Effect of Growth Substrate on Yield and Chemical Composition of Pot-Grown Portulaca oleracea

The use of manure as a growing medium for horticultural crop cultivation is a sustainable practice that may allow a reduction in the production costs and the environmental burden of bulky waste management. For this purpose, the current study investigated the partial substitution of peat with manure at various rates (0% (GS1), 100% (GS2), 80% (GS3), 60% (GS4), 40% (GS5), and 20% (GS6)) in pot-cultivated purslane. Our results indicate that the substitution of peat with manure may increase crop yield by 60% to 80%. Moreover, the nutritional value was improved for specific manure rates; for example, the ash and carbohydrate contents in leaves increased at 60% and 20%, respectively, while the fat and carbohydrate contents in shoots increased at 80% and 20%, respectively. P content increased in both leaves and shoots when manure was added to the growing medium, while application at low rates (e.g., 20%) resulted in decreased N and K content. Finally, regarding leaf total phenol and flavonoid contents, as well as antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, values increased when manure was added at 40% to 60%; in shoots, increased values were observed for these parameters when manure was applied at 0% or 100%. In conclusion, our results suggest that peat substitution with manure is a viable, sustainable practice in purslane cultivation in pots without compromising the yield and quality parameters of plants. However, more species and different types of manure must be tested to design tailor-made growing media for horticultural crops.