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Salt problems in turfgrass sites are becoming more common. The effects of mowing height on salinity tolerance and associated mechanisms are not well understood. The objective of this study was to examine the effects of mowing height and the level of salinity on turf quality, canopy photosynthetic rate (Pn), total nonstructure carbohydrate (TNC) content, shoot reducing sugar content (RSC), Na+ and K+ content in shoots and roots of creeping bentgrass (Agrostis palustris Huds.). Sod pieces of `L-93' were grown in a greenhouse for over 7 months. Plants were subjected to three mowing heights: 6.4, 12.7, and 25.4 mm, and to four salinity levels of irrigation water: control, 5 dS·m–1, 10 dS·m–1, and 15 dS·m–1 prepared using ocean salts. Increasing salinity resulted in reduced turf quality, increased shoot Na+, reduced K+, and reduced K to Na ratio, to a greater extent for bentgrass mowed at 6.4 mm mowing height. Reducing sugar content in shoot increased with increasing salinity level except at 15 dS·m–1 and 6.4 mm mowing regime where RSC declined. Compared to the 25.4 mm mowing height, mowing height at 6.4 mm caused 32-39% reduction in TNC, a 25% to 37% increase in Na+ content, and 45% to 51% decrease in K content in shoots, which resulted in substantial decrease in K/Na ratio. These results demonstrated that the reduction of creeping bentgrass salt tolerance under low mowing height was associated with carbohydrate depletion that reduced the plant's genetic abilities to generate osmo-protectants (such as reducing sugar), to reduce Na+ accumulation in shoots, and to selectively uptake and transport K+. Therefore, a moderate increase in mowing height could improve salinity tolerance of creeping bentgrass.
Salt problems in turfgrass sites are becoming more common. The effects of mowing management on salinity tolerance are not well understood. The objective of this study was to examine the effects of three mowing regimes on turf quality and growth responses of `L-93' creeping bentgrass (Agrostis palustris L.) to salinity stress. Sods of `L-93' creeping bentgrass were grown in containers (45 cm long and 10 cm in diameter) in a greenhouse. Treatments included three mowing regimes (clipping three times weekly at 25.4 mm, four times at 12.7 mm, and daily at 6.4 mm) and four levels of irrigation water salinity (control, 5, 10, and 15 dS·m-1). The relationship of increasing soil salinity with increasing irrigation water salinity was linear in each soil layer. Increasing salinity reduced turf quality and clipping yield more severely and rapidly when mowed at 6.4 mm than at 12.7 or 25.4 mm. Regression analysis of soil salinity and turf quality suggested that turf quality of creeping bentgrass mowed to 6.4, 12.7, and 25.4 mm fell to an unacceptable level when soil salinity reached 4.1, 12.5, and 13.9 dS·m-1, respectively. Data on turf quality, clipping yield, and verdure indicated that salinity damage becomes more severe under close mowing conditions and that a moderate increase in mowing height could improve salinity tolerance of creeping bentgrass.
Salt-tolerant turfgrass is highly desirable in areas associated with saline soils or saline irrigation waters. To determine the salt tolerance of 14 saltgrass [Distichlis spicata var. stricta (Greene)] selections, two greenhouse studies were conducted by means of a hydroponic culture system. Five salinity levels (from 2 to 48 dS·m−1) were created with ocean salts. In general, turf quality decreased and leaf firing increased as salinity increased. However, varying levels of salt tolerance were observed among selections based on leaf firing, turf quality, root growth, and clipping yield. Selections COAZ-01, COAZ-18, CO-01, and COAZ-19 exhibited the best turf quality and the least leaf firing at 36 and 48 dS·m−1 salinity levels in both Experiments 1 and 2. At the highest salinity level (48 dS·m−1), COAZ-18 and COAZ-19 exhibited the highest root activity among all accessions. Salinity levels that caused 25% clipping reduction ranged from 21.2 to 29.9 dS·m−1 and were not significantly different among entries. The data on 25% clipping reduction salinity of saltgrass generated in this study rank saltgrass as one of the most salt-tolerant species that can be used as turf.