Effect of plot management and fertilizer treatments on the growth biomass yield and seed quality of two guinea grass varieties

An experiment was conducted at the Teaching and Research Farm, University of Agriculture, Abeokuta to evaluate the effect of plot management and fertilizer treatments on the growth, biomass yield and seed quality of two guinea grass varieties, namely Panicum maximum (unimproved) and P. maximum (Ntchisi). The experiment was established at the same time at two sites in a 2x2x3 factorial experimental layout with twelve treatments and three replicates. The three factors considered are the two varieties of P. maximum, plot management involving the weeded and unweeded plots and three levels for fertilizer application of Okg/ha,400kg/ha applied once at 4 weeks after planting (WAP) and 400kg/ha split into two equal halves and applied at 4 and 8 WAP. Data were collected at the 6th, 12th, 18th and 24th WAP for growth parameters and the seeds were harvested from 24th -27th WAP. The mean plant height (301.3cm) and mean leaf length (106.58cm) for P. maximum (unimproved) were higher (P<0.05) than P. maximum (Ntchisi) but mean leaf width (4.38cm) and mean leaf number per plant (234.35) were higher (P<0.05) for P. maximum (Ntchisi) than P. maximum (unimproved) especially for treatments that received fertilizer. The mean value recorded for tiller density (435.75 tiller/m2) showed that P. maximum (Ntchisi) had significantly higher value (P<0.05) than P. maximum (unimproved) at all stages of growth irrespective of plot management. The mean dry matter yields of P. maximum (Ntchisi) with weeded plots and split fertilizer application (33.5t/ha) were significantly higher (P<0.05) than other treatments, while the two P. maximum varieties with weeded plots and no fertilizer applied recorded the least DM yields (1O.7t/ha). The mean value for stem proportion for P. maximum (unimproved), with unweeded plot and single fertilizer application (70.97%) were higher (P<0.05) than other treatments while the mean leaf proportion for P. maximum (Ntchisi), with weeded plots and split fertilizer applications (54.96%) were also significantly higher (P<0.05). Significant (P<0.05) differences were only observed for the seedling length for the 3rd seed harvest for P. maximum (unimproved) in the unweeded plots with split fertilizer application. The highest viability mean value (15%) for the seeds harvested were recorded for the treatment involving P. maximum (unimproved) with unweeded plots and split application of fertilizer at 24W AP. Seedling vigour was also higher (P<0.05) for P. maximum (unimproved) with unweeded plots and split fertilizer application at 24 WAP. More fungi (150 x 106) were associated with the seeds from P. maximum (unimproved) plots that were without fertilizer application. The bacteria mean population count (112 x106) was observed to be higher for P. maximum (Ntchisi) in the weeded plot with Okg/ha fertilizer. It could be concluded that the viability of the harvested seeds for P. maximum (unimproved) was higher than P. maximum (Ntchisi) irrespective of the plot management practices employed. The unimproved variety of P. maximum is therefore more promising for production of viable seed for field establishment of the grass. The dry matter yields of P. maximum (Ntchisi) with weeded plots and split fertilizer application was however better.