Physiology, morphology, and growth of individual plants of selected and unselected bahiagrass populations

Selection in 'Pensacola' bahiagrass (Paspalum notatum Flugge var. 'saurae' Parodi) has resulted in populations with higher forage yields. This research was conducted to study physiological and morphological traits that might be related to the yield increases. Plants of populations representing selection Cycles 0 (Pensacola), 9 ('Tifton 9') and 14 (T14) were grown in the greenhouse and leaf photosynthesis and plant growth were measured. Height and diameter were measured and rhizomes were counted on spaced plants of the same populations in the field. One field experiment was established with seedlings, and another with seedlings and plants taken from plots mowed to 3.5 cm every 2 wk for 2 yr. Leaf photosynthesis was higher for Pensacola than for Tifton 9 and T14. Dry weights of greenhouse-grown plants were similar at 84 d of age, but for older plants of Tifton 9 and T14 weights were 31 and 58% greater, respectively, than for Pensacola. Tifton 9 and T14 were 26 and 60% taller, respectively, than Pensacola at 84 d of age, and height/diameter ratios of field-grown plants were greater for Tifton 9 and T14, Pensacola had more rhizomes than Tifton 9 and T14. Plants of T14 from mowed plots were more prostrate and had 2.8 times more rhizomes than those from seedlings, but for Tifton 9 and Pensacola the source of plants had no effect. Winter survival at this location was greater than 90% for Pensacola, but it was 51 and 64% for T14 in two experiments. It appears that selection for increased yield in bahiagrass resulted in taller plants with fewer rhizomes, a greater tendency for winter injury, and a greater susceptibility to population shifts under close, frequent mowing.