Two approaches, irrigation with impaired waters, and use of subsurface drip irrigation, have been identifi ed as strategies to reduce the use of potable water for landscape irrigation. A study was conducted at New Mexico State University in Las Cruces in 2008 and 2009 to investigate the establishment of Princess 77 bermudagrass [Cynodon dactylon (L.)] and Sea Spray seashore paspalum [Paspalum vaginatum (Sw.)] seeded in March (dormant) or June (traditional). Th e grasses were irrigated at 98% reference evapotranspiration with saline [electrical conductivity (EC) = 2.3 dS m -1 ] or potable (EC = 0.6 dS m -1 ) water from either a sprinkler or a subsurfacedrip system. Establishment did not diff er between the two grasses regardless of seeding date, irrigation type, or water quality. Generally, grasses that were seeded dormant reached 75% cover faster and exhibited greatest ground cover at the end of both growing seasons. When data were averaged over water qualities and seeding dates, sprinkler irrigation resulted in greater ground cover (90% in 2008 and 92% in 2009) than drip irrigation (58% in 2008 and 80% in 2009) at the end of both research periods. Highest EC levels at rootzone depths of 0 to 10 cm were observed in November 2009 on plots drip irrigated with saline water, averaging 4.4 dS m -1 compared to 2.3 dS m -1 on sprinkler irrigated plots. Our results indicate that when using subsurface-drip irrigation, early seeding is required to successfully establish seashore paspalum and bermudagrass from seed in one growing season.New Mexico State Univ., Las Cruces, NM 88003.

A study was conducted at New Mexico State University in Las Cruces, NM, from 2010 to 2012 to investigate the effects of deficit irrigation on bermudagrass (Cynodon dactylon L.) cultivar Princess 77 and seashore paspalum (Paspalum vaginatum Swartz) cultivar Sea Spray treated with either soil surfactants [Revolution (modified methyl capped block copolymer) or Dispatch (alkyl polyglucoside blended with a straight block copolymer)] or a plant growth regulator [Trinexapac‐ethyl (TE); 4‐(cyclopropylhydroxymethylene)‐3,5‐dioxocyclohexanecarboxylic acid]. Irrigation was applied daily at 50% reference evapotranspiration from either a sprinkler or a subsurface drip system with either potable (electrical conductivity [EC] = 0.6 dS m−1) or saline (2.3 dS m−1) water. Normalized Difference Vegetation Index (NDVI) and visual ratings were determined monthly to assess stand quality and turf stress. Princess 77 treated with TE showed the highest quality and the highest NDVI (0.655) on 10 out of 15 sampling dates. Positive effects of TE applications were also observed on Sea Spray quality, NDVI, and fall color retention. Subsurface drip irrigation resulted in higher quality and NDVI during the third year of the study when compared with sprinkler irrigation. Salinity buildup in the root zone did not negatively affect visual quality of the tested warm‐season species. Generally, sprinkler irrigation system and turf treated with Revolution promoted higher water distribution uniformity (lower standard deviations) than the other treatments. Further research is needed to investigate if greater drought tolerance of subsurface drip–irrigated turf is the result of increased water‐use efficiency due to altered root morphology.

A study was conducted in New Mexico from 2005 to 2007 to investigate the effects of two potable water‐saving strategies, irrigating with saline water and using subsurface systems, on changes in rootzone salinity and quality of nine warm‐season turfgrasses. Plots were irrigated using either sprinklers or subsurface drip with water of 1 of 3 salinity levels (0.6, 2.0, and 3.5 dS m−1). Plots were rated monthly for quality during the growing seasons and bi‐annually for spring and fall color. Soil samples were collected bi‐annually (June and November) and analyzed for electrical conductivity (EC), Na, and sodium adsorption ratio (SAR) at depths of 0 to 20 and 50 to 60 cm. Electrical conductivity and Na values in 0 to 20 cm peaked in June of 2005 and 2006 and dropped to lower levels after the summer rainy season. With the exception of moderately saline irrigated plots in 2005, summer EC did not differ between drip and sprinkler irrigated plots for any of the three water qualities. Electrical conductivity, Na, and SAR at a rootzone depth of 0 to 20 cm were highest in June 2006 reaching 4.7 dS m−1, 1024 mg L−1, and 16.1, respectively. For most of the grasses tested, EC, Na, or SAR values showed no significant relationship with turf quality. Drip irrigation resulted in earlier green‐up than sprinkler irrigation but had no effect on summer quality or fall color retention. Most of the warm season grasses included in this study maintained an acceptable quality level when drip‐irrigated with saline water.

– Synoptic fish surveys of river and irrigation canal sites and a path‐analytic approach evaluate seasonal changes in fish assemblages in canal systems and river reaches of the middle Rio Grande, NM (USA). The objective was to assess how fish assemblages within the Isleta Reach respond to irrigation season and off‐season variations in water and fish contributions from upstream river channels (Albuquerque Reach) and from the Peralta irrigation system. Eighteen species of fish were found in the irrigation canals, 13 in the Isleta Reach and 15 in the Albuquerque Reach. The proportion of nonnative fishes was higher in canals (56%) than in the river (11%). Species rank abundances were used in path analyses of fish species compositions during the irrigation season and off‐season. During the irrigation season, path coefficients indicated fish movements downstream from the Albuquerque Reach (0.55) to the Isleta Reach exceeded contributions by the conveyance‐return (0.29) and drain‐return (0.05) canals. However, as the river de‐watered the return canals were important refuge habitats for native fishes. The 0.05 value represented a major decline relative to the path coefficient for the upstream Peralta drain canal (0.72). During the off‐season path coefficients indicated fish movements of 0.47 downstream in the river and 0.59 in the conveyance‐return canal but a negligible value for the drain‐return canal (‐0.06). Irrigation management could be modified to favour native fish ecology by controlling movement of nonnative predators in canal systems and in providing refuge habitats for native fish during periods when water demand exceeds the supply.

A 3‐yr study was conducted in New Mexico to investigate the effects of saline water on changes in quality, cover, and root zone salinity of seven cool‐season turfgrasses. Plots were irrigated using either sprinklers or subsurface drip with water of 0.6, 2.0, or 3.5 dS m−1. From March to November plots were rated monthly for quality, and green cover was determined using digital image analysis. Soil samples were collected at depths of 0 to 10, 10 to 20, and 50 to 60 cm in June and November and analyzed for electrical conductivity (EC), Na, and sodium adsorption ratio (SAR). Changes in soil EC, Na content, and SAR reflected seasonal changes in irrigation and natural precipitation and EC and Na values were highest (6.1 dS m−1 and 943 mg L−1, respectively) in June of 2006 on drip irrigated plots at depths of 0 to 10 cm. Electrical conductivity was higher in drip irrigated than sprinkler irrigated plots on four of the six sampling dates. Irrigation type and water quality did not affect EC and Na at soil depths of 50 to 60 cm. For four of the seven grasses tested, EC, Na, or SAR values showed a significant but weak relationship (0.18 < r2 < 0.27) with turf quality, indicating that more than one stressor affected visual ratings. With the exception of tall fescue [Festuca arundinacea (Schreb.)], cool‐season grasses could not be maintained at acceptable quality levels in the arid transitional climate when irrigated with saline water from either a sprinkler or a subsurface drip system.

Subsurface capillary irrigation (SCI), drip lines surrounded by a patented membrane, is purported to conserve irrigation water by applying water more evenly and efficiently. A study was conducted at New Mexico State University from 2009 to 2011 to investigate the establishment of tall fescue (Festuca arundinacea L.) and Kentucky bluegrass (Poa pratensis L.) irrigated using either SCI or a sprinkler irrigation system in combination with saline (electrical conductivity [EC] = 2.8 dS m−1) or potable water (EC = 0.6 dS m−1). Tall fescue was seeded in September 2009 and in October 2010 for the second establishment experiment together with Kentucky bluegrass. Seedling density 30 d after seeding (DAS) was greater on sprinkler‐irrigated plots than on SCI plots. Generally, sprinkler‐irrigated plots achieved greater ground coverage at the end of the establishment period than SCI plots. Capillary‐irrigated plots reached 75% ground cover as fast as sprinkler‐irrigated ones in 2010 (202 and 212 DAS. respectively) but were slower in 2011. At the end of both growing seasons, higher EC levels were measured in SCI plots than in sprinkler‐irrigated plots. The highest Na concentration (26.3 mmolc L−1) and Na adsorption ratio (13.0) were measured on plots irrigated through SCI with saline water. Results suggest that SCI can be used to establish cool‐season turfgrass; however, grow‐in of subsurface‐irrigated turf can be delayed compared with sprinkler irrigation. Further research is needed to determine if acceptable turf quality can be maintained past establishment when using a SCI system in combination with lower quality, saline water.

SUMMARY: The influence of salinity on survival, specific gravity, and size of eggs of the endangered Hybognathus amarus (Rio Grande silvery minnow) was studied to provide insight into factors affecting their potential dispersal and fate. Under low salinity conditions egg specific gravity declined significantly in the first hour after spawning as the perivitelline space of the egg filled with water. Egg specific gravity achieved a minimum value approximately 1 h post-spawning and remained approximately constant until hatching, which occurred near 48 h post-spawning at 20ºC. Specific gravity of the egg depended on the salinity of the water surrounding the egg: hardened eggs changed rapidly in diameter and specific gravity when exposed to water of higher salinity. Size and specific gravity of H. amarus eggs also differed when the eggs were incubated in different groundwater sources. Experiments indicated that calcium chloride saline solution had a greater effect on egg specific gravity and size than did solutions of sodium or potassium chlorides. Survival of H. amarus eggs declined sharply at salinity greater than 3 (practical salinity units, PSU) and was only 5% at a salinity of 8. Habitat restoration to benefit H. amarus should consider the salinity of habitats in which eggs incubate.Keywords: fish egg drift, buoyancy, osmosis, survival, Hybognathus amarus. RESUMEN: EFECTOS DE LA SALINIDAD SOBRE LA GRAVEDAD ESPECÍFICA Y LA VIABILIDAD DE HUEVOS DE UNA CARPA NORTEAMERICANA (CIPRINIDAE). -El efecto de la salinidad sobre la supervivencia, gravedad específica y talla de los huevos del ciprínido puesto en peligro de extinción, Hybognathus amarus, fue estudiado para proporcionar información sobre los factores que afectan la dispersión y el destino de los huevos. Bajo condiciones de salinidad baja la gravedad específica del huevo disminuyó de forma significativa durante la primera hora después de la puesta, a medida que el espacio del perivitelino del huevo se fue llenando de agua. La gravedad específica del huevo alcanzó un valor mínimo 1 hora después de la puesta y quedó aproximadamente constante hasta eclosión, que ocurrió alrededor de 48 horas tras la puesta a 20˚C. La gravedad específica del huevo dependió de la salinidad del agua que le rodeaba. Los huevos con corion endurecido cambiaron rápidamente en diámetro y gravedad específica cuando fueron expuestos a agua de salinidad más alta. El tamaño y la gravedad específica de los huevos de H. amarus también se diferenciaron cuando los huevos fueron incubados en diferentes fuentes de agua subterránea. Los experimentos indicaron que la solución salina del cloruro de calcio tuvo un mayor efecto sobre la gravedad específica del huevo que las soluciones de los cloruros del sodio o del potasio. Expuestos a soluciones de salinidad de más de 3 (PSU), la supervivencia de los huevos de H. amarus disminuyó claramente, bajando a sólo el 5% en la solución de 8. La restauración del hábitat con el objetivo de beneficiar a H. amarus debe considerar la salinidad de los hábitats en los...

Core Ideas We describe the use of a plant growth regulator and a soil surfactant for water conservation. We investigated whether the beneficial effects of a surfactant and a plant growth regulator on drought stressed bermudagrass were enhanced when applied in combination versus individually. We investigated if both products affect soil moisture under reduced irrigation. Soil surfactants and plant growth regulators (PGR) have shown potential to lower irrigation requirements and increase turfgrass quality under drought conditions. A study was conducted from 2014 to 2016 to investigate the soil surfactant Revolution, (modified methyl capped block copolymer [Aquatrols, Paulsboro, NJ]), or the plant growth regulator ‘PrimoMaxx’ (A.I. trinexapac‐ethyl [4‐(cyclopropylhydroxymethylene)‐3,5‐dioxocyclohexanecarboxylic acid]) (Syngenta, Basel, Switzerland), or a combination of both on percent green coverage, turfgrass color, quality, soil volumetric water content (VWC) and uniformity on Princess 77 bermudagrass (Cynodon dactylon L.) grown on a loamy sand (mixed, thermic Typic Torripsamments) and irrigated at either 80%, 65%, or 50% of reference evapotranspiration for short grass (ETOS). With the exception of plots irrigated at 50% ETos in 2015, bermudagrass receiving trinexapac‐ethyl (TE) either in combination with Revolution or alone exhibited darker green color when compared to untreated controls at all irrigation levels throughout the research period. At 50% ETos, plots treated with any of the three chemical treatments had greater quality (with 1 = worst, 9 = best) than control plots from July to September, with quality ratings of 6 or greater from June to August. Whereas VWC was not consistently enhanced by all treatment combinations, applications of Revolution, TE, and the combination of both resulted in increased VWC uniformity and greater irrigation use efficiency. Our results suggest that by using a surfactant, a PGR, or both, bermudagrass quality can be maintained with 15 to 30% less irrigation water than the optimal rate (80% ETos) without a reduction in color or quality.