Foliar application of 5-aminolevulinic acid to promote bioactive potential and nutritional value of purslane, a vegetable for future

Abstract

Decent taste and the salt and drought tolerance of purslane (Portulaca oleracea L.) make it a potential vegetable crop for the future. This study investigates the effects of foliar application of 5-aminolevulinic acid (5-ALA), a new plant growth regulator, on the growth, mineral composition, and bioactive compounds of purslane. Three different levels of 5-ALA (0, 25 and 50 mg L^-1) were sprayed at 1) two leaved stage and 2) upon the onset of inflorescence appearance on purslane seedlings. Results showed that 5-ALA application enhanced biomass accumulation in the plant shoot and increased shoot length. Concentration of nitrogen, potassium, magnesium, zinc and iron increased in the shoots of 5-ALA treated plants, while the calcium concentration remained unaffected. Phenolic compounds of the plant were catechin, chlorogenic acid, and ellagic acid, with catechin being the main compound. Further on, Trans-ferulic acid, hesperedin and eugenol were detected in the extract of 5-ALA-treated plants. Application of 5-ALA also increased fatty acids in the plant leaves. Total phenolics, ascorbic acid contents and antioxidative activity of shoot were increased in the 5-ALA-treated plants. Moreover, pH of root exudates of the plants was decreased in 5-ALA treated plants. The results revealed that exogenous 5-ALA has growth regulatory effects and can enhance the growth, and improve nutritional quality and pharmaceutical properties of P. oleracea. In this regard, the best results were obtained by application of 50 mg 5-ALA L^-1.