YIELD DISTRIBUTIONS OF SPACED PLANTS WITHIN PENSACOLA BAHIAGRASS POPULATIONS DEVELOPED BY RECURRENT RESTRICTED PHENOTYPIC SELECTION

Pensacola bahiagrass (Pb), Paspalum notatum Flugge var, saure Parodi, is a warm season perennial sward grass grazed by livestock on more tha n a million hectares in the southeastern USA. This research was design ed to evaluate the 5-yr effect of recurrent restricted phenotypic sele ction (RRPS) on the average yield and the distribution of spaced plant yield (SPY) components within broad-based Population A and narrow-bas ed Populations B and E. RRPS Cycles 0, 9, and 18 in Population A, and Cycles 0, 5, and 10 in Population B produced 5-yr average spaced-plant -population progress (SPPP) yields of 364, 1014, 1767, 823, 1158, and 1427 g plant(-1), respectively. The average SPY increase in Population A proceeded at the same rate from RRPS Cycles 16 to 22 as from 0 to 1 6 previously reported. The average SPY increase proceeded at a faster rate at RRPS Cycles 5, 6, and 7 for very narrow based Population E tha n for Populations A and E. Comparison of SPYs from different cycles in the 5-yr SPPP tests revealed that RRPS increased the number of high y ielding plants and reduced the number of low yielding plants in succes sive cycles. RRPS Cycle 18 of Population A that produced two plants yi elding 4540 g in the SPPP test had 27 plants weighing only 454 g. Seve n, 14, and 22 cycles of RRPS were required to create plants with SPYs yielding 4086 g in 100-plant populations of E, B, and A, respectively.