Response of vegetative yield characters and yield of biomass fractions of wild-watermelon Cucumis africanus to irrigation interval and NPK fertilizer

Wild-watermelon, Cucumis africanus, is among important indigenous crop plants in rural Limpopo Province of South Africa, primarily used as an ethno-botanical crop and a leafy green vegetable. An experiment laid out in a split-plot design and replicated five times was conducted at the Horticultural Research Unit, University of Limpopo, South Africa. The objective was to study the effects of irrigation frequency (2, 4 and 6 day interval) and fertilizer application rate of nutrient mixture containing nitrogen, phosphorus and potassium (NPK)  (0 Kg NPK ha-1, 60-40-20 kg NPK ha-1, 120-80-40 kg NPK ha-1 and 180-120-60 kg NPK ha-1) on leaf and non-leaf yield characters of C. africanus. The treatment of four day irrigation interval and 120-80-40 kg NPK ha-1application rate produced significantly higher (P ≤ 0.05) vegetative yield characters and biomass of plant fractions than the extreme treatments of short two day irrigation intervals and low 60-40-20 kg NPK ha-1; and long six day irrigation intervals and 180-120-60 kg NPK ha-1. In conclusion, the results of the study indicate that C. africanus can be successfully grown using conventional production methods and supply rural households with good yields of a leafy green vegetable as well as providing raw materials needed for ethno-botanical purposes.   Key words: Leafy vegetable, leaf yield characters, root/shoot ratio, ethno-medicine.