Effect of vermicompost leachate in Ceratotheca triloba under nutrient deficiency

Ceratotheca triloba (Bernh.) Hook.f. commonly known as an African foxglove is an indigenous plant which occurs in most parts of South Africa. The species is commonly consumed as a leafy vegetable and utilized for its medicinal properties. Although the high nutritional value of the species and medicinal properties are well documented, information related to critical aspect of cultivation is currently limited. Therefore, this study aimed to evaluate the effect of vermicompost leachate (VCL) on growth, nutritional, phytochemical, and antioxidant levels in C. triloba at different growth stages under nutrient-deficient conditions. After in vitro germination, seedlings were grown in the greenhouse for 2 and 4 months under nitrogen (–N); phosphorus (–P); and potassium (–K) deficiency conditions, and were treated with VCL. Vermicompost leachate did not improve the growth of C. triloba plants under the nutrient-deficient conditions. Although –N-deficient plants with or without VCL caused a decline in growth parameters, they significantly enhanced phytochemicals in 2-month-old plants. In most cases, the application of VCL to –P- and –K-deficient plants improved the photosynthetic pigments, protein, and phenolic, as well as flavonoid accumulation. Harvesting time was also found to play a crucial role in the accumulation of evaluated parameters in nutrient-deprived plants. From these findings, it can be deduced that VCL has a potential to minimize the effect of nutrient deficiency especially under –P and –K deficiency in C. triloba plants.