Total Nonstructural Carbohydrate Assessment in Creeping Bentgrass at Different Mowing Heights

Abstract

Any future precision turfgrass management system will benefit from the evaluation of turfgrass stress through indirect measurements of plant components. One such component might be the accumulation dynamics of total nonstructural carbohydrates (TNC). The effects of mowing height (MH) on TNC concentrations were measured in a field experiment. Clippings were collected from eight creeping bentgrass cultivars {Agrostis palustris Huds. [= A stolonifera var. palustris (Huds.) Farw.]} mowed at three different heights (0.64, 1.27, 1.90 cm) from 1998 through 2001. Clippings were evaluated 29 times by sampling early in the photoperiod before 1200 h. Collected clippings were instantly frozen in liquid nitrogen and freeze-dried before TNC analyses. The TNC levels were predicted with near infrared reflectance spectroscopy (NIRS) after building a predictive equation for each carbohydrate fraction with conventional laboratory values. Seasonal trends in TNC concentrations and differences in TNC accumulation among creeping bentgrass cultivars were also evaluated. Mowing heights showed significant differences in TNC content, with 0.64-cm mowed plots having higher TNC levels than 1.27- and 1.90-cm mowed plots on 13 of the 29 dates of evaluation. No consistent differences were observed in TNC concentrations among different cultivars across different growing seasons. However, there were significant seasonal fluctuations in average TNC content at all MHs. The average TNC content of the clippings during 1999 and 2000 started decreasing in mid-July, showing the lowest TNC content in August. The average TNC content showed an increasing trend in September, exhibiting the highest amount of TNC accumulation in October and November.