Growth Rates of Turfgrasses Propagated Vegetatively

Vegetative propagation is valuable as a cultural method in commercial sod production and as a tool in turfgrass research. Experiments were performed in the greenhouse and in the field in order to describe and compare growth rates in vegetative propagation of seven warm season turfgrasses. Daily growth rates were calculated as the logarithm of the quotient final/initial fresh weights, divided by the number of days between planting and harvest. By means of this criterion an elemental biological concept was demonstrated as a measure of rapidity of vegetative propagation and as a predictor of sod production time. The soil medium for most experiments was a Hallandale fine sand, a siliceous, hyperthermic, Typic Psammaquent. Maximum growth rates of turfgrass species ranged from l.8% per day for centipedegrass [Eremochloa ophiuroides (Munro) Hack.] to 9.2% for common bermudagrass [Cynodon dactylon (L.) Pers.]. These rates were larger than growth rates in commercial sod production, that were estimated to be no more than 2.6% per day. Duration of growth periods may explain the disparity between theoretical and observed growth rates. Growth periods of as long as two years are used in commercial sod production; much shorter intervals were used in our studies. A comparison of growth rates for various durations of growth periods suggested that for zoysiagrass (Zoysia japonica Steud.) and St. Augustinegrass (Stenotaphrum secundatum [Walt.] Kuntze) growth was not strictly exponential, but was sigmoidal. The levelling off of growth rates as turfgrasses become larger, or more densely sodded, may be explained by self-inhibition through crowding. It appears possible to use frequent divisions to rapidly propagate warm season turfgrasses far initial increase of foundation blocks and experimental plantings. This and other cultural practices may be applied to improving the efficiency of commercial sod production. We propose the use of growth rate analysis as a method for describing and comparing cultural practices. Dry weight is preferred as the growth criterion, in contrast to fresh weight, coverage, or possibly other parameters. This simple model may be a powerful tool, as well, for testing genotypic response to pests and environmental stresses.