Patent Application
20240065122
Latin name of the genus and species of the plant claimed: Stenotaphrum secundatum interploid hybrid
Variety denomination: ‘DALSA 1618’
St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze) is a warm-season turfgrass commonly planted in residential and commercial landscapes across the southern United States. Genetic variability in St. Augustinegrass is partitioned within and between ploidy levels. Diploids (2n=18) and polyploids (2n≥27) exhibit varying degrees of tolerance to abiotic stress such as drought, shade and cold, as well as resistances to insect pests and pathogens. With limited water during early stages of drought stress conditions, polyploids are less likely to wilt and enter dormancy as compared to diploids (Busey, 1996). ‘Floratam’, a polyploid cultivar, is still considered the most drought tolerant standard for St. Augustinegrass. Shade tolerance has generally been observed in diploids like ‘Amerishade®’ (also known as ‘TR 6-10’; U.S. Plant Pat. No. 17,095) and ‘DelMar’ (U.S. Plant Pat. No. 6,372) while ‘Floratam’ (not patented) is shade sensitive. The ability to tolerate freezing temperatures is directly related to a plant's ability to acclimate to colder temperatures prior to exposure to freezing temperatures (Kimball et al., 2017). Diploid cultivars like ‘Raleigh’ (not patented) and ‘Palmetto®’ (also known as ‘SS-100’; U.S. Plant Pat. No. 9,395), e.g., have superior cold tolerance whereas ‘Amerishade®’ (diploid) and ‘Floratam’ (polyploid) are more sensitive to winterkill due to a lack of cold acclimation. Although some diploid germplasm accessions have expressed pest resistance (Carbajal et al., 2020), polyploids like ‘Floratam’ generally demonstrate greater resistance than diploids to southern chinch bugs (Blissus insularis Barber) but have similar resistance to gray leaf spot (Pyricularia grisea Sacc.). Furthermore, diploids such as ‘Amerishade®’ with more diminutive or dwarf-like growth habits are slower to establish than polyploids like ‘Floratam’, though some diploids like ‘Raleigh’ and ‘Palmetto®’ exhibit faster establishment rate (Moseley et al., 2021). Dwarf cultivars are preferred by consumers for their tolerance to lower mowing heights and reduced mowing frequency.
Turfgrass breeders have primarily utilized genetic variability present within diploid St. Augustinegrass germplasm for new cultivar development. Sterility barriers and abnormal chromosome pairing between ploidy levels have hindered the extensive use of polyploid germplasm in making genetic improvements until embryo rescue technology was utilized to develop interploid (polyploid×diploid) (Genovesi et al., 2009 and 2017) and inter-specific hybrids of St. Augustinegrass with pembagrass (Genovesi et al., 2017). Interploid hybrids of St. Augustinegrass have been shown to exhibit enhanced turfgrass quality under extreme drought conditions and moderate shade environments (Chandra et al., 2015; Meeks and Chandra, 2019 and 2021). However, commercial viability of some of the interploid hybrids has been hindered due to issues related to sod tensile strength and harvestability. Thus, sod harvestability has become a strong focus for the future of St. Augustinegrass production of widely adaptable and desirable interploid hybrids. ‘DALSA 1618’, an interploid hybrid, was developed at Texas A&M AgriLife Research-Dallas and was evaluated in multiple environments across the southern U.S. to study it's biotic and abiotic stress tolerance, visual turfgrass quality characteristics, herbicide tolerance for weed management, and sod tensile strength.
The present disclosure relates to a new and distinct Stenotaphrum secundatum interploid hybrid variety named ‘DALSA 1618’. ‘DALSA 1618’, formerly tested as ‘TAES 5896-09’ and ‘TXSA-156’, was produced in 2009 near Dallas, TX from a cross between ‘TAES 5384’ (female parent; unpatented) and ‘Amerishade®’ (male parent; U.S. Plant Pat. No. 17,095). ‘TAES 5384’ is an aneuploid (2n=2x=30, Milla-Lewis et al., 2013) exhibiting antibiosis to southern chinch bug (Blissus insularis Barber) and resistance to gray leaf spot disease (Pyricularia grisea Sacc.); and ‘Amerishade®’ is a dark green semi-dwarf diploid cultivar (2n=2x=18, Riordan, 2006) with tolerance to moderate shade densities. Due to ploidy differences and potential genetic incompatibility, embryos were rescued in vitro to produce a population of 756 interploid progeny. ‘DALSA 1618’ represents an individual interploid progeny from this population. ‘DALSA 1618’ was first asexually propagated in Dallas, Texas at the Texas A&M AgriLife Research Center via stolon propagation.
‘DALSA 1618’ is an interploid hybrid St. Augustinegrass that when compared to the polyploid, ‘Floratam’, has a similar leaf blade width and stolon thickness, but shorter leaf length and stolon internode length. The performance of ‘DALSA 1618’ varied depending on the geographic locations and environmental conditions. Overall, ‘DALSA 1618’ established faster than ‘CitraBlue®’ (also known as ‘FSA 1602’; U.S. Plant Pat. No. 32,645) and similarly to other tested commercial cultivars. Along latitudes 32 and 33 and coastal locations, ‘DALSA 1618’ exhibited high turfgrass quality which was generally higher than ‘Floratam’. In Ft. Lauderdale, FL, the quality ratings of ‘DALSA 1618’ was not as high as ‘CitraBlue®’ but maintained acceptable quality similar to other cultivars. When drought stressed, ‘DALSA 1618’ retains a darker green color and higher quality longer like the most drought tolerant cultivar, ‘Floratam’, such that it can tolerate reduced irrigation rate of once every two weeks when weekly irrigation is not available or restricted. Under the combined stressor of cold and shade, ‘DALSA 1618’ performed better than ‘Floratam’ which is both cold and shade sensitive. Under moderate shade, ‘DALSA 1618’ maintains its genetic color and high shoot density like shade tolerant diploid cultivars which contributes to its high turfgrass quality. The leaf elongation rate of ‘DALSA 1618’ is also like that of shade tolerant diploids ‘Palmetto®’ and ‘Raleigh’. As an interploid hybrid, ‘DALSA 1618’ exhibited carly greenup which was better than ‘Floratam’ and in most environments was like ‘Raleigh’. Furthermore, ‘DALSA 1618’ expresses less cold sensitivity than ‘Floratam’ (not patented) and ‘CitraBlue®’ (a.k.a. ‘FSA 1602’; U.S. Plant Pat. No. 32,645).
In summary, ‘DALSA 1618’ exhibits comparable establishment and drought resistance to ‘Floratam’ but with improved turfgrass quality, spring greenup, and cold and shade tolerances. ‘DALSA 1618’ has the same level of tolerance to large patch as other cultivars, but requires further testing. As for gray leaf spot, ‘DALSA 1618’ is like that of ‘CitraBlue®’ and either comparable to or better when compared to other tested cultivars. These combinations of traits are unique in a St. Augustinegrass cultivar, which should allow ‘DALSA 1618’ to succeed in multiple environments across the southern United States.
‘DALSA 1618’ turf can be distinguished from ‘TAES 5384’ (female) at least based upon their turf color. Specifically, ‘DALSA 1618’ exhibits a darker green leaf color as compared to its female parent ‘TAES 5384’. ‘DALSA 1618’ turf can be distinguished from ‘Amerishade®’ (male parent) at least based upon their internode length and diameter. Specifically, ‘DALSA 1618’ exhibits longer stolon node and greater internode diameter as compared to its male parent ‘Amerishade®’. Additionally, ‘DALSA 1618’ exhibits more stolon anthocyanin pigmentation as compared to its male parent ‘Amerishade®’.
‘DALSA 1618’ is illustrated by the accompanying photographs, which show the turf's vegetative and floral characteristics. The colors shown are as true as can be reasonably obtained by conventional photographic procedures.
The following detailed description sets forth the distinctive characteristics of ‘DALSA 1618’. Vegetative and floral data were collected in Dallas, TX from propagated material under greenhouse conditions. Color references are to the Munsell Color Chart; 1977 Edition of the Munsell Color Charts for Plant Tissues, unless otherwise indicated. Color designations provided refer to both mature and immature stages unless otherwise indicated. If any Munsell color designations below differ from the accompanying photographs, the Munsell color designations are accurate.
‘DALSA 1618’ was propagated into five-gallon pots in late August 2020, fertilized with 12-9-6 (N-P-K, Miracle-Gro® Liquifeed Bloom Booster), and maintained under greenhouse conditions (85° /65° F.). ‘DALSA 1618’ began flowering on Nov. 15, 2020 and had nearly completed flowering by May 21, 2021 when floral measurements were collected from the 12 tallest inflorescences (
‘DALSA 1618’ produces flat, thick, spike-like racemes often with two or three axillary/tillering rachis from the same culm, with most commonly a total of three (
Experiments were conducted under greenhouse conditions for the purpose of comparing the morphology of ‘DALSA 1618’ to different sets of commercial cultivars. The plant material for the first experiment was propagated on Sep. 30, 2019. For each of ‘DALSA 1618’ and five cultivars (‘Captiva®’ (a.k.a ‘NUF76’; U.S. Plant Pat. No. 21,280), ‘Floratam’, ‘Palmetto®’, ‘Raleigh’, and ‘Seville’ (U.S. Plant Pat. No. 4,097)), eight rooted stolons containing three nodes and an apical meristem were planted into each of two replicate 15.2 cm square pots filled with potting soil mixed with Osmocote® Classic slow-release fertilizer (14-14-14, ICL Specialty Fertilizers) at a rate of 5 kg·m3. Liquid rooting solution was applied weekly for the first two weeks followed by monthly applications of 24-8-16 (N-P-K, Miracle-Gro®, Scotts Company, Inc.) at 3.3 g·L. Pots were trimmed every two weeks to encourage establishment. Trimming was suspended on 30 Jan 2020. After 43 days, morphological measurements were recorded on Mar. 13, 2020. The leaf length of ‘DALSA 1618’ (42.7 mm) emerging from the 5th node is like ‘Raleigh’, shorter than ‘Floratam’, but longer than ‘Palmetto®’, ‘Captiva®’, and ‘Seville’ (Table 1). However, the leaf width (6.0 mm) is like the polyploid cultivar, ‘Floratam’, which is wider than the diploid cultivars, ‘Captiva®’, ‘Palmetto®’, ‘Raleigh’, and ‘Seville’. The internode length between the 5th and 6th nodes for ‘DALSA 1618’ (66.8 mm) is shorter than ‘Floratam’ and ‘Raleigh’, but longer than ‘Palmetto®R’, ‘Seville’, and ‘Captiva®’. Internode and node diameters of ‘DALSA 1618’ (3.0 mm and 10.1 mm, respectively) are like ‘Floratam’, which is thicker than other tested cultivars. The average number of nodes within 30.5 cm for ‘DALSA 1618’ (5.0) is like ‘Palmetto®’, which is fewer than ‘Captiva®’ and ‘Seville’, but more than ‘Raleigh’ and ‘Floratam’ (
The plant material for a second experiment was derived from replicate mother pots that were refreshed with new potting medium between Aug. 25th and Aug. 30th in 2021 for each ‘DALSA 1618’ and four cultivars ('Amerishade®', ‘DelMar’, ‘Floratam’, and ‘Raleigh’). Pots were fertilized every two weeks with 20-20-20 water soluble fertilizer and left untrimmed for 70 days. Data was collected on Nov. 8, 2021. For all sets of material, twelve samples were measured for each of seven traits using a digital caliper. Leaf length and leaf blade width were recorded from the first fully expanded leaf emerging from the 5th node. Internode length and diameter were measured between the 5th and 6th nodes. Node diameter was measured horizontally on the 5th node. The number of nodes within 30.5 cm were recorded for each stolon measured. Unmown leaf length was measured from the longest fully expanded leaves. Results showed that the leaf length of the first fully expanded leaf at the 5th node for ‘DALSA 1618’ (37.2 mm) is like ‘Raleigh’ and ‘DelMar’ and shorter than ‘Amerishade®’ and ‘Floratam’ (Table 1). Leaf width for ‘DALSA 1618’ (7.8 mm) is like ‘DelMar’ and ‘Floratam’ and wider than ‘Amerishade®’ and ‘Raleigh’. The internode length for ‘DALSA 1618’ (85.4 mm) is like ‘Raleigh’ which was is shorter than ‘Floratam’ but longer than both ‘Amerishade®’ and ‘DelMar’. The internode diameter of ‘DALSA 1618’ (2.8 mm) in this set of material is thicker than all four cultivars, while the node diameter is like ‘Floratam’ and ‘Raleigh’ which is wider than ‘Amerishade®’ and ‘DelMar’. The average number of nodes within 30.5 cm for ‘DALSA 1618’ (4.0) was like ‘Amerishade®’ and ‘Raleigh’, but greater than ‘Floratam’, and less than ‘DelMar’. The unmown leaf length of ‘DALSA 1618’ (21.5 cm) and ‘Floratam’ are similar in length, which was greater than ‘Amerishade®’, ‘DelMar’, and ‘Raleigh’.
In the 2012 Specialty Crop Research Initiative Shared Spaced-Plant Nurseries (SCRI SSPN), ‘DALSA 1618’ ranked 22 nd out of 165 entries across all seven locations (College Station, TX; Dallas, TX; Gainesville, FL; Griffin, GA; Tifton, GA; ‘Raleigh’, NC; and Stillwater, OK) in 2012-2013 under normal management conditions, and it ranked 3rd under drought stress conditions (data not provided). Therefore, it was advanced for further environmental testing in the 2016 NTEP and 2016 SCRI RFT.
Turfgrass quality, spring greenup, leaf texture, genetic color, shoot density, seasonal color, drought tolerance, and resistance to pests and pathogens were all rated on a 1 to 9 scale where 9= excellent performance following NTEP guidelines (Morris and Shearman, 1999). Other traits such as establishment and green cover were rated either visually or digitally as a percentage. In the 2012 SCRI space-plant nursery, turfgrass quality was rated under non-stress (normal) and drought stress conditions. Actual means across all locations and years were regressed against predicted means and ranks were assigned from greatest mean quality to least mean quality. During the 2016 NTEP, establishment was rated periodically during the first full year as a percentage of plot cover. Traits evaluated included turfgrass quality (monthly), spring greenup, winterkill, leaf texture, genetic color, shoot density (spring, summer, and fall), seasonal color (fall and winter), drought tolerance (wilting, dormancy, recovery), and resistance to large patch (Rhizoctonia solani Kühn) and gray leaf spot diseases. In the 2016 SCRI RFT, percent green cover and turfgrass quality were rated in each location. Spring greenup, fall color retention, and resistance to gray leaf spot were additionally rated in Dallas, TX. The salinity tolerance study evaluated changes in quality, green cover, and total biomass over seven weeks in comparison to the freshwater control groups. Final means for each trait were divided by the freshwater control groups means to calculate a percent index.
During the 2017 St. Augustine Shade Study, plot establishment was digitally captured as percent green cover using a light box every two weeks from Aug. 11, 2017 through Oct. 6, 2017 and Jun. 28, 2018 through Oct. 4, 2018. Images were processed (Richardson et al., 2001) and batch analyzed (Karcher and Richardson, 2005) with hue settings of 45 to 120 and saturation settings of 10 to 100. All visual traits were rated on a 1 to 9 scale where 9 =excellent and 1 =very poor with 6=minimum acceptable. Turfgrass quality, plot color, and shoot density were rated every two weeks beginning Aug. 16, 2017 through Oct. 12, 2017 and from Jun. 28, 2018 through Oct. 4, 2018. Turfgrass quality was additionally rated monthly in 2019 from May 15th through Sep. 17th. Fall color was rated on Nov. 15, 2019. Spring greenup was rated on May 16, 2018 and Apr. 23, 2019. Prevalence of gray leaf spot was rated on Jul. 26, 2018 and Oct. 4, 2018. Winter injury from 2017 to 2018 killed all plots of ‘Floratam’, but ‘DALSA 1618’ and other cultivars survived in all three replications. Therefore, data from ‘Floratam’ will not be presented after 2017. Leaf lengths were measured with a ruler (cm) every two weeks before mowing events beginning on Aug. 22, 2017 through Oct. 6, 2017 and Jun. 28, 2018 through Oct. 5, 2018. The two longest unmown leaves in each plot were measured from the leaf tip to the base of the leaf collar. Average lengths and days since the last mowing event were then used to calculate daily leaf elongation rates (DER, mm·d−1).
During the herbicide tolerance study, turfgrass quality (1-9), establishment data (0-100%) and phytotoxicity (0-100%) were visually rated at each location. Turfgrass quality was rated monthly, establishment data was rated every two weeks until 95% establishment was reached, and phytotoxicity was rated every week for the duration of the herbicide residual. Data for the 2021 sod tensile strength study was collected on Jul. 27 at both locations. Data included sod tensile strength (STS), sod handling quality (data not shown), and volumetric water content (VWC). Prior to data collection, each site conducted a dry down study in order to have consistent moisture content in the plots for harvesting.
All analyses, including principal components analysis, were performed using JMP Pro 10 (SAS Inc., Cary, NC). Morphological data were analyzed using the least squared means method with genotype as fixed effects, and experiments 1 and 2 will be presented separately. For traits rated on a 1 to 9 scale, entry, date or year, and entry by date or by year were treated as fixed factors and replications as random factors. Data were combined for each entry if interactions were not significant. For establishment, turfgrass quality, spring greenup and percent green cover data, means were compared by date of collection and not combined across dates. If the analysis of variance and effect tests were significant, means were separated using Fisher's protected LSD at the 0.05 probability level.
As part of the 2016 SCRI RFT, the percent green cover retention of ‘DALSA 1618’ was tested in College Station, TX under varying water conservation methods (approaches A and B) in 2017 and 2018. Under approach “A”, ‘DALSA 1618’ retained green cover similarly to ‘Floratam’ (standard for drought resistance) under all irrigation levels except for once weekly treatments on 26 Apr 2017 and 1 Jun. 2018, the first data point in each year (Table 14). At these times, percent green cover for ‘DALSA 1618’ was higher than ‘Floratam’. Results from approach “B” were generally similar to approach “A” where percent green cover retention was like ‘Floratam’ but also ‘Palmetto®’ for all dates evaluated (Table 15).
Turfgrass quality was additionally evaluated under drought stress for approaches A, B, and C (Dallas, TX) on a 1 to 9 scale where 6=minimum acceptable. For approach “A”, no differences were observed between ‘DALSA 1618’ and ‘Floratam’ within each treatment in 2017 where both genotypes had quality ratings above the minimum acceptable level (Table 14). In 2018, mean quality for both genotypes were below acceptable when irrigated less than once every two weeks. However, ‘DALSA 1618’ has a higher quality than ‘Floratam’ for reduced irrigation at once every two weeks and once weekly. No differences were observed when irrigation was applied twice weekly. These results are slightly different from Erikson et al. (2019) who performed a similar study in Florida which included other elite experimental lines, ‘CitraBlue®’, ‘Palmetto®’, and ‘TamStar®’ (also known as ‘Dalsa 0605’; U.S. Plant Pat. No. 27,393). Over the course of their 20-month study, ‘DALSA 1618’ had superior quality to all three commercial cultivars in all irrigation treatments including the most restrictive bimonthly, monthly, and unirrigated regimes. Perhaps the inclusion of more genotypes in this study and geographical location imparted better separation between ‘DALSA 1618’ and ‘Floratam’.
In summary, ‘DALSA 1618’ is an interploid hybrid St. Augustinegrass that when compared to the polyploid. ‘Floratam’, has a similar leaf blade width and stolon thickness, but shorter leaf length and stolon internode length. The performance of ‘DALSA 1618’ varied depending on the geographic locations and environmental conditions. Overall, ‘DALSA 1618’ established faster than ‘CitraBlue®’ and similarly to other tested commercial cultivars. Along latitudes 32 and 33 and coastal locations, ‘DALSA 1618’ exhibited high turfgrass quality which was generally higher than ‘Floratam’. In Ft. Lauderdale, FL, the quality ratings of ‘DALSA 1618’ was not as high as ‘CitraBlue®’ but maintained acceptable quality similar to other cultivars. When drought stressed, ‘DALSA 1618’ retains a darker green color and higher quality longer like the most drought tolerant cultivar, ‘Floratam’, such that it can tolerate reduced irrigation rate of once every two weeks when weekly irrigation is not available or restricted. Under the combined stressor of cold and shade, ‘DALSA 1618’ performed better than ‘Floratam’ which is both cold and shade sensitive. Under moderate shade, ‘DALSA 1618’ maintains its genetic color and high shoot density like shade tolerant diploid cultivars which contributes to its high turfgrass quality. The leaf elongation rate of ‘DALSA 1618’ is also like that of shade tolerant diploids ‘Palmetto®’ and ‘Raleigh’. As an interploid hybrid, ‘DALSA 1618’ exhibited early greenup which was better than ‘Floratam’ and in most environments was like ‘Raleigh’. Furthermore, ‘DALSA 1618’ expresses less cold sensitivity than ‘Floratam’ and ‘CitraBlue®’. In summary, ‘DALSA 1618’ exhibits comparable establishment and drought resistance to ‘Floratam’ but with improved turfgrass quality, spring greenup, and cold and shade tolerances. ‘DALSA 1618’ has the same level of tolerance to large patch as other cultivars, but requires further testing. As for gray leaf spot, ‘DALSA 1618’ is like that of ‘CitraBlue®’ and either comparable to or better when compared to other tested cultivars. These combinations of traits are unique in a St. Augustinegrass cultivar, which should allow ‘DALSA 1618’ to succeed in multiple environments across the southern United States.
‡Entries with a common letter are not significantly different.
†WAP, weeks after planting
‡Entries within columns with a common letter are not significantly different at the 0.05 probability level.
†Entries within columns with a common letter are not significantly different at the 0.05 probability level.
