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  • Author or Editor: J. B. Beard x
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Abstract

Snowmobiles used as recreational vehicles on winter dormant turfgrass areas have become an increasingly widespread activity in recent years. Because of this recreational demand, certain portions of or routes within parks, golf courses, and other large turfgrass areas are being set aside for winter snowmobile use. Serious damage to turfgrasses occurs in some situations, whereas in others, there has been no significant damage. To the best of our knowledge, there are no published reports of studies regarding snowmobile traffic effects on turfgrasses (3). Thus, the objective of this investigation was to assess the effects of 6 intensities of snowmobile traffic on 2 winter dormant turfgrasses covered with 5 depths of snow.

Open Access

Abstract

The morphological progression of low-temperature discoloration as affected by gibberellic acid (GA3) applied exogenously was determined for ‘Ormond’ (chill-tolerant) and ‘Tee Dee’ (chill-sensitive) bermudagrass [Cynodon dactylon (L.) Pers.] and ‘Floratam’ (chill-tolerant) and ‘Texas Common’ (chill-sensitive) St. Augustinegrass [Stenotaphrum secundatum (Walt) Kuntze] while exposed to chilling temperatures of 7°C (day)/5° (night) for 14 days. Visible symptoms on all cultivars occurred first and progressed most rapidly on horizontal leaf blades and stems which were directly exposed to light. Leaf blades and stems deep in the canopy or shaded by other plant parts were the last to show injury. Bleaching and/or the formation of a purple pigmentation occurred in the leaf blades and stems of both bermudagrass cultivars within 3 days of chilling stress. The symptoms occurred first and proceeded more rapidly on ‘Tee Dee’. Both St. Augustinegrass cultivars showed visual symptoms after 5 or more days of chilling stress. Wilting was followed immediately by the development of water-soaked lesions and finally by total necrosis. The application of GA3 at 62.5 g ha-1 stimulated shoot growth of both chill-stressed bermudagrass cultivars and almost completely prevented development of a purple pigmentation in the leaf blades and stems. GA3 did not stimulate shoot growth, and it increased the rapidity and severity of the chilling-injury symptom development on the blades and stems of both St. Augustinegrass cultivars, indicating a possible toxicity effect at the rate used.

Open Access

Abstract

Leaf anatomy and CO2 compensation concentration (Γ) were used to determine the carbon fixation pathway for 10 cool season and 5 warm season turfgrass species. Turfgrasses of the subfamily Festucoideae were representative of C3 plants. Turfgrass species of the subfamily Panicoideae and Eragrostoidea were representative of C4 plants. Turfgrasses classified traditionally as cool season or warm season species correlated with C3 and C4 plant types, respectively. Both techniques of C3 and C4 classification proved equally reliable in this study, however, the utilization of Kranz leaf anatomy required less preparation.

Open Access

Root hairs contributed variously to total root length, ranging from a low of 1% for `Emerald' zoysiagrass (Zoysia japonica Steud. x Z. tenuifolia Willd. ex Trin) and 5% for `Georgia Common' centipedegrass [Eremochloa ophiuroides (Munro.) Hack], to a high of 95% and 89% for `Texturf 10' and `FB 119' bermudagrasses [Cynodon dactylon (L.) Pers.], respectively. Genotypes ranking highest for root lengths with root hairs also ranked highest for root lengths without root hairs and for number of main roots per plant. In terms of root lengths with root hairs, first-order lateral roots contributed more to total root length than root lengths of either main roots or second-order lateral roots for all nine genotypes. Number and length of root hairs arising from either main or lateral roots were not significantly affected by their relative distance from the cap of the main root. `Texturf 10' and `FB 119' bermudagrasses ranked highest for root and root-hair extent.

Free access

Abstract

High temperatures during simulated shipping were more consistently injurious to ‘Merion’ Kentucky bluegrass (Poa pratensis L.) sod than other factors tested. Sod produced with increasing amounts of nitrogen had increased rates of temperature rise. Higher nitrogen levels also increased respiration, percent leaf kill, and ethylene production. There was no consistent effect of 6-benzylamino purine (BA) on sod storage life. Mowing to 2 cm prior to harvest reduced the amount of living tissue, causing lower temperatures, lower respiration rates, and less sod injury. Root production after sod transplanting was greatest from sod grown with 0 and 100 kg/ha of nitrogen fertilization and decreased with higher nitrogen rates.

Open Access

Abstract

Sods of ‘Merton’ Kentucky bluegrass (Poa pratensis L.) were placed in atmospheres containing 0, 9, 18, or 27% CO2; 0, 2, 4, 8, or 16% O2; and 0, 2, 4, or 8 ppm C2H4. Neither CO2 nor C2H4 toxicity nor O2 deficiency caused sod injury in commercial sod toads. Ventilation tubes inserted in commercial sod toads failed to increase gas exchange and heat dissipation beyond a 3-cm distance.

Open Access

Abstract

Root growth of St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] and bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Davy] (C-4 plants), show distinct seasonal patterns different from those of the cool-season perennial grasses (C-3 plants). Root growth continued after winter shoot dormancy occurred, and at soil temperatures below 10°C. Severe browning of the entire root system was observed just after spring shoot greenup followed by a delay of about 3 weeks in new root initiation and replacement, even though significant shoot development was occurring prior to this period of root initiation.

Open Access

The objectives of this investigation were to determine the stomatal frequencies of 12 perennial cool-season turfgrasses, encompassing nine species, and their associated evapotranspiration (ET) rates under nonlimiting soil moisture and controlled environmental conditions. Significant differences in stomatal density were found among the 12 cool-season turfgrasses on both the abaxial (P > F = 0.0008) and adaxial (P > F = 0.0009) leaf surfaces. Significant differences (P > F = 0.0007) in ET rates also were found among the 12 cool-season turfgrasses. The Kentucky bluegrass (Pea pratensis L.) cultivars exhibited the highest ET rates, while the fine-leafed fescues (Festuca rubra and longifolia L.) exhibited the lowest rates, except for `Big Horn' sheep fescue (Festuca ovina L.), which exhibited an intermediate ET rate. No significant correlation was found between ET rate and either adaxial or abaxial stomatal density. It was concluded that, under nonlimiting soil moisture conditions, stomatal density was not reliably associated with ET rate.

Free access
Authors: , , and

Cultivar selection is one method used for the conservation of irrigation water. The primary objective of this research was to evaluate the evapotranspiration (ET) rates of 24 well-watered, turf-type bermudagrass (Cynodon spp.) genotypes under field conditions and established on a fritted clay root zone contained in plastic minilysimeter pots. A secondary objective was to correlate ET rate to leaf extension rate, a potential rapidly assessed predictor of the amount of leaf surface area present for ET. ET rates were determined by the water-balance method. Both the overall ET and leaf extension rate differed significantly among genotypes. ET rates were not correlated with leaf extension rates in individual years. Our data indicated a potential for water savings based on bermudagrass cultivar selection that was similar to the reported potential water savings based on warm-season turfgrass species selection.

Free access

The primary objective of this research was to determine the evapotranspiration (ET) rates of 10 well-watered St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] genotypes under field conditions and in a controlled-environment chamber with a high evaporative potential. A secondary objective was to correlate ET rate to leaf extension rate, shoot density, and abaxial and adaxial leaf blade stomatal densities. Overall ET rates among genotypes were not significantly different in the field study, but they were significantly different under the higher evaporative potential of the chamber study. ET rates under field conditions were not correlated to ET rates under chamber conditions. ET rates were not correlated to leaf extension rates in the field or chamber. ET rates in the chamber were correlated neither with shoot nor with stomatal densities. Overall ET rates in the field study were not correlated to stomatal densities, but were correlated to shoot density (r = 0.77).

Free access