Effects of Nitrogen and Phosphorus on Some Quality Attributes of Roselle (Hibiscus sabdariffa var. sabdariffa L.) Under Irrigation .

Page(s): 7 (2), 16-25,10 RefA field experiment was conducted for two consecutive seasons (1994/95 and 1995/96) in the Experimental Farm of the Faculty of Agriculture at Shambat in order to study the effects of nitrogen and phosphorus on some quality attributes of roselle (Hibiscus sabdariffa var. sabdariffa L.) under irrigation. The treatments consisted of four nitrogen levels (0, 20, 40 and 80 kg N/ha) and four phosphorus levels (0, 25, 50 and 100 kg P2O5/ha). Urea (46%N) and triplesuperphosphate (48%P2O5) were used as sources of nitrogen and phosphorus, respectively. The fertilizers were applied at sowing in bands 5 cm deep on one side of the ridge. The experiment was laid out in a randomized complete block design with four replications. The results showed that both nitrogen and phosphorus significantly increased anthocyanin content in calices, with P having a greater effect than N on this character. However, calyx protein content was significantly increased by nitrogen only. On the other hand, nitrogen and phosphorus application resulted in a significant decrease in oxalic acid content in the calices. The effects of both nutrients on the quality attributes studied were manifested at the higher levels of the nutrients.Khartoum University Pres