Purslane is produced as a crop in Europe and other parts of the world, but is regarded as a weed in North America. American researchers explored the possibility of increasing purslane’s nutritional value through nitrogen supplementation.
They tested two varieties of purslane – Green Leaf and Golden Leaf – with growing media containing various concentrations of nitrogen, harvesting the crop 45 days after planting.
While both varietals showed increased concentrations of phytochemicals as nitrogen levels increased, only the Green Leaf type showed statistically significant improvements.
High phytochemical concentrations
“Purslane in the study accumulated high concentrations of carotenoid phytochemicals,” the authors wrote in their study, published in the journal HortScience.
“Nitrogen treatment significantly influenced shoot tissue beta-carotene, lutein, neoxanthin, total carotenoids, chlorophyll a, chlorophyll b, total chlorophyll, and the chlorophyll a to b ratio in purslane shoot tissues,” they added.
By raising nitrogen concentrations from 13 mg per litre to 105 mg per litre, the researchers increased chlorophyll a levels by 110% to 143.64 mg per 100 g fresh weight, chlorophyll b by 49%, and total carotenoid pigments by 45% to almost 30 mg per 100 g fresh weight for Green Leaf purslane.
The researchers noted the nutritional benefits of chlorophyll and carotenoids.
“Data are mounting on the role of dietary chlorophyll in the protection against harmful chemical mutagens and carcinogens. Therefore, additions of chlorophyll in diets may be nutritionally beneficial.
“The nutritional contributions of dietary carotenoid phytochemicals are as provitamin A compounds, photoprotection against ageing eye diseases, and as antioxidants in chronic disease prevention,” they added.
Nitrogen abundance allows chlorophyll creation
The authors wrote that nitrogen scarcity is often the limiting factor for plant growth. They noted that nitrogen is a structural component of chlorophyll, and linked the dramatic increase in chlorophyll concentrations to a greater nitrogen abundance.
“Nitrogen is also a structural component of the chlorophyll molecule. Higher nitrogen treatment concentrations may have resulted in greater nitrogen uptake and translocation for chlorophyll biosynthesis within the purslane cultivars.
"High chlorophyll concentrations would improve the nutritional functionality of purslane,” they wrote.
“Nutritionally Important Pigments in Purslane (Portulaca oleracea) Differ between Cultivars and in Response to Nitrogen”
Authors: D.A. Kopsell, K.J. Whitlock, C.E. Sams