Water extracts of Spirulina platensis and Chlorella vulgaris enhance tomato (Solanum lycopersicum L.) tolerance against saline water irrigation

Abstract

The research aimed to examine the enhancement effect of Spirulina platensis (blue-green microalga or Cyanobacterium) and Chlorella vulgaris (green microalga) water extracts as biological stimulant in improving growth parameters, chlorophyll content, yield, and fruit quality of tomato plants under salinity stress. Tomato seeds (Solanum lycopersicum L. of cv. Agyad) were soaked in three microalgae water extracts at a 10% concentration (Chlorella vulgaris, Spirulina platensis, and Chlorella:Spirulina at a ratio of 1:1). Chemical and biochemical analyses for the used materials and products were achieved. After germination, tomato transplants were irrigated with saline water at three levels of saline water (2, 4, and 7 dS/m) using sea salt. Successive grown tomato transplant at 7.0 dS/cm were infused in clayey soil. The grown plants were preyed by algal extract and irrigated by the same solution. Vegetative growth, yield, shelf life, and chlorophylls (a and b) were determined. It was found that the highest vegetative growth, yield, and chlorophyll content were measured in tomato transplants with the Spirulina:Chlorella mixture, followed by Spirulina platensis and Chlorella vulgaris water extracts; all of these measurements increased significantly in response to microalgae treatments. Experimental tomato fruits of Chlorella and mixture treatments can stay for 45 days at room temperature. Both algal extracts and their mixture enhanced the bioaccumulation of micronutrients (Fe, Zn, Mn, and Cu), compared with the control, while Chlorella extract surpassed Spirulina and mixture extracts. Concerning the used dried algae and their water extract, Spirulina platensis surpasses Chlorella vulgaris for protein and ash content.