Evaluation of salt tolerance in almond [<i>Prunus dulcis</i> (L.) Batsch] rootstocks

Abstract

In this study, four interspecific Prunus rootstocks (‘HS314’, ‘HS312’, ‘HS302’ and ‘GF677’) and the Iranian almond cultivar ‘Sahand’ were subjected to four different salinity levels (1.5, 3, 6 and 9 dSm^-1) to determine the effects of salt level on growth parameters and chemical compositions. The results obtained indicate that increased salinity level had significant negative effects on leaf chlorophyll content, leaf area, dry and fresh weight of root and shoot. In addition, increasing the salinity level in general caused an increase in leaf proline concentration; however, the different genotypes were significantly different in response to the salinity level. According to these findings, proline content increase in ‘Sahand’ cultivar was lower than those of the other studied genotypes were. The majority of the plant's responses to the high salinity levels (6 and 9 dSm^-1) were significant with no deleterious effects observed on plant growth triggered by lower salt concentrations of 1.5 and 3 dSm^-1. A significant decrease in total chlorophyll and chlorophyll b content was also found at the high salinity levels but no significant change in chlorophyll a was evident. The potassium (K⁺), magnesium (Mg²⁺), calcium (Ca²⁺), sodium (Na⁺) and chloride (Cl^-) ion concentrations of the leaves and roots were significantly different among the studied genotypes due to their exposure to different salinity levels. The concentration of Mg²⁺, Cl^- and Na⁺ as well as the Na⁺/K⁺ ratio in the leaves of all the genotypes were increased by the salinity stress, whereas it had no significant effect on the Ca²⁺ and K⁺ concentrations as well as the Na⁺/Ca²⁺ ratio. The result obtained in this study suggest that ‘HS314’ and ‘GF677’ interspecific hybrids may represent novel sources of salinity tolerance.

Keywords: Breeding, interspecific hybridization, proline, salinity