Effect of N, P and Fym Rates On Dm Accumulation and Uptake of K, Ca and Mg By Roselle (HIBISCUS SABDARIFFA L.) In The Northern Guinea Savannah Zone of Nigeria

An investigation was conducted during 2005, 2006 and 2007 wet seasons at the experimental farm of the institute of Agricultural Research, Samaru (11o 11ŒN, 07o 38ŒE, 686m above sea level) to study the effect of N, P and farmyard manure (FYM) rates on dry matter (DM) accumulation and uptake of cations by Roselle in the Northern Guinea Savanna agro-ecological zone of Nigeria. The experiment consisted of three levels of N (0, 60 and 120 kg N ha -1 )) in the form of urea, three levels of P (0, 13.2 and 26.4 kg P ha -1 )) in the form of single super phosphate (SSP) and three levels of FYM (0, 5 and 10 t ha -1 ). A total of twenty seven  treatments were laid out in a split plot design with three replications. The factorial combinations of N and P were assigned to the main plots, while the FYM was allocated to the sub-plots. The result showed that application of 60 kg N and 5 t FYM ha -1 ) recorded significant increase in DM accumulation in Roselle, while applied P had no significant effect on DM production. Combined application of 120 kg N ha -1 ) with 5 t FYM ha -1 ) was optimum for DM production in Roselle. N application reduced K and Mg content but increased the uptake of the nutrients. Similarly, FYM reduced K and Ca content of shoots, while the uptake of these nutrients was increased by manure application. P application increased K and Mg , but reduced Ca contents of shoots. Application of P did not however exert significant effect (P<0.05) on the K and Mg uptake, but reduced Ca uptake of Roselle. Further trial of N application at higher rates is recommended in the study area. KEY WORDS : DM Accumulation, FYM, Nutrients, Multiproduct, Roselle, and gZoborodoh