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  • Author or Editor: Vincent A. Fritz x
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Recent adoption of a raised bed production system for improved drainage on muck soils prompted experimentation to improve N use efficiency. The established methods of N fertilization was to simply broadcast 908 kg·ha–1 of 10–26–27 prior to planting in single rows. The raised bed production system results in a concentrated rooting zone directly underneath the raised bed. A system that places the N fertilizer within the root zone of influence at a peak time of crop utilization would increase N use efficiency, reduce fertilizer costs, and promote appropriate environmental stewardship. The use of a spoke wheel injector to sidedress N fertilizer effectively reduced total fertilizer costs by half, while producing onion yields equal to or greater than the established broadcast method under the raised bed production system. In addition, the use of the spoke wheel injector was not intrusive to the integrity of the raised bed, which allowed realization of benefits from using raised beds for the entire growing season.

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Germination and stand establishment of shrunken-2 sweet corn is a major production-related problem, particularly during early spring in the upper Midwest U.S. Several potential physical and physiological factors have been identified as contributors to poor stand establishment. Poor pericarp integrity and high sucrose levels may lead to non-uniform moisturization and imbibitional injury. Studies were conducted to determine if the use of “controlled moisturization” preplant treatments reduced imbibitional injury and improved germination and seedling vigor. Both laboratory and field results will be discussed.

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Turnips (Brassica rapa. subsp. rapa L.) produce glucosinolates (GSLs), thioglucosides whose hydrolyzed derivatives have been shown to provide chemopreventive benefits. Two cultivars of turnips [‘Just Right’ (JR) and ‘Scarlet Queen’ (SQ)] were grown under three different temperature regimes to assess the role of temperature on GSL production in roots and shoots. When compared with low-temperature treatments, high-temperature treatments increased total and individual GSLs in a tissue- and genotype-specific manner. When compared with low-temperature treatments, total GSLs were ≈70% and 130% higher in JR shoots and roots, respectively, grown at high-temperature treatments. High temperatures also increased total GSLs in SQ shoots and roots by ≈80% and 85%, respectively, when compared with low temperatures. Gluconasturtiin (GNS, 2-phenylethyl GSL) concentration was inversely correlated with temperature with high-temperature treatments resulting in 20% and 48% less GNS than low-temperature treatments in JR and SQ roots, respectively. The indolic GSL, 1-methoxyglucobrassicin (1MGB; 1-methoxy-3-ylmethyl GSL), was the root GSL most elevated by increased temperature resulting in a 1000% increase on average in both cultivars between the low- and high-temperature treatments. These results show promise for the use of temperature to enhance the health-promoting properties of turnip because 1MGB has potent chemopreventive effects. Gene expression analysis suggests that some BrMYB transcription factor expression levels are associated with temperature-dependent changes in GSL accumulation; however, this association varies between cultivar and tissue type.

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It is commonly recommended to apply phosphorus- or nitrogen- and phosphorus-containing water-soluble fertilizers to annual vegetables at transplant to improve establishment and enhance yield. Plastic mulches are also recommended to increase soil temperature and enhance yield through similar root growth-promoting mechanisms early in the season. Our aim was to determine if the recommendations for transplant fertilizer solutions and plastic mulch are justified, and if the effects are interactive in a clay loam soil with moderate or high levels of existing phosphorus fertility and organic matter. We transplanted ‘Plum Dandy’ tomato (Solanum lycopersicum) in 2014 and 2015 into a field with high fertility using black polyethylene mulch or no mulch, and transplant solution containing water, 320 mg/plant nitrogen, or 320 mg/plant nitrogen + 475 mg/plant phosphorus. Mulch was removed 26 to 28 days after transplanting to eliminate midseason and late season mulch effects. We found yield-promoting and maturity-hastening effects in both years from transplant solutions containing both nitrogen and phosphorus (18% greater total ripe fruit weight than water control), and similar benefits of early season black plastic mulch (24% greater total ripe fruit weight than no mulch), indicating usefulness of either treatment in tomato production. We found no interactive effects of mulch and transplant solution.

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Disease management is an important step in any crop establishment system. Emergence of field-seeded crops may take several weeks for many species and represents a vulnerable stage of plant growth. This paper considers various biological, chemical, and physical seed treatments for improved seed performance. The role of seed quality and cultural practices in seedling establishment also is reviewed. Multidisciplinary approaches to improving horticultural crop establishment are promising.

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The objective of this study was to examine seed maturity at harvest as it relates to seed vigor in two commercial shrunken-2 (sh2 J sweet corn hybrids (Zea mays L. var rugosa Bonaf., cvs. Florida Staysweet, Crisp N' `Sweet 710). Seed harvest began at 0.76 g H2O/g fresh weight in 1987 and at 0.70 g H2O/g fresh weight in 1988 and 1989, and was continued at gradually declining moisture levels until frost. In five different tests of seed performance, seed of `Florida Staysweet' (FLASS) harvested between 0.23 to 0.57 g H2O/g fresh weight in 1987 possessed the highest seedling vigor. In 1988 and 1989, maximum vigor was achieved by FLASS seed harvested from 0.40 to 0.60 g H2O/g fresh weight and `Crisp N' Sweet 710' (CNS) seed harvested from 0.45 to 0.65 g H2O/g fresh weight. Standard germination test, seedling growth cold test (SGCT), and seed leachate conductivity provided the most consistent results to `determine optimum seed maturity. Seed weight was not as reliable an indicator of seed vigor in 1988 and 1989 as it was in 1987, and endosperm and embryo weights did not correlate with seedling vigor in any year.

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Abstract

Sand nutrient cultures (containing different Ca2+ compositions) were used to modify the petiole Ca2+ concentrations in Chinese cabbage (Brassica campestris Group pekinensis). Petiole sections (6.5 cm2) from inner and outer leaves, 30 and 60 days after transplanting, were inoculated with Erwinia carotovora ssp. carotovora to evaluate resistance to soft rot incidence and disease progression. Xylem exudates collected from the plants in the sand nutrient culture were analyzed for Ca2+ concentration. Elevated petiole Ca2+ concentrations were not correlated with the development of soft rot in inoculated petiole sections. Plant age and petiole position (inner and outer) did not consistently affect soft rot development. There was a trend of reduced soft rot in inoculated petiole (inner) sections of ‘Hakuran’ plants as the xylem exudate Ca2+ levels increased.

Open Access

This study was conducted to determine if changes in the raffinose: sucrose ratio in embryos of shrunken-2 sweet corn (Zea mays L.) hybrids were related to differences in seed leachate conductivity between two hybrids harvested at four maturities and artificially dried to 0.10 g H2O/g fresh weight. The ratio of raffinose: sucrose differed for `Crisp N' Sweet 710' (CNS) and `How Sweet It Is' (HSII). The mass ratio of raffinose: sucrose in CNS was >0.3 in seed harvested between 0.44 to 0.64 g H2O/g fresh weight and increased as seed dried from the initial harvest moisture to 0.10 g H2O/g fresh weight. Raffinose: sucrose ratios of HSII were <0.3 at all harvests between 0.55 to 0.72 g H2O/g fresh weight, but changes during desiccation were not as pronounced. Leachate conductivity of whole seeds of CNS and HSII decreased as seeds were harvested at progressively lower moisture contents. We suggest that a higher raffinose: sucrose ratio may be indicative of increased seed vigor in shrunken-2 hybrids.

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