Development of High Soil pH Tolerant Centipedegrass Cultivars.

Centipedegrass may exhibit chlorosis and reductions in growth when exposed to soil pH above 7.5. A systematic germplasm collection was made in central and southern China in the fall of 1999 to broaden the centipedegrass germplasm base in the U.S. Ten seed from each Chinese accession were planted in pots (15.2 cm diameter) containing a Brownfield Sandy Clay Loam (loamy, mixed, superactive, thermic Arsenic Aridic Paleustalfs; pH of 8.4) excavated from the Quaker Research Farm in Lubbock, TX. Seed germination was monitored over four weeks. Each seedling was transplanted into individual pots (15.2 cm diameter) containing soil previously described. Each seedling became a “clonal” entry in the research trial. ‘Common’ and ‘TifBlair’ centipedegrass cultivars were added for comparison. Fertilizer (7N – 7P₂O₅ – 7K₂O) was applied at time of transplant at 24 kg N/ha. Plants were irrigated with 5.0 cm water/wk with an automated irrigation system. Natural light was supplemented with artificial light at 500 µmol^.m^-2 s^-1 photosynthetic photon flux in a 12-h day to approximate summer light intensity and photoperiod. Conditions in the greenhouse were maintained at day/night temperatures of 36/30 °C. Clonal entries were grown in the greenhouse for two months. Digital photographs were taken two months after transplant with a Nikon 10.0 megapixel camera mounted on a light box. Pictures were analyzed using WinCam 2007 software to determine % cover and % green tissue. ‘TifBlair’ and ‘Common’ exhibited 47% cover and 50 to 57% green tissue 2 months after transplant (MAT). TC 437-2, TC 427-7, and TC-437-3 exhibited 80 to 87% cover and 90 to 92% green tissue 2 MAT, while TC 434-3, TC 427-1 and TC 434-4 exhibited 71 to 74% cover and 77 to 82% green tissue. TC 427-99 and TC 437-8 exhibited slow growth (56 to 59% cover), but good color (75 to 86% green tissue).