Selection of New Zoysiagrass Genotypes for Golf Course Fairways, Greens, and Tees in the Upper Transition Zone

A set of 70 experimental zoysiagrass genotypes along with three standards, ‘Meyer,' ‘Innovation,' and ‘KSUZ 1201,' were evaluated for turf performance in the northern transition zone. The genotypes were previously selected from a set of 935 progeny that resulted from pairwise crossings of cold-hardy zoysiagrass parents with fine-textured, under-utilized zoysiagrasses. All 70 progeny survived the winter of 2019–2020 and thus were evaluated based on their turf performance. The preference of selection was based first upon spring green up ratings, followed by leaf texture (finer preferred), vigor, turf quality, and wilt during dry down. A total of 20 best progeny were selected and harvested for propagation on October 12, 2020. Only one genotype, ‘6844-31’ had a texture rating of 8.0 (1 to 9 scale; 9 = finest texture) and four other genotypes had texture ratings higher than 7.0 among the selected 20 best progeny. The progeny will be established in larger replicated plots at several locations including Kansas State University Olathe Horticulture Center, Olathe, KS, starting in the summer of 2021

Summary A set of 70 experimental zoysiagrass genotypes along with three standards, 'Meyer', 'Innovation', and 'KSUZ 1201', were evaluated for turf performance in the northern transition zone. The genotypes were previously selected from a set of 935 progeny that resulted from pairwise crossings of cold-hardy zoysiagrass parents with fine-textured, under-utilized zoysiagrasses. All 70 progeny survived the winter of 2019-2020 and thus were evaluated based on their turf performance. The preference of selection was based first upon spring green up ratings, followed by leaf texture (finer preferred), vigor, turf quality, and wilt during dry down. A total of 20 best progeny were selected and harvested for propagation on October 12, 2020. Only one genotype, '6844-31' had a texture rating of 8.0 (1 to 9 scale; 9 = finest texture) and four other genotypes had texture ratings higher than 7.0 among the selected 20 best progeny. The progeny will be established in larger replicated plots at several locations including Kansas State University Olathe Horticulture Center, Olathe, KS, starting in the summer of 2021.

Rationale
Meyer zoysiagrass, a relatively coarse-textured, cold-hardy zoysiagrass is commonly used on golf course fairways and tees in the transition zone. However, fine-textured zoysiagrass cultivars for use on golf course tees, fairways, and putting greens that can tolerate the freezing temperatures in the transition zone are not available. More progress in developing the fine-textured cultivars for the transition zone is needed.

Objectives
To identify new, cold-hardy, and fine-textured zoysiagrass genotypes for use on golf course tees, fairways, and putting greens in the northern transition zone.

Study Description
We selected 70 experimental hybrids from a set of 935 progeny in a previous nursery plot (Chhetri et al., 2020). Those 70 hybrids were established along with three standards, Meyer, Innovation, and KSUZ 1201 (a cold-hardy experimental), on July 2, 2019. The study area was established using plugs planted into tilled ground at Kansas State University Olathe Horticulture Center, Olathe, KS. Each plot measured 3 × 3-ft with no alley in between. Immediately after planting, Ronstar G (a.i. oxadiazon 2%, Bayer Environmental Science) was applied at 2 lb of a.i. per acre and irrigation was applied to prevent drought stress (until a dry down period in late summer).
Mowing was started at a height of 3 inches, and once plugs were beyond that height, it was gradually reduced to 0.5 inches. The plots were arranged in a completely randomized design with two replicates.
Leaf texture on a scale of 1-9 (where 1 = coarse-textured and 9 = fine-textured) and plant vigor on a scale of 1-9 (where 1 = poor growth and 9 = best growth) were recorded on September 27, 2019, and October 6, 2020. Spring green up (where 1 = brown, dormant and 9 = completely green) was recorded on April 7, 2020. Turf quality was rated on a scale of 1-9 (1 = brown dead turf, 6 = minimally acceptable, and 9 = ideal uniform turf) on October 6, 2020. Visible wilting was recorded as a measure of drought tolerance on a scale of 1-9 in which 1 = completely brown, 9 = no wilt on August 27, 2020.

Results
All 70 progeny and three standard genotypes survived the winter of 2019-2020. The genotypes were determined first depending upon spring green up, followed by leaf texture, vigor, turf quality, and wilt during dry down. Based upon this, 20 genotypes were selected as the top performers ( Figure 1).
Kansas State University Agricultural Experiment Station and Cooperative Extension Service