Growth and physiological response to organic and/or inorganic fertilisers of wild Solanum nigrum L. cultivated under field conditions in Eastern Cape Province, South Africa

Abstract

Wild vegetables are a rich source of nutrients and yet these plants have been neglected by the agricultural fraternity and consumers in favour of conventional vegetables such as spinach and cabbage. Although wild vegetables usually grow as weeds alongside crops such as maize during the planting season, a renewed interest by researchers has led to efforts to domesticate these plants due to their favourable nutritional qualities, for food and to preserve their knowledge. Solanum nigrum is a popular wild vegetable consumed by the rural populace of the Eastern Cape Province of South Africa and was selected for domestication. A field trial was conducted at the University of Fort Hare research farm located at 32°47′3″S, 26°50′43″E from September to December 2012 to investigate the effect of goat manure and inorganic fertiliser on the growth and physiological response of S. nigrum with a view to determine the best fertiliser option for successful cultivation. Five treatments (control, 100 kg N/ha, 8.13 t manure/ha, 100 kg N/ha + 8.13 t manure/ha and 50 kg N/ha + 4.07 t manure/ha) were arranged in plots in a randomised complete block design with five replicates. Plant height, total number of leaves formed, chlorophyll content, moisture content, root:shoot ratio, leaf area and stem diameter were measured using standard plant growth measurement methods. Application of 100 kg N/ha + 8.13 t manure/ha produced the highest plant height, total number of leaves and chlorophyll values. Applying 100 kg N/ha produced the highest moisture content, root:shoot ratio and stem diameter. Organic fertiliser alone did not have a positive effect on the growth parameters. Therefore, the application of 100 kg N/ha + 8.13 t manure/ha is recommended for the cultivation of S. nigrum in the Eastern Cape for optimum results.