Effect of nitrogen fertiliser on the growth and calyx yield of two cultivars of roselle
AbstractField experiments were carried out during the 2000 and 2001 rainy seasons on the field of National Horticultural Research Institute at Bagauda (latitude 11o 33’ N and longitude 8o 23’E of the equator). The experiment was aimed at evaluating the response of roselle cultivars to different levels of N in combination with 50 kg P/ha and establishing an
optimum N fertilizer requirement by roselle. Five rates of nitrogen (0, 30, 60, 90 and 120 kg N ha-1) were combined with deep red and pure white cultivars of roselle in a randomized complete block design arrangement with three replications. Application of N significantly (p < 0.05) increased plant height, number of leaves, branches, pods, calyx and seed yields
o roselle. Application of 50 kg P/ha as basal dressing significantly (p < 0.05) influenced the production of calyces among the cultivars. In Nothern Guinea savanna, calyx yield of 2.38 t/ha fresh weight with a corresponding dry matter of 1.02 t/ha were significantly different (p < 0.05) when 30 kg N/ha was applied to deep red cultivar and second season (2001) was better than the first season (2000). Similarly, significantly differences (p <
0.05) were recorded in the seed yields of roselle cultivars in 2001 season and 60 kg N/ha produced optimum levels of 690.0 kg/ha for deep red and 550.0 kg/ha for pure white cultivars seed yields in Northern Guinea savanna.