Clipping Frequency Effects On Growth, Greenness Index and Water Status of Bermuda Grass.

The abundance and vigour of certain species can increase or decrease when plants are subjected to repeated defoliation and such species are sometimes referred to as increaser or decreaser species, respectively. Increaser species are able to over-compensate for the loss of plant tissue by increased growth rates when subjected to increased clipping frequency. The objectives of this research were to determine whether Bermuda grass (Cynodon dactylon (L.) Pers) varieties commonly used in the Caribbean region could be characterized as increaser or decreaser species, and to examine the physiological bases of the observed responses. In an initial study, potted Bermuda grass ‘Princess-77’ was subjected to three clipping frequencies (5, 10 and 15-day clipping intervals) and two fertilizer levels. A follow-up study examined the effects of the same clipping frequencies on three varieties: ‘Princess-77’, ‘Sahara’ and the interspecific hybrid ‘Tifway B419’ (C. dactylon (L.) Pers. x C. transvaalensis Burtt-Davy). The effects of clipping interval were examined in a third study using ‘Princess-77’ with growth duration varying between 5 and 19 days in 2-day steps. Dry mass of clippings, tissue moisture content, soil moisture content, turf height and greenness index were determined in all studies. The results suggest that Bermuda grass is a decreaser species with dry mass production being severely reduced at the highest clipping frequency regardless of the fertilizer level. ‘Tifway B419’ had the highest growth rates and dry mass production. Tissue moisture content and greenness index were highest with the 15-day clipping cycle. Instantaneous growth rate for ‘Princess-77’ was highest at 11 days, while the average growth rate continued to increase up to 15 days after clipping. These results have implications for the management of Bermuda grass as turfgrass or pasture.