Bahiagrass Regrowth and Physiological Aging

Abstract

Pensacola Bahiagrass (Paspalum notatum Flugge) grows by adding new phytomers to the terminal ends of vegetative stolons. A new phytomer and its attached leaf is added on average each 7 to 12 days during growth as long as the tiller is vegetative. The new leaf is supplied with energy primarily for the first 2 to 3 days of growth and, from 3 days of age until fully expanded at 12 days, photosynthates are retained by the leaf. After 12 days, exports are made to other sinks in the sheath, stolon, root, and new tillers. An investigation was completed in which (a) shoot growth (leaves) of plants fertilized with 0, 100, or 300 kg/ha of N were measured for length and clipped at the top of the stolon daily or weekly until the stolons died, (b) photosynthesis rate of leaves of different ages was determined, and (c) photosynthesis was correlated with leaf chlorophyll, and N content by weeks. Thirteen weeks of daily or weekly clipping were required to kill the stolons and regrowth amounted to 749 to 850 kg/ha of dry leaves. Total length of shoot regrowth per square meter ranged between 13 to 22 m for the 13 weeks and was negatively related to N application rate. Photosynthesis started dropping after approximately 25 days, but leaf N and chlorophyll contents were relatively stable for the first 45 days. After 45 days of age all three factors declined rapidly until leaf death occurred 60 ± 6 days after initiation. Stolons live much longer than do leaves.