Alleviation of Salt Stress Adverse Effect and Enhancing Phenolic Anti-oxidant Content of Eggplant by Seaweed Extract

Salinity either of soil or of irrigation water causes restriction in growth, yield, and quality of several vegetable crops such as eggplant. To alleviate the adverse effect of salt stress on the growth and fruit yield of eggplant, a pot experiment was conducted at the Experimental Station Farm, Faculty of Agriculture, Ain Shams University, during two successive summer seasons (2011 and 2012). The experiment included nine treatments which were the combination of three salinity levels of irrigation solutions (320, 3200, and 4800 ppm sodium chloride), and three levels of seaweed (Ascophyllum nodosum) extract levels from Acadian Sea plants Limited, Dartmouth, Nova Scotia, Canada(0, 2.5, and 5.0 cm(3) L-1). Salt stress (320, 3200, and 4800 ppm) significantly decreased vegetative growth and reduced total yield and fruit quality. Applied bio-stimulants positively alleviated the negative effects of moderate salinity stress levels (3200 ppm) and partially counteracted the harmful effects of salinity under the highest salinity stress level (4800 ppm). Sea weed extract (SWE) at highest concentration (5.0 cm(3) L-1) was the most effective anti-salinity stress agents. Salinity stress levels increased super oxide dismutase (SOD), ascorbic peroxidase (APX) activity, and also Na content but decreased K content in the shoot and fruit of eggplants. In general, all of the applied seaweed slightly increased, either by itself or combined with different salinity stress levels, the activity of SOD and APX, significantly increased K content. These results provide support for the field application of bio-stimulants and antioxidant compounds to alleviate the symptoms and effects of salty soils.