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- Author or Editor: T.P. Riordan x
Stolon nodal segments of Buchloe dactyloides (Nutt.) Engelm. were removed from greenhouse grown plants and placed on Gamborg's B5 medium in order to determine nodal position and 2,4-D level required to give maximum callus initiation. 2,4-D levels used were 5uM, 16uM, 35uM, and 50uM. Six nodal segments were grouped according to position on the stolon, from the most recent node (node one) to the basal node (node 6). It was concluded that node 4 gave statistically greater callus mass than nodes 1, 2, 3, 5, and 6. Increasing levels of 2,4-D suppressed callus initiation, with maximum response occurring at 5uM 2,4-D.
The concept that greater callus mass will induce competence was investigated. The second most immature nodal segments were removed from heavily fertigatcd greenhouse grown plants. Shoots initiated from those nodes were only cut back to one-third their total length. They were subjected to the following treatments: (1) dicamba from 1μM to 5μM in increments of 1.0; (2) B5 medium salt concentrations from 1/3x to 5/3x in increments of 1/3; (3) sucrose levels from 2% to 10% in increments of 2; (4) casein hydrolysate from 0 to 200mg/l in increments of 50. The experiment consisted of twenty-five different treatment combinations in a central composite rotatable second order design. Explants were placed in continuous cool white fluorescent light at 26°C.
Dicamba, B5 salts, and sucrose had significant effects on callus mass (p<.12), while casein hydrolysate had no notable effects on callus mass (p ≥ .57). It was determined that optimum response occurred at 5/3x concentration of B5 salts, 10% sucrose, and 5.0μM dicamba. White, compact calli were observed in treatment combinations that yielded callus fresh weights of two-hundred milligrams or higher.
Buffalograss [Buchloë dactyloides (Nutt.) Engelm] is a drought-resistant, dioecious species, native to the Central Great Plains, which shows excellent potential as a low-maintenance turfgrass. Although buffalograss can be propagated vegetatively, there is a need for seeded turf-type cultivars. To assist in developing seeded cultivars, heritabilities of turf characteristics were estimated. Heritabilities from maternal half-sib analyses ranged from h2 = 0.04 ± 0.03 for the 1988 uniformity rating to h2 = 0.62 ± 0.26 for the 1989 spring color rating. Heritability estimates calculated from offspring-parent regression were also variable and generally lower than maternal half-sib analysis. The results suggest that some turf characteristics are highly heritable and that growing conditions markedly affect heritability estimates.
Mini-lysimetry was used for evapotranspiration (ET) assessment of six tall fescue cultivars (Festuca arundinacea Schreb.) grown under field conditions. Crop coefficients (Kc) and fraction of available soil water were calculated. Cultivars differed in ET by as much as 18%. Turf-types had lower ET than forage-types, with ET rates of 6.6 and 7.2 mm·day–1, respectively. ‘Kenhy’ and ‘Kentucky 31’ had the highest and ‘Rebel’ and ‘Mustang’ had the lowest total ET for 16 days measured during Summer 1984. Cultivars differed in extraction of available soil water and capacity to meet ET demand. Cultivars differed in wilting tendency. ‘Mustang’ and ‘Rebel’ had low ET, but wilted early. ‘Adventure’ had a relatively high ET, but did not show signs of wilt.
Tall fescue (Festuca arundinacea Shreb.) cultivars differed in thatching tendency 3 years after establishment. Thatch accumulation was greater in turf-types than forage-types. Thatch accumulation was positively correlated to verdure (r = 0.92) and total cell wall (TCW) content per square meter (r = 0.90) of cultivars.
Oat straw mulch reduced plant production and quality. Turfgrass clipping mulch produced 2.5 times the fresh plant weight of the no mulch treatment and 5 times that of the oat straw mulch. All mulches reduced weeds when compared to no mulch. Alfalfa hay and turfgrass clippings were more effective than oat straw. Water vapor loss and soil temperatures were reduced by the mulches. Soil moisture beneath the oat straw was less than the other mulches. Oat straw had the lowest N content but did not reflect lower N in plants growing in it. Kentucky bluegrass mulch ranked best of the species tested, perennial ryegrass was second. While, tall fescue, fine fescue, and buffalograss were intermediate in ranking. Creeping bentgrass gave the poorest performance and ranked the same as the no mulch treatment.
Sixty Kentucky bluegrass (Poa pratensis L.) cultivars and experimental lines and 24 bluegrass blends were investigated for thatching tendency. Cultivars and experimental lines differed in thatch accumulation during the course of this 5-year study. Increasing N level from 10 to 20 g N m-2 season -1 had no effect on thatch accumulation. Thatch accumulation in cultivars and experimental lines was correlated (r = 0.87) to verdure, indicating vigorous cultivars had greater thatching tendency. Thatching tendency of cultivars was correlated (r = 0.74) to their total cell-wall content expressed on a mg dm-2 basis. Accumulation of thatch in blends approximated the mean accumulation for cultivars growing in pure stands. These results indicate a potential for reducing thatch accumulation in Kentucky bluegrass lawns through blending of appropriate cultivars.
Twenty-one Kentucky bluegrass (Poa pratensis L.) cultivais differed significantly in their thatching tendency during 4 years of study. ‘Glade’, ‘Cheri’, and ‘Victa’ accumulated the most thatch, while ‘S-21’, ‘A-34’, and ‘Park’ accumulated the least. Increasing mowing heights from 2.5 cm to 5.0 cm significantly increased the tendency to accumulate thatch. Increasing nitrogen nutritional levels from 10 g m−2 to 20 g m−2 did not increase thatching tendency.
Warm-season turfgrasses are grown throughout the warm humid, sub-humid, and semiarid regions. The objective of this study was to determine the adaptation of six warm-season turfgrass species and several of their cultivars to Mediterranean growing conditions of Turkey by evaluating turfgrass establishment rate, quality, color, and percentage of turfgrass cover. Information of this nature is lacking and would be helpful to turfgrass managers and advisers working in the region. A study was conducted over a 2-year period in two locations of the Mediterranean region of Turkey. The warm-season turfgrass species studied were bermudagrass (Cynodon dactylon), buffalograss (Buchloë dactyloides), zoysiagrass (Zoysia japonica), bahiagrass (Paspalum notatum), seashore paspalum (Paspalum vaginatum), and centipedegrass (Eremochloa ophiurioides). Tall fescue (Festuca arundinacea) was included as a cool-season turfgrass species for comparison. Twenty cultivars belonging to these species were evaluated for their establishment, turfgrass color and quality, spring green-up, and fall color retention. Bermudagrass, bahiagrass, and seashore paspalum established 95% or better coverage at 1095 growing degree days [GDD (5 °C base temperature)], buffalograss and centipedegrass at 1436 GDD, and ‘Zenith’ and ‘Companion’ Zoysiagrass had 90% and 84% coverage at Antalya after accumulating 2031 GDD. ‘Sea Spray’ seashore paspalum; ‘SWI-1044’, ‘SWI-1045’, ‘Princess 77’, and ‘Riviera’ bermudagrass; ‘Cody’ buffalograss; and ‘Zenith’ zoysiagrass exhibited acceptable turfgrass quality for 7 months throughout the growing season. ‘Argentine’ and ‘Pensacola’ bahiagrass; ‘Sea Spray’ seashore paspalum; and ‘SWI-1044’ and ‘SWI-1045’ bermudagrass extended their growing season by retaining their green color 15 days or longer than the rest of the warm-season cultivars and/or species in the fall. The warm-season species stayed fully dormant throughout January and February. Zoysiagrass and buffalograss cultivars showed early spring green-up compared to the other warm-season species studied. Results from this study support the use of warm-season turfgrass species in this Mediterranean region, especially when heat stress and water limitations exist. Tall fescue did not survive summer heat stress necessitating reseeding in fall.