Journal of Agricultural Science and Technology A 6 (2016) 411-416 doi: 10.17265/2161-6256/2016.06.006 Effects of Different NaCl Doses on Morphological and Physiological Parameters in Mentha piperita L. Ozlem Altuntas 1 , Sebnem Kusvuran 2 and Hayriye Yildiz Dasgan 3 1. Department of Horticulture, Faculty of Agriculture, Inonu University, Malatya 44260, Turkey 2. Department of Plant and Animal Production, Kizilirmak Vocational School, Karatekin University, Kizilirmak, Cankiri 18280, Turkey 3. Department of Horticulture, Faculty of Agriculture, Cukurova University, Balcali, Adana 01250, Turkey Abstract: Salt stress is one of the most serious limiting factors for crop growth and production. This study was carried out to evaluate the effects of salt stress in four Mentha piperita L. varieties, in greenhouse conditions. The seedlings were irrigated with ½ Hoagland nutrition solutions. Following 10 d of growth in the pots, the seedlings were subjected to salt stress with different concentrations of NaCl (0, 50 and 100 mM, respectively). Responses of the mint varieties to salt stress were evaluated using some plant growth and physiological parameters, such as plant height, root length, shoot and root fresh and dry weight, and ion concentrations in leaves, such as Na, K, Ca and Cl. Salt stress caused reduction in physiological parameters. However, this reduction was significant at 100 mM NaCl compared to 50 mM NaCl. These two concentrations of NaCl increased Na and Cl contents in leaves. However, K and Ca contents were decreased with salinity. The results showed that Mentha piperita cv. Sewiss and Granada were found more tolerant to salt stress than cv. Marokko and Citaro. Key words: Growth, Mentha piperita L., mineral nutrition, salt stress, seedlings. 1. Introduction Agricultural production in arid and semi-arid regions around the world is under the threat of multiple abiotic stresses, such as salinity. Salinity stress is one of the most serious abiotic stresses that cause reduction in plant growth, development and yield in many regions of the world. Plants employ many strategies in response to abiotic stresses that ultimately enhance the plant growth and productivity in stressful environments. These phenomena include change in morphological and developmental pattern (growth plasticity), as well as physiological and biochemical processes against several stresses [1]. The symptoms of salt damage in plants change according to species. Salinity is a factor that affects whole metabolism of a plant, as well as its morphology and anatomy. Salinity reduces the ability of plants to Corresponding author: Ozlem Altuntas, Ph.D., research fields: vegetable growing (in open field and greenhouse), plant physiology and bio-fertilizers. absorb water, causing a reduction in growth rate and a suite of metabolic changes similar to those caused by water stress. The initial reduction in shoot growth is probably due to loss of cellular turgor pressure and hormonal signals generated by the roots [2]. Salinity, the common and comprehensive negative influence, can lead to apparent stunting of plant growth. From another point of view, slower growth is an available measure for plant survival under stress [3, 4]. Tang et al. [4] indicated that all of the physiological performances are the adaptive strategies for plants under salt stress. Some nutritional disturbances are expected under saline condition, resulting in high ratios of Na/Ca and Na/K. In presence of NaCl excess in the medium, Na and Cl are accumulated in plant organs, and these saline ions can affect other mineral elements uptake through competitive interactions or by affecting the ion selectivity of membranes, which cause nutrient deficiencies in plants [5]. Salt-tolerant plants differ from salt-sensitive ones in having a low D DAVID PUBLISHING