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In this study, five cultivars of cut chrysanthemum Chrysanthemum ×morifolium Ramat., ‘Jinba’, ‘Yuuka’, ‘Fenguiren’, ‘Xueshen’, and ‘Huangjin’ were used to explore the functions of 5-azacytidine (5-azaC) on chrysanthemum growth and flower development. The results showed that 5-azaC had different effects on the growth of the five cultivars during in vitro culture. The final statistics showed that low concentrations promoted plant growth, whereas high concentrations inhibited growth; however, each cultivar had different growth curves, demonstrating that 5-azaC had no consistent inhibitory actions on growth. On the basis of the squaring time and flowering time statistics, we found that 5-azaC had a certain effect on the flowering time of all cut chrysanthemums, and all of these cultivars showed extremely early strains. Summer chrysanthemum (‘Yuuka’, ‘Fenguiren’, ‘Xueshen’, and ‘Huangjin’) treatments led to both early and delayed flowering. When the statistics were analyzed for different individuals, we found that the treatments shortened the squaring time in early-flowering plants. In ‘Jinba’, an autumn chrysanthemum, the treatment helped broken juvenile limitations and allowed plants to undergo photoperiod induction in the early stage. Additionally, we also determined the flower diameter differences in these treatments; ray florets from ‘Yuuka’ and ‘Huangjin’ trended to show tubular florets, and the location of tubular and ray florets were changed in ‘Xueshen’ capitulum. In conclusion, on the basis of flowering time in five early varieties of cut chrysanthemum, we propose that 5-azaC may regulate the methylation level of genes that control flower induction and flower development. These results provide phenotypic data and material for exploring the function of DNA methylation in regulating flowering.

Seasonal variations in temperature and solar radiation in the warm climatic region of the transition zone increase difficulty of creeping bentgrass [Agrostis stolonifera var. palustris (Huds.)] management throughout the year. The impact of winter shade on bentgrass quality and subsequent residual effects of winter shade in spring and summer months has not been investigated. Therefore, a 2-year field study investigated trinexapac-ethyl (TE) [4-(cyclopropyl-α-hydroxy-methylene)-3,5-dioxy-cyclohexanecarboxylic acid ethyl ester] as a winter management strategy to alleviate winter shade stress and determined the winter shade tolerance of ‘L-93’ creeping bentgrass under various reduced light environments. Treatments included a full-sunlight control; 58% and 96% morning, afternoon, and full-day shade artificial; and TE (0.02 kg a.i./ha) applied every 2 weeks from December to July. Data collection included daily light measurements (photosynthetic photon flux density), monthly canopy and soil temperatures, visual turfgrass quality (TQ), chlorophyll concentration, clipping yield, total root biomass, and total root nonstructural carbohydrates. Under 96% shade, canopy temperatures were reduced ≈57% from December to February, whereas soil temperatures were reduced 39% in February compared with full sunlight. Afternoon shade (58%) maintained acceptable TQ throughout winter for both years. Applying TE every 2 weeks in the winter negatively impacted bentgrass quality; however, TE enhanced spring and summer quality. Morning or afternoon shade minimally impacted parameters measured. Overall, moderate winter shade may not limit ‘L-93’ creeping bentgrass performance as a putting green in the transition zone. Results suggest winter shade does not contribute to creeping bentgrass summer decline because all shade-treated plots fully recovered from shade damage in spring months.

Creeping bentgrass (Agrostis stolonifera var. palustris Huds.) is desirable as a putting green turfgrass in the transition zone as a result of year-round green color, ball roll, and playability. However, management challenges exist for bentgrass greens, including winter temperature fluctuations. Frosts often cause cancellations or delays of tee time resulting in lost revenue. In response to this winter golf course management issue, a research project was initiated at Clemson University from 1 Dec. 2005 and 2006 to 1 Aug. 2006 and 2007 on a ‘L93’ creeping bentgrass putting green to determine the impacts of foot traffic or mower traffic and time of traffic application on bentgrass winter performance. Treatments consisted of no traffic (control), foot traffic, and walk-behind mower traffic (rolling) at 0700 and 0900 hr when canopy temperatures were at or below 0 °C. Foot traffic included ≈75 steps within each plot using size 10 SP-4 Saddle Nike golf shoes (soft-spiked sole) administered by a researcher weighing ≈75 kg. A Toro Greensmaster 800 walk-behind greens mower weighing 92 kg with a 45.7-cm roller was used for rolling traffic. Data collected included canopy and soil temperatures (7.6 cm depth), visual turfgrass quality (TQ), clipping yield (g·m⁻²), shoot chlorophyll concentration (mg·g⁻¹), root total nonstructural carbohydrates (TNC) (mg·g⁻¹), soil bulk density (g·cm⁻³), and water infiltration rates (cm·h⁻¹). Time and type of traffic significantly influenced bentgrass winter performance. On all TQ rating dates, 0700 hr rolling traffic decreased TQ by ≈1.1 units compared with foot traffic at 0700 hr. In December, regardless of traffic application time, rolling traffic reduced bentgrass shoot growth ≈17%. However, in February, chlorophyll, soil bulk density, and water infiltration differences were not detected. By the end of March, all treatments had acceptable TQ. Root TNC was unaffected in May, whereas shoot chlorophyll concentrations were unaffected in May and August. This study indicates bentgrass damage resulting from winter traffic is limited to winter and early spring months and full recovery should be expected by summer.

As a result of the increasing popularity of fine-leafed zoysiagrasses on golf courses, a 2-year field study was conducted to assess ‘Diamond’ zoysiagrass [Zoysia matrella (L.) Merr.] putting green performance at The Cliff’s Communities Turfgrass Research Facility in Marietta, SC. Factors included four nitrogen (N) fertility rates and two trinexapac-ethyl (TE) regimes. Foliar applications of 0, 4.9, 9.8, and 14.7 kg·ha⁻¹ N were made once weekly for 7 and 15 weeks in 2009 and 2010, respectively. Trinexapac-ethyl was tank-mixed and applied weekly for 7 weeks during July to August at 0 or 0.017 kg a.i./ha totaling 0.120 kg a.i./ha for both growing seasons. Putting green performance was measured by assessing turf quality (TQ), ball roll distance (BRD), surface firmness (SF), leaf tissue nutrient concentrations, and thatch accumulation. Turfgrasses receiving 4.9 kg N/ha weekly exhibited acceptable TQ and greater SF and BRD than plots receiving 14.7 kg N/ha weekly on all rating dates in 2010 before seasonal dormancy. Trinexapac-ethyl reduced clipping yield by 15% to 43% and influenced BRD, SF, and tissue nutrient concentration across the 2-year study. Surface firmness decreased as total N input increased during the 2010 growing season and is presumably the result of an increase in leaf tissue causing a cushioned putting surface. Linear regression of thatch accumulation and SF were analyzed and found to be significant at four rating dates in 2010 indicating that as thatch organic matter increased, SF decreased. Nitrogen input for ‘Diamond’ zoysiagrass putting greens grown in the transition zone should begin at 73.5 kg·ha⁻¹/year with supplemental N applications applied as needed.