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Wild caught shrimp can have a shortened shelf life compared to farm raised shrimp due to handling and on-ship limitations. The loss of freshness in shrimp is partly due to autolytic reactions caused by endogenous enzymes such as polyphenol oxidase. The objective of this study was to determine the effect of sulfi tes combined with modifi ed atmosphere packaging (MAP) on the shelf life of non-frozen shrimp. Fresh South Atlantic white shrimp were subjected to one of four treatments, no bisulfi te rinse-air packaged, 1.25% bisulfi te rinse-air packaged, 1.25% bisulfi te rinse-MAP (60% CO2, 18% O2, 22% N2) and 1.25% bisulfi te rinse-MAP (36% CO2, 64%N2). The quality and freshness of shrimp was measured by determining total aerobic bacterial populations, package gas headspace analysis, shrimp volatiles (GC-MS), meat pH, nucleotide degradation, and visual analysis. Fresh non-frozen shrimp treated with a combination of sulfi tes and MAP maintained the shelf life of fresh shrimp up to 10 days while shrimp in non-MAP without sulfi te and non-MAP with sulfi te developed black spots within 2 and 6 days, respectively. Both MAP treatments slowed bacterial growth while the MAP with high CO2 and with O2 was more effective in preventing off odors and nucleotide degeneration.

Ultradwarf bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy] cultivars require considerable field research to determine best management practices for successful long-term culture. A field study was conducted in 2004 and 2005 on an experimental 'TifEagle' bermudagrass putting green in Clemson, SC, to examine effects of plant growth regulators (PGRs) applied bimonthly and three mowing heights on turf performance. The PGRs included ethephon [(2-chloroethyl)phosphonic acid] at 1.91 kg a.i. ha ―1 , flurprimidol [α-(1-methylethyl)-α-[4-(trifluoro-methoxy)phenyl]-5-pyrimidine-methonol] at 0.07 kg a.i. ha ―1 , trinexapac-ethyl [4-(cyclopropyl-α-hydroxymethylene)-3,5-dioxo-cyclohexane carboxylic acid ethyl ester] at 0.0175 kg a.i. ha ―1 , all pairwise PGR combinations at half the individual rates, and a nontreated control. Turf was mowed five times weekly at 2.50, 3.25, or 4.00 mm. Lateral regrowth with ethephon and trinexapac-ethyl was comparable to nontreated turf, while flurprimidol impeded lateral regrowth ∼25%. All three PGRs reduced dry clipping weights, with flurprimidol most effective (>50% each harvest) and ethephon least effective (maximum 17%). Turf quality for trinexapac-ethyl, ethephon, and flurprimidol was excellent (8.0-8.4), acceptable (6.8-7.1) and unacceptable (3.6-5.2), respectively. Compared to the control, root length density increased 33% with trinexapac-ethyl, unaffected by ethephon, and reduced 25% with flurprimidol. Flurprimidol increased ball roll distances in morning (AM) and (PM) by 21 and 26 cm, respectively, trinexapac-ethyl provided increases of 5 and 10 cm, respectively, while ethephon had no effect, compared to the control. No evidence of synergistic effects was observed for PGR combinations. Raising mowing heights increased lateral regrowth, turf quality, and root length density but decreased ball roll distances. Best overall performance of TifEagle bermudagrass was achieved with trinexapac-ethyl, as it increased root length density, provided excellent turf quality, reduced vertical growth, did not impede lateral regrowth, and increased ball roll distances, compared to the control.

Biodiesel, defined as mono-alkyl esters of long-chain fatty acids derived from vegetable oils or animal fats, is an attractive renewable fuel alternative to conventional petroleum diesel fuel. Biodiesel produced from oils such as cottonseed oil and poultry fats suffer from extremely poor cold flow properties because of their high saturated fatty acid content. In the current study, Ethyl Levulinate (ethyl 4-oxopentanoate) was investigated as a novel, bio-based cold flow improver for use in biodiesel fuels. The cloud (CP), pour (PP), and cold filter plugging points (CFPP) of biodiesel fuels prepared from cottonseed oil and poultry fat were improved upon addition of ethyl levulinate at 2.5, 5.0, 10.0, and 20.0% (vol). Reductions of 4–5 °C in CP, 3–4 °C in PP and 3 °C in CFPP were observed at 20 vol % ethyl levulinate. The influence of ethyl levulinate on acid value, induction period, kinematic viscosity and flash point was determined. The kinematic viscosities and flash points decreased with increasing content of ethyl levulinate. All samples (≤15 vol % ethyl levulinate) satisfied the ASTM D6751 limit with respect to flash point, but none of the 20 vol % blends were acceptable when compared to the higher EN 14214 specification. Acid value and oxidative stability were essentially unchanged upon addition of ethyl levulinate. In summary, ethyl levulinate appears acceptable as a diluent for biodiesel fuels with high saturated fatty acid content.

Overseeded perennial ryegrass (Lolium perenne L.) aggressively competes with bermudagrass (Cynodon dactylon (L.) Pers.) for resources and may adversely affect spring transition by releasing allelochemicals into the environment. Growth chamber studies examined germination and growth of 'Arizona Common' bermudagrass in soil amended with 0%, 2%, 12%, or 23% perennial ryegrass root or shoot debris or in soil treated with irrigation water in which perennial ryegrass roots at 0, 5, 10, or 20 gL -1 or shoots at 0, 10, or 20 gL -1 had been soaked. Inhibitory effects on bermudagrass ger- mination and growth were most extensive when soil was amended with ryegrass shoot debris, because germination, root ash weight, root length density, and root mass density were reduced 33%, 55%, 30%, and 52%, respectively. Soil amended with ryegrass root debris only inhibited bermudagrass-specific root length. Application of irrigation water containing either ryegrass root or shoot extracts only inhibited bermudagrass-specific root length. In conclusion, results obtained when soil was amended with shoot debris demonstrated perennial ryegrass can inhibit bermudagrass germination and growth in controlled environments. Overseeding a permanent grass such as bermudagrass with perennial ryegrass com- plicates spring transition, because perennial ryegrass is usually growing optimally and its upright growth shades the base grass. Although interstand competition between species greatly impacts transition, ryegrass allelopathy has been proposed as another contributing factor. Alle- lopathy, the suppression of growth of one plant species by another through the release of chemicals into the environment, has been im- plicated as a mechanism of interference be- tween many plant species. Allelopathic effects of perennial ryegrass on bermudagrass have been suggested but not examined. Perennial ryegrass has been reported to have inhibitory effects on 'Zenith' zoysia- grass (Zoysia japonica Steud.) (Zuk and Fry, 2006), alfalfa (Medicago sativa L.) (Chung and Miller, 1995), nodding thistle (Carduus nutans L.) (Nicholson et al., 1990), white clover (Trifolium repens L.) (Mattner and Parbery, 2001), and lettuce (Lactuca sativa

The low temperature operability, kinematic viscosity, and acid value of poultry fat methyl esters were improved with addition of ethanol, isopropanol, and butanol with increasing alcohol content. The flash point decreased and moisture content increased upon addition of alcohols to poultry fat methyl esters. The alcohol type did not result in a statistically significant difference in low temperature performance at similar blend ratios in poultry fat methyl esters. In addition, blends of ethanol in poultry fat methyl esters afforded the least viscous mixtures, whereas isopropanol and butanol blends were progressively more viscous, but still within specifications contained in ASTM D6751 and EN 14214. Blends of alcohols in poultry fat methyl esters resulted in failure of the flash point specifications found in ASTM D6751 and EN 14214. Flash points of butanol blends were superior to those of isopropanol and ethanol blends, with the 5 vol.% butanol blend exhibiting a flash point (57 °C) superior to that of No. 2 diesel fuel (52 °C). Blends of alcohols in poultry fat methyl esters resulted in an improvement in acid value with increasing content of alcohol. An increase in moisture content of biodiesel was observed with increasing alcohol content, with the effect being more pronounced in ethanol blends versus isopropanol and butanol blends. Finally, none of the alcohol–methyl ester samples exhibited a phase separation at sub-ambient temperatures.

Soil solarization is the use of solar radiation to disinfest moist soil covered with clear polyethylene mulch during warm months. Beneficial effects of soil solarization are lower pathogen populations, reduced disease, and higher yield. Information on the duration of solarization benefits is necessary to achieve effective and efficient implementation of this management strategy. A 3-year study investigated effects of single- and multiple-year soil solarization on Pythium spp., Pseudomonas spp., and damping-off of broccoli (Brassica oleracea L.) and cucumber (Cucumis sativus L.). Soil was solarized 10 weeks in 2003 only; 2004 only; 2003 and 2004; 2004 and 2005; 2003, 2004, and 2005; or not solarized. Soil was sampled from 0 to 10 cm deep and population densities of Pythium spp. and Pseudomonas spp. assayed at monthly intervals from the start of solarization until 2 months after solarization. Cucumber and broccoli were planted one month after solarization ended or plots were left fallow. During solarization...

Seasonal variations in temperature and solar radiation in the warm climatic region of the transition zone increase difficulty of creeping bentgrass [Agrostis stolonifera var. palustris (Huds.)] management throughout the year. The impact of winter shade on bentgrass quality and subsequent residual effects of winter shade in spring and summer months has not been investigated. Therefore, a 2-year field study investigated trinexapac-ethyl (TE) [4-(cyclopropyl-α-hydroxy-methylene)-3,5-dioxy-cyclohexanecarboxylic acid ethyl ester] as a winter management strategy to alleviate winter shade stress and determined the winter shade tolerance of ‘L-93’ creeping bentgrass under various reduced light environments. Treatments included a full-sunlight control; 58% and 96% morning, afternoon, and full-day shade artificial; and TE (0.02 kg a.i./ha) applied every 2 weeks from December to July. Data collection included daily light measurements (photosynthetic photon flux density), monthly canopy and soil temperatures, visual turfgrass quality (TQ), chlorophyll concentration, clipping yield, total root biomass, and total root nonstructural carbohydrates. Under 96% shade, canopy temperatures were reduced ≈57% from December to February, whereas soil temperatures were reduced 39% in February compared with full sunlight. Afternoon shade (58%) maintained acceptable TQ throughout winter for both years. Applying TE every 2 weeks in the winter negatively impacted bentgrass quality; however, TE enhanced spring and summer quality. Morning or afternoon shade minimally impacted parameters measured. Overall, moderate winter shade may not limit ‘L-93’ creeping bentgrass performance as a putting green in the transition zone. Results suggest winter shade does not contribute to creeping bentgrass summer decline because all shade-treated plots fully recovered from shade damage in spring months.

‘Diamond’ zoysiagrass [Zoysia matrella (L.) Merr.] has a potential to become a new alternative warm-season putting green turfgrass. The main objective of the study was to determine factors affecting establishment speed for ‘Diamond’ zoysiagrass as a putting green in the southern transition zone of the United States. Two sprigging rates, three nitrogen (N) sources, two N rates, and two mowing heights (2.5 and 3.2 mm) were compared at Clemson University, Clemson, SC. Sprigs of ‘Diamond’ zoysiagrass were planted at rates of 91 or 182 m3·ha−1 in 2007 and repeated in 2008. Urea, ammonium nitrate, and ammonium sulfate were applied at 1.7 or 3.4 g N/m2/week from weeks after sprigging (WAS) 3 to 10. Rates were halved from WAS 11 to 16. The N fertilizers were applied as solutions weekly for 16 weeks. Weekly percent cover, turf color ratings, root and clipping sample, and ball rolling were collected for both years. A significant difference occurred in turf cover between high and low sprig rates. Turf color and cover results show that high rates of fertility associated with high rates of sprigs produced 100% turf cover at WAS 11 and 13 in both years. At the 2.5-mm mowing height, ball rolling reached 258 cm in August and was significantly faster than the 3.2-mm mowing height. Results show ‘Diamond’ zoysiagrass can be established within the same growing season to meet a playable putting green quality, but the establishment speed may vary depending on summer monthly temperature fluctuations.

Warm-season turfgrass quality declines under shade due to reduced photosynthesis, increased disease pressure, reduced carbohydrate production, tree root competition, and reduced lateral stem growth. Another factor limiting turfgrass growth and development under tree shade is variable qualities of light fi ltered by trees. However, effects of various fi ltered wavelengths on turfgrass performance are lacking and deserve research. Therefore, a greenhouse project investigated the physiological and morphological responses of ‘Diamond’ zoysiagrass [Zoysia matrella (L.) Merr.], ‘Sea Isle 2000’ seashore paspalum (Paspalum vaginatum Swartz.), and ‘Tifway’ and ‘Celebration’ bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] to variable light spectral qualities. Light treatments included a control without any shade cloths and four different color shade cloths fi ltering wavelengths 560 to 720 nm (blue shade cloth), 360 to 520 nm (yellow shade cloth), 360 to 560 nm (red shade cloth), and 360 to 720 nm (black shade cloth). The percent light reduction for each cloth was about 65% relative to the control. Data collected included visual turfgrass quality (TQ), relative clipping yield, relative chlorophyll concentration, relative shoot width, relative root biomass, relative root length density, relative specifi c root length, and root and shoot total nonstructural carbohydrates. Diamond was the least affected turfgrass by the color shade cloths, while Celebration and Sea Isle 2000 performed similarly. Tifway was the most sensitive turfgrass with the lowest TQ under color shade cloths. Yellow and red shades were least detrimental, while black shade most negatively inhibited parameters measured, followed by blue shade. This study implies different types of shade signifi cantly impact the TQ of warmseason turfgrasses.

Canola oil was transesterified using a 1 : 1 molar mixture of methanol and ethanol (M/E) with potassium hydroxide (KOH) catalyst. The effects of catalyst concentration (0.5–1.5 wt-%), molar ratio of M/E to canola oil (3 : 1 to 20 : 1) and reaction temperature (25–75 7C) on the percentage yield measured after 2.5 and 5.0 min were optimized using a central composite design. A maximum percentage yield of 98% was obtained for a catalyst concentration of 1.1 wt-% and an M/E to canola oil molar ratio of 20 : 1 at 25 7 Ca t 2.5 min, whereas a maximum percentage yield of 99% was obtained for a catalyst concentration of 1.15 wt-% and all molar ratios of reactants at 25 7C at 5 min. Statistical analysis demonstrated that increasing catalyst concentration and molar ratio of reactants resulted in curvilinear and linear trends in percentage yield, both at 2.5 and 5 min. However, reaction temperature, which affected the percentage yield at 2.5 min linearly, was insignificant at 5 min. The resultant mixed methyl/ethyl canola esters exhibited enhanced low-temperature performance and lubricity properties in comparison to neat canola oil methyl esters and also satisfied ASTM D6751 and EN 14214 standards with respect to oxidation stability, kinematic viscosity, and acid value.

Experiments were conducted to determine the effect of vitamin A deficiency in chicks on tissue ascorbic acid, plasma oxidant status and antioxidant capacity, and renal L-gulonolactone oxidase activity (GULO) in broiler chickens. Chicks were reared in battery cages and fed a practical diet with vitamin A (control) or the same diet without supplemental vitamin A from day-old to 23 or 30 days of age. The treatments were arranged in a randomized complete block design with 6-8 replications. At termination body weight, feed intake, and tissue weights were recorded and tissues analysed for ascorbic acid, GULO activity, antioxidant activty, and oxidant status. Growth, feed intake, relative weights of bursa of Fabricius, liver, spleen and testis were significantly reduced in vitamin A-deficient chicks. Vitamin A deficiency depressed renal GULO activity by 20% (P

Managing warm-season turfgrasses with reduced sunlight is challenging due to C 4 plant morphological limitations, such as reduced lateral stem growth. Adjusting cultural management practices, such as N and trinexapac-ethyl (TE) [4-(cyclopropyl-a-hydroxy-methylene)-3,5-dioxocyclohexanecarboxylic acid ethyl ester], application may benefit turfgrass performance when sunlight is reduced. Therefore, a 2-yr field study from 15 June to 15 September in 2006 and 2007 at Clemson University investigated the best management practices for sustaining a high quality 'Champion' bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy] putting green maintained at a 3.2-mm mowing height under reduced sunlight. Treatments included full-sunlight, 55% full-day shade, TE (0.02 kg a.i. ha -1 2 wk -1 ), Fe (2.7 kg ha -1 2 wk -1 ), and N as liquid urea at 147, 293, and 440 kg ha -1 yr -1 . Data collection included visual turfgrass quality (TQ), total clipping yield, clipping chlorophyll concentration, root total nonstructural carbohydrates (TNC), thatch accumulation, and thatch depth. Overall, Fe applications minimally impacted parameters measured. Increasing N rates linearly increased TQwhen grown under full sunlight. Applying N at ∼40% lower (147 kg ha -1 yr -1 ) than the typical recommended rates for ultradwarf bermudagrass putting greens improved Champion TQ under reduced light compared to higher N rates. Applying TE resulted in a linear TQincrease for full sunlight and shade-grown Champion bermudagrass. Under reduced sunlight, a 15% chlorophyll concentration increase was noted for TE-treated plots compared to nonTE-treated plots. Shade reduced thatch accumulation 40% compared to sun-grown Champion, which suggests less aggressive cultivation practices are required for thatch control under reduced light. Champion bermudagrass did not provide an acceptable putting green quality when grown under 55% full-day shade, however, adjusting management practices enhanced Champion bermudagrass quality under reduced light.

Creeping bentgrass (Agrostis stolonifera var. palustris Huds.) is desirable as a putting green turfgrass in the transition zone as a result of year-round green color, ball roll, and playability. However, management challenges exist for bentgrass greens, including winter temperature fluctuations. Frosts often cause cancellations or delays of tee time resulting in lost revenue. In response to this winter golf course management issue, a research project was initiated at Clemson University from 1 Dec. 2005 and 2006 to 1 Aug. 2006 and 2007 on a ‘L93’ creeping bentgrass putting green to determine the impacts of foot traffic or mower traffic and time of traffic application on bentgrass winter performance. Treatments consisted of no traffic (control), foot traffic, and walk-behind mower traffic (rolling) at 0700 and 0900 hr when canopy temperatures were at or below 0 °C. Foot traffic included ≈75 steps within each plot using size 10 SP-4 Saddle Nike golf shoes (soft-spiked sole) administered by a researcher weighing ≈75 kg. A Toro Greensmaster 800 walk-behind greens mower weighing 92 kg with a 45.7-cm roller was used for rolling traffic. Data collected included canopy and soil temperatures (7.6 cm depth), visual turfgrass quality (TQ), clipping yield (g·m−2), shoot chlorophyll concentration (mg·g−1), root total nonstructural carbohydrates (TNC) (mg·g−1), soil bulk density (g·cm−3), and water infiltration rates (cm·h−1). Time and type of traffic significantly influenced bentgrass winter performance. On all TQ rating dates, 0700 hr rolling traffic decreased TQ by ≈1.1 units compared with foot traffic at 0700 hr. In December, regardless of traffic application time, rolling traffic reduced bentgrass shoot growth ≈17%. However, in February, chlorophyll, soil bulk density, and water infiltration differences were not detected. By the end of March, all treatments had acceptable TQ. Root TNC was unaffected in May, whereas shoot chlorophyll concentrations were unaffected in May and August. This study indicates bentgrass damage resulting from winter traffic is limited to winter and early spring months and full recovery should be expected by summer.

Limited information comparing foliar versus granular fertilization of turfgrasses is available. The objective of this research was to evaluate liquid and/or granular N fertilization on turfgrass quality, clipping yield, and root biomass of ‘L-93’ creeping bentgrass. Treatments consisted of two annual nitrogen (N) inputs, 127 and 190 kg ha−1, using 100% granular urea fertilizer, 50% granular urea + 50% liquid urea fertilizer, or 100% liquid urea fertilizer. These results suggest a rate of at least 190 kg N ha−1 yr−1 is needed to maintain acceptable bentgrass quality in the transition zone of the U.S. Combining both liquid and granular methods appear superior compared to relying on one method exclusively.

Transesterification of cottonseed oil was carried out using ethanol and potassium hydroxide (KOH). A central composite design with six center and six axial points was used to study the effect of catalyst concentration, molar ratio of ethanol to cottonseed oil and reaction temperature for percentage yield (% yield) and percentage initial absorbance (%A385nm) of the biodiesel. Catalyst concentration and molar ratio of ethanol to cottonseed oil were the most significant variables affecting percentage conversion and %A385nm. Maximum predicted % yield of 98% was obtained at a catalyst concentration of 1.07% (wt/wt) and ethanol to cottonseed oil molar ratio of 20:1 at reaction temperature of 25 °C. Maximum predicted %A385nm of more than 80% was obtained at 0.5% (wt/wt) catalyst concentration and molar ratio of 3:1 at 25 °C. The response surfaces that described % yield and %A385nm were inversely related. Gossypol concentration (% wt), oxidative stability and %A385nm of biodiesel were found to be highly correlated with each other. Hence, color %A385nm is a measure of the amount of pigments present in biodiesel fuels that have not yet been subjected to autoxidation. High gossypol concentration also corresponds to a fuel with high oxidative stability. The fatty acid ethyl esters (FAEE) produced from cottonseed oil had superior oxidative stability to fatty acid methyl esters (FAME) produced from cottonseed oil.

Thatch is a layer of partially decomposed organic matter between green shoot tissue and the soil surface, and mat is thatch partially intermixed with topsoil. Excessive thatch-mat layering (>2.54 cm) is generally detrimental to turfgrass management, and numerous techniques including various mechanical and topdressing regimes, have been attempted to reduce its severity. This factorial experiment investigated the effectiveness of combining mechanical-biological and topdressing treatments for controlling thatch-mat levels in an established USGA-specified golf green planted with 'A -1 ' creeping bentgrass [Agrostis stoloniferous L. var. palustris (Huds.)]. Two levels of topdressing were used, and the mechanical-biological treatments included vertical mowing at two different depths and timings, core cultivation, grooming, a biological granular supplement (Thatch-X), and combinations of core cultivation with grooming and/or vertical mowing. Differences among the mechanical-biological treatments were detected following 2 consecutive yearly applications. Thatch-mat depth (mm) was 12 to 15% greater for Thatch-X and topdressing alone compared with other treatments. Organic matter content (g kg -1 ) increased 32% for the untreated and decreased 19% for core cultivation combined with vertical mowing and grooming, whereas all other treatments maintained pre-study levels. Compared with the untreated, surface hardness was reduced ∼9% for all treatments using core cultivation, while water infiltration rates increased 127 to 168%. Vertical mowing treatments improved water infiltration rates by 40 to 65%. Turfgrass quality was not greatly impacted by the mechanical-biological treatments as ratings ranged from 8.4 to 10.0. However, mower scalping and dry spots contributed to unacceptable or only marginally acceptable turfgrass quality (6.4-7.2) for the untreated by the end of the study. Compared with topdressing alone, ball roll distance was decreased 6% by vertical mowing 7 days after treatment (DAT) and 5 to 8% by core cultivation up to 14 DAT. Sand topdressing alone was insufficient for managing thatch-mat levels in an established creeping bentgrass golf green.

Dwarf bermudagrass (Cynodon dactylon x C. transvaalensis Burtt-Davy) and creeping bentgrass (Agrostis stolonifera L.) are planted for golf greens in the U.S. transition zone, but management regimes, such as the use of a plant growth regulator (PGR), often vary for long-term culture of the two species. The objective of this experiment was to investigate application regimens of the PGR trinexapac-ethyl (TE), on growth, quality, and performance of creeping bentgrass and bermudagrass putting greens in Clemson, SC. 'L-93' creeping bentgrass and 'TifEagle' bermudagrass putting greens, established in summer 2002 and mowed at 3.2 mm, received TE over 12 wk in three regimens: 0.017 kg ha 1 wk -1 , 0.033 kg ha) -1 2 wk -1 (biweekly), or 0.05 kg ha -1 3 wk -1 (triweekly) from May to August 2003 and 2004. Creeping bentgrass was not discolored from TE, but unacceptable bermudagrass discoloration (>20%) occurred on one, two, and six dates for weekly, biweekly, and triweekly regimens, respectively. All TE regimens reduced bermudagrass clippings approximately 50% from nontreated bermudagrass across all dates, while creeping bentgrass clipping reductions, approximately 20 to 35% from nontreated grass, were inconsistent. The root masses of both species treated with TE regimens were similar to nontreated turf. Bermudagrass aerification recovery was reduced on two, two, and four dates after weekly, biweekly, and triweekly TE regimens, respectively. All TE regimens increased morning and evening bermudagrass golf ball roll distance approximately 25 cm from morning distances of nontreated turf.

Centipedegrass [Eremochloa ophiuroides (Munro) Hack.] is widely grown throughout the southeastern United States as a low-maintenance turfgrass; however, limited peer-reviewed research is available on “best” cultural practices for established centipedegrass. This research was conducted to examine the long-term effects of mowing height and fertility regimens providing various rates and application times of soil-applied granular Fe and N on centipedegrass quality and surface coverage. Soil type was a Cecil sandy loam (clayey, kaolinitic, thermic Typic Hapludult) with a pH of 5.5. A mowing height of 3.8 cm was equal to or better than the 1.9 cm mowing height throughout the study. The rate of N fertilization played an important role in achieving optimal turfgrass quality and coverage with the two highest rates (97.6 and 195.2 kg·ha−1 N), generally providing similar results when applied as split applications in May and August and mowed at 3.8 cm. These treatments provided turfgrass quality ratings of 8.3–9.0, turfgrass color ratings of 8.1–8.7, and turfgrass coverage of 94% to 98% over a 3-year period. The addition of soil-applied Fe sulfate at a rate of 24.4 kg·ha−1 Fe was not beneficial to centipedegrass performance or color. Results indicate that the addition of 97.6 kg·ha−1 N, using split-applications in May and August and a mowing height of 3.8 cm for established centipedegrass, should achieve acceptable turfgrass quality and coverage.

Studies were conducted for 12 wk from June 16 to September 8, 2003 and July 10 to October 4, 2004 with the objective of evaluating growth regulation, lateral regrowth, and injury of Tifway bermudagrass [Cynodon dactylon (L.) × C. transvaalensis Burtt-Davy Tifway] in response to two GA-inhibiting plant growth regulators, trinexapac-ethyl and flurprimidol. Trinexapac-ethyl was applied alone at 0, 0.052, and 0.104 kg ai/ha and flurprimidol alone at 0, 0.14, and 0.28 kg ai/ ha, plus all combinations. Applications were made every 3 wk for the duration of the study. Tifway bermudagrass clipping yield was reduced 33% and 54% by trinexapac-ethyl at 0.104 kg/ha at 4 and 8 wk after initial treatment (WAIT), respectively. Flurprimidol at 0.28 kg/ha reduced clipping yield 49% 8 WAIT. Lateral regrowth was reduced 20% 2 WAIT by trinexapac-ethyl at 0.104 kg/ha, and 26% 2 WAIT by flurprimidol at 0.28 kg/ha. Lateral regrowth was reduced 13% 4 WAIT by trinexapac-ethyl at 0.104 kg/ha, and 15% 4 WAIT by flurprimidol at 0.28 kg/ha. Overall, acceptable injury (

With synthetic nematicide options becoming limited, two studies were initiated to investigate the usefulness of selective botanical extracts for the suppression of sting (Belonolaimus longicaudatus Rau) nematodes. Plant materials were from greenhouse-grown mature specimens of spotted spurge (Chamaesyce maculata L. Small); poinsettia (Euphorbia pulcherima Willd. 'Freedom Red'); lantana (Lantana camara var. hybrids); mature, field-grown tall lettuce (Lactuca canadensis L.); and goldenrod (Solidago altissima L. var. scabra), plus a seed meal extract from Brassica jwicea 'Pacific Gold' (BSM). Nematodes were exposed to 1.2-mL extract of either shoot or roots of each plant spedes. Nematode mortality counts were made daily for 4 d. In Study 1, effects of botanical extracts on nematode mortality were evaluated when applied directly to laboratory-controlled sting nematode populations in test tubes. Root extracts of spurge, poinsettia, and lantana provided 69,70, and 57% mortality, respectively, by 96 h while goldenrod and tall lettuce root extracts and the untreated provided 0% mortality. Shoot portions of poinsettia and spurge provided 95 to 98% mortality while goldenrod, tall lettuce, and lantana shoot extracts had 64, 40, and 25% mortality, respectively. Greenhouse studies evaluated the most successful laboratory extracts in a soil environment and included poinsettia shoot extracts and BSM. Poinsettia shoot extracts with irrigation provided 70% control compared with the untreated pots while poinsettia nonirrigated provided 73% control. Brassica sp. seed meal with irrigation provided 92% control while BSM nonirrigated provided 99.5% control. Brassica sp. seed meal, poinsettia, and spurge shoot extracts showed most promise as possible biocontrol agents of sting nematodes.

Plant growth regulators (PGRs) improve turf color by inhibiting leaf growth and may reduce fertilization requirements of bermudagrass [Cynodon dactylon (L.) Pers. X C. transvaalensis Burtt-Davy] golf greens by reducing nutrients removed through clipping collection. To test this hypothesis, growth, color, and nutrient allocation of 'TifEagle' bermudagrass maintained at 3.2 mm were investigated in field experiments conducted in Clemson, SC, from April to August in 2003 and 2004. Ammonium nitrate was applied at 6,12,18, or 24 kg N ha -1 wk -1 with a PGR, trinexapac-ethyl {[4-(cydopropyl-[α]-hydroxymethylene)- 3,5-dioxo-cydohexane carboxylic add ethyl ester]) (TE), at 0 or 0.05 kg a.i. ha -1 3 wk -1 . Turf required 18 to 24 kg N ha -1 wk -1 from May to June and ≤12 kg N ha -1 wk -1 from July to August to maintain acceptable color (≥-7, 1-9 scale). Trinexapac-ethyl initially caused discoloration but bermudagrass recovered and had color enhanced 10 to 25% from nontreated. Trinexapac-ethyl reduced clippings 67% from nontreated while clippings, percentage of lateral regrowth, and aerification recovery increased with N rate. Bermudagrass treated with TE had similar root mass to nontreated but 5% greater stolon and rhizome mass, 18% higher chlorophyll concentration, up to 67% reduced lateral regrowth, and up to 38% reduced aerification recovery. Trinexapac-ethyl reduced leaf N, P, K, Mg, S, and Fe concentrations 10 to 25% and increased rhizome concentrations 8 to 36%. Nutrients recovered through clippings were reduced ≈70% from TE applications while TE-treated turf had increased N, P, K, Ca, Mg, S, Mn, and Fe retention in stolons and rhizomes. Overall, TE enhanced color while redudng nutrient translocation from rhizomes to leaves, thus increasing bermudagrass nutrient retention.

Studies on bermudagrasses (Cynodon spp.) have demonstrated variability in salinity response among species and cultivars. However, information on ultradwarf bermudagrass cultivars in relative salinity tolerance associated with trinexapac-ethyl (TE) [4-(cyclopropyl-α-hydroxy-methylene)-3,5-dioxocyclohexanecarboxylic acid ethyl ester], a cyclohexanedione type II plant growth regulator (PGR), remains unknown. Therefore, two replicated greenhouse studies were conducted to determine the salinity tolerance of two ultradwarf bermudagrass cultivars treated with TE on turfgrass quality (TQ), total root biomass, and root and shoot tissue nutrient concentration. Turfgrasses included `TifEagle' and `Champion' bermudagrass (Cynodondactylon(L.) Pers. × C. transvaalensisBurtt-Davy). Daily sodium chloride (NaCl) exposure was 0, 12.90 (8,000 ppm), 25.80 (16,000 ppm), and 38.71 dS·m–1 (24,000 ppm). Biweekly TE applications (active ingredient 0.02 kg·ha–1) were initiated 2 weeks after salinity exposure. `Champion' was more salt-tolerant than `TifEagle' based on TQ and root mass. At 12.90, 25.80, and 38.71 dS·m–1 of NaCl, nontreated (without TE) `Champion' consistently outperformed nontreated `TifEagle' with greater TQ on most rating dates. At 12.90 dS·m–1, TE treated `Champion' (8.0) had greater TQ than nontreated `TifEagle' (6.1) at week 10. Regardless of TE application, after 2 weeks of applying 25.80 dS·m–1 of NaCl, both cultivars fell below acceptable TQ (–1. In conclusion, the two bermudagrass cultivars responded differently when exposed to moderate levels of NaCl.

Dwarf-type bermudagrasses [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davey] tolerate long-term golf green mowing heights but require heavy nitrogen (N) fertilizations. Inhibiting leaf growth with trinexapac-ethyl (TE) could reduce shoot growth competition for root reserves and improve nutrient use efficiency. Two greenhouse experiments evaluated four N levels, 6 (N6), 12 (N12), 18 (N18), and 24 (N24) kg N/ha/week, with TE at 0 and 0.05 kg·ha–1 a.i. every 3 weeks to assess rooting, nutrient allocation, clipping yield, and chlorophyll concentration of `TifEagle' bermudagrass grown in PVC containers built to U.S. Golf Association specification. Trinexapac-ethyl enhanced turf quality on every date after initial application. After 8 weeks, high N rates caused turf quality decline; however, TE treated turf averaged about 25% higher visual quality from nontreated turf, masking quality decline of high N fertility. `TifEagle' bermudagrass treated with TE had clippings reduced 52% to 61% from non-TE treated. After 16 weeks, bermudagrass treated with TE over all N levels had 43% greater root mass and 23% enhanced root length. Compared to non-TE treated turf, leaf N, P, and K concentrations were consistently lower in TE treated turf while Ca and Mg concentrations were increased. Root N concentrations in TE treated turf were 8% to 11% higher for N12, N18, and N24 fertilized turf than respective N rates without TE. Compared to non-TE treated turf, clipping nutrient recoveries were reduced 69% to 79% by TE with 25% to 105% greater nutrients recovered in roots. Bermudagrass treated with TE had higher total chlorophyll concentrations after 8 and 12 weeks. Overall, inhibiting `TifEagle' bermudagrass leaf growth appears to reallocate nutrients to belowground tissues, thus improving nutrient use efficiency and root growth. Chemical name used: trinexapac-ethyl, [4-(cyclopropyl-[α]-hydroxymethylene)-3,5-dioxo-cyclohexane carboxylic acid ethylester].

Greenhouse and laboratory experiments were conducted to investigate the response of common lambsquarters to POST applications of halosulfuron–methyl plus 2,4-D admixtures and to investigate the effects of 2,4-D on the absorption, translocation, and metabolism of halosulfuron. In the greenhouse, halosulfuron at 0, 4.5, 9, 18, and 36 g ai/ha was applied alone and mixed with 2,4-D at 0, 17, 35, and 70 g ai/ha POST to 7.5- to 9-cm seedlings, and plant fresh weights were determined 4 wk after treatment (WAT). Halosulfuron alone did not control this weed, while fresh weights of common lambsquarters treated with 2,4-D declined hyperbolically as rates increased. A synergistic response for mixtures of these herbicides occurred, as observed fresh weights for all combinations were less than expected based on independent action and the calibrated marginal responses. In the laboratory, 7.5- to 9-cm seedlings were treated POST with commercially formulated halosulfuron at 9 and 18 g/ha and 2,4-D at 0, 70, and 140 g/ha, respectively, followed by foliar-applied14C-halosulfuron. Absorption of14C-halosulfuron increased with time, and absorption and translocation were not influenced by the addition of 2,4-D. Results from these studies inferred that halosulfuron and 2,4-D were generally synergistic on common lambsquarters and that mechanisms other than absorption, translocation, and metabolism may explain this response.

Inhibiting shoot growth of dwarf bermudagrass [Cynodon dactylon(L.) Pers. × C. transvaalensis Burtt-Davey] with a plant-growth retardant, trinexapac-ethyl (TE), may redirect nutrients and photosynthate away from leaf tissue to promote root growth and improve nutrient-use efficiency. Two greenhouse experiments evaluated three rates of TE, 0.025, 0.05, and 0.075 kg a.i. ha−1, applied every three weeks on ‘TifEagle’ bermudagrass for 12 weeks. Lysimeters constructed to United State Golf Association specifications were arranged in a randomized complete block design with four replications. Increased TE rates quadratically reduced clipping yield 38%–75%, improved turf quality 6%–13%, and enhanced chlorophyll concentrations 30%–70% over the untreated grass. Dry-root mass increased with TE rate 11%–37% after 12 weeks. Total clipping nutrients recovered from five sampling dates were reduced by approximately 50%, 85%, and 90% for turf receiving TE at 0.025, 0.05, and 0.075 kg ha−1 3 wk−1, respectively. That...

●ADDITIONAL INDEX WORDS. drought resistance, Cynodon spp., water, evapotranspiration, volumetric soil water content, turfgrass quality, rooting, turfgrass SUMMARY. A 2-year greenhouse study was conducted at Clemson University, Clemson, S.C., in 2003 and 2004 to determine drought responses of six bermudagrass (Cynodon spp.) cultivars at four irrigation intervals. Cultivars selected from the 2002 National Turfgrass Evaluation Program Bermudagrass Trial were ‘SWI-1012’, ‘Arizona Common’, ‘Tift No.3’, ‘Tifsport’, ‘Aussie Green’, and ‘Celebration’. Treatments included 5-, 10-, and 15-day irrigation intervals plus a control (irrigated daily). Volumetric soil water content (VSWC) and evapotranspiration (ET) rates were recorded every 3 days. Turfgrass quality (TQ) was observed weekly and root weight was measured at the end of a 6-week study. ‘Aussie Green’ and ‘Celebration’ produced the highest TQ rating (>7) at week 4 when watered daily. After 4 weeks of the 5-day irrigation interval, all cultivars showed unacceptable quality ratings (

Preferential use of creeping bentgrass Agrostis stoloniferous L. var. palustris (Huds.) on golf putting greens has expanded into the hotter, more environmentally stressful regions of the southeastern United States where turfgrass decline is problematic during summer months. Methods of reducing temperatures in the putting green microclimate would enhance bentgrass survival under heat stress conditions. The objectives of this study were to evaluate the bentgrass putting green microclimate under combined misting and/or subsurface fan systems with surface fans. Field studies were conducted in the summers of 2001 and 2002 on a 'Crenshaw' creeping bentgrass putting green located in Clemson, SC. Treatments consisted of surface fan only, surface fan plus misting, surface fan plus subsurface fan, and surface fan plus misting and subsurface fan. Fan treatments were applied from 1100 to 1500 h on days when temperatures were greater than or equal to 29.5 degrees C, there was no visible cloud cover, and wind speed < 1.0 m s(-1). Surface fan plus misting treatments reduced putting green canopy, soil surface, and soil temperatures by as much as 9, 7, and 6 degrees C, respectively, while increasing canopy relative humidity and soil moisture content. Benefits were generally observed over a range of 5 m from the fan. These treatments demonstrate great potential for improving canopy and soil microclimate conditions influencing bentgrass survival in a heat stress environment. Surprisingly, the use of subsurface fans did not enhance the cooling effect provided by surface fans. Fan/mist systems should be investigated further to determine possible disease occurrence during extended use periods.

Excessive (>1.3 cm) thatch and mat layering of turfgrass is considered undesirable because it reduces hydraulic conductivity, water infiltration, increases localized dry spots and pest problems, and reduces pesticide effectiveness and turf tolerance to temperature extremes. The objective of this 2-yr study was to determine the efficacy of topdressing alone and in combination with several mechanical and biological methods to control thatch-mat accumulation in a newly established 'L-93' creeping bentgrass [Agrostis stolonifera L. var palustris (Huds.) Farw.] sand-based golf green. Mechanical and biological methods included vertical mowing at various depths and timings, core cultivation, grooming, a biological thatch control agent (Thatch-X), and combinations of core cultivation with grooming, core cultivation with vertical mowing, and core cultivation combined with grooming and vertical mowing. No treatment prevented thatch-mat accumulation, and thatch-mat depth for all treatments were similar to, or greater than, the untreated at the end of the study. Increases in percent organic matter content during the study ranged from 53% for core cultivation combined with grooming and vertical mowing to 123% for the untreated. Combinations of core cultivation plus vertical mowing with or without grooming were the most effective at minimizing thatch-mat accumulation. These treatments decreased percent organic matter 38 and 45%, respectively, compared with the untreated. Surface hardness was reduced an average of 19% by treatments that included core cultivation, and the cultivation treatments increased water infiltration rates an average of 58% in 2001 and 188% in 2002 compared with the untreated. Turf quality was not adversely affected by any management practice and remained acceptable (greater than or equal to 7.0) throughout the study.

Visual inspection is a commonly used inspection method, but effects of noise on visual inspection have not been studied extensively. The objective of this study was to investigate the effects of noise on visual search performance. The effects of continuous, intermittent, and random noise conditions emitted from single and multiple sources on the accuracy of an inspector to perform easy and difficult inspection tasks was examined. When compared to the continuous noise treatment, random and intermittent noise patterns were shown to have negative effects on the easy search task accuracy. Additionally, the results indicate that single source noise enhances search performance of difficult tasks. A larger study would likely detect noxious effects of multiple noise sources on difficult search task performance. Relevance to industry A thorough understanding of inspection is important for continued quality, reliability and safety in manufacturing, maintenance, security and other industries. The results of this study can be applied to inspection tasks conducted in workplace conditions that are similar to those employed in the current study.

In highly automated inspection systems today, humans act in a supervisory capacity, i.e., monitoring the process during normal operations and intervening to take manual control when necessary to override faulty automation. Research has concluded that the intervention behavior of supervisors is based on their trust in the automation. However, several problems remain with the current trust paradigm, the most important ones concerning the ambiguity and inaccuracy of the data. An original theoretical framework relating machine properties to operator perceptions is needed. To achieve this framework, machine properties need to be mapped to these perceptions through the development of quantifiable dimensions, referred to as uncertainty. Uncertainty, unlike trust, can be easily quantified and, therefore, can be related to system properties. This research attempts to measure uncertainty using a Line Length Experiment Module that simulates a real-life automated system monitored by an inspector. The experiment tests the ability of a human inspector to identify defects relative to the machine's ability to do so, rather than trying to gauge their competencies separately and subsequently comparing them. Three levels of uncertainty, established using National Institute of Standards and Technology (NIST) guidelines, were administered in the experiment, with the users rating their trust at each level through questionnaires. The results showed that the overall trust in the system had a significant inverse relationship with the system uncertainty. Hence, the performance of hybrid systems can be improved by decreasing uncertainty, an improvement that will have an impact on quality. Relevance to industry Trust of humans in machines is important in the performance of hybrid systems. Increasing this trust will improve overall system performance of systems.

Micropropagation of black-stemmed elephant ear (C. esculenta (L.) Schott `Fontanesii')' and upright elephant ear (A. macrorrhizos G. Don) were compared in semi-solid agar media and agitated, liquid thin-film bioreactor vessels at four explant densities (33, 100, 165, and 330 explants/L of media) using two growth regulator combinations: 1) 1 μm benzylaminopurine (BA)—growth medium, and 2) 3 μm BA plus 3 μm ancymidol—multiplication medium. The thin-film liquid system outperformed agar culture for most measured responses. Some exceptions were relative dry weights at higher explant densities and multiplication rate of Colocasia. When the thin-film liquid system was compared to agar culture, Alocasia explants produced their greatest biomass and had the least residual sugar at the highest explant density. Alocasia explants multiplied most rapidly and had the greatest relative dry weight on liquid media at the low explant densities. Alocasia plants were larger in growth medium than multiplication medium and larger in liquid medium than agar medium. When compared to agar, Colocasia in the thin-film liquid system produced the greatest biomass at the highest explant density in growth medium, had the greatest relative dry weight at the lowest explant density, and used the most sugar at the highest explant density. Alocasia and Colocasia would likely produce greater fresh and dry weight at the highest explant density if additional sugar were supplied during thin-film culture. Greater growth in thin-film culture of Alocasia and Colocasia is due in part, to greater availability of sugar in liquid compared to agar medium.

St. Augustinegrass [(Stenotaphrum secundatum (Walt.) Kuntz.] is the preferred warm-season turfgrass for Florida's commercial and residential landscapes with an estimated 0.7 million hectare under growth and management. Limited published information is available on St. Augustinegrass response to plant growth retardants (PGRs). A 2-yr study was implemented to monitor St. Augustinegrass turf quality, lateral stolon growth, percent cover, mowing frequency, cumulative turfgrass clippings, and seedhead suppression following PGR application. Treatments were applied on 23 June 1995 and 22 June 1996 as a single application (SIA) at label use rate (LUR) or as twin split applications (TSA) at half LUR each: the sequential application was only used when mowing interval equaled the untreated. The PGRs and rates were flurprimidol [α-(1-methylethyl)-α-[4-(trifluoro-methoxy) phenyl]-5-pyrimidine-methanol] and paclobutrazol [(+/-)-(R*,R*)-β-[(4-chloro-phenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol] at 1.12 kg ha -1 for SIA and 0.56 kg ha -1 for TSA, trinexapac-ethyl [4-(cyclopropyl-α-hydroxymethylene)-3,5-dioxocyclohexane carboxylic acid ethylester] and mefluidide [N-[2,4-dimethyl-5-[[trifluoromethyl)sulfonyl]amino]phenyl]acetamide] at 0.28 kg ha -1 for SIA and 0.14 kg ha -1 for TSA, and imazapic [(±)-2-[4,5-dihydrol-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-methyl-3-pyridine-carboxylic add] at 0.028 kg ha -1 for SIA and 0.014 kg ha -1 for TSA. Responses were observed for a 12-wk period following initial application, and turf quality was acceptable (>7) for all PGRs. Turf quality for imazapic was generally better than the untreated for Weeks 6 to 10. Greatest control of lateral stolon growth 10 wk after initial application was achieved with TSA of imazapic (68%) and mefluidide (61%). Percent cover 12 wk after initial application was lowest for SIA and TSA imazapic (66 and 53%, respectively). Greatest reduction in mowing frequency was provided by trinexapac-ethyl (50%), while flurprimidol and mefluidide reduced mowing frequency by 26 and 20%, respectively. The only PGR that reduced cumulative turfgrass clippings (CTC) was trinexapac-ethyl (63%). Greatest seedhead inhibition during peak production (about 35%) was provided by imazapic and mefluidide. The two most effective PGRs were trinexapac-ethyl (reduced mowing frequency and CTC) and imazapic (controlled lateral stolon growth and seedhead production), while mefluidide demonstrated some potential. Combinations of these products could be examined in future studies.

A multiplicative model of stomatal conductance was developed and tested in two functionally distinct ecotypes of Acer rubrum L. (red maple). The model overcomes the main limitation of the commonly used Ball-Berry model (Ball et al. 1987) by accounting for stomatal behavior under soil drying conditions. We combined the Ball-Berry model with an integrated expression of abscisic acid (ABA)-based stomatal response to ABA concentration ([ABA]) in bulk leaf tissue (g fac ), which coupled physiological changes at the leaf level with those in the root. The factor g fac = exp(-β[ABA] L ) incorporated the stomatal response to [ABA] into the Ball-Berry model by down regulating stomatal conductance (g s ) in response to physiological changes in the root. The down regulation of g s is pertinent under conditions where soil drying may modify the delivery of chemical signals to leaf stomata. Model testing indicated that the multiplicative model was capable of predicting g s in red maple under wide ranges of soil and atmospheric conditions. Concordance correlation coefficients were high (between 0.59 and 0.94) for the tested ecotypes under three environmental conditions (atmospheric, rhizospheric and minimal stress). The study supported the use of g fac as a gas exchange function that controls water stress effects on g s and aids in the prediction of g s responses.

The quantum yield of photosystem II, determined by chlorophyll fluorescence and the quantum yield of CO 2 uptake, determined from gas exchange, are two physiologically important measurements in clarifying the response to environmental stress. Both measurements, however, require an accurate assessment of leaf light absorption in the photosynthetically active radiation wavelength range (400–700 nm). To date, integrating sphere and field-portable spectroradiometer measurements of leaf reflectance, transmittance, and absorptance are time consuming, costly, and cumbersome. It is therefore desirable to determine if SPAD meter chlorophyll concentration estimates could be used in lieu of an integrating sphere and field-portable spectroradiometer for determining leaf reflectance, transmittance, and absorptance in woody plant species. An integrating sphere and field-portable spectroradiometer were used to measure reflectance, transmittance, and absorptance of leaf samples at 2 nm intervals between 400 and 700 nm. A paired SPAD 502 hand-held chlorophyll estimate was also determined for each sample. Regression analysis revealed a strong relationship between the SPAD estimate and leaf transmittance and absorptance. The reflectance relationship, although still present, was not as accurate. The study indicates that the SPAD meter could be used to provide a rapid estimate of leaf absorbance and transmittance in the 400–700 nm wavelength range in woody plant species.

Daily and seasonal net photosynthesis (Anet), transpiration (E), absorbed photosynthetically active radiation (Qa) and light-use efficiency (epsilonc) in a red maple container nursery were simulated with MAESTRA, a three-dimensional canopy model. Effects of canopy heterogeneity were simulated by imposing changes in crown spacing. The light transfer sub-model, a distribution model of incident, direct, diffuse and scattered radiation within MAESTRA, was validated against field measurements of light interception on an intra-crown scale. In the container nursery, we found that a fiber-optic-based method of integrating photosynthetically active radiation (Q) was more suitable for crown-layer light transfer measurements and adjustments than either orthogonal line or individual quantum sensor measurements. The model underestimated intercepted Q by 9.3, 18 and 11.1% for crown layers 1, 2 and 3, respectively; however, there were linear relationships between model estimates and observations made with each of the three measurement methods. We used the validated and parameterized light transfer model to assess intra-crown and intra-canopy light transfer on a layer, crown and canopy basis, and investigated effects of tree size ratio and tree spacing interactions on Anet, E, Qa and epsilonc in the container nursery. Heterogeneous crown and canopy photosynthesis were predicted to exceed values for a uniform canopy under space-limiting conditions. Tree size ratio had large effects on Anet, E, Qa and epsilonc when light to lower-canopy layers was limited by inadequate space between crowns. Increasing Qa at lower-crown layers had the largest impact on whole-crown and whole-canopy Anet, E, Qa and epsilonc. Increases in canopy productivity led to increased water use. Simulations of heterogeneous stands with adequate soil water indicated that light absorption is maximized under space-limiting conditions as a canopy crown moves toward heterogeneity. Nursery and plantation productivity per unit land area was optimized by tactical placement of trees of several sizes, but this was accompanied by increased canopy water use.

The addition of leonardite may increase, or at least maintain, production quality of ornamental plants and permit reductions in fertilizer inputs. The objective of this study was to determine the effects of a Utah-mined leonardite on early stages of zinnia (Zinnia elegans Jacq. `Small World Pink') and marigold (Tagetes patula L. `Janie Yellow') growth. The Utah leonardite was characterized by comparing it to the International Humic Substances Society's leonardite standard. Zinnia and marigold seedlings and transplants were grown in sand and 1 sand: 1 peat media (by volume) with leonardite additions of 0%, 3.125%, 6.25%, and 12.5%. Both species showed positive growth responses to 3.125% leonardite in each medium compared to fertilizer alone. Plant responses to increased leonardite additions were generally quadratic, and optimal leonardite levels were estimated. For growing zinnias, optimal conditions were determined to be 7.5% leonardite in a sand medium for seedlings and 8% in a sand-peat mixture for transplants. A sand-peat medium containing 7% leonardite was determined to be optimal for growing marigold seedlings and transplants. Addition of leonardite to growing medium offers promise for reducing fertilizer use during production of some ornamental plants.

Field studies were conducted in 1995 and 1996 to investigate postemergence tank mixtures of sethoxydim with various acetolactate synthase (ALS)- and non–ALS-inhibitor herbicides for weed control in sethoxydim-resistant (SR) corn. Giant foxtail control with sethoxydim was 96% and was equal to control with tank mixtures of sethoxydim plus bentazon, dicamba, dicamba plus atrazine, bromoxynil, and nicosulfuron plus bromoxynil. Giant foxtail control with sethoxydim plus atrazine, sethoxydim plus bentazon plus atrazine, and sethoxydim plus ALS-inhibiting herbicides plus 2,4-D was reduced to 60 to 89%. Common ragweed control was equal to or above 91% for tank mixtures that included bentazon plus atrazine, dicamba, dicamba plus atrazine, halosulfuron plus 2,4-D, and CGA 152005 plus primisulfuron plus 2,4-D, and the tank mixture of nicosulfuron plus bromoxynil. Common lambsquarters control was equal to or above 91% from all broadleaf herbicide treatments except bentazon and the tank mixture of halosulfuron plus 2,...

This study was designed to estimate transpiration in a container nursery under both irrigated and water stressed conditions using a biologically based canopy model. The model, MAESTRA, was parameterized with a suite of physiological measurements and an explicit response function for soil moisture deficit was incorporated. The model was validated against transpiration measurements monitored by the stem heat balance method in both irrigated and non-irrigated plots. Distinct disconnects between estimated and measured values were found at high soil moisture deficits. The data justify the incorporation of a soil moisture component to simulate transpiration of plants with root zones in limited soil volumes. The agreement between measured and modelled canopy transpiration separated at a soil moisture deficit of 0.85 or greater, however, estimates of daily transpiration simulated by the model were in agreement with sap-flow measurements when water was not limiting. The data indicate that cuticular conductance at soil moisture deficits ≤0.85 may explain the separation in model estimates and actual plant water loss. © 2002 Elsevier Science B.V. All rights reserved.

Summary The inconsistent beneficial responses to dietary ascorbic acid (AsA) may be due to dietary factors that alter biosynthesis or tissue turnover of AsA. It has been suggested on the basis of altered tissue AsA that dietary fluoride is a determinant of biosynthesis in chickens. Fluoride may enter the food chain of poultry via industrial contamination, feed ingredients and drinking water. The goal of this study was to ascertain whether dietary fluoride at 300 mg/kg influences l-gulonolactone oxidase (GLO) activity in commercial meat-type chickens. The experimental diet was fed from day-old to 3 weeks and responses measured. Growth and feed conversion were not affected by fluoride in the diet. Dietary fluoride neither inhibited nor enhanced GLO activity nor did it increase or decrease AsA concentration in plasma, liver, kidney, adrenal gland and muscle (pectoralis major). Tissue AsA concentration in ascending order was adrenal > liver > kidney > pectoralis major > plasma. The results are consistent with that reported for the rat and calculations based on the results eliminate fluorine contamination for the inconsistent responses of immature chickens to dietary AsA.

Current environmental concerns demand intensive research on conservation tillage for cotton production. Studies were conducted in 1994 and 1995 at Florence, SC, to evaluate weed and cotton response to various weed management systems in cotton with reduced tillage. Broadcast application of pendimethalin at 1.1 kg ai/ha and fluometuron at 2.2 kg ai/ha preemergence (PRE) followed by pyrithiobac at 0.07 kg ai/ha early postemergence (EPOST) was more effective than was a 38-cm band of these herbicides in controlling naturally occurring populations of sicklepod, Palmer amaranth, goosegrass, and southern crabgrass and in providing cotton yields equal to yields under weed-free conditions. With the 38-cm band of PRE and EPOST herbicides, two supplemental weed treatments at 3 and 7 wk after planting using glyphosate applied at 0.84 kg ae/ha POST with a hooded sprayer or a no-till cultivator was required to achieve acceptable weed control, but cotton yields were less than yields for the broadcast treatment ...

The baseline sensitivity of Monilinia fructicola in a peach orchard not previously exposed to demethylation-inhibiting (DMI) fungicides was determined for propiconazole, using the concentration in an agar medium required to suppress radial growth of mycelium by 50% (EC50) The baseline sensitivity was found to be approximately 0.03 μg/ml. Prolonged, regular exposure of the natural population of M. fructicola to propiconazole in the test orchard over a 3-year period (29 total applications) resulted in a wider range of sensitivity (EC50 of 0.02 to 2.16μg/ml) among isolates than was observed in the initial population (EC50 of 0.02 to 0.15 μg/ml). Comparisons with isolates from commercial orchards where DMI fungicides were used regularly showed that sensitivities were comparable to, or less than, those of isolates from the population in the test orchard that had been exposed to propiconazole for the 3-year period. M. fructicola in South Carolina peach orchards might now be less sensitive to DMI fungicides than when those fungicides were first introduced for brown rot control, although effective disease control in the field has been maintained.

Current environmental concerns justify renewed evaluation of crop management strategies that offer promise for maintaining or increasing productivity while reducing environmental impacts. Field studies were conducted using weed-free conditions to determine the effects of corn (Zea mays L.) leaf orientation on light interception, vegetative and reproductive development, and grain yields. DeKalb 689' was handseeded in north-south rows to achieve populations of 22 000 and 33 000 plantslacre. Controlled seed positioning in the soil was used to attain across-row and with-row leaf orientations, while conventional planting provided random leaf orientation. Light interception, intraspecific competition among corn plants, and grain yield were affected by leaf orientation and plant population. At selected row positions 8 wk after planting, light interception for across-row leaf orientation exceeded random and with-row orientations by up to 10 and 25%, respectively, while light interception for the high plant population exceeded the low population by up to 15%. Across-row and random leaf orientations produced 8% greater leaf area than with-row orientation. Greater intraspecific competition was indicated for the high plant population due to lower leaf area, leaf biomass, and stalk biomass per plant than the low population. Grain yields were greater at the high than the low plant population for all leaf orientations. At the high plant population, across-row leaf orientation yielded 10 and 21% more than random and with-row orientations, respectively. Therefore, across-row leaf orientation at the high plant population should provide more rapid canopy closure, enhance crop competition with weeds, and reduce dependence on herbicides while enhancing grain yields.

Field studies were conducted in South Carolina to evaluate the herbicides acifluorfen, chlorimuron, and imazaquin for control of Palmer amaranth and smooth pigweed in soybean, when applied 3 wk after weed emergence. Palmer amaranth was more difficult to control than smooth pigweed. Compared to untreated controls, acifluorfen, chlorimuron, and imazaquin reduced Palmer amaranth and smooth pigweed biomass 78 and 96%, 80 and 98%, and 82 and 99% at 30 d after treatment (DAT), 60 DAT, and at soybean harvest, respectively. The high rate (140 g/ha) of imazaquin provided greater control of Palmer amaranth than other herbicide treatments at soybean harvest. Except for the 140 g/ha rate of imazaquin, inadequate control of Palmer amaranth resulted in lower soybean seed yields for all herbicide treatments than the weed-free control. However, all herbicides controlled smooth pigweed to provide soybean seed yields similar to the weed-free control. Nomenclature: Acifluorfen, 5-(2-chloro-4-(trifluoromethyl)phenoxy)-2-nitrobenzoic acid; chlorimu- ron, 2-(((((4-chloro-6-methoxy-2-pyrimidinyl)amino)carbonyl)amino)sulfonyl)benzoic acid; imaza- quin, 2-(4,5-dihydro-4-methyl-4-( 1-methyethyl)-5-oxo- lH-imidazol-2-yl)-3-quinolinecarboxylic acid

Dwarf-type bermudagrass (Cynodon dactylon Pers. × C. transvaalensis Burtt-Davy) putting greens tolerate long-term mowing heights of 3.2 mm but require heavy nitrogen (N) fertilizations that increase ball roll resistance. Applying a plant growth regulator, such as trinexapac-ethyl (TE), could reduce uneven shoot growth from high N fertility and improve putting green ball roll distances. Field experiments were conducted from April to August 2003 and 2004 in Clemson, SC to investigate effects of ammonium nitrate applied at 6, 12, 18, or 24 kg N/ha per week with TE applied at 0 or 0.05 kg a.i. per ha every 3 weeks on `TifEagle' bermudagrass ball roll distances (BRD). BRD were measured weekly with a 38-cm stimpmeter in the morning (900 to 1100 hr) and evening (>1700 hr) beginning 1 wk after initial TE treatments. Interactions were not detected among N, TE, or time of day. TE increased BRD about 15% from non-TE treated. BRD was reduced with increased N rate and from am to pm; however, bermudagrass treated with TE averaged 10% longer PM BRD than am distances of non-TE treated. Overall, increased N fertility and diurnal shoot growth may reduce BRD but TE will be an effective tool for mitigating these effects on bermudagrass putting greens. Chemical name used: [4-(cyclopropyl-[α]-hydroxymethylene)-3,5-dioxo-cyclohexane carboxylic acid ethyl ester] (trinexapac-ethyl).

Field studies were conducted in 1991 to 1993 to determine the effects of PRE and POST herbicides alone and in factorial combinations on sicklepod control, weed biomass, and soybean seed yields. Herbicides evaluated were metribuzin PRE, metribuzin + chlorimuron PRE, imazaquin PRE and POST, chlorimuron POST, and AC 263,222 POST POST herbicides alone provided better sicklepod control than PRE herbicides alone. However, sequential (SEQ) treatments [PRE followed by (fb) POST] provided better sicklepod control than single herbicide treatments. Metribuzin and metribuzin + chlorimuron alone or used in a SEQ program provided similar PRE control of sicklepod, and both controlled sicklepod better than imazaquin in 1991 and 1992. Chlorimuron alone or in a SEQ program provided better POST control than AC 263,222 or imazaquin alone when soil moisture levels at planting favored weed seed germination. When soil moisture levels at planting were unfavorable for weed seed germination, the residual activity of imazaquin provided the best season-long control. SEQ herbicide applications allowed soybean to attain higher seed yields than single (PRE or POST) herbicide treatments all 3 yr. However, only metribuzin fb chlorimuron in 1991 and 1992 and imazaquin fb imazaquin and imazaquin fb chlorimuron in 1993 allowed soybean to achieve seed yields similar to weed-free soybean. Soybean seed yields were greater with POST than with PRE herbicides 2 of 3 yr, but no single herbicide treatment provided soybean seed yields similar to weed-free soybean.

Use of creeping bentgrass [Agrostis stoloniferous L. var. palustris (Huds.)] on golf greens has expanded into the hotter, more humid regions of the United States where its quality is often low during summer months. The summer decline in bentgrass quality may be partially attributed to respiration rates exceeding photosynthesis during periods of supraoptimal temperatures and adverse soil conditions, such as excessive CO2 and inadequate O2 levels. The objectives of this study were to examine the effects of high temperature, high soil CO2, and irrigation scheduling on creeping bentgrass growth. A growth chamber study was conducted using `A-1' creeping bentgrass. Treatments included all combinations of three day/night temperature regimes (26.5/21 °C, 29.5/24 °C, and 32/26.5 °C), three irrigation schedules (field capacity daily, field capacity every two d, and half field capacity daily), and four soil CO2 injection levels (10%, 5%, 0.03%, and a noinjection control). Creeping bentgrass shoot and root dry weights and net photosynthetic rates were greater for day/night temperatures 2 reduced bentgrass net photosynthesis by 37.5 μmol CO2/m2/s. Shoot and root total nonstructural carbohydrates also were lowest for highest temperature regime. Respiration exceeded gross photosynthesis at 32/26.5 °C when 5% and 10% CO2 injection levels were used, indicating a carbon deficit occurred for these conditions. Irrigation volume and frequency did not affect bentgrass growth. High temperatures combined with high soil CO2 levels produced poorest turf quality.

Field experiments were established to evaluate coffee senna control in cotton with registered PRE, early POST-directed (EPD), and late POST-directed (LPD) herbicides and with pyrithiobac applied PRE and early POST. Fluometuron and norflurazon applied PRE controlled coffee senna 87 and 65%, respectively, 6 wk after planting (WAP). Methazole applied EPD controlled coffee senna 96% 2 wk after application, whereas fluometuron and MSMA applied EPD controlled 70 and 16%, respectively. LPD applications of cyanazine, diuron, and prometryn averaged only 45% control 8 WAP. MSMA applied LPD controlled coffee senna only 12%. Fluometuron and norflurazon applied PRE followed by methazole applied EPD and cyanazine applied LPD controlled coffee senna 98 and 99% 6 WAP, respectively. PRE, early POST, and PRE followed by early POST applications of pyrithiobac controlled coffee senna 88, 89, and 95% 6 WAP, respectively. Seed cotton yields were similar to weed-free cotton with all treatments except MSMA applied EPD and the LPD treatments, all of which provided unacceptable (12 to 49%) control 8 WAP.