A study was initiated at Bracy's Nursery, Amite, La., in Apr. 1997 to evaluate the influence of seven controlled-release fertilizer sources and three top-dressed application rates in production of 4-gal (15.7-L) containers of `LaFeliciana' peach and swamp red maple. The fertilizers tested were Osmocote Plus 15-9-11, Osmocote Plus 16-8-12, Woodace 20-5-10, Woodace 20-4-11, Customblen 24-4-6, Nutricote (Type 270) 17-7-8, and Nutricote (Type 360) 17-6-8. Application rates were 1.75, 2.25, and 2.75 lb N per cubic yard. The experiment was completely randomized within blocks (species) and each treatment was replicated five times. A control treatment was also included. For `LaFeliciana' peach, Nutricote and Osmocote yielded the superior results when shoot height and visual quality ratings were determined in October (6 months after initiation). Increases in application rate did not significantly increase shoot height or visual quality ratings in most cases. For swamp red maple, shoot height was not affected by fertilizer source or application rate. Caliper ranged from 19.2 to 23.0 mm but was only slightly influenced by fertilizer source and application rate. Visual quality ratings were significantly higher for Osmocote Plus 16-8-12 when compared to some of the other fertilizer sources.
Allen D. Owings and Edward W. Bush
Nickolee Zollinger, Teresa Cerny-Koenig, Roger Kjelgren, Rich Koenig, and Kelly Kopp
Although salinity is becoming an increasing concern for landscape plants in many areas of the West, few studies have been carried out to evaluate salinity responses of ornamental plants, especially herbaceous perennials. We investigated salinity tolerance of four traditionally grown and four Intermountain West native ornamental herbaceous perennials. Penstemo×mexicali `Red Rocks', Leucanthemum×uperbum `Alaska', Echinacea purpurea, Lavandula angustifolia, Geranium viscosissimum, Eriogonum jamesii, Penstemon palmeri, and Mirabilismultiflora were irrigated with water containing a mixture of 2 CaCl2: 1 NaCl at salinity levels of 0.33 (tap water control), 2.2, 5.4, and 8.3 dS·m-1 for 8 weeks. Growth, visual quality, and gas exchange were assessed. Mirabilis multiflora and L.×uperbum `Alaska' showed high salt tolerance based on visual quality. No noticeable leaf necrosis was observed for either species at any salinity level. However, over the 8-week period, growth rates for L. superbumwere reduced by 35%, 58%, and 72% compared to the control for the 2.2, 5.4, and 8.3 dS·m-1 salinity levels, respectively. The decrease in growth did not reduce visual quality. Growth rates for M. multiflora were slightly higher than the control for the 2.2 and 5.4 dS·m-1 salinity levels and dropped about 20% at the highest salinity level. Echinaceapurpureashowed the lowest tolerance to salinity, as evidenced by substantial margin burn at all salinity levels as well as high mortality; all plants in the highest salinity treatment died.
Sandra B. Wilson, Nihal C. Rajapakse, and Roy E. Young
Hosta (Hosta tokudama Makeawa `Newberry Gold') plantlets were micropropagated photoautotrophically (without sucrose in medium) or photomixotrophically (with 2% sucrose in medium) for 3 weeks at 23 °C under 80 μmol·m-2·s-1 photosynthetic photon flux (PPF) prior to long-term storage. Plantlets were stored for 4, 8, or 12 weeks at 5, 10, or 22 °C in darkness or under white (400-800 nm), blue (400-500 nm), or red (600-700 nm) light at or near light compensation points. Illumination during storage was necessary to maintain dry weight and regrowth potentials of plantlets in vitro, but light quality had no effect on these parameters. All photoautotrophic plantlets stored in darkness were of poor quality at the time of removal from storage and died when transferred to the greenhouse. Dark-stored photomixotrophic plantlets survived storage for 12 weeks at 5 °C, but declined in appearance (visual quality) as the storage duration increased. Decline in visual quality was greater when plantlets were stored at 10 and 22 °C. Leaf dry weight of illuminated plantlets increased and percentage of leaf yellowing decreased as storage temperature increased. Recovery of illuminated plantlets from photomixotrophic storage was best when plantlets were stored at 22 °C. These plantlets were characterized by increased visual quality (color and form) and increased dry weight compared with those in other treatments. After 60 days in the greenhouse, the dry weight of these plantlets was similar for 4-, 8-, and 12-week storage durations, indicating flexibility in storage time if specific light and temperature provisions are met.
Erik H. Ervin, Xunzhong Zhang, and John H. Fike
High ultraviolet-B (UV-B; 290-320nm wavelength) may significantly contribute to kentucky bluegrass (Poa pratensis L.) sod death at harvest and transplanting. As terrestrial UV-B levels continue to increase due to a depletion of the stratospheric ozone layer this problem may worsen. Epidermal attenuation from pigments and detoxification of reactive oxygen species by antioxidant metabolites and enzymes are involved in plant defense against oxidative stress caused by UV-B. Our objective was to determine whether the attenuation and detoxification systems of kentucky bluegrass could be artificially boosted by exogenous applications of ascorbic acid (AA), alpha-tocopherol (AT), or a colorant before exposure to high levels of UV-B. Ascorbic acid, AT, and the colorant Green Lawnger (GL), were applied to plugs of mature kentucky bluegrass alone or in combination, and then subjected to artificial, continuous UV-B exposure (70 μmol·m-2·s-1); three greenhouse experiments were conducted. By 3 to 5 days after UV-B initiation, visual quality and photochemical efficiency, as measured by chlorophyll fluorescence were significantly reduced. However, in Expt. 1, AA alleviated decline of visual quality, delayed loss of photochemical efficiency, and increased recovery relative to the control. In Expt. 3, decreased endogenous AT and antioxidant enzyme activities were measured due to UV-B stress. Application of AA, AA + AT, or GL partially alleviated photochemical efficiency decline from 4 to 12 days after initiation of UV-B. In addition, application of the chemical treatments increased leaf tissue AT concentrations by 32% to 42%, increased SOD activity by 30% to 33% and increased catalase activity by 37% to 59%, relative to the control as measured 10 days after UV-B initiation. Greater AT concentration and SOD and catalase activities were associated with greater visual quality under UV-B stress. The results of these studies indicate that kentucky bluegrass UV-B tolerance may be increased by supplementing its pigment and antioxidant defense systems with foliar applications of AA, AT or GL.
Silvina I. Portela and Marita I. Cantwell
Although minimal processing increases the perishability of products, largely due to microbial decay, quality changes may be similar between tissues from intact produce and fresh-cut pieces. This study compared pulp quality changes of intact cantaloupe melons and of sanitized fresh-cut pieces (1.8 x 3-cm cylinders) during storage in air at 2.5 (cv. Corona) and 5 °C (cv. Corona and Durango) for 15 days. Quality evaluations included subjective (visual quality, decay, translucency, aroma, off-odor) and objective (color, firmness, SSC) measurements. At 5 °C, visual quality of the pieces was below the limit of salability by day 15 due to decay, whereas pulp from stored melons was excellent. Pulp from intact melons did not suffer from development of translucency as did the fresh-cut pieces. At 5 °C, pulp from intact fruit had higher aroma scores than pieces, but there were no differences in off-odor scores. At 2.5 °C there were no differences in the subjective quality measurements of pulp from intact or fresh-cut pieces. Pulp from intact fruit had higher chroma (at 2.5 and 5 °C) and L* (only at 5 °C) than the pieces after 6 or 15 days, depending on the variety. There were no differences in hue between intact and fresh-cut pulp. Pulp from intact and fresh-cut pieces had similar firmness changes and SSC during storage at 2.5 and 5 °C. We conclude that pulp of intact fruit and fresh-cut pieces had similar quality up to 15 days at 2.5°C; but at 5 °C, the fresh-cut pieces lost intrinsic quality (visual quality, aroma, and color) before the pulp of intact fruit did.
Ma. Teresa MartÌnez-Damian and Marita I. Cantwell
Spinach is not packed commercially in modified-atmosphere packaging due to difficulties in maintaining beneficial conditions during distribution, where temperature fluctuations can occur. However, low O2 and high CO2 atmospheres can be useful to retard yellowing and deterioration. In two experiments we studied developing and full-size leaves stored at 7.5 °C in air and controlled atmospheres of 0.5% O2 + 10%CO2 and 5%O2 + 10% or 20% CO2. Subjective quality evaluations (visual quality, decay, discoloration, off-odors, and yellowing) and objective evaluations (L*a*b* color values, chlorophyll, pH and titratable acidity, ammonia, and ethanol and acetaldehyde) were conducted every 3 days during 15 days. The developing leaves had higher visual quality and lower off-odor scores during storage than did the full-size leaves. In air storage, leaves were below the limit of salability by day 12. The atmospheres containing 10% CO2 were similarly effective in maintaining the visual quality and greenness of the leaves, and reduced off-odors in developing but not full-size leaves. The 20% CO2 atmosphere resulted in some leaf damage. Ammonia concentrations increased during storage, with lowest and highest concentrations in leaves stored in air and 20% CO2, respectively. Tissue pH only slightly increased from 6.5 in air-stored samples, but increased notably during storage in the controlled atmospheres. At 2.5 and 7.5 °C, a plastic film providing a 5% O2 and 6% CO2 atmosphere resulted in better quality spinach than that obtained with either a 10% O2 and 3% CO2 package atmosphere or the commercial perforated polybag.
Panayiotis A. Nektarios, Georgios Tsoggarakis, Aimilia-Eleni Nikolopoulou, and Dimitrios Gourlias
Two field studies (winter and summer) were performed to evaluate the effect of three different fertilizer programs and a urea formaldehyde resin foam (UFRF) soil amendment on sod establishment and anchorage. Fertilizer treatments involved were 1) a quick release (QR) granular fertilizer (12-12-17); 2) a slow release (SR) fertilizer (27-5-7); and 3) a foliar (FL) fertilizer (20-20-20). The application rate was 50, 30, 0.35 g·m-2 for QR, SR, and FL, respectively. The substrate consisted of sandy loam soil, and in half of the plots UFRF flakes were incorporated in the upper 100 mm at a rate of 20% v/v. The effects of the fertilizer and soil amendment on sod establishment were evaluated through measurements of the dry weight of clippings and roots and the visual quality of the turf. Sod anchorage was measured by determination of the vertical force required to detach a piece of sod. For each treatment the initial and final pH, EC, available P, exchangeable K, Ca, Mg, and Fe were also determined. It was found that FL reduced clipping yield but retained turf visual quality similar to the other fertilizer treatments except in winter, when it resulted in the worst quality ratings. However, FL fertilizer promoted root growth and provided high vertical detachment force values and therefore enhanced sod establishment. Slow release fertilizer resulted in moderate top growth and visual quality of the turf during winter, but delayed sod establishment. Quick release fertilizer increased top growth and improved turfgrass visual quality during the winter, but root growth and vertical detachment force were reduced, indicating poorer sod establishment. UFRF did not enhance sod establishment since there was a negative effect on root growth when temperatures were below 10 °C, without however affecting vertical detachment force. Differences in soil P, K, Ca, Mg and Fe between treatments were inconsistent between the two studies, except for final K concentration, which was higher for QR fertilization than SR and FL. Foliar fertilization can enhance sod establishment compared to QR and SR, by accelerating sod anchorage and root growth. QR can be used in late autumn to improve winter green up of the sod. UFRF does not improve or accelerate sod establishment and possesses a minimal capacity to improve soil properties of sandy loam soils.
Chieri Kubota and Mark Kroggel
Increasing numbers of greenhouse vegetable growers purchase transplants from specialized transplant propagators. Possible deterioration of transplants during transportation limits the market size as well as the potential sources of high-quality transplants. To determine the best conditions for transportation of seedlings, tomato (Lycopersicon esculentum Mill., cv. Durinta) seedlings with visible flower trusses were placed for 4 days inside growth chambers to evaluate the effects of short-term exposure to different air temperatures (6, 13, or a conventional transportation temperature of 19 °C) under darkness or illumination at 12 μmol·m–2·s–1 PPF. Plants were evaluated for visual quality, photosynthetic ability, growth, and fruit yield. Lower temperatures and illumination significantly maintained visual quality of the seedlings. Lower temperature maintained high photosynthetic ability of seedlings during the 4-day treatment. After transplanting in the greenhouse, a significant number of trusses exhibited flower abortion or delayed fruit development when seedlings were treated at 19 °C regardless of light intensity. Results suggested that 6 to 13 °C was the best transportation temperature for up to 4 days, which was later validated by an actual transportation trial between British Columbia and Arizona.
Allen D. Owings, Gordon E. Holcomb, Anthony L. Witcher, C. Allen Broyles, and Edward W. Bush
Performance evaluations of numerous annual and perennial herbaceous ornamentals were conducted in landscape settings in 2004 at the LSU AgCenter in Baton Rouge. A mid-summer through fall evaluation of Kong coleus found no difference in flowering performance and visual quality ratings of the five available cultivars. In a sun/shade study, Kong coleus cultivars in 60% shade were about 50% shorter than those in sun. Other impressive coleus have been Aurora Black Cherry and Mississippi Summer Sun. The Stained Glassworks series of coleus have been average performers. The Son series of lantanas (Sonrise, Sonset, Samson, Sonshine) have been top performers in terms of visual quality and continual bloom. All-America daylilies most prevalent to rust symptoms have included Judith, Leebea Orange Crush, Starstruck, Lady Lucille, and Chorus Line. Some rust has also been noted on Plum Perfect and Frankly Scarlet. Profusion Apricot and Profusion White have been less susceptible to Xanthomonas bacterial petal blight than Profusion Fire, Profusion Cherry, and Profusion Orange. Earth Kind roses, being promoted by Texas A&M, are being evaluated for landscape performance along with black spot and powdery mildew susceptibility. Most problematic cultivars thus far have included Georgetown Tea, Clotilde Soupert, Nacogdoches, Reve d'Or, New Dawn, Souvenir de St. Anne's, Spice, Lamarque, Puerto Rico, Sarah Jones, Ducher, and Louis Philippe. Lady Bird cosmos have been good late summer/early fall landscape performers.
Allen Owings, Gordon Holcomb, Anthony Witcher, Allen Broyles, and Edward Bush
All-American daylily cultivars named from 1994–2004 were evaluated for landscape performance and daylily rust (Pucciniahemerocallidis) susceptibility during 2003 and 2004. Cultivars included `Black-Eyed Stella', `Bitsy, `Leebea Orange Crush', `Plum Perfect', `Judith', `Starstruck', `Frankly Scarlet', `Lullaby Baby', `Lady Lucille', and `Chorus Line'. Bareroot plants were planted in raised beds composed of an Olivier silt loam soil in full sun and received irrigation as needed to prevent stress. Visual quality ratings were made weekly from 19 Apr.–25 Oct. 2003 and 15 Mar.–20 Sept. 2004. Visual quality ratings included growth habit, based on compactness, foliage color, uniformity, and overall aesthetics, and flowering, based on longevity and visual appeal. Other flower observations were made in regard to time in bud and peak blooming periods over the same time frames. Flowering observations indicated that `Black Eyed Stella' and `Bitsy' were the only cultivars showing reliable repeat bloom potential. Among the other cultivars, `Judith' was the earliest to bud and bloom, but also had a blooming period of only 2–3 weeks compared to 4–5 weeks of bloom for other cultivars. Daylily rust ratings were taken in Sept. and Nov. 2003 and in Aug. and Nov. 2004. Rust was most severe on `Judith', `Leebea Orange Crush', `Starstruck', and `Lady Lucille'. `Judith' and `Leebea Orange Crush' showed rust symptoms earlier than other cultivars. `Plum Perfect', `Frankly Scarlet', `Bitsy', `Black Eyed Stella', and `Lullaby Baby' were least susceptible to daylily rust.