UV-B Radiation Impacts Shoot Tissue Pigment Composition in Allium fistulosum L. Cultigens

Plants from the Allium genus are valued worldwide for culinary flavor and medicinal attributes. In this study, 16 cultigens of bunching onion (Allium fistulosum L.) were grown in a glasshouse under filtered UV radiation (control) or supplemental UV-B radiation [7.0 mol⋅m −2 ⋅s −2 (2.68 W⋅m −2 )] to determine impacts on growth, physiological parameters, and nutritional quality. Supplemental UV-B radiation influenced shoot tissue carotenoid concentrations in some, but not all, of the bunching onions. Xanthophyll carotenoid pigments lutein and -carotene and chlorophylls a and b in shoot tissues differed between UV-B radiation treatments and among cultigens. Cultigen "Pesoenyj" responded to supplemental UV-B radiation with increases in the ratio of zeaxanthin + antheraxanthin to zeaxanthin + antheraxanthin + violaxanthin, which may indicate a flux in the xanthophyll carotenoids towards deepoxydation, commonly found under high irradiance stress. Increases in carotenoid concentrations would be expected to increase crop nutritional values

Effect of Soybean Oil Fatty Acid Composition and Selenium Application on Biodiesel Properties

Biodiesel consisting principally of monounsaturated fatty acid methyl esters (FAME) has been reported to have the optimal balance between cold flow properties and oxidative stability, therefore producing a superior fuel. In addition, treating biodiesel with antioxidants such as selenium (Se) also increases oxidative stability. Fuel properties including acid value (AV), cloud point (CP), iodine value (IV), pour point (PP), peroxide value (PV), induction period (IP), onset temperature (OT), and kinematic viscosity (KV) were used to evaluate a newly developed Roundup Ready® soybean recombinant inbred line (RIL) and a commercial cultivar. The RIL had a fatty acid profile with elevated levels of monounsaturated FAME. TN07-93RR was determined as the more desirable line for production of biodiesel, based on its fatty acid composition and subsequent fuel properties. The commercial cultivar AG3906 contained the highest abundance of polyunsaturated FAME and exhibited comparatively high IV and low oxidative stability. AG3906 was therefore not acceptable under the European biodiesel standard, EN 14214. However, TN07-93RR and AG3906 both were considered satisfactory according to the American biodiesel standard, ASTM D6751. Foliar treatment of soybean plants with varying amounts of Se had no effect on subsequent biodiesel oxidative stabilities

Cytochrome P450 Inhibitors Reduce Creeping Bentgrass (Agrostis stolonifera) Tolerance to Topramezone

Creeping bentgrass (Agrostis stolonifera L.) is moderately tolerant to the p-hydroxyphenylpyruvate dioxygenase-inhibiting herbicide topramezone. However, the contribution of plant metabolism of topramezone to this tolerance is unknown. Experiments were conducted to determine if known cytochrome P450 monooxygenase inhibitors 1-aminobenzotriazole (ABT) and malathion alone or in combination with the herbicide safener cloquintocet-mexyl influence creeping bentgrass tolerance to topramezone. Creeping bentgrass in hydroponic culture was treated with ABT (70 μM), malathion (70 μm and 1000 g ha(-1)), or cloquintocet-mexyl (70 μM and 1000 g ha(-1)) prior to topramezone (8 g ha(-1)) application. Topramezone-induced injury to creeping bentgrass increased from 22% when applied alone to 79 and 41% when applied with malathion or ABT, respectively. Cloquintocet-mexyl (70 μM and 1000 g ha(-1)) reduced topramezone injury to 1% and increased creeping bentgrass biomass and PSII quantum yield. Cloquintocet-mexyl mitigated the synergistic effects of ABT more than those of malathion. The effects of malathion on topramezone injury were supported by creeping bentgrass biomass responses. Responses to ABT and malathion suggest that creeping bentgrass tolerance to topramezone is influenced by cytochrome P450-catalyzed metabolism. Future research should elucidate primary topramezone metabolites and determine the contribution of cytochrome P450 monooxygenases and glutathione S-transferases to metabolite formation in safened and non-safened creeping bentgrass

Accumulation and Bioavailability of Dietary Carotenoids in Vegetable Crops

Carotenoids are lipid-soluble pigments found in many vegetable crops that are reported to have the health benefits of cancer and eye disease reduction when consumed in the diet. Research shows that environmental and genetic factors can significantly influence carotenoid concentrations in vegetable crops, and that changing cultural management strategies could be advantageous, resulting in increased vegetable carotenoid concentrations. Improvements in vegetable carotenoid levels have been achieved using traditional breeding methods and molecular transformations to stimulate biosynthetic pathways. Postharvest and processing activities can alter carotenoid chemistry, and ultimately affect bioavailability. Bioavailability data emphasize the importance of carotenoid enhancement in vegetable crops and the need to characterize potential changes in carotenoid composition during cultivation, storage and processing before consumer purchase

Seed Germination Response of Rapid-Cycling \u3cem\u3eBrassica oleracea\u3c/em\u3e Grown Under Increasing Sodium Selenate

Breeding plants to be more efficient at micronutrient accumulation is a proposed strategy for fighting worldwide malnutrition of humans. Selection for increased selenium (Se) in Brassica oleracea L. is possible. However, when present at high levels, micronutrients such as Se can affect seed germination and subsequently hamper breeding efforts. The objectives of this study were: (1) to evaluate the accumulation of Se in seeds of B. oleracea; and (2) to determine effects that Se accumulation may have on seed germination. Plants of a rapid-cycling B. oleracea population were grown in nutrient solutions with sodium selenate (Na2SeO4) concentrations up to 7 mg L-1 (2.93 mg Se L-1). Seeds and leaves were harvested from the selenized plants and analyzed for Se content using atomic absorption spectrophotometry. Germination percentage and rate were determined by sowing seeds in moistened towels, placing them in an incubator at 21°C, and observing radicle emergence. Selenium accumulated in the seeds, but at a lower level than in the leaves. Seed Se content increased linearly with increasing Na2SeO4 in solution culture. A significant difference in germination percentage occurred if Na2SeO4 was in solution at 5 mg L-1 or higher. However, even at the higher selenate treatments, germination percentage never fell below 94%. Germination rate was little affected by the Se content in the seeds. These observations provide evidence that Se accumulation in seeds is not likely to hamper breeding efforts for Se enrichment in B. oleracea at Se levels similar to this study

Pre-harvest Cultural Growing Conditions Can Influence Carotenoid Phytochemical Concentrations in Vegetable Crops

Carotenoids are secondary plant metabolites that serve antioxidant functions in plant photosynthetic processes, as well as in actions of disease reduction in mammalian systems. The antioxidant activity associated with carotenoids is attributed to their unique chemical structures. The production of antioxidant compounds within plants can increase, or decrease, in response to various forms of environmental stress. Stress is a term used to collectively describe numerous conditions that can have negative impacts on plant performance. Stress responses form continuums from very rapid physiological changes to much slower morphological changes. Plant secondary metabolites, such as carotenoids, serve functional roles to overcome the negative consequences to plant growth and development caused by a stressful environment. Carotenoid accumulation appears to be shaped by a plant species’ physiological, genetic, and biochemical attributes, as well as environmental growth factors, such as light, temperature, and soil fertility. Pre-harvest cultural management factors will also influence the accumulation of carotenoids in plant foods. Carotenoid accumulations have been shown to change in response to environmental manipulations, which can increase stress imposed on the growing plants. Changes in the growing air temperature, irradiance level, irradiance photoperiod, and nutritional fertility regime can all influence plant carotenoid accumulations. Manipulation of cultural growing conditions and time of harvest will influence plant physiological status, which can determine phytochemical (carotenoid) concentrations present in fruit and vegetable crops

Sequentially Reducing Sulfate Fertility During Onion Growth and Development Affects Bulb Flavor at Harvest

A major decision in producing onions with mild flavor on low sulfur soils is determining when to stop applying SO4-2 to the crop. Sulfate (SO4-2) is necessary for good early growth, but high levels of available SO4-2 late in the season increase bulb pungency. The objective of this research was to determine how sequentially reducing the availability of SO4-2 during onion growth and development would affect flavor intensity and quality of Granex-type onions. Starting 77 days before harvest, SO4-2 concentrations were lowered from 1 mM to 0.05 mM on different blocks of onions in a greenhouse experiment at bi-weekly intervals. Total leaf and bulb S were measured at harvest to monitor S accumulation as SO4-2 fertility was sequentially reduced. Bulbs were harvested and analyzed for flavor precursors and their biosynthetic intermediates, gross flavor intensity as measured by enzymatically developed pyruvic acid (EPY), and soluble solids content. As SO4-2 fertility reductions were delayed during the experiment, total leaf and bulb S increased linearly. In addition, bulb EPY concentrations increased linearly as SO4-2 reduction was delayed, indicating increases in overall flavor intensity. While the total concentration of flavor precursors did not significantly change in response to lowering SO4-2 fertility during the experiment, the concentrations of MCSO to 1-PRENCSO did. MCSO concentration decreased and then increased in a quadratic manner. MCSO produces fresh onion and cabbage like flavors. 1-PRENCSO, on the other hand, increased linearly as the high SO4-2 fertility level was extended through bulb maturation. Increasing concentrations of 1-PRENCSO causes onions to have significantly more heat and mouth burn when eaten. Reducing available SO4-2 49 days prior to harvest coincided with a reduction in EPY and a change in the flavor biosynthetic pathway that appeared to be associated with the metabolic changes occurring with the onset of bulbing. Chemical names used: enzymatically developed pyruvic acid (EPY); methyl cysteine sulfoxide (MCSO); 1-propenyl cysteine sulfoxide (1-PRENCSO)

Nitrogen Concentration Affects Nutrient and Carotenoid Accumulation in Parsley

Previous research has suggested that the herbal crop parsley (Petroselinum crispum Nym.) has a relatively high concentration of nutritionally important carotenoid phytonutrients, such as lutein-zeaxanthin and β -carotene. Nitrogen (N) has the most direct impact on plant growth, but influence of N on phytonutritional quality is contradictory. Therefore, the objectives of this study were to measure the effects of different concentrations of N on growth, elemental accumulation, and carotenoid production in parsley. \u27Dark Green Italian\u27 parsley was greenhouse-grown in a nutrient solution with 6.0, 13.1, 26.3, 52.5, or 105.0 mg N L-1. After 8 weeks, plants were harvested and analyzed for biomass production, micro- and macronutrient concentrations, and lutein-zeaxanthin and β -carotene levels. Increasing N in the nutrient solution increased plant biomass, leaf tissue N, phosphorus (P), potassium (K), lutein-zeaxanthin, β -carotene, and chlorophyll. Leaf iron (Fe), manganese (Mn), and molybdenum (Mo) decreased with increases in N in nutrient solutions. Quadratic increases in response to increasing solution N occurred for leaf calcium (Ca), magnesium (Mg), sulfur (S), boron (B), copper (Cu), and zinc (Zn). Increasing the elemental and carotenoid concentrations in parsley through N fertility modification would be expected to increase the nutritional value of this culinary herbal crop

Nitrogen Levels Influence Biomass, Elemental Accumulations, and Pigment Concentrations in Spinach

Spinach (Spinacia oleracea L.) has one of the highest United States per capita consumption rates among leafy vegetable crops, and also ranks second for lutein and β-carotene carotenoid concentration. The objectives of this study were to determine the effects of nitrogen (N) concentration on elemental and pigment accumulation in spinach. Two spinach cultivars (\u27Melody\u27 and \u27Springer F1\u27) were greenhouse grown in nutrient solution culture under N treatments of 13, 26, 52, and 105 mg L- 1. Leaf tissue biomass increased from 45.6 to 273.2 g plant- 1 and from 127.0 to 438.6 g plant- 1 as N increased from 13 to 105 mg L- 1 for \u27Springer F1\u27 and \u27Melody\u27, respectively. Leaf tissue N, phosphorus (P), calcium (Ca), magnesium (Mg), copper (Cu), and zinc (Zn) responded to N treatments. Lutein accumulations, expressed on a fresh weight basis, responded quadratically to increasing N treatments for \u27Springer F1\u27. Maximum lutein values were 110 and 76 μ g g- 1 on a fresh weight basis, and maximum β-carotene values were 85 and 57 μ g g- 1 on a fresh weight basis for \u27Springer F1\u27 and \u27Melody\u27, respectively. Interestingly, N levels had a significant effect on carotenoid accumulation in both \u27Springer F1\u27 and \u27Melody\u27 when the pigments were expressed on a dry weight basis. Leaf tissue lutein increased from 0.59 to 1.06 mg g- 1 and from 0.59 to 0.90 mg g- 1 on a dry weight basis with increasing N treatments for \u27Springer F1\u27 and \u27Melody\u27, respectively. Reporting lutein and β-carotene on both a fresh and dry weight basis may be the most accurate way to express the carotenoid values of spinach