retention capacity of these substrates, which render them extremely difficult in retaining a sufficient water–air balance ( De Boodt and Verdonck, 1972 ; Heiskanen, 1993 ; Puustjärvi, 1977 ). As a result, organic substrates are mixed with inorganic
Paraskevi A. Londra, Angeliki T. Paraskevopoulou, and Maria Psychoyou
Luke Miller, George Vellidis, and Timothy Coolong
water applied for watermelon grown using a smartphone vegetable irrigation–scheduling application (VegApp), water balance (WB), and soil moisture sensor (SMS) methods at Tifton, GA, in 2016 and 2017. In 2017, the VegApp accounted more appropriately for
Luke Miller, George Vellidis, Osama Mohawesh, and Timothy Coolong
volume and daily water use for tomato irrigated using smartphone vegetable irrigation scheduling application (VegApp), water balance (WB), and soil moisture sensor (SMS) methods at Tifton, GA in 2016 and 2017. Table 3. Average mo.ly soil water tension at
cultivation in Massachusetts takes place in converted (before prohibition by regulation) and manufactured wetlands. In Massachusetts, cranberries are grown in coastal watersheds and often depend on small lakes as their water source for irrigation, harvest, and
Jong Suk Lee and Young A. Kim
Rose (Rosa hybrida) cvs. Red Velvet, First Red, Sonia, and Saphir stems harvested at bud stage were kept in deionized water or preservative solution (3% sucrose + 200 ppm HQS + 0.1 mM ethionine) at 21°C under continuous light (1200 lux). Vase life of `First Red' and `Saphir' was much longer than those of `Red Velvet' and `Sonia' held in deionized water. Severe bent-neck was observed in `Red Velvet' flowers held in deionized water in 8 days after harvest. Rose flowers held in preservative solution resulted in extended vase life and inhibited senescence and bent-neck in four cultivars. Neck strength of `First Red' and `Saphir' rose flowers having no bent-neck and long vase life was stronger than `Red Velvet' and `Sonia' having frequent bent-neck and short vase life. Neck strength was also increased by preservative solution. Faster changes of water balance to minus value were detected in the rose flowers held in deionized water than those held in preservative solution. `Red Velvet' flowers having much absorption of water but more transpiration caused a fast change to a minus value in water balance and early bent-neck. Cell sap pH gradually increased in petal and stem of rose cultivars during senescence. Cell sap pH of flowers held in distilled water were higher than those held in preservative solution. Increased cell sap pH of rose flowers caused rapid change to blueing and yellowing of petals.
Jane E. Spinti, Rolston St. Hilaire, and Dawn VanLeeuwen
We surveyed homeowners with residential landscapes in Las Cruces, N.M., to determine design features participants valued in their landscapes, their attitudes toward the landscape use of desert plants and opinions on factors that would encourage respondents to reduce landscape water use. We also determined whether the willingness to use desert plants in their landscapes related to the length of residency in the southwestern United States. At least 98% of respondents landscaped to enhance the appearance of their home and increase their property value. About half (50.6%) of the participants strongly agreed or agreed that the main reason to landscape was to display their landscape preferences. Many participants indicated they would use desert plants to landscape their front yard (80.3%) and back yard (56.3%), but relatively lower percentages of participants actually had desert landscapes in their front yard and back yard. Regardless of their property value, respondents were more likely to use desert plants in their backyard the shorter their stay in the desert. Data revealed that participants rank water shortages as the factor that would most likely cause them to reduce the amount of water they applied to their landscapes. We conclude that homeowners report willingness to use desert plants but desert-type landscapes are not a widespread feature of managed residential landscapes. Furthermore, water shortages and the length of time respondents spent in a desert environment would most likely influence water use in their landscapes.
Soo-Hyung Kim, Kenneth A. Shackel, and J. Heinrich Lieth
We thank Alexandra Rosati and Jonathan Guan from the NSF Young Scholars Program for carrying out stem water potential measurements and preliminary photosynthesis measurements, respectively. We thank Drs. Loren Oki and Mark Roh for helpful comments
Michael R. Sweatt and Jayne M. Zajicek
Castilleja indivisa grows hemiparasitically attached to the roots of various nearby plants. Studies were done using several host plants to determine the effects of the parasitic relationship on the growth of C. indivisa and the host plants. Transpiration rates, and leaf water potentials of C. indivisa, and various hosts, were also measured at various soil moisture levels. Carbon transfer between C. indivisa and each host was examined using a 14CO2 tracing technique.
The various hosts used in this experiment enhanced the growth of C. indivisa by 200-700% compared to non-parasitic controls. Transpiration rates of non-parasitic controls remained relatively low at all soil moisture levels while transpiration rates of parasitic C. indivisa increased rapidly as soil moisture increased, and generally exceeded that of its host at low to medium soil moisture levels. Leaf water potentials of non-parasitic controls were generally more negative than other treatments. Carbon exchange between C. indivisa and its hosts was insignificant and appears not to be a major nutritional factor.
Roger Kjelgren and Janet Cole
We investigated water loss of shade trees over turf and asphalt in an arid and humid climate for Russian olive and silver maple. Total daily tree water loss, and dawn-to-dusk stomatal conductance (gs) and leaf temperature (Tl), as well as air temperature, surface temperature, and vapor pressure deficit, were measured in Logan, Utah, and Stillwater, Okla., in early and mid-summer. Midday air temperatures in mid-summer were similar at both locations, 30 to 35 °C. Comparable vapor pressure deficits (VPD, kPa) were much higher in Logan, 3.5–5.0, than Stillwater, 2–2.5. Differences in humidity and air temperature between asphalt and turf were negligible at both Stillwater and Logan. Midday surface temperatures for asphalt and turf averaged 34 and 50 °C, respectively, in Logan, but were 10 °C higher for both surfaces in Oklahoma. The effect of higher longwave radiation from hotter surfaces on stomatal conductance and water loss of trees over asphalt in Stillwater was not consistently different for either species from those over turf. However, at Logan, Tl of trees over asphalt were consistently 2 to 4 °C higher and gs was 10% to 20% lower than those over turf. Stomatal closure for trees over asphalt resulted in water loss that was the same or slightly lower as trees over turf. The effect of paved surfaces on tree water loss appears to be more pronounced in an arid than a humid climate. The combined effect of higher VPD in an arid region and greater longwave radiation from hotter paved surfaces induces stomatal closure that limits water loss, and likely photosynthesis. By contrast, in humid regions, increased tree radiation interception over asphalt does not appear to trigger stomatal closure due to lower VPD.
Peitao Lü, Xinmin Huang, Hongmei Li, Jiping Liu, Shenggen He, Daryl C. Joyce, and Zhaoqi Zhang
analytical balance ( He et al., 2006 ; Liu et al., 2009 ; Macnish et al., 2008 ). This approach is appropriate to provide an accurate assessment of general trends in water uptake and water loss of cut flowers over time. However, it is costly in terms of