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Frank G. Bethea Jr., Dara Park, Andrew Mount, Nick Menchyk and Haibo Liu

Foliar fertilization is a common practice to deliver nitrogen (N) to turfgrasses. The mechanisms of foliar applied nutrient uptake, particularly the effects of the leaf cuticle layer, have not been clearly characterized in turfgrasses. The objectives of this study were to determine the effect of acute moisture stress on the morphological and compositional components of the cuticle and the resulting effect on foliar-applied N absorption. Creeping bentgrass (Agrostis stolonifera L.) was irrigated to return 100% or 50% evapotranspiration rate (ET) for 10 days to examine cuticular modifications resulting from acute moisture stress and foliar N uptake with and without a surfactant. Acute water stress increased the total cuticle wax by 11%, mostly as a result of the compound 1-hexacosanol, and increased crystalloid density creating a rougher leaf surface. The 50% ET treatment significantly reduced recovery of 15N-labeled urea by 14%, which was attributed to the increased total cuticle wax and crystalloid density making the surface less receptive to foliar applications. The surfactant addition to the urea solution increased 15N-labeled urea recovery by 21% and absorption of 15N in 50% ET plants to levels consistent with the 100% ET plants. These results suggest that acute moisture stress modifies the cuticle wax load and morphology, thereby hindering foliar absorption; however, a surfactant addition can help to mitigate this effect and increase absorption of N.

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John B. Stiglbauer, Haibo Liu, Lambert B. McCarty, Dara M. Park, Joe E. Toler and Kendal Kirk

‘Diamond’ zoysiagrass [Zoysia matrella (L.) Merr.] has a potential to become a new alternative warm-season putting green turfgrass. The main objective of the study was to determine factors affecting establishment speed for ‘Diamond’ zoysiagrass as a putting green in the southern transition zone of the United States. Two sprigging rates, three nitrogen (N) sources, two N rates, and two mowing heights (2.5 and 3.2 mm) were compared at Clemson University, Clemson, SC. Sprigs of ‘Diamond’ zoysiagrass were planted at rates of 91 or 182 m3·ha−1 in 2007 and repeated in 2008. Urea, ammonium nitrate, and ammonium sulfate were applied at 1.7 or 3.4 g N/m2/week from weeks after sprigging (WAS) 3 to 10. Rates were halved from WAS 11 to 16. The N fertilizers were applied as solutions weekly for 16 weeks. Weekly percent cover, turf color ratings, root and clipping sample, and ball rolling were collected for both years. A significant difference occurred in turf cover between high and low sprig rates. Turf color and cover results show that high rates of fertility associated with high rates of sprigs produced 100% turf cover at WAS 11 and 13 in both years. At the 2.5-mm mowing height, ball rolling reached 258 cm in August and was significantly faster than the 3.2-mm mowing height. Results show ‘Diamond’ zoysiagrass can be established within the same growing season to meet a playable putting green quality, but the establishment speed may vary depending on summer monthly temperature fluctuations.