Lack of cold hardiness may limit widespread use of newly released zoysiagrass (Zoysia spp.) cultivars in the transition zone. Our objectives were to quantify differences in the winter injury of 35 zoysiagrass genotypes in field plots in West Lafayette, IN, and the freeze tolerance of 13 genotypes in a cold stress simulator as well as determine the relationship between leaf width, establishment rate, and autumn growth with winter injury. Winter injury varied between years and among genotypes in the field study. Zoysia japonica Steud. genotypes had less winter injury each year than Z. matrella (L.) Merr. genotypes. Genotypes of Z. japonica available as seed had less winter injury (2% in both years) than genotypes of Z. japonica (41%, 2005; 54%, 2006) and Z. matrella (51%, 2005; 73%, 2006) available only as vegetative propagules. ‘Meyer’, ‘Chinese Common’, and ‘Zenith’ were the commercially available cultivars exhibiting the least winter injury (<7%) in both years, whereas ‘Victoria’, ‘DeAnza’, ‘Diamond’, and ‘Empress’ had the most winter injury (>88%) both years. There was a relationship (r2 = 0.48, P = 0.0088) between freeze tolerance (LT50) in the cold stress simulator and winter injury in the field. Freeze tolerance ranged from −8.4°C (Diamond) to −11.5°C (Meyer and Zenith). Meyer has been the industry standard for zoysiagrass, but our research has identified other commercially available cultivars and genotypes with winter injury similar to Meyer.

Figueiredo, Marcelo R. A.; Leibhart, Lacy J.; Reicher, Zachary J.; Tranel, Patrick J.; Nissen, Scott J.; Westra, Philip; Bernards, Mark L.; Kruger, Greg R.; Gaines, Todd A.; and Jugulam, Mithila, "Metabolism of 2,4-dichlorophenoxyacetic acid contributes to resistance in a common waterhemp (Amaranthus tuberculatus) population" (2017 This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1002/ps.

Cold hardiness among zoysiagrass (Zoysia spp.) genotypes varies, but the physiological basis for cold hardiness is not completely understood. The objective of this study was to determine the relationship of carbohydrate (starch, total soluble sugars, total reducing sugars, sucrose, glucose, and raffinose family oligosaccharides) and proline concentrations with the cold acclimation of zoysiagrass and the lethal temperature killing 50% of the plants (LT50). Thirteen genotypes of zoysiagrass were selected with contrasting levels of winter hardiness. Plants were grown for 4 wk of 8/2°C day/night cycles and a 10‐h photoperiod of 300 μmol m−2 s−1 to induce cold acclimation. Rhizomes and stolons were sampled from nonacclimated and cold‐acclimated plants and used for carbohydrate and proline analysis. Concentrations of soluble sugars and proline increased during cold acclimation, while starch concentrations decreased. Starch, sugar/starch ratio, glucose, total reducing sugars, and proline in cold‐acclimated plants were correlated (r = 0.61, −0.67, −0.73, −0.62, and −0.62, respectively) with LT50 These correlations indicate that higher concentrations of total reducing sugars, glucose, and proline are positively associated with zoysiagrass freeze tolerance, whereas higher concentrations of starch appeared detrimental to freeze tolerance.

seeded earlier. Further research confirmed that seeded bermudagrass should be established as early as possible Bermudagrass [Cynodon dactylon var. dactylon (L.) Pers.] and in late spring to increase winter survival (Munshaw et zoysiagrass (Zoysia japonica Steud.) cultivars established by seed are Hensler et al., 1999). However, Ahring et al. desirable for golf and athletic turfs because of minimum establishment (1975) reported an experimental strain of bermudagrass costs, but little is known about their management during establishment. Seeding dates, seeding rates, post-seeding N fertility, and herbi-was not affected by freezing when seeded as late as 21 cide safety on seedling 'Mirage' bermudagrass and 'Zenith' zoysiagrass July in Oklahoma, indicating potential improvements were investigated in Indiana and Kentucky. Under the conditions in cold hardiness through plant breeding. Portz et al. of our studies, optimum bermudagrass establishment occurred when (1981) reported that zoysiagrass could be successfully seeded 1 June to 15 July at 12 to 49 kg ha Ϫ1 , when Ͼ950 growing established in Southern Illinois when seeded 1 July. degree days (GDD, 5؇C base) accumulated by first frost and when Although seeded zoysiagrass cultivars are generally tol-49 kg ha Ϫ1 N mo Ϫ1 was applied. Earlier seeding dates provided more erant of winters in the transition zone (NTEP, 2001), bermudagrass cover after the first winter. Optimum zoysiagrass estabno information exists on the effect of seeding date on lishment occurred when seeded from 1 to 15 June at 49 to 98 kg ha Ϫ1 , establishment and winter survival. Thus, defining the when Ͼ 1750 GDD accumulated by first frost, and when 49 kg ha Ϫ1optimum seeding dates for bermudagrass and zoysia-N mo Ϫ1 was applied. Increasing N from 49 kg ha Ϫ1 mo Ϫ1 to 98 kg ha Ϫ1 mo Ϫ1 did not hasten establishment of either species. Quinclorac

A barrier to widespread zoysiagrass (Zoysia spp.) use is its slow establishment rate. Our objectives were to quantify differences in establishment rate of zoysiagrass cultivars and genotypes as well as determine the underlying factors associated with differential growth rates. Thirty‐five genotypes of zoysiagrass were transplanted into field plots in June 2004 and 2005. Establishment rate and stolon growth of zoysiagrass genotypes were measured in the field and then four cultivars with contrasting establishment rate were used for further growth analysis in a growth chamber. Mean establishment rate [loge (coverage) d−1] and coverage (cm2) 91 d after planting (DAP) in the field were faster for Z. japonica than Z. matrella genotypes. The Z. japonica Genotype 6186 had the greatest coverage 91 DAP. ‘El Toro’, ‘Chinese Common’, and ‘Palisades’ were among the Z. japonica genotypes that produced more coverage 91 DAP than the mean (1943 cm2), while ‘Meyer’ produced less coverage than the mean. ‘Zorro’ was among the fastest establishing Z. matrella genotypes, and ‘Diamond’ was the slowest. Growth analysis indicated El Toro and Zorro, which establish faster than Meyer and Diamond, partition more dry matter to stolons and rhizomes than leaves. This is consistent with field data where El Toro and Zorro have greater total stolon length than Meyer and Diamond. Zoysiagrass genotypes that partition more dry matter to stems instead of leaves establish the quickest.