Field trials were conducted during the 2022 and 2023 wet seasons at the research farms of the Institute for Agricultural Research, Samaru; Agricultural research station, Minjibir; and Agricultural research station, Mokwa; in the northern Guinea savanna, Sudan savanna and southern Guinea savanna agro-ecological zones of Nigeria respectively, to evaluate the productivity of roselle as influenced by NPK fertilizer application. The treatments consisted of factorial combinations of three (3) rates of NPK fertilizer (30:15:15, 60:30:30, and 90:45:45 kg NPK ha-1), and two times of fertilizer application (1 = full dose at planting and 2 = split-application) and control (0:0:0). The treatments were laid in RCBD and replicated three times. The gross plot size was 13.5 m2 (6 ridges, 4.5 m × 3 m) while the net plot was 6 m2. Seeds were sown at 30 cm intra-row spacing with 3-4 seeds per hole and later thinned to one plant per stand. Fertilizer treatment was applied using NPK 20:10:10. Data collected were subjected to Analysis of Variance (ANOVA) using SAS software and means were separated using DMRT at 5% level of probability. The results highlight the significant influence of fertilizer management on roselle productivity, with increasing NPK fertilizer application leading to increase in yields. Split application of fertilizer emerged as a superior strategy compared to full-dose application at sowing, enhancing nutrient uptake efficiency and resulting in higher yields of capsules, calyces, and seeds. In conclusion, split-application of 90:45:45 kg NPK ha-1 gave the highest capsule number (35-45), calyx yield (288-650 kg ha-1) and seed yield (202-496 kg ha-1) across the three locations in both years.

Roselle, NPK fertilizer, Savanna, Yield, Nutrient management

agronomy

Presentation: oral presentation