Sugars in watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] cultivars grown at Leesburg, Florida, were determined by liquid chromatography in 1976, 1977, and 1979. There was a wide variation among cultivars in the ratio of total reducing sugars, fructose plus glucose, to the nonreducing sugar, sucrose. This ratio was dependent upon cultivar and stage of maturity. In 1979, sugars in developing fruit of 8 watermelon cultivars were determined at 7 intervals from 12 to 36 days after anthesis. Initial development of sugar was more rapid in the cultivars ‘Sugarlee’, ‘Crimson Sweet’, ‘Dixielee’, and ‘Yellow Baby’ than in ‘Charleston Gray’ and ‘Jubilee’. Early development of sugar is especially important for production of high quality fruit when melons are harvested before full maturity for the commercial trade. In general, fructose and glucose increased until the 24th day and declined thereafter, whereas sucrose was not detected until the 20th day and increased thereafter. The relative sweetness at all stages was calculated.
A gas chromatographic method for the determination of alcohol in citrus juice by analysis of headspace is described. The volume of juice is not critical, but the bath temperature for samples must be constant. Juice samples should be analyzed as soon as possible, or kept refrigerated to avoid alcohol production by contaminating organisms.
Tobelle’ sweet corn (Zea mays var. saccharata (Sturtev.) Bailey) stored for 3 weeks at 1.7°C and 98100% relative humidity in controlled atmospheres (2 or 21% 02 with 0, 15, or 25% CO2) or at low atmospheric pressure (50 mm Hg) did not differ significantly in appearance or flavor. Sucrose content of stored corn remained higher in 2% O2 at normal or low atmospheric pressure (76 mm Hg) than in other atmospheres. Ethanol content increased during storage, except in 21% O2 without added CO2, and was highest in corn stored in atmospheres containing 25% CO2. The high sucrose content of ‘Florida Sweet’ even after 3-weeks-storage suggests that for maintenance of high market quality, breeding cultivars that retain quality in combination with prompt precooling offers more chance of success than modified atmospheres.
The objectives of this study were to show the variations of internal gases of Orlando tangelos, Temple oranges, and Marsh grapefruit before storage and how waxing, storage temperatures, and various external O2 and CO2 concentrations affected internal gas composition. These tests were part of an overall project to determine the best controlled atmosphere (CA) conditions for storage of citrus fruits. Since internal O2 and CO2 concentrations may affect fruit quality (1), one concern in the addition of CO2 to the external atmosphere during CA storage was that the concentration of this component would continue to build up internally. Eaks and Ludi (1) have shown that the internal atmospheres of citrus fruits are affected by temperature, washing, and waxing. Vines and Oberbacher (4) found that certain packinghouse treatments increased CO2 concentrations within citrus fruits.
Ethanol content of juice of citrus fruits showed greater changes during storage and subsequent holding than did acetaldehyde, total soluble solids, titratable acid, or pH. In general, total soluble solids remained unchanged, titratable acid tended to decrease, and pH to increase slightly during storage but showed no effect due to storage temp. Acetaldehyde increased moderately during storage and more extensively during a 1-week holding period at 21.0°C. All fruits increased in ethanol during storage. Ethanol increased in grapefruit more at 1.0° than at 4.5° or 10.0°, while ethanol increased in oranges more at 10.0° than at 4.5° or 1.0°. This behavior may afford a new criterion for a rational basis for establishing optimum storage conditions.
Nitrogen uptake by two N-deficient turfgrass species was characterized by measuring N depletion from a complete nutrient solution. The uptake rate of both and was enhanced up to 6-fold in N-deficient perennial ryegrass (Lolium perenne L.) compared to N-sufficient controls, reaching a maximum of about 0.3 and 0.4 g N/m2 per hr for and , respectively. Deficiency-enhanced uptake exceeded uptake by controls for about 72 hr following resupply of N. Nitrogen uptake was enhanced to a similar degree by N deprivation in Kentucky bluegrass (Poa pratensis L.). Mowing had no effect on uptake by N-deficient perennial ryegrass turf, whereas mowing inhibited uptake by N-sufficient turf by ≈60%. Deficiency-enhanced uptake was found to be the result of an increased capacity for N absorption (Imax) rather than an increased affinity for N (Km). Imax values increased from 0.24 and 0.73 mg N/g dry weight per hr for N-sufficient ryegrass turf for and , respectively, to 1.44 and 2.68 mg N/g dry weight per hr for N-deficient turf. Km values increased slightly, from 14 μm for both N forms for N-sufficient turf to 24 and 39 μm for and , respectively, for N-deficient turf.
Water conservation in a landscape is an important issue because periodic water shortages are common in many regions of the world. This increases the importance of specifying landscape plants that require less water and matching the plant to site microclimates. Our objectives were to establish water-use rates for three herbaceous landscape plants and to determine the level of water reduction these plants can tolerate while maintaining both visual and landscape quality. Water use rates were determined for Schizachyrium scoparium (Little bluestem), Hosta spp. (Hosta) and Festuca cinerea `Dwarf' (Dwarf blue fescue) in studies using pot lysimeters at the Univ. of Nebraska Horticulture Research Greenhouse facility. Each lysimeter was watered to saturation, allowed to drain to field capacity, and weighed. The lysimeters were weighed again 24 h later, and the process was repeated to determine daily evapotranspiration. Results indicated that hosta used less water than dwarf blue fescue and little bluestem. In a subsequent study to compare the relative effects of withholding irrigation among these species, seven groups of five replicates of each species were grown in 1 peat: 0.33 vermiculite: 0.66 soil: 1 sand (by volume) in 7.6-L containers. Each container was watered to saturation, allowed to drain for 24 h to reach field capacity, and allowed to dry down in 10-day increments. Results of the dry-down study indicated that little bluestem maintained the best visual quality for the longest duration of drought, followed by dwarf blue fescue and hosta in decreasing order of visual quality.
The long voyage of Florida grapefruit (Citrus paradisi Macf.) to Japan and extended marketing periods on arrival were associated with a problem with excess diphenyl (biphenyl) residues. Japanese food additive regulations have necessitated reliance on the vapor-phase fungistat diphenyl, for which residues in the fruit increase with time after packing. Residues in some shipments unexpectedly exceeded the Japanese tolerance of 70 ppm. Experiments designed to identify the effect of various factors on diphenyl residues are reported. The amount of diphenyl, temperature before refrigerated transit and exposure time, especially before refrigeration, affected diphenyl residues. Air filtration had little effect. Very early season grapefruit (harvest started before legal maturity) in August and September 1978 absorbed excessive diphenyl residues. Excessive absorption of diphenyl by grapefruit is apparently characteristic of very early fruit.
Smart irrigation controllers are capable of substantially decreasing landscape water applications under residential high water-use conditions in Florida. Their implementation has been incentivized by governmental agencies and water utilities in an effort to reduce public-supply water demand and conserve water resources. However, the bulk of the research on smart controllers for urban landscapes has focused on performance dimensions. To successfully promote them, feedback from end-users is critical. This paper provides an evaluation of homeowner response to evapotranspiration (ET)-based and soil moisture sensor (SMS)-based smart controllers installed as part of a pilot project conducted in Orange County, FL. The objectives of the study were to collect demographic information, assess conservation attitudes and irrigation system knowledge, and gather feedback on the use of smart controllers from the pilot project’s residential cooperators. Data were collected through an online survey and analyzed using relative frequency distributions, text analysis, independent means t tests, and logistic regression. Results indicated that a majority of survey participants were satisfied with their controllers and planned to continue using them. Both ET and SMS controllers were consistently praised for saving money and irrigating efficiently. However, the likelihood that participants would continue using their controllers after the completion of the project was only significantly predicted by their levels of technical knowledge regarding the workings of the devices and whether they had experienced any challenges operating them. Efforts to promote both initial and long-term adoption may be most effective by emphasizing the economic benefits of investing in smart irrigation controllers and by disseminating best management practices that facilitate their understanding and successful operation.
The depletion of N applied to a moderately N-deficient Kentucky bluegrass (Poa pratensis L.) turf was measured using a soil sampling procedure. Nitrogen as either Ca(NO3)2 or (NH4)2SO4 was applied in solution at 5 g N/m2 and washed into the thatch and soil with an additional 0.3 cm of water. Both N forms were located primarily in the thatch and upper 1 cm of soil. The was present in the soil solution, while the was mainly exchangeable (86%). The concentrations of and in the soil solution were 452 and 56 μg N/ml, respectively, in the upper 1 cm of soil. Depletion of both and from the turf was very rapid, with 70% to 80% of the applied N disappearing during the first 24 hr. Essentially all of the applied N was depleted by 48 hr. Results using (l5NH4)2SO4 indicate that ≈75% of the depletion is attributable to absorption by the turf. Similar results were obtained following fertilization of perennial ryegrass (Lolium perenne L.), tall fescue (Festuca arundinaceae Schreb.), and creeping bentgrass (Agrostis palustris Huds.).