Native plants for ecosystem restoration are commonly grown in containers in greenhouses. Within greenhouses, overhead irrigation is the most widely used system to irrigate plants ( Leskovar, 1998 ). Overhead irrigation systems are chosen for their
Jeremy R. Pinto, Rhiannon A. Chandler and R. Kasten Dumroese
Anthony S. Davis, Matthew M. Aghai, Jeremiah R. Pinto and Kent G. Apostol
container seedling production. Overhead irrigation is the most widely used form of irrigation in tree seedling nurseries ( Landis et al., 1989 ; Leskovar, 1998 ) as a result of its simplicity, low-cost installation, and capacity to reduce toxic buildup of
Diane Feliciano Cayanan, Youbin Zheng, Ping Zhang, Tom Graham, Mike Dixon, Calvin Chong and Jennifer Llewellyn
study indicated that using a free chlorine concentration less than 2.5 mg·L −1 , applied daily through overhead irrigation, should not adversely affect the growth or appearance of woody shrubbery nursery liners. Because our research was conducted in the
R.C. Beeson Jr.
Elaeagnus pungens Thunb., Ligustrum japonicum Thunb., Photinia ×fraseri `Red Top', and Rhododendron sp. `Fashion' (azalea) growing in 10.4-liter containers were irrigated only at dawn with overhead impact sprinklers or pulse-irrigated three or four times each day with a drip system. Plant water potential was measured diurnally each week for 24 weeks, and growth was measured at the end of the growing season in December. Overhead irrigation resulted in less growth of all species than plants maintained near 100% container moisture with pulse irrigation. With the exception of photinia, more growth was associated with significantly lower daily accumulated water stress. Water stress of overhead-irrigated plants was generally not severe enough to cause stomata1 closure.
Richard C. Beeson and Thomas H. Yeager
Ligustrum japonicum, Rhododendron indica `Southern Charm' and Viburnum odoratissimum in 10-L containers were placed in a square grid pattern and overhead irrigated using impact sprinklers (30.3 L/min). Plants were irrigated with 12.5 mm with containers touching and, at 5 cm spacings, up to 50 cm between containers. Irrigation water reaching container surfaces (percent capture) increased for all species as container spacing increased. However, the increase in percent capture did not increase irrigation application efficiency because the percent of production area covered by the containers declined as spacing increased. Application efficiency declined with each increase in spacing to a low of 7%. The effects of intraand inter-canopy interference are discussed.
Matthew J. Koch and Stacy A. Bonos
, salinity screening methods using overhead irrigation were developed, in the field and greenhouse, to more accurately mimic the effects that turf managers would experience in field situations when using wastewater irrigation ( Dai et al., 2008 ; Koch and
Shawn T. Steed, Allison Bechtloff, Andrew Koeser and Tom Yeager
containers. Container production is resource intensive (hand labor, fertilizer, herbicide, etc.) and commonly occurs with overhead irrigation that inefficiently applies large volumes of water ( Yeager et al., 2010 ). Although inefficient with regard to plant
R.C. Beeson Jr. and G.W. Knox
Volume of water captured in a container as a function of sprinkler type, spacing, plant type, and container size was measured for marketable-sized plants. Percent water captured was calculated and a model to predict this value derived. Percent water captured was inversely related to the leaf area contained in the cylinder over the container when containers were separated, and with total plant leaf area at a pot-to-pot spacing. This relationship was independent of leaf curvature (concave vs. convex). Canopy densities were less related to percent water captured than leaf areas. Irrigation application efficiencies separated by spacing ranged from 37% at a close spacing to 25% at a spacing of 7.6 cm between containers. Container spacing, canopy shedding, and possibly some canopy retention of water later lost by evaporation were determined to be the main factors associated with the low efficiencies. The results suggest that higher irrigation application efficiencies would be maintained only if plants were transplanted to larger containers before reaching maximum canopy size rather than spacing existing containers to achieve more room for canopy growth.
Edward Bush, Ann Gray, Virginia Thaxton and Paul Wilson
Proper irrigation management is essential for producing quality container-grown woody ornamentals and reducing off-site runoff. Research has shown that tensiometers can be used as an effective tool to schedule irrigation for woody ornamentals. The objective of this experiment was to compare the effect of cyclic and tensiometric irrigation methods on growth of lantana. Lantana camara `New Gold' liners were established in a 3 pine bark: 1 peat:1 mason sand (by volume) medium. Low-tension switch tensiometers were compared to scheduled overhead [one time a day (1×) at 0600 and cyclic irrigation three times a day (3×) at 0600, 1200, and 1800] for the production of 1-gallon lantana plants. Three low-tension tensiometers (1/block) were set at 7 cb and allowed to irrigate over a 12-hour period. Three separate planting dates occurred and then terminated after ≈7 weeks. Tensiometric irrigation increased root and shoot growth compared to scheduled irrigation for the 24 May 1999 harvest date. Cyclic irrigation produced plants with shoot and total root weights >1× and tensiometer treatments for the September harvest date. Tensiometers sharply reduced irrigation requirements compared to scheduled irrigation volume by at least 50% of the 1× and 3× treatments weekly. Analysis of nutrients in leachate for June indicated increased B and Fe concentrations in the 3× irrigation treatment. Lower concentrations of Ca, Mg, and Na were measured in August. Lantana growth was acceptable for all irrigation treatments and harvest dates.
Aaron L. Warsaw, R. Thomas Fernandez, Bert M. Cregg and Jeffrey A. Andresen
irrigation efficiency with only 13% to 26% of applied overhead irrigation being retained in the container ( Weatherspoon and Harrell, 1980 ). If not captured, water, fertilizers, and other agricultural chemicals can leave the production area and enter