Carbohydrate Partitioning in Creeping Bentgrass as Influenced by Nitrogen Fertilization and a Plant Growth Regulator.

Total nonstructural carbohydrate (TNC) in turfgrasses is a valuable indicator of assimilate translocation and physiological responses to management practices and environmental conditions. Allocation of TNC in turfgrass roots, crown, and shoots dictate their performance under stress conditions. Furthermore, TNC content can be influenced by different turfgrass management practices, such as nitrogen fertilization and application of plant growth regulator (Trinexapac ethyl-TE). However, limited information is available on the effects of N fertility and plant growth regulators (TE) on TNC distribution in creeping bentgrass (Agrostis stolonifera L.). The objective of this study was to determine the effect of N fertilization and TE on TNC partitioning of creeping bentgrass (cv. Penncross). The field study was initiated in the spring of 2006 on a 4-yr-old sand based putting green. This experiment was arranged as a split-plot design, with nitrogen fertilization as the main plot (13.63, 22.72, and 36.36 kg N ha^-1 year^-1) and TE as the sub-plot (with and without TE) with four replications. Nitrogen was applied monthly from May to October, and TE (Primo Maxx) was applied in three applications from April to August (0.47 kg a.i. ha^-1). Root and shoot samples were collected from each plot at 15-d intervals and analyzed for TNC content. Higher visual turf quality (8.5 to 9) was observed with increasing nitrogen rate and 3 to 8 days after the each application of TE. Nitrogen fertilization and TE both significantly influenced TNC of turfgrass shoots, but neither of these cultural practices had any significant effect on TNC content of turfgrass roots in our study. The moderate and low N levels (22.72, and 13.63 kg N ha^-1 year^-1) resulted in higher shoot TNC content during spring and fall compared to higher N level (36.36 kg N ha^-1 year^-1).