Comparative studies between diploid and tetraploid Dez Orange ['Citrus sinensis' (L.) Osb.] under salinity stress

• Published in: Australian Journal of Crop Science Vol. 7; no. 10; pp. 1436 - 1441
• Main Authors: Alireza Shafieizargar, Yahya Awang, Abdul Shukor Juraimi, Radziah Othman
• Format: Journal Article
• Language: English
• Published: Lismore, N.S.W Southern Cross Publishers 01.09.2013
• Subjects: Adaptation; Effect of minerals on; Plant genetics; Plants; Soils, Salts in
• ISSN: 1835-2693

Due to salt-sensitivity nature of citrus, it is imperative to provide rootstocks and cultivars that are tolerant to saline conditions. In this study, responses of tetraploid (4X) and its corresponding diploid (2X) Dez orange (Citrus sinensis (L.) Osb.) cultivar to different concentrations of NaCl (0, 20, 40 and 60 mM) were investigated using a randomized complete block design with four replications. Plant mineral concentrations, proline accumulation, malondialdehyde (MDA) and H2O2 contents were measured. Results indicated that increasing NaCl concentration significantly reduced leaf N and P contents in both diploid and tetraploid plants but reduction of these nutrients were lower in tetraploids (2.15 to 1.51%, 2.35 to 1.78% in diploid and tetraploid plants respectively, at P=0.05). Results also showed that the accumulation of Na and Cl was lower in tetraploids. Reduction of K in tetraploid was lower as opposed to diploid plants (1.18 and 0.98% in leaves and, 0.50 and 0.48 in roots at 60 mM NaCl, respectively). Free proline content in the leaves of both plants increased with increasing NaCl level with a more marked increase was observed in tetraploid plants than those in diploids (62.3 and 54.8 µmol/g FW at 60 mM NaCl, respectively). Tetraploid plants contained lower concentration of MDA (37.1 and 44.3 nmol/g FW at 60 mM NaCl, respectively) and H2O2 (58.8 and 62.5 µmol/g FW at 60 mM NaCl, respectively). Results obtained in this study suggested that tetraploid Dez orange exhibited a better adaptation to salinity stress than its corresponding diploid in its seedling stage.