Bioactivity of Cyanobacterial Biomass Related to Amino Acids Induces Growth and Metabolic Changes on Seedlings and Yield Gains of Organic Red Beet

Abstract

In order to increase the understanding about Arthrospira platensis biomass use to plant growth promotion, the aim of this study was to determine total free amino acid content on lyophilized biomass and the biomass bioactivity on bioassay, as well as, the effects of foliar applications of aqueous suspension of biomass on seedlings growth ascertaining biochemical variables related to the potential bioactivity, and also at field on organically grown red beet yield. The results identified the bioactivity and expressed well the capacity of plant growth promotion related to stimulus on chlorophyll synthesis and on amino acid and protein increments on seedlings leaves. The yield had significant improvement related to hypocotyl growth. The results could be justified by the content of free amino acids on biomass, being them the highest amount of potential bioactive compounds of cyanobacteria. The Arthrospira platensis lyophilized biomass could be considered an efficient biofertilizer-biostimulant source, promoting yield gains by a sustainable way.

Plant Biostimulants from Cyanobacteria: An Emerging Strategy to Improve Yields and Sustainability in Agriculture

“…plant growth [43,54,61,62,64,75,76,78] germination [70,72] macro-and micronutrient content [64,71] pigment content [62,64,75,76,78] photosynthesis rate [64] essential oil content [61] phytohormones content [78] antioxidant activity [43] tolerance to thermal stress [65] reduction of heavy metal content [54] rice [43] spinach [54] peppermint [61] lupin [62] willow [64] Sida hermaphrodita [65] wheat [71] cotton [72] cumin [70] cantaloupe [75] lettuce [76] chrysanthemum [78] Arthrospira platensis plant growth [50,[79][80][81][82][83][84][85][86][87][88] macro-and micronutrient content [53,79,…”

“…The enzymatic hydrolysates obtained from A. platensis have been shown to contain valuable biocompounds including L-amino acids, amounting to about 60% of total protein content [103,104]. The supply of L-amino acids is considered beneficial in plant nutrition as they are directly used by plants for protein synthesis [86] and their exogenous application has been reported to increase nutrient uptake [105]. In contrast, D-amino acids can produce phytotoxic effects when supplied at similar concentrations [106].…”

“…In the case of foliar application of A. platensis biomass on red beets, the effective concentration has been reported to change with cultivar [ 86 ]. The Early Wonder and the Scarlet F1 cultivars presented similar improvements in fresh and dry weight (ca +65%) at the highest tested concentration (3 g L −1 ), while a lower concentration (1.5 g L −1 ) was effective only on the Early Wonder cultivar (ca +50%), indicating different effects of the same dose as a function of plant genotype.…”

“…The use of cyanobacteria, applied in different forms on both roots and leaves, has been shown to positively affect root development and root/shoot ratio in various plant species, such as lettuce [ 50 ], radish [ 83 ], rice [ 43 ], tomato [ 47 , 80 ], peppermint [ 61 ], strawberry [ 107 ], maize [ 108 ], red beet [ 86 ], cucumber [ 99 ], and petunia [ 84 ]. A larger root system increases the root surface area and directly improves nutrients and water uptake from soil, thereby enhancing plant growth and vigor [ 59 ].…”

“…Many other studies reported increased chlorophyll content in plants treated with cyanobacterial extracts; such effect can be attributed to a better nutrient use efficiency by plants or to a protective effect of the biostimulant, that reduces chlorophyll degradation and delays plant senescence [ 47 , 59 , 80 , 90 ]. Exogenous application of amino acids is known to stimulate nitrogen metabolism efficiency and synthesis of chlorophylls in treated plants [ 86 ]. Phytohormones such as cytokinins, betaines, and gibberellins in cyanobacterial extracts may play a role in reducing chlorophyll degradation mainly through inhibition of chlorophyllase activity [ 115 , 116 ].…”