Title : NPK fertilizer requirements for Jatropha zeyheri indigenous tea under greenhouse conditions
Abstract:
Jatropha zeyheri is an indigenous crop to South Africa, which contains tea brewing and medicinal properties commonly utilized by local communities in rural areas of South Africa. Indigenous teas have been receiving much attention due to their health benefits. Domestication and commercialization of indigenous herbal teas have gained popularity in recent years. However, domestication of J. zeyheri will require optimum NPK fertiliser mixture to improve yield and quality. Therefore, the study was intended to determine whether different fertiliser application rates will optimize yield parameters of J. zeyheri tea under greenhouse conditions. At two-leaf stage, J. zeyheri seedlings were transplanted into 25 cm diameter plastic pots. Each pot was filled with heated-pasteurised sandy soil and Hygromix at 3:1 (v/v) ratio and placed in a spacing of 0.30 m × 0.30 m inter-and intra-row spacing. Treatments, viz., 0, 2, 4, 8, 16 and 32 g of NPK 2:3:2 (22) fertiliser mixtures were arranged in a randomized complete block design, with five replications. Treatments were initiated a week after transplanting, and 130 days after that, treatments had highly significant effects on chlorophyll content, leaf width and dry root mass, contributing 70, 78 and 62% in total treatment variation (TTV), respectively. In contrast, vine length, stem diameter and leaf length were significant contributing 47, 60 and 49% in TTV, respectively. In contrast, treatment had no significant effects on normalized difference vegetation index, number of leaves and dry shoot mass. Jatropha zeyheri plant variables exhibited positive quadratic relations with increasing fertiliser levels. Fertiliser requirements for J. zeyheri were optimized at 3.34 g fertiliser/plant, which translates to 33 kg NPK fertiliser/ha for 10 000 plants of J. zeyheri. In conclusion, J. zeyheri appears to qualify as a low-input tea crop.
Key words: Domestication, fertiliser, food security, indigenous tea, sustainable crops
