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Szu-Chin Peng, Iou-Zen Chen, and Cheng-Yung Cheng

also varied among species. Thus, in the application of the floating culture system, plant provenance and genotype should be considered when considering optimum water temperatures. Applications of exogenous auxin also were effective in promoting

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Francisco Alcon, Mari Carmen García-Martínez, María Dolores De-Miguel, and María Ángeles Fernández-Zamudio

. Agr. Res. 6 320 332 Garibaldi, A. Minuto, A. Grasso, V. Gullino, M.L. 2003 Application of selected antagonistic strains against Phytopthora criptogea on gerbera in closed soilless systems with

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Pinghai Ding*, Minggang Cui, and Leslie H. Fuchigami

Reserve nitrogen is an important factor for plant growth and fruiting performance in tree fruit crops. The fall foliar urea application appears to be an efficient method for increasing N reserves. The effect of fall foliar urea application on N reserves and fruiting performance were studied with four year old `Gala'/M26 trees grown in 20 gallon containers in a pot-in-pot system from 2001 to 2003 at the Lewis-Brown Horticulture Farm of Oregon State Univ.. The trees were either sprayed with 0 or 2 times 3% urea after harvest in October. Shoot and spur samples were taken at the dormant season for reserve N analysis. Fruit performance was recorded in the following growing season. The fall foliar application significantly increased spur N reserve and had the trend to increase shoot N reserve but not significantly. The fall foliar application significantly increased tree fruit set and cluster fruit set. With normal fruit thinning, fall foliar urea application has the trend to increase both tree yield and average fruit size; without fruit thinning, fall foliar urea application has the trend to increase tree yield. These results indicate that fall foliar urea application an effective method to increase reserve N for maintaining tree yield.

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Matthew Kleinhenz, Annette Wszelaki, Sonia Walker, Senay Ozgen, and David Francis

Successful organic farming requires synchronizing soil-based processes affecting nutrient supply with crop demand, variable among and within crops. We report here on two studies conducted in transitional- (TO) and certified-organic (CO) systems containing subplots that, annually, were either amended with compost or not amended prior to vegetable crop planting. Dairy-manure compost was added at rates providing the portion of a crop's anticipated nitrogen requirement not provided by a leguminous rotation crop and/or carryover from previous compost application. In the TO study, potato (2003), squash (2004), green bean (2005), and tomato (2006) were planted in main-season plots in open fields and high tunnels, and beet, lettuce, radish, spinach, and swiss chard were planted in high tunnels in early spring and late fall. Long-term CO open-field plots (±compost) were planted to multiple varieties of lettuce, potato, popcorn, and processing tomato in 2004–2006. Drip irrigation was used in all TO plots and CO lettuce and processing tomato plots. Treatment effects on crop physical and biochemical variables, some related to buyer perceptions of crop quality, were emphasized in each study. Yield in TO, compost-amended plots exceeded yield in unamended plots by 1.3 to 4 times, with the greatest increases observed in high-tunnel-grown mesclun lettuce and the smallest response observed in potato. Similar results were found in CO plots, although compost effects differed by crop and variety. The data suggest that: 1) compost application and the use of specific varieties are needed to maximize yield in organic vegetable systems in temperate zones, regardless of age; and 2) production phase management may influence buyer-oriented aspects of crop quality.

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Dennis R. Decoteau, Heather A. Hatt, John W. Kelly, Margaret J. Mcmahon, Nihal Rajapakse, Roy E. Young, and Robert K. Pollock

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M.L. Baker, D.R. Earhart, and V.A. Haby

When poultry litter (PL) is applied to meet the nitrogen (N) needed for plant growth, phosphorus (P) can accumulate, leading to non-point source pollution of surface water. This study was conducted at Overton, Texas on a Bowie fine sandy loam (fine-loamy, siliceous, thermic, Plinthic Paleudults) to investigate the use of warm- and cool-season forage legumes in rotational cropping systems to remove excess P. Cropping systems were: spring legume—fall vegetable (SL-FV), spring vegetable—fall legume (SV-FL), and spring vegetable-fall vegetable (SV-FV). Warm- and cool-season legumes were Iron and Clay cowpea and crimson clover, respectively. Poultry litter rates were 0, 1X, 2X, 4X, and commercial blend (CB) as subplots. Fertility treatments were applied to vegetable plots only. The crop, IX PL and CB rate for each season were: spring 1995—watermelon, 2.2 t·ha-1, 48.8N—12.2P—28K kg·ha-1; fall 1995—turnip, 8.3 t·ha-1, 89.6N—24.4P—28K kg·ha-1; spring 1996—tomato, 6.7 t·ha-1, 100.9N—17.1P—78.5K kg·ha-1. Soil P increased at all depths sampled (0-15, 15-30, and 30-45 cm) as PL rate increased. Residual P from CB was equal to the control. Through spring 1996, soil P concentration in the surface 0-15 cm was increased by all systems. System SV-FL reduced P accumulation by 35.6 mg·kg-1 when compared to SL-FV and 44.7 mg·kg-1 when compared to SV-FV. Residual P continued to increase as PL rate increased. Rate of increase was reduced by a system of SV-FL.

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Arlie A. Powell, Karl Harker, Roger Getz, and Eugene H. Simpson

In order to provide timely weather information to county agents (CEA) and growers, a sophisticated user friendly weather information program was developed that provides over 900 weather files daily to users. This program uses a 420 Sun Server that automatically downloads files from the NWS office on the AU campus and makes them instantly available to CEA offices via the Extension Network. Growers may obtain information from CEAS or use their personal computers to access a “Weather Board”. A chilling/growing degree hour (GDH) model (mod. 45) has been developed for peaches that provides a good estimate of when rest is completed and allows prediction of phenological stages through flowering. This information assists growers with orchard management decisions. Studies with peaches were conducted using the chilling/GDH model to properly apply hydrogen cyanamide (Dormex) to replace lack of chilling. This work resulted in an effective application timing based on chilling accumulation and allowed development of a forecast model for grower use.

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Yulan Xiao and Toyoki Kozai

A photoautotrophic or sugar-free medium micropropagation system (PAM) using five large culture vessels (volume = 120 L each) with a forced ventilation unit for supplying CO2-enriched air was developed and applied to commercial production of calla lily (Zantedeschia elliottiana) and china fir (Cunninghamia lanceolata) plantlets. The culture period of calla lily plantlets in the PAM was reduced by 50%, compared with that in a conventional, photomixotrophic micropropagation system (PMM) using small vessels each containing a sugar-containing medium. Percent survival ex vitro of calla lily plantlets from the PAM was 95%, while that from the PMM was 60%. The production cost of calla lily in the PAM was reduced by about 40%, compared with that in the PMM, and the initial investment per plantlet for the PAM was ≈10% lower than that for the PMM. The sales price of ex vitro acclimatized calla lily plantlet was increased by 25% due to its higher quality, compared with plantlets produced in the PMM.

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Kazuhiro Fujiwara, Toshinari Sawada, Yoshikatsu Kimura, and Kenji Kurata

A light-emitting diode (LED)-low light irradiation (LLI) storage system was developed for suppressing the change in dry weight and maintaining the quality of green plants during long-term storage. In this system, the carbon dioxide (CO2) exchange rate was maintained at zero by automatically adjusting the photosynthetic photon flux density (PPFD) with a proportional-integralderivative (PID) controller. The voltage supplied to the LEDs was controlled by the difference between the inflow (400 μmol·mol-1) and outflow CO2 concentrations in the storage case. Grafted tomato (Lycopersicon esculentum; scion = `House Momotaro'; rootstock = `Anchor T') plug seedlings were stored at 10 °C for 35 days under four different LLI conditions as a system operating test: fixed red light irradiation at 2 μmol·m-2·s-1, PID-controlled red light irradiation with no blue light, and PID-controlled red light irradiation with blue light at 0.2 or 1.0 μmol·m-2·s-1. The results showed that the automatic PPFD control during LED-LLI helped suppress changes in dry weight during storage as expected. Furthermore, it was found that addition of a low percentage of blue light improved the morphological appearance of the seedlings and reduced the PPFD required to suppress the change in dry weight.

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Kathleen Delate

102 WORKSHOP 13 (Abstr. 686-687) Vegetable Cropping Systems Research: Techniques, Evaluation, and Application Tuesday, 25 July, 2:00-4:00 p.m.