Seasonal Changes in Stolon Reserves of Bermudagrass Cultivars As Affected by Various Nitrogen Fertilization Schedules.

In the transition zone, a primary concern in managing bermudagrass [Cynodon dactylon (L.) Pers.] is turf survival under low temperatures during dormancy. The objectives of this study were to determine the effects of three nitrogen (N) fertilization schedules on stolon accumulation of carbohydrates and proteins and spring green-up of four seeded bermudagrass cultivars. A field trial was conducted at Padova University (northeastern Italy) on plots seeded in June 2008. Four bermudagrass cultivars (Princess-77, Riviera, SWI 1014, and Yukon) were compared under three N fertilization schedules: i) 6.7 g N m^-2 in May, June, and August; ii) 5 g N m^-2 in May, June, August, and October; and iii) 4 g N m^-2 in May, June, August, September, and October. Plots (3 × 2 m) were fertilized using ammonium nitrate and were mowed weekly at 45 mm with clippings removed. Spring green-up was estimated weekly as a green percent ground cover from 15 Mar. to 15 June 2010. Turf samples measuring 20 × 20 × 4 (depth) cm were collected monthly from Sept. 2009 to Apr. 2010 and the stolons were separated from the remainder of the samples for subsequent laboratory analyses. Starch, water-soluble carbohydrates (WSC), and crude protein (CP) content of stolons were determined on a dry matter basis. Results of this study pointed out wide differences among cultivars in terms of spring green-up and stolon carbohydrate content. ‘Riviera’ and ‘Yukon’ were characterized by early spring green-up and high stolon storage of starch and WSC, whereas ‘Princess-77’ had late green-up and low carbohydrate levels. Shifts of fertilizer applications until late-season had limited influence on stolon carbohydrates, but enhanced CP accumulation during acclimation and led to an enhanced spring green-up regardless of cultivar.