Compost tea improves growth, nutrients and antioxidants in corms of Hypoxis hemerocallidea

Abstract

Background: The wild population of Hypoxis hemerocallidea continues to decline rapidly because of overharvesting for medicinal use. This has necessitated the development of sustainable cultivation protocols for the species to promote its conservation.

Aim: The impact of varying concentrations of compost tea extract on the growth, nutrient, antioxidant, and phytochemical contents of slow-growing corms H. hemerocallidea were investigated.

Setting: Corms of H. hemerocallidea were irrigated with municipal water and graded concentrations (0.25, 0.5, 0.75 and 1) of compost tea.

Methods: The nutrient content of the treated plant materials was analysed using the atomic absorption spectrophotometer while phytochemical and antioxidant contents were analysed following referenced methods.

Results: The highest growth parameters were recorded in corms treated with 0.5 of compost tea. The extracted compost tea did not have a significant influence on the phenolic content and antioxidant capacity of the plant; however, significant variability was observed in the flavonols and FRAP (ferric reducing antioxidant power) values at P < 0.05. Similarly, the concentration of certain mineral elements such as N, P, K, Ca and Mg varied significantly in the leaves whereas elemental compositions of the treated roots of H. hemerocallidea.

Conclusion: The compost tea did not have a significant effect on the phenolic content, oxygen radical absorbance capacity and ABTS (2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic) acid) antioxidant properties and nutrients in the plant although significant differences were observed in the flavonols and FRAP content of leaves, corms and roots.

Contribution: The study contributes to the development of an organic cultivation protocol to conserve wild relatives of H. hemerocallidea.