Effect of Different Levels of Mineral Fertilization and Phenological Stage on Growth and Biomass Production of Paspalum plicatulum

The direct effect of six levels of mineral fertilization with NPK (17-17-17) on the growth and biomass production of Paspalum plicatulum was evaluated at different phenological stages at the Bareng Agronomic Research Station at the Fouta Djallon Central Plateau (Middle Guinea). A factorial design comparing six doses of nitrogen fertilizer (0; 50; 100; 150; 200 and 250 kg N/ha) and three phenological stages (bolting, flowering and after seed set) on plots of 8 m² (4 x 2 m) in four replicates, for a total of 72 experimental plots was used. At each phenological stage, 64 plants were collected per treatment for measurements of heights and diameters. Stem, leaf and whole plant biomass assessment was done on each plot based on nitrogen fertilizer level and phenological stage. The results obtained showed that the mineral fertilization and the phenological stage influence in a positive way (P <0.05) the height and the diameter of P.plicatulum. Regardless of the phenological stage, the highest height and diameter were obtained with a dose of 200 kg N/ha. In addition, the biomass of stems and whole plants of P. plicatulum was increased (p <0.05) with the phenological stage regardless of the level of fertilization. The highest leaf biomass was obtained at bolting (4.12 t DM/ha). The results obtained show that under the agro-ecological conditions of the Central Plateau of Fouta djallon where the test was conducted, the direct effect of fertilization at a rate of 200 kg N/ha makes it possible to obtain the highest growth. P. plicatulum plants were elevated in height, diameter and biomass produced. Plants in the 150 and 200 kg N/ha fertilizer plots had the highest leaf-to-stem ratios (p˂0.05) at bolting. Regardless of the level of fertilization, the best leaf-to-stem ratios of P. plicatulum were obtained at bolting.

Keywords: Paspalum plicatulum, growth, biomass, mineral fertilization, phenological stage.