Effects of Water Deficit Induced by PEG and NaCl onChickpea (Cicer arietinum L.) Cultivars and Lines at Early Seedling Stages

G.U. Journal of Science 22(1): 5-14 (2009) www.gujs.org Effects of Water Deficit Induced by PEG and NaCl on Chickpea (Cicer arietinum L.) Cultivars and Lines at Early Seedling Stages Tuğçe KALEFETOĞLU MACAR1, Özlem TURAN 1, Yasemin EKMEKÇĐ 1♠ 1 Hacettepe University, Faculty of Science, Department of Biology, Ankara, Turkey Received: 23.07.2007 Revised:23.10.2008 Accepted: 02.12.2008 ABSTRACT The effects of water deficit induced by different osmotic potential levels [0 (control), -0.4, -0.6 and -0.8 MPa] of PEG 6000 and NaCl treatments on chickpea (Cicer arietinum L.) cultivars and lines at germination and early growth stages by sampling on 4th and 8th days of incubation consisting of 4 days each of dark and subsequent 16 hours illumination. All of these treatments affected germination percentages of all genotypes but PEG was more effective in inhibition than NaCl at the MPa levels tested. The experimental studies showed that all of the genotypes tested could be classified as tolerant, moderately tolerant and sensitive ones. But the tolerance levels were not found to be correlated directly with MPa levels applied, as Canıtez and ILC-3279 were tolerant to PEG, but ILC-3279 was sensitive to NaCl treatment. Within this context the classification can be summarized as below: PEG tolerant (Canıtez and ILC-3279), moderately tolerant (AkN 87, FLIP 87-59C, Gökçe and Uzunlu), sensitive (AkN 290 and ER 99). NaCl tolerant (Uzunlu and FLIP 87-59C), moderately tolerant (Gökçe, Canıtez, AkN 290 and AkN 87) and sensitive (ER 99 and ILC-3279). Key Words: Drought, early seedling stage, germination, NaCl, PEG, salinity, water deficit 1. INTRODUCTION Chickpea (Cicer arietinum L.) is an ancient legume crop believed to be originated in South East Turkey, and the adjoining part of Syria [1, 2]. It is the fourth most important food legume with a total annual global production of 9.1 million M tones from 11.2 million ha [3]. Besides being an important source of human and animal food, chickpea also plays an important role in the maintenance of soil fertility, particularly in the dry, rainfed areas [4, 5]. One of the most important abiotic factors limiting plant germination and early seedling stages is water stress brought about by drought and salinity [6, 7], which are widespread problems around the world [8]. Salinity and drought affect the plants in a similar way [9]. Reduced water potential is a common consequence of both salinity and drought [10]. Water stress acts by decreasing the percentage and rate of germination [11] and seedling growth [8, 12, 13]. Since chickpea is grown mostly as a rainfed and post-rainy season crop, water stress during vegetative and/or reproductive growth stages is one of the most limiting factors for the chickpea growth [14]. Germination of seeds, one of the most critical phases of plant life, is greatly influenced by salinity [15]. Salinity ♠ Corresponding author, e-mail: is reported to decrease as well as delay germination of most of the crops. Chickpea is a salt-sensitive crop especially during germination [16]. Lower levels of salinity delayed germination whereas higher levels reduced the final percentage of seed germination [17] and vegetative plant growth is suppressed under saline conditions [18]. In addition, salinity imposes on plants other stresses such as ion toxicity, as a result of ion entry in excess of appropriate compartmentation, and nutrient imbalances, as commonly seen in the displacement of potassium by sodium. In fact, salinity damage is mainly due to altered water relations caused by high salt accumulation in the intercellular spaces [19]. Drought, like salinity, plays an important role not only in determining germination rates, but also influences seedling development [20]. Establishment of seedlings is the most critical life stage in dry environments and a lack of soil moisture is often a major reason for seedling mortality [21]. With increasing drought stress, water availability decreases, changing the percentage and velocity of germination and growth of seedlings adversely. Osmotic solutions are used to impose water stress reproducibly under in vitro conditions [7]. PEG 6 ♠ G.U. J. Sci., 22(1): 5-14 (2009)/ Tuğçe KALEFETOĞLU MACAR, Özlem TURAN, Yasemin EKMEKÇĐ widely used to induce water stress, is a non-ionic water polymer, which is not expected to penetrate into plant tissue rapidly [22]. PEG molecules with a Mr ≥ 6000 cannot penetrate the cell wall pores [23]. Because PEG does not enter the apoplast, water is withdrawn not only from the cell but also from the cell wall. Therefore, PEG solutions mimic dry soil more closely than solutions of low–Mr osmotica, which infiltrate the cell wall with solute [24]. The present investigation has been performed to evaluate chickpea (Cicer arietinum L.) tolerance to osmotic stress induced by polyethylene glycol (PEG) or NaCl during germination and the early seedling stages of plant development. Eight chickpea genotypes [four cultivars (Gökçe, Canıtez, ER 99 and Uzunlu) and four lines (AkN 87, AkN 290, ILC-3279 and FLIP 87-59C)] were tested. This is the first work aimed at selecting drought and salinity tolerant chickpea genotypes in the germination and early seedling stages by using PEG or NaCl in in vitro conditions. 2. MATERIALS AND METHODS The seeds of chickpea cultivars and lines were obtained from Ankara Central Research Institute for Field Crops for this research. The effects of drought and salt stresses induced by different osmotic potential levels [0 (control), -0.4, -0.6 and -0.8 MPa] of polyethylene glycol 6000 (PEG 6000) and NaCl treatments on germination and early seedling development of chickpea (Cicer arietinum L.) cultivars and lines were investigated for two sampling dates (4 and 8 days). The seeds of the cultivars (Canıtez, ER 99, Gökçe and Uzunlu) and the lines (AkN 87, AkN 290, FLIP 8759C, ILC-3279) which were imbibed in deionized water were incubated under dark conditions for 4 days and subsequently 16 h photoperiod with 250 µmol.m-2s-1 light intensity for four days at 23±2 °C on humidified filter paper with an aliquot of solution of different osmotic potentials of PEG 6000 or NaCl. The wet filter papers were changed when germination of seeds was measured for the first sample day after sowing. The osmotic potentials of PEG 6000 were calculated as described by Michael and Kaufman [25] . At end of the each sampling dates, the percentage of germination (%) was determined and, the length of roots and epicotyls of genotypes were also measured (mm seedling-1) for PEG and NaCl treatments. Determination of the tolerance of the genotypes used based on the inhibition percentage of root elongation as compared with the control groups for both of the treatments. Then genotypes were classified according to their tolerance index values. The experiment was arranged in a completely randomized design with three replicates of eight seedlings per replications (n=24) in each sampling da (...truncated)