They were grown in 14 cm plastic pots containing soil mixture of peat:sand (1:1) and maintained in a controlled greenhouse conditions in a private nursery located on Alexandria-Cairo Desert Road. The soil was fertilized with 2 g l -1 Crystalon (19% N: 19% P: 19% K, Chema Industries, Egypt). The plants were maintained at natural light conditions and the temperature ranged between 15 and 28 ℃ . Plants were watered every two days with 2000 and 4000 ppm NaCl solution. The plants subjected to saline conditions (watered with 2000 and 4000 ppm NaCl solution) were treated with 7 ml/L weekly application of Seaweed extracts (SWE) (Ascophyllum nodosum, Stella Maris, Acadian Seaplants, Canada) as foliar spray until drop-off two weeks ahead of saline conditions. A foliar spray of 5-aminolevulinic acid (Sigma-Aldrich, Germany) at (3, 5 and 10 ppm) was applied weekly until drop-off to all plants during saline conditions and untreated plants were considered as controls. Experiments continued for 6 weeks in two consecutive seasons of 2016 and 2017 and the plants were distributed in three blocks and each treatment was represented by 5 replicates with a total number of 270 plants. The NaCl was added to the tank gradually and the electrical conductivity (EC) was measured using EC meter.

There were significant increases in branch length and number of branches per plant, fresh and the dry weight in Seaweed extracts (SWE) + 5-aminolevulinic acid (ALA) treated plants under saline irrigation conditions compared to control. These morphological improvements associated with several physiological changes in treated plants including increased accumulation of specific phenols (robinin, rutin, apigein, chlorogenic acid and caffeic acid) and increased antioxidant activities of leaf extracts. There were also increased the chlorophyll composition and the accumulation of sugars and proline. Improved transpiration and photosynthetic rates as well as stomatal conductance were also detected in treated plants. The expression of several genes responsible for water management, flavonoid accumulation and antioxidants accumulation was enhanced in SWE + ALA treated plants.

Under normal and saline irrigation conditions, there were changes in genes expression following SWE and ALA applications.The transcription levels of ANN1 and ANN2 increased significantly in SWE + ALA treatments compared to control under non-saline and saline conditions . However, transcription levels of MYB44 showed no significant variations among treatments. PIP1, P5CS1 and CHS relative expressions was higher in plants treated with SWE + ALA under normal and saline irrigation conditions . The transcription levels of the redox responsive genes of APX1 and GPX3 were significantly higher in SWE + ALA treated plants compared to control treatments . Increasing ALA amount from 3 to 10 ppm had no significant effects on APX1 transcription levels under non-saline conditions. In addition, the application of SWE or ALA only had no significant effects on GPX3 transcription levels under non-saline conditions.