PLANT CELL BIOTECHNOLOGY AND MOLECULAR BIOLOGY

Salinity is one of the serious limiting factors for plant growth and productivity, which is accentuated by the ongoing climate change. Bituminaria bituminosa (L.) Stirton genotypes are the most promising new option for drought-prone areas with large ecological adaptation to climatic changes. As no information is available about the response of B. bituminosa to salinity, the aim of this research was to study salt tolerance of some B. bituminosa (L.) genotypes, investigating the main agro-physiological and biochemical response. Six B. bituminosa genotypes (Ourika, Oujda, Chaouen, Sefrou, Fez, Meknes) grown in a greenhouse were tested. Control plants were grown in a salt-free nutrient medium, while treated plants were supplemented with three NaCl concentrations (3, 6 and 9 g/l) in the solution and were irrigated every day. There were three replications and pots were arranged according to the split plot design with a randomized complete block. The effects of salt stress on growth, physiological and biochemical parameters were determined. The Data was subjected to a two-way analysis of variance. The main results showed a significant effect (P<.001) of salt treatment on vegetative growth by decreasing plant height by 41%, leaf number by 51%, fresh biomass yield by 56% and dry biomass yield by 67% at severe salinity. Salt stress decreased also the relative water content by 32%, net photosynthetic rate by 46%, stomatal conductance by 72% and chlorophyll fluorescence by 17%, but increased leaf proline and soluble carbohydrates contents by 212% and 158% respectively at severe salinity conditions. Among the studied genotypes, Sefrou seemed to be the most productive and tolerant genotype to salinity with high biomass yield, high photosynthetic and PSII activity and high relative water content but with a less accumulation of compatible solutes (proline and soluble carbohydrates), whereas Oujda revealed to be a sensitive genotype with high proline and soluble carbohydrates accumulation, suggesting that accumulation of compatible solutes (proline and soluble carbohydrates) could not be related to B. bituminosa osmotic adjustment and salt tolerance. These findings revealed the key pathways for screening genotypes and providing knowledge about stress tolerance mechanisms, which could be useful to plant breeders for selecting and developing salt-tolerant genotypes.