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Matthew D. Stevens, Brent L. Black, John D. Lea-Cox, Ali M. Sadeghi, Jennifer Harman-Fetcho, Emy Pfeil, Peter Downey, Randy Rowland, and Cathleen J. Hapeman

The environmental effects of the three strawberry (Fragaria ×ananassa) cold-climate production systems were compared: the traditional method of conventional matted row (CMR) and the two more recently developed practices of advanced matted row (AMR) and cold-climate plasticulture (CCP). Side-by-side field plots were instrumented with automated flow meters and samplers to measure and collect runoff, which was filtered and analyzed to determine soil, pesticide, and nitrogen losses. Although annual mean runoff volumes were similar for all three production systems, the soil losses from CMR plots were two to three times greater than the CCP plots throughout the study and two to three times greater than the AMR plots only in the first year of the 3-year study. In general, decreases in erosion and runoff volumes were observed in plots that were disturbed less by machine operations and had less foot traffic as a result of decreased need for hand weeding and in the plots that used straw mulch in the furrows between the beds. Timing and intensity of precipitation events also influenced the amount of soil erosion. Pesticide residues and nitrogen losses were also greatest in the runoff from the CMR plots. The two systems that used drip fertigation, AMR and CCP, also had higher nitrogen uptake efficiencies. Overall, the CCP and AMR systems performed similarly for most criteria; however, considering the nonrenewable nature of the plastic mulch and the need to dispose of the plastic mulch in a landfill, the AMR system was more environmentally sustainable than the CCP system.

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Rie Sadohara, James D. Kelly, and Karen A. Cichy

effects were significant for all the color values of sweetened paste, but the environmental effects were significant only for a*, b*, and C* values ( Table 2 ). G×E effects were significant only for the a* value. Similar to the unsweetened paste, all white

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Peng Hwang, J. Creighton Miller Jr., and B. Greg Cobb

Field studies were conducted at two Texas locations: Lubbock, near the major production area for Texas potatoes, and College Station which is hotter and more humid. Early and late plantings were established at each location to compare cool and hot growing conditions. Nine genetically diverse cultivars, including those previously reported to be heat resistant or susceptible, were used in this study. Results indicated that the distribution of soluble carbohydrate and starch differed significantly among plant parts. In leaves and stems, glucose and fructose were the major soluble carbohydrates, while sucrose was the major soluble carbohydrate in tubers. Total soluble carbohydrate and starch content in leaves, stems and roots from the early plantings were significantly higher than those from the late plantings. Inositol increased significantly in the College Station late stress environment.

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Paul M. Lyrene

The effects of environmental factors, including chilling duration during dormancy and temperature during flower bud expansion, were studied on the following blueberry flower parameters: corolla length, corolla aperture diameter, stigma location relative to the apex of the corolla tube, position of the anthers relative to the stigma and to the apex of the corolla, and style length. Flowers on plants that were chilled over 1400 hours differed little from those that received only 310 chill units. Flowers that developed under warmer temperatures had significantly wider corolla apertures. In one experiment but not the other, corolla length and style length increased under warmer temperatures. For nearly every parameter in each of three experiments, there were significant environment × clone interactions. Overall, however, it appeared that neither lack of chill units during dormancy nor warm temperatures during flower development changed flower morphology enough to affect fruit set.

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D. Michael Glenn, R. Scorza, and W.R. Okie

Two unpruned narrow-leaf and two unpruned standard-leaf peach [Prunus persica (L.) Batsch.] selections were evaluated for physiological components related to water use efficiency {WUE [carbon assimilation (A) per unit of transpiration (T)]}. The purpose of the study was to assess the value of narrow-leaf phenotypes to improve WUE in peach and separate the environmental component of canopy geometry from the genetic components. The narrow-leaf characteristic itself did not confer improved WUE. The interception of light was a key determinant of WUE in these genotypes. Internal shading of the tree by excessive leaf area reduced daily WUE measured in gas exchange studies. Canopies that intercepted more than 75% of the photosynthetically active radiation (PAR) had reduced daily WUE. Dormant season pruning of the four genotypes lowered isotopic carbon discrimination and therefore increased seasonal WUE compared to unpruned trees. None of the genotypes had a significant correlation of seasonal WUE with leaf and fruit weight. Analysis of covariance indicated that `Bounty' and both narrow-leaf genotypes had greater leaf and fruit weight than `Redhaven' for a given level of PAR interception. `Bounty' had the least internal canopy shading of the four genotypes. Genetic differences in peach growth types can be selected for factors increasing WUE as well as increased productivity. Future work in peach breeding to improve WUE and productivity must take into consideration light interception, productivity, and WUE in an integrated manner to make real progress in the efficient use of water and light in the orchard environment.

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James C. Delouche

Abstract

The concentration of seed production for some crops in specific areas of the U.S. and of other countries is persuasive testimony of the influence of environmental factors on seed development and quality. The environmental factors that have contributed to the selection and establishment of these specialized seed production areas can be sketched in rather broadly in brief reviews of some of the areas.

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D. Michael Glenn, Ralph Scorza, and William R. Okie

Two unpruned willow leaf and two unpruned standard leaf peach [Prunuspersica(L.) Batsch.] selections were evaluated for physiological components related to water use efficiency (WUE). The purpose of the study was to assess the value of willow leaf phenotypes to improve water use efficiency in peach and separate the environmental from the genetic components. The willow leaf characteristic itself did not confer improved water use efficiency. Light interception was a key determinant of WUE in these genotypes and the relationship of WUE with intercepted photosynthetically active radiation (PAR) by the entire canopy indicated a significant negative correlation. Internal shading of the tree by excessive leaf area reduced WUE and canopies that intercept more than 60% of the PAR have reduced WUE. While WUE is improved by reducing the amount of PAR interception of the canopy, productivity is reduced. Neither of the willow leaf genotypes had a significant correlation of WUE with yield (leaf and fruit weight); however, the standard leaf type cultivars, `Bounty' and `Redhaven', had significantly different regressions that indicate greater productivity in `Bounty' for a given level of WUE. `Redhaven' was the least productive cultivar; `Bounty' was the most productive, and the two willow leaf genotypes were intermediate in the relationship of intercepted PAR with yield. Therefore, genetic differences in peach growth types can be selected for both increased WUE as well as increased productivity. Future work in peach breeding to improve WUE and productivity must take into consideration light interception, productivity, and WUE in an integrated manner to make progress in the efficient use of water and light.

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Ji Yeon Kang, Khalid E. Ibrahim, Doo Hwan Kim, Wha-Jeung Kang, and John A. Juvik

Gluconasturtiin is a glucosinolate (GS) present in Chinese cabbage and its breakdown product, phenelethyl isothiocyanate (PEITC), inhibits phase I enzyme activation of endogenous carcinogenic compounds and enhances phase II enzyme detoxication, reducing cancer risk and promoting health in humans. This study was conducted to evaluate the interaction between the genotype and the environment to influence GSs in Chinese cabbage. Twenty-five accessions were grown in three environments and tissue quantified for GS levels by HPLC. While gluconasturtiin was observed to be the most abundant GS form, 3-indolylmethyl GS (glucobrassicin) and 1-methoxy-3-indolylmethyl-GS (neoglucobrassicin) were also found. Significant differences were observed among tissues, genotypes and environments in GS concentration and composition. Gluconasturtiin ranged from 0.56 μmol·g-1

DW in leaf tissue of Hau No. 2 to 11.89 μmol·g-1 DW in Chilsung. There were dramatic differences among different tissues of the same genotype with young leaf and root tissues having significantly higher concentrations of gluconasturtiin than other tissues. Gluconasturtiin in Sandong No. 5 ranged from 1.69 μmol·g-1 DW in mature leaves to 18.69 μmol·g-1 DW in root tissue. GS content of the same genotypes in three different environments indicated that plants grown in the greenhouse had higher GS content compared to field grown plants. Results of this study indicate that genotypic variation and the growing environment have substantial effects on GS content in Chinese cabbage. This investigation provides important information for future genetic and molecular studies and has identified Chinese cabbage genotypes that offer superior health benefits to consumers.

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Jan E.P. Debaene and I.L. Goldman

Onion is a species within the Allium genus with great culinary importance. Onion extract contains organosulfur compounds that influence pungency and inhibit blood platelet aggregation. Antiplatelet activity has the potential of reducing cardiovascular disease. Onions are typically held in postharvest storage for up to 160 days, during which time volatile organosulfur compounds may be affected. A study was conducted to evaluate antiplatelet activity, pungency, and percent solids during cold storage of onions grown in replicated plots in Wisconsin and Oregon in 1994 and 1995. Organosulfur compound concentration and antiplatelet activity were also measured in progeny derived from crosses of inbred lines contrasting for pungency grown during 1995 and 1996 in Wisconsin. For the first study, bulbs were evaluated for antiplatelet activity, percent solids and pungency at 40day intervals after harvest. Significant differences were detected for these traits among years, states, dates of sampling, and lines. During the 120-day postharvest period in 1994, antiplatelet activity increased by 25% and 80% for Oregon and Wisconsin, respectively, averaged over all lines. During the same period in 1995, antiplatelet activity decreased by 35% and 4% in the two locations. For three out of four lines, antiplatelet activity was 4.6% higher for Wisconsin than Oregon. Averaged over states, antiplatelet activity was 9.7% higher in 1994 compared to 1995. Pungency was positively correlated with antiplatelet activity in Wisconsin. Broad-sense heritabilities were calculated for antiplatelet activity and organosulfur compound concentration. These data demonstrate that environmental factors influence postharvest flux of antiplatelet activity and pungency in onion.

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Krista C. Shellie and George L. Hosfield

Genetic and environmental interactions for bean cooking time, water absorption, and protein content were estimated with 10 dry bean (Phaseolus vulgaris L.) cultivars grown at three locations in Rwanda, Africa, during five consecutive harvests. The genotypic variance component was larger than genotype × environment variance components for the cooking time index and percent water absorption. No significant genotypic effect was observed for seed protein content. The phenotypic correlation (-0.37) between the cooking time index and percent water absorption was not strong enough to justify the use of water absorption as an indirect selection method for cooking time. The most efficient allocation of resources to evaluate the cooking time of common bean cultivars with a 25-pin bar-drop cooker was four field replications over two harvests at two locations. Water absorption was evaluated most efficiently with four field replications over two harvests at a single location.