Salinity, which is one of the abiotic stress factors, severely restricts plant production as a result of the negative effects of plants in different growth and development periods. Therefore, it is extremely important to determine the tolerance limits of plants to salinity in order to eliminate the limiting effect in terms of plant growth. Flax is an industrial plant that is used for multiple purposes and has commercial importance in the world. This research was carried out in controlled laboratory conditions in 2021 to determine the effects of salinity on the germination of flax seeds.In the study, germination rate, root length, root fresh weight, shoot length and shoot fresh weight were evaluated. The result showed that significant differences between different NaCl solutions for all evaluated characters. Although the highest value was obtained in the control group in Mures variety, the highest value was obtained in 25 nM NaCl concentration in all other characters except for the germination rate in Dakota variety. The highest germination rate of 93.3% was obtained from the control application (0 mM NaCl) in both varieties. On the other hand, there was no germination in both varieties in 200 mM application.

In agricultural production, one of the limiting factors on plant growth and yield is soil salinity. The plant growth regulators are of considerable importance in alleviating the negative effect of salt stress. The study was carried out to determine the effects of salicylic (SA) and gibberellic acid (GA3) on the growth and some physiological characters in canola (Brassica napus L.) under salinity conditions in greenhouse. For this purpose, a factorial experiment set up as completely randomized design was conducted with three levels of SA (0, 0.5 and 1 mM) and GA3 (0, 50 and 100 mg l-1) and four levels of NaCl (0, 50, 100 and 150 mM) with three replications. In the study, leaf area, plant height, electrolyte leakage, chlorophyll content and the loss of leaf turgor were investigated. Salt treatments reduced significantly all of the considered parameters, compared with the control. Salinity caused a significant reduction of 63 and 67%in plant height and leaf area, respectively, as compared to the control plants. On the contrary, electrolyte leakage was markedly increased (six-fold) with increasing NaCl levels. Gibberellic acid increased significantly plant height and reduced the loss of leaf turgor, without a significant improve in other parameters. The results indicated that application of SA and GA3 to salinity stressed plants did not significantly affect canola vegetative growth. However, GA3 caused a partial decrease in the adverse effect of salinity.

In this context, it is necessary to select and develop salt-tolerant genotypes that can grow in salty soils and have high yields, and formulate strategies which may enhance the plant survival under salinity stress. Melatonin (N-acetyl-5-methoxytryptamine) is an important biological hormone that provides resistance to abiotic stress conditions and can be secreted by plants. Melatonin concentration in plants varies depending on genotype, temperature and growth period. Increase in melatonin concentration is associated with increased SNAT and HIOMAT/ASMT enzyme activity. It plays an important role in gibberellic acid and abscisic acid biosynthesis during the germination and provides plant growth and development. Exogenous application of melatonin significantly alleviates chlorophyll degradation and stomatal closure caused by salt stress, improves photosynthesis and enhances plants' salt tolerance. Besides it significantly reduces the harmful effects of salinity by regulating plant physiology, improving plant morphology, photosynthesis and activities of antioxidant enzymes. The present review discusses the recent studies on the effect of melatonin on plant growth and physiology against salt stress that have important impacts on plant growth and development have been given according to the findings of various researches. It also highlights the mechanim/s of melatonin-induced salinity stress tolerance in plants.

The increase in salinization in agricultural lands adversely affects crop production. In particular, yield and quality losses occur in many vegetables such as lettuce, which are grown and consumed in every season. Realizing these losses in crop production, more careful fertilization and agricultural practices should be done. Yedikule lettuce seeds were used in the study to draw attention to these negative aspects. The study, which was carried out for two years, was designed with 0, 50, 100 and 150 mmol doses of salt according to a randomized parcel design with three replications and four pots in each replicate. Each 2-liter pot was filled with a 2:1 ratio of peat: perlite mixture and the study was carried out with 2 lettuces in each pot. As a result of the study, when the plant weight data of the first year and the second year are examined, it is seen that the weight loss of lettuce plants and damage to the plants increase when the salt doses increase. It was observed that the highest plant weight loss occurred at 150 mmol salt dose. Membrane damage index in lettuce leaves was observed to increase as the salt dose increased. It was observed that the leaf water rate decreased with increasing salt doses. Membrane damage index and leaf water content of lettuce plants were more negatively affected at 150 mmol of salt in both years. Potassium, calcium and magnesium contents in lettuce leaves were statistically decreased due to increasing salt doses in both years, while sodium content increased with increasing salt doses and the highest sodium content was observed at 150 mmol dose in both years. As seen in these results, increasing salt doses reduce the nutrient content and plant weight in lettuce plants and cause physiological damage to the plant, resulting in yield and quality loss.

The Arbuscular mycorrhizal fungi (AMF) are microorganisms that live symbiotically with plant roots and have many benefits to soil and plants. In this study, some effects of AMF which are known to be soil and plant beneficial, have been evaluated and solution proposals have been put forward against heavy metal and salinity stress in the soil. Salt accumulation and high concentrations of heavy metal in the soil affects negatively the microbial diversity and activity. Removal of salt acumulation and heavy metal from contaminated soil by chemical and physical methods is both very expensive and ineffective. Therefore, AMF are important for alleviating the heavy metal and salt stress in plants. AMF can alter plant physiol¬ogy and root morphology, increase the uptake of nutrients and water from the soil through an extensive hyphal network, decrease the use of chemical fertilizer, interact with other soil microorganisms plant growth promoting, induce of some resistance parameters in the plants and produce the glomalin which develops the properties and structure of soil. AMF are eco-friendly solutions according to traditional methods and the use of suitable plant-fungi combinations increases the chances of success of these applications.