VOL. 10, NO. 4, APRIL 2015 ISSN 1990-6145 ARPN Journal of Agricultural and Biological Science © 2006-2015 Asian Research Publishing Network (ARPN). All rights reserved. www.arpnjournals.com 124 EFFECTS OF ASCORBIC ACID ON THE SEED GERMINATION, SEEDLING GROWTH AND LEAF ANATOMY OF BARLEY UNDER SALT STRESS Kürşat Çavuşoğlu and Göksel Bilir Department of Biology, Süleyman Demirel University, Faculty of Arts and Science, Isparta, Turkey E-Mail: kursatcavusoglu@sdu.edu.tr ABSTRACT In this work, the effects of ascorbic acid pretreatment on the seed germination, seedling growth (coleoptile percentage, radicle length, coleoptile length, radicle number and fresh weight) and leaf anatomy of barley under saline conditions were studied. In parallel with concentration rise, salt stress inhibited the germination and seedling growth of barley seeds. The inhibitive effect of salt on seed germination and seedling growth was alleviated in varying degrees, and dramatically, by ascorbic acid application. On the other hand, it was determined that ascorbic acid affected in different degrees on the various parameters of leaf anatomy of barley seedlings, and this difference was statistically important. Keywords: barley, leaf anatomy, ascorbic acid, salt stress, seed germination, seedling growth. INTRODUCTION Salinity is one of the most important problems in the agriculture areas of the world. Nearly 20% of the world’s cultivated area and nearly half of the world’s irrigated lands are affected by salinity (Zhu, 2001). The salt-affected soils contain excess salts which affect plants by decreasing the osmotic potential of the soil solution (osmotic stress), interfering with normal nutrient uptake, inducing ionic toxicity, and associating nutrient imbalances (An et al., 2003). Processes such as seed germination, seedling growth and vigour, vegetative growth, flowering and fruit set are adversely affected by high salt concentration, ultimately causing diminished economic yield and also quality of production (Sairam and Tyagi, 2004). In addition, it is evident that there are big changes in leaf morphology and anatomy of the plants growing in saline soils (Çavuşoğlu et al., 2007, 2008). Ascorbic acid (AA), the main source of vitamin C for humans, is a small and water-soluble antioxidant molecule. It is also an essential compound for plants, with important roles as an antioxidant and as a modulator of plant development through hormone signalling (Pastori et al., 2003). In addition, AA plays important roles in many physiological processes such as seed germination (Tavili et al., 2009), seedling growth (Özdener and Kutbay, 2008), flowering (Barth et al., 2006), membrane permeability (Mukherjee and Choudhuri, 1985), ion intake to roots (Gonzalez-Reyes et al., 1994), photosynthesis (Foyer and Lelandais, 1993), respiration (Bartoli et al., 2006), senescence (Kim et al., 2008), protein and nucleic acid contents (Garg and Kapoor, 1972) and activities of enzymes as peroxidase, superoxide dismutase (Ejaz et al., 2012). On the other hand, there are few studies about the effects of AA on the seed germination and seedling growth under normal and saline conditions. Some experimental studies have shown that exogenous application of AA stimulates the germination percentage and early seedling growth of wheat (Afzal et al., 2006), bean (Shaddad et al., 1990; Azooz and Al-Fredan, 2009), pea (Burguieres et al., 2007), tomato (Barh et al., 2008) and sorghum (Arafa et al., 2009) seeds germinated in distilled water and saline medium. Unfortunately, it has not been encountered any study concerning effects of AA on the leaf anatomy of barley seedlings grown in both normal and saline conditions until now, especially on the parameters examined in this study. The purpose of this study is to observe the influences of AA in the reducing of the inhibitive effects of salt stress on the seed germination, seedling growth and leaf anatomy of barley. MATERIALS AND METHODS The seeds, salt and ascorbic acid concentrations In this study, barley (Hordeum vulgare cv. Bülbül 89) seeds were used. The seeds were surface sterilized with 1% sodium hypochloride. Salt (NaCl) concentrations used were 0.0, 0.25, 0.275, 0.30, 0.325, 0.35, 0.375 and 0.40 M. Ascorbic acid (AA) concentration used in the experiments was 1 μM. AA and NaCl concentrations were determined in a preliminary investigation conducted by us. Germination of the seeds Germination experiments were carried out at a constant temperature (20°C), in the dark in an incubator. Barley seeds in adequate amount were pretreated in the beakers containing sufficient volume of distilled water (control, C) or aqueous solution of AA for 24 h at room temperature. At the end of this pretreatment, the solutions were filtered immediately and the seeds were dried in vacuum (Braun and Khan, 1976). 25 seeds from every application were arranged into Petri dishes (10 cm diameter) lined by 2 sheets of Whatman No. 1 filter paper moistened with 7 ml of the salt solution. After sowing, Petri dishes were placed into an incubator for germination for 7 days. It was assumed that the radicle should be 10 mm long for germination to take place (Ungar, 1974). At the end of the 7 th day, after determination of the final germination percentages, the coleoptile emergence