tip of barley: Role of differentiating metaxylem vessels

X‐Ray microanalysis of fully hydrated, bulk‐frozen samples was used to measure concentrations of potassium, sodium and chloride in various cell types along seminal roots of barley (Hordeum vulgare L. cv. California Mariout) seedlings (1 to 150 mm from the tip). In the cytoplasm of all meristematic cells 1 mm from the root tip, the average concentrations of potassium and chloride were ca 200 and 15 mM, respectively. The potassium level was also high in the vacuoles of incipient xylem elements and did not drop to significantly lower values until 10 mm from the tip in protoxylem, 50 mm in early metaxylem and 150 mm in late metaxylem (LMX). Light microscopy observations (Nomarski optics) of hand‐cut sections showed the presence of cytoplasmic strands and also the presence of intact cross walls in LMX up to a distance of 100 mm. Both quantitative analysis of ion contents and structural observations suggested that LMX elements act as a large transitional sink of accumulated ions and therefore may not function as a main pathway of transport until perforation of the end wall takes place 100–150 mm from the root tip. Treatment with 50 mM NaCl resulted in higher concentrations of sodium and chloride in LMX elements than in the surrounding cells, suggesting that living xylem elements, which develop a large central vacuole at an early stage of root differentiation, may assist in alleviating salinity stress in the meristematic region of barley root tips. Further, it is proposed that reabsorption of sodium and chloride from the LMX, especially before the disappearance of the cross walls, may provide a means of salinity tolerance.