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Shawn D. Lyons, William B. Miller, H. Christian Wien, and Neil S. Mattson

determining competency to flower and may affect factors related to crop quality, such as inflorescence size and number of flowers produced per plant ( De Hertogh and Le Nard, 1993 ), but the optimum bulb size for these cultivars has not been determined. The

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Ryan M. Warner

calculated as 7.3 °C and 5.5 °C for petunia ‘Easy Wave Coral Reef’ and ‘Wave Purple’, respectively ( Blanchard et al., 2011a ). In addition to influencing crop timing, temperature also influences crop quality parameters, such as flower production, branching

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Matthew D. Kleinhenz

Declines in cabbage (Brassica oleracea var. capitata) crop quality may result from delaying harvest to allow for greater total yield. An accurate, reliable, rapid and inexpensive method to estimate yield before harvest not requiring direct weight measurements would assist cabbage growers and handlers in harvest scheduling. Results from 3 years of study during which a tool to predict cabbage yield was developed and tested are reported here. The tool was developed using plots containing a total of 13 cabbage varieties (fresh market and processing types) planted in May to July 1999 and 2000 at the Ohio Agricultural Research and Development Center (OARDC) Vegetable Crops Research Branch in Fremont, Ohio. Exhaustive measurement of marketable yield and traits of hundreds of individual heads taken from these plots revealed simple mathematical relationships among head number, size, density, and yield. The tool was tested by comparing marketable yield predicted using a formula based on these head trait relationships to direct measures of crop yield in three different studies: 1) a factorial of nine varieties and 2 planting dates completed in Fremont in 1999, 2000, and 2001, 2) a survey of 12 commercial cabbage fields in northwestern Ohio encompassing six varieties and various planting dates and fertility regimens, in 2001, and 3) a factorial of 32 varieties and 2 planting dates (10 May, 20 June) completed in Fremont in 2001. The R2 for predicted and actual marketable yield in commercial fields and experimental plots ranged from 0.72 to 0.97. Of 510 individual estimatesof marketable yield, 48% were within 10% of actual yield values. The average quotient of predicted divided by actual marketable yield for 510 estimates made for commercial and experimental samples in 1999-2001 was 0.975. Results from this study were applied to the development of a table of potential use to crop managers in obtaining preharvest estimates of cabbage crop marketable yield. The table and its underlying assumptions are easily adjusted for local conditions.

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Matthew D. Kleinhenz and Annette Wszelaki

Yield and relationships among head traits were recorded in order to better understand the effects of planting date and cultivar selection on crop quality characteristics and to help increase the efficiency of cultivar development, evaluation, and selection. A total of seven cultivars of fresh market-type cabbage (Brassica oleracea L., Capitata Group) were planted in May and June of 1999 and 2000 at the OARDC Vegetable Crops Research Branch in Fremont, Ohio. Total and marketable yield, head traits (e.g., size, weight, density), and core dimensions were recorded at harvest. Main effects of year (Y), planting date (PD), and cultivar (C) and the Y × C interaction significantly affected seven to 10 of 10 head and core traits. However, the PD × C interaction was significant for head density, the ratio of head polar and equatorial diameter, and core base width. The Y × PD interaction was significant for six of 10 head and core traits. May planting tended to result in greater yield and larger, heavier heads with greater polar/equatorial diameter values relative to June planting. However, head density was unaffected by planting date. The number of head and core traits affected by planting date differed among cultivars. For example, six of 10 head and core traits were significantly affected by planting date in `Cheers' and `DPSX315' while one trait was affected by planting date in `SuperElite Hybrid'. The weight of numerous, individual, market-ready, trimmed heads showed a strong (avg. R 2 value = 0.92) quadratic relationship to average head diameter. These data suggest that large-scale germplasm evaluations may benefit by including multiple plantings, as head weight, volume, diameter, and shape were affected by planting date, possibly due to variation in temperature and rainfall patterns. The data also suggest that routine measurement of numerous head traits in the same evaluations may be unnecessary, as selected traits (e.g., diameter and weight, head volume, and core volume) were strongly related.

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Aparna Gazula, Matthew D. Kleinhenz, Joseph C. Scheerens, and Peter P. Ling

Although nutritional value, texture, size, shape, flavor, and freedom from defects are major indicators of lettuce crop quality ( Arthey, 1975 ), leaf color is particularly important because it is often the first trait that registers with

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Pierre C. Robert

A better awareness of soil and crop condition variability within fields brought the notion, in the early 1980s that variable management within fields by zones rather than whole fields would increase profitability by doing the right thing at the right place in the right way. At the same time, the microcomputer became available and made possible the acquisition, processing, and use of spatial field data as well as the development of a new kind of farm machinery with computerized controllers and sensors. Precision agriculture (PA) has been considered for most common cropping systems and some specialty crops, worldwide. It is particularly well adapted to high value crops such as many horticultural crops. PA is still in infancy and its adoption varies greatly but precision agriculture is the agricultural system of the future. It offers a variety of potential benefits in profitability, productivity, sustainability, crop quality, food safety, environmental protection, on-farm quality of life, and rural economic development.

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Aparna Gazula, Matthew D. Kleinhenz, John G. Streeter, and A. Raymond Miller

Pigment concentrations in leaf tissue affect the visual and nutritional value-based indices of lettuce crop quality. To better discern the independent and interactive effects of temperature and cultivar on anthocyanin and chlorophyll b concentrations, three closely related Lolla Rosso lettuce cultivars (`Lotto', `Valeria', and `Impuls'), varying primarily in the number of genes controlling anthocyanin concentrations, were subjected to different air temperatures in controlled environments. Fifteen-day-old seedlings previously grown at 20 °C day/night (D/N) were transplanted into growth chambers maintained at 20 °C (D/N), 30/20 °C D/N and 30 °C D/N air temperatures. Twenty days later, leaf tissue was sampled for measures of pigment concentrations, calculated based on spectrophotometric absorbance readings taken at 530 nm (anthocyanin) and 660 nm (chlorophyll b) respectively. Although significant, the temperature × cultivar interaction resulted from differences in the magnitude (not direction) of the change in pigment concentrations among cultivars with changes in temperature. Regardless of cultivar, anthocyanin and chlorophyll b concentrations were highest, moderate and lowest after growth at 20 °C D/N, 30/20 °C D/N and 30 °C D/N respectively. Likewise, irrespective of temperature, anthocyanin and chlorophyll b concentrations followed the pattern `Impuls' (three genes) > `Valeria' (two genes) > `Lotto' (one gene). These data provide additional strong evidence that lettuce leaf pigment concentrations and growing temperatures are negatively related. The data also suggest that low temperatures during the dark phase may mitigate high temperature-driven reductions in lettuce leaf pigment levels.

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Patricia Millner, Sara Reynolds, Xiangwu Nou, and Donald Krizek

High tunnels and protected horticultural structures provide organic and conventional growers with an economic means for extending the harvest season of fresh fruits and vegetables in a wide range of climate zones in North America and elsewhere. This report focuses on benefits associated with high tunnel production of fresh organic produce, including recent data on phytonutrient quality. In addition, this report discusses concerns and knowledge gaps associated with the use of composts and manures relative to food safety of fresh produce and survival of enteric pathogens in the moist, cool, reduced ultraviolet conditions often prevalent in high tunnels during cool-season production. The role of preplant and production elements of Good Agricultural Practices and Good Handling Practices applicable to high tunnel systems is provided.

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Yanjun Guo, Terri Starman, and Charles Hall

Retail environments are rarely optimal for ornamental plants, and wilting caused by water stress is a major cause of postproduction shrinkage. The objective of this study was to determine the effect of two levels of substrate moisture content (SMC) applied during greenhouse production on angelonia (Angelonia angustifolia) ‘Angelface Blue’ and heliotrope (Heliotropium arborescens) ‘Simply Scentsational’ growth and physiological parameters and subsequent postproduction quality during simulated retail conditions. At the end of production, angelonia total plant shoot dry weight (DW) was reduced with 20% SMC compared with 40% SMC, and plants grown with 20% SMC had higher shoot coloring percentage, reduced internode length, and required less irrigation labor–related costs compared with 40% SMC. Heliotrope grown at 20% SMC produced the same size plant as 40% SMC, but had a higher shoot coloring percentage at the end of production and postproduction, indicating lower SMC resulted in higher visual quality compared with 40% SMC. For both species, 20% SMC increased plant visual quality compared with 40% SMC and reduced irrigation water input throughout production, resulting in reduced production costs and increased floral crop economic value.

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Annette Wszelaki, Sally Miller, Douglas Doohan, Karen Amisi, Brian McSpadden-Gardener, and Matthew Kleinhenz

The influence of organic soil amendments (unamended control, composted dairy manure, or raw dairy manure) and weed treatments [critical period (CP) or no seed threshold (NST)] on diseases, growth parameters, yield, and postharvest quality was evaluated over 3 years in a transitional organic crop rotation of tomato, cabbage, clover, and wheat. More growth, yield, and postharvest quality parameters were affected by amendment treatments in cabbage than in tomato. Significant differences in yield among amendment treatments were found in 2001 and 2003 in cabbage, with higher marketable and total yields in amended vs. control plots. Soil management effects on cabbage varied annually, though amendments were required to maximize crop growth, as head weight, size, and volume and core volume of treatment plots exceeded the control plots in 2002 and 2003. Few differences were found between weed treatments, although in 2001 cabbage heads from the NST treatment were larger than heads from the CP treatment. Similar results were found in tomato in 2003. Also, the CP treatment had a higher Area Under the Disease Progress Curve than the NST treatment in tomato in 2003. Overall, disease pressure was highest in tomato in 2001. But disease levels within years were mostly unaffected by amendment treatments. In cabbage, disease was more common in 2002 than in 2003, although head rot was more prevalent in compost-amended plots in 2003 than in manure-amended or control plots. Tomato postharvest quality parameters were similar among amendment and weed treatments within each year. Soil amendment may enhance crop yield and quality in a transitional-organic system. Also, weed management strategy can alter weed populations and perhaps disease levels.