Abstract
The present study aimed to investigate the effect of four seaweeds (Sargassum crassifolia, Acanthophera najadiformis, Enteromorpha flexuosa and Ulva lactuca) water extracts on germination percentages, fresh and dry weights, leaf area, leaf area ratio (LAR), net assimilation rate (NAR), photosynthetic pigments, carbohydrate, and protein of Vigna unguiculata. Vigna seeds were pre-soaked for 6 hours in different extract concentrations (0, 5, 10, 40, and 80%) of the seaweeds, and then germinated in 0%, 10% and 20% of the different extracts. Presoaking of the plant seeds in low concentration of seaweeds extract (5%) has promoted their germination especially those extracts of Acanthophera najadiformis and Enteromorpha flexuosa which caused the greatest germination percentage. The maximum values of shoot and root length were obtained by the seeds pre-soaking in 5% or 10% of the different seaweeds extracts. Leaf areas, leaf area ratio (LAR), relative growth rate (RGR) and net assimilation rate (NAR) were increased in response to treatment the seeds with seaweeds extract which reflects the improvement of the plant growth. Chlorophyll a, b and carotenoids contents were also increased in response to treatment the seeds with seaweeds extracts. Carbohydrate and protein contents of the seedlings showed marked increases by the seeds pre-soaking in the seaweeds extract. Seeds pre-soaking in the seaweed extracts for a definite time were more effective compared to seeds germination in a medium containing the extracts.

Key words: Seaweeds, Vigna unguiculata, germination, LAR, NAR, photosynthetic pigments, protein, carbohydrate