Yield of selected and unselected bahiagrass populations at two cutting heights

Yields of bahiagrass (Paspalum notatum Flugge) have been increased over that of 'Pensacola' through several cycles of selection. To determine factors contributing to the increased yields, a field experiment was conducted for 3 yr to examine yields, biomass, and leaf area index of three populations representing Cycles 0 (Pensacola, original population), 9 ('Tifton 9') and 14 (T14). Plots were mowed every 2 wk at 3.5- and 10-cm heights and quadrat samples were taken to estimate dry weights of stubble after mowing plus rhizomes. In the first harvest year, T14 yielded more than the other two populations when mowed at 3.5 cm, but less when mowed at 10 cm. Yields averaged across the second and third years and across cutting heights were 20 and 25% higher for Tifton 9 and T14, respectively, than for Pensacola. Total biomass (excluding roots) was higher in July of the first year for Pensacola than for Tifton 9 and T14, and for the latter two, harvested yield made up a larger percentage of the total. However, in July of the third year neither biomass nor percentage of the biomass harvested differed among the populations. Stubble plus rhizome weights increased throughout the 3-yr period and were higher for Pensacola than Tifton 9 and T14 because of its more prostrate growth habit. If the annual increase in weight of stubble plus rhizomes were added to harvested yields, then biomass production by Tifton 9 and T14 was 12.4 and 12.9 t [ha.sup.-1] [yr.sup.-1], respectively, compared with 10.4 t [ha.sup.-1] [yr.sup.-1] for Pensacola. Thus, it appears that selection for increased yield has resulted in increased allocation of dry matter to harvestable foliage and possibly a greater production of non-root biomass.