Several Pesticides Influence the Nutritional Content of Sweet Corn

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Several Pesticides Influence the Nutritional Content of Sweet Corn Matthew A. Cutulle, Gregory R Armel, Dean Adam Kopsell, Henry P Wilson, James Brosnan, Jose J. Vargas, Thomas E hines, and Rebecca M Koepke-Hill J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.7b05885 • Publication Date (Web): 12 Feb 2018 Downloaded from http://pubs.acs.org on February 13, 2018

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Journal of Agricultural and Food Chemistry

Several Pesticides Influence the Nutritional Content of Sweet Corn

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Matthew A. Cutulle,1,4 Gregory R. Armel,2,4 Dean A. Kopsell,3,4 Henry P. Wilson,5 James T.

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Brosnan,4 Jose J. Vargas,4 Thomas E. Hines,5 Rebecca M. Koepke-Hill,4

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Coastal Research and Education Center, Clemson University, Charleston, SC 29414.

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Global Herbicide Development Group, BASF Corp., Research Triangle Park, NC 27709, USA.

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Environmental Horticulture Department, The University of Florida, Gainesville, FL, 32611,

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USA.

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Plant Sciences Department, The University of Tennessee, Knoxville, TN 37996, USA.

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Eastern Shore Agricultural Research and Extension Center, Virginia Polytechnic Institute and

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State University, Painter VA 23420.

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* To whom correspondence should be addressed. Phone: (843) 402-5399 Fax: (843) 571-4654

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E-mail:[email protected]

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One-sentence summary: Herbicides targeting the inhibition of photosynthesis, carotenoid and

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amino acid biosynthesis were applied with or without a safener that enhances P450 metabolism,

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and these mixtures changed levels of mineral elements, proteins, amino acids, sugars, fiber, and

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fatty acids in sweet corn kernels.

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ACS Paragon Plus Environment


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Abstract: Herbicides are pesticides used to eradicate unwanted plants in both crop and non-crop

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environments. These chemistries are toxic to weeds due to inhibition of key enzymes or

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disruption of essential biochemical processes required for weedy plants to survive. Crops can

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survive systemic herbicidal applications through various forms of detoxification including

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metabolism that can be enhanced by safeners. Field studies were conducted near Louisville,

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TN and Painter, VA to determine how the herbicides mesotrione, topramezone, nicosulfuron, and

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atrazine applied with or without the safener isoxadifen-ethyl would impact the nutritional quality

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of ‘Incredible’ sweet corn (Zea mays L. var. rugosa). Several herbicide treatments increased the

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uptake of the mineral elements phosphorous, magnesium, and manganese by 8 to 75%. All

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herbicide treatments increased protein content by 4 to 12%. Applied alone, nicosulfuron

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produced similar levels of saturated, monounsaturated, and polyunsaturated fatty acids when

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compared to the non-treated check, but when applied with isoxadifen-ethyl, fatty acids increased

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28 and 44%. Nicosulfuron plus isoxadifen-ethyl or topramezone or the combination of all three

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actives increased the concentrations of fructose and glucose (40 to 68%) whereas reducing levels

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of maltose or sucrose when compared to the non-treated check (-15 to -21%). Disruptions in

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biochemical pathways in plants due to the application of herbicides, safeners or other pesticides

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has the potential to alter the nutrient quality, taste and overall plant health associated with edible

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crops.

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Keywords: amino acids, carotenoids, fatty acids, fiber, herbicide

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1. INTRODUCTION Pesticides are substances that are used to repel, eradicate, or destroy the life cycle of

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pests. Over 900 million metric tons of pesticides are used annually in the United States to

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control many pests including, but not limited to insects, microbes, rodents, and weeds.1

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Pesticides that control weeds are referred to as herbicides. There are over 300 commercially

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available herbicides that target 27 different mechanisms within plants, including enzymes

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involved in the biosynthesis of carotenoids, chlorophyll, amino acids, fatty acids, lipids, and

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cellulose. The application of a pesticide concomitantly providing pest control and improved

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nutrition in a single crop system is not intuitive, although these chemicals induce physiological

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responses in both crops and weeds. Furthermore, collective societal attitudes towards pesticides

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are associated with less healthy fruits and vegetables.2 However, exploitation of plant

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biosynthetic pathways using pesticides may reveal chemical technologies that provide weed

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control and improve the nutrition of crops.

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The term hormesis describes how a low dose of a toxic substance, such as a pesticide, can

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be used to increase growth or output of certain biological processes.3,4 Low use rate applications

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of herbicides applied to specific crops can increase biomass, growth, protein content, and disease

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resistance. In these scenarios, herbicides were usually applied at sub-lethal or less than optimal

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rates to crops that would have been severely injured or killed had the herbicide been applied at

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an optimal dose.4,5,6 How herbicides applied to edible crops at registered rates can impact

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biosynthetic pathways responsible for the production or uptake of key nutrients beneficial to

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consumers of these plants has not been demonstrated.

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Mesotrione is a member of the triketone family of herbicides, which are structurally similar to leptospermone, a natural phytotoxin obtained from the Californian bottlebrush plant

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(Callistemon citrinus Stapf.).7 Mesotrione primarily controls broadleaf weeds from both a foliar

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and soil residual perspective.7 Topramezone is a member of the pyrazolone family of herbicides

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and typically provides better grass control and crop selectivity in corn compared to mesotrione,

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but has limited soil residual activity.7 Both herbicides are carotenoid biosynthesis inhibitors

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(CBI) currently labeled for weed control in corn (Zea mays L.) production.8 These herbicides

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competitively inhibit the enzyme p-hydroxyphenylpyruvate dioxygenase (HPPD), an essential

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component for the biochemical conversion of tyrosine to plastoquinone and α-tocopherol.

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Plastoquinone is a critical cofactor for phytoene desaturase, as well as an intermediate electron

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carrier in the photosynthetic electron transport chain.

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Nicosulfuron is a sulfonylurea herbicide that kills weeds by inhibiting the enzyme

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acetolactate synthase (ALS). This enzyme is responsible for the biosynthesis of the branched

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chain amino acids valine, leucine, and isoleucine. Nicosulfuron primarily control grass weeds in

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a grass crop like corn; however, nicosulfuron has limited selectivity in sweet corn (Zea mays L.

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var. rugosa).9,10 Using a safener, isoxadifen-ethyl, with nicosulfuron permits its use in several

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sweet corn varieties.11 Safeners like isoxadifen-ethyl, are a chemically diverse group of

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compounds that increase expression of enzymes such as glutathione S-transferases and

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cytochrome P450 monooxygenases.12 Activation of these enzymes results in detoxification of

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some herbicides. In the case of isoxadifen-ethyl, sweet corn hybrids that are heterozygous for a

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specific P450 (i.e., CYPcyp) can safely be treated with mixtures of certain HPPD and ALS

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inhibiting herbicides and isoxadifen-ethyl.11 Often ALS, HPPD inhibitors, and herbicides

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safeners like isoxadifen-ethyl will be applied in mixtures to provide broad-spectrum weed

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control with optimal crop tolerance in several different types of corn, including sweet corn.13

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Corn is the leading cereal crop in the world with greater than 1 billion metric tons

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produced annually and is ideally suited to conduct nutritional studies.14 Improvement in

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molecular and genomic technologies have allowed for improved nutrition in crops like corn.15 In

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addition to nutritional benefits, sweet corn has a significant impact on the U.S. agricultural

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economy. A total of 210,972 hectares of sweet corn were harvested commercially in 2014 in the

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U.S. with a total production value of $1.09 billion.16

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Improving sweet corn nutrition through herbicide and safener applications could

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potentially be valuable by aiding in dietary changes that may decrease the incidence of diabetes,

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cardiovascular disease, and metabolic syndromes.15 Applications of mesotrione plus atrazine

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increased carotenoid (antioxidant) content in sweet corn, but nothing is known regarding what

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other nutrient impacts may occur from use of these mixtures.17 Additionally, there are no reports

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on how ALS inhibitors or safeners will impact the nutrient quality of sweet corn. Our research

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aims to understand how inhibitors of HPPD and ALS with and without the safener isoxadifen-

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ethyl can impact the uptake of mineral elements and the production of key nutrients including

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proteins, amino acids, fatty acids, fiber, sugars, and various antioxidants.

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2. MATERIALS AND METHODS Field and laboratory studies were conducted in 2009 to evaluate postemergence (POST)

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applications of mesotrione, topramezone, and nicosulfuron in mixtures with atrazine applied

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alone or with the safener isoxadifen-ethyl. The sweet corn variety ‘Incredible’ was chosen for

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these studies based on the findings of Kopsell et al. (2009) that determined it was moderately

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tolerant to HPPDs, and able to yield increased antioxidant content via applications of mesotrione

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plus atrazine.17 The ‘Incredible’ variety is a yellow kernel genotype and is a sugar enhanced

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variety, but also maintains its sweetness longer than standard sweet corn varieties.18

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2.1 Field Trials Field trials were established at the East Tennessee Research and Education Center

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Blount Unit in Louisville, TN (35.84 latitude, -83.95 longitude) on June 3rd 2009. ‘Incredible’

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sweet corn was seeded in a randomized complete block design with three replications. A second

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trial location was established at the Eastern Shore Agricultural Research and Extension Center in

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Painter, VA (37.58 latitude, -75.83 longitude). In TN, seeds were drill planted at a depth of 2.5

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cm in a Emorysilt loam soil (Fine-silty, siliceous, active, thermic Fluventic Humic Dystrudepts)

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silt loam soil (fine loamy, siliceous, thermic, Humic Hapudult) spaced at 25 cm in row and 76

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cm between rows. Each plot consisted of four rows of corn, 6.1 m in length. Sweet corn was

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planted similarly at the VA location into a Bojac sandy loam (Typic Hapludults) with less than

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1% organic matter.. Preemergence (PRE) applications were made to all plots using S-metolachlor

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+ atrazine (Biceps II Magnum: Syngenta Crop Protection, Inc.) at 2190 g of active ingredient per

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hectare (g ai/ha) to reduce weed pressure in the plots. The insecticide lambda-cyhalothrin

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(Warrior: Syngenta Crop Protection, Inc.) was applied preemergence (PRE) to all plots at 32 g

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ai/ha in order to reduce stand loss from insects like cutworms (Agrotis spp.).

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This field study included the following seven treatments: (1) nicosulfuron 35 g ai/ha, (2)

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mesotrione 105 g ai/ha, (3) topramezone 18 g ai/ha, (4) nicosulfuron 35 g ai/ha + isoxadifen-

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ethyl 13 g ai/ha, (5) nicosulfuron 35 g ai/ha + topramezone 18 g ai/ha + isoxadifen-ethyl 13 g

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ai/ha, (6) nicosulfuron 35 g ai/ha + mesotrione 105 g ai/ha + isoxadifen-ethyl 13 g ai/ha, and a

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(7) treated check (atrazine at 560 g ai/ha). All treatments included atrazine at 560 g ai/ha.

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Atrazine, a common broadleaf herbicide used in corn production and controls weeds by

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inhibiting site A of the Qb binding niche of the D1 protein in photosystem II (PSII).19 Like

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mesotrione, rapid metabolism of atrazine affords tolerance in maize genotypes.19 Treatments

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contained an adjuvant of crop oil concentrate applied at 1% v/v and were applied to sweet corn

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plants approximately 5 to 10 cm in height. Herbicide and safener application rates were

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extrapolated from the product label. In Tennessee, herbicide treatments were applied using a CO2

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powered backpack sprayer calibrated to deliver 215 liters per hectare water carrier volume using

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an 8002 flat fan nozzle. In Virginia, herbicides treatments were applied with compressed air

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from a tractor mounted sprayer calibrated to deliver 236 liters per hectare water carrier volume

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using an 8003 flat fan nozzle. All plots were manually hand-weeded as necessary to prevent

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potential variations in yield and nutrient content associated with weed competition.

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Visual observations of foliar injury were measured approximately seven days following

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herbicide treatment. Antioxidant, sugar, amino acids, protein, fatty acids, mineral elements, and

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fiber content in mature sweet corn kernels were measured 45 days after treatment.

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2.2 Harvest and Laboratory Analysis Eight uniform sweet corn ears were collected from the center of the treated area of each plot

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and stored for 48 h in a walk-in cooler (4 C). During processing, a 5 cm section was cut from the

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central region of each ear of the experimental samples and saved for nutrient analyses. Five g of

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tissue was macerated for chemical preparation. Sugar content was assessed using a method

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developed by Zygmunt, fatty acids by Sukhija and Palmquist, amino acids and proteins by

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AOAC, fiber by Soest et al., antioxidants (carotenoids and gamma tocopherol) by Kurilich and

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Juvik along with Davies and Kost, and mineral content by OMOA.20-27

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2.3 Data Analysis

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All data was converted to percent change compared to the treated check and subjected to

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analysis of variance (ANOVA), and means were subsequently separated using Fisher’s protected

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LSD at the 95% confidence interval. Normaility diagnostics were applied to data and were

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considered acceptable based on the Shapiro-Wilk diagnostic. All data were pooled across

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statistical runs considering no run-by-treatment interactions were observed.

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Results and Discussion

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3.1 Amino Acids

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There were no significant differences in sweet corn yield among treatments although

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application of mesotrione alone resulted in the greatest visual damage to corn plants (8%) (Table

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1). When evaluating amino acid content, plants treated with nicosulfuron alone produced similar

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concentrations of amino acids when compared to the treated check except for proline, which was

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reduced by 7%. However, when nicosulfuron was applied with isoxadifen-ethyl, this treatment

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resulted in the highest kernel amino acid content, significantly raising all amino acids except

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alanine and methionine by 9 to 28%. The largest increase in amino acids from the nicosulfuron

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plus isoxadifen-ethyl treatment was in lysine, which is beneficial from a nutrition perspective[e

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considering corn is naturally deficient in lysine.28 This deficiency of lysine in corn is most

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concerning in areas where corn is used as the primary source of dietary protein in both humans

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and domesticated animals.28 Topramezone alone and nicosulfuron plus isoxadifen-ethyl

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increased the amount of the branched chain amino acids leucine and isoleucine by 8 to 14%

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(Table 2). The benefits of increased branched chain amino acid consumption for humans

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include increased muscle tissue along with decreased muscle fatigue.29 In addition, branched

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chain amino acids also help regulate many mammalian biosynthetic including the regulation of

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blood sugar and the prevention of insulin insensitivity.30

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3.2 Fatty Acids

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Analysis of fatty acid content also highlighted some significant differences when

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comparing nicosulfuron applied alone or with isoxadifen-ethyl. The nicosulfuron plus

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isoxadifen-ethyl treatment was the only treatment to yield total fatty acid content significantly

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greater than the treated check (Table 3). This treatment significantly increased all fatty acid

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saturation groupings by 28 to 44%. The individual fatty acids that were increased by the

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nicosulfuron plus isoxadifen-ethyl treatment included arachidic acid, behenic acid, oleic, linoleic

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acid, alpha-linoleic acid, and palmitic acid. Another important trend to note is that application of

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nicosulfuron plus isoxadifen-ethyl increased poly-unsaturated fatty acids by 44% relative to the

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check. Polyunsaturated fatty acids reduce bad cholesterol and the risk of heart disease in

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humans.31

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3.3 Protein, Fiber, and Minerals

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When evaluating protein, fiber, and mineral content extracted from kernels, the

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nicosulfuron plus isoxadifen-ethyl treatment resulted in superior nutrient content (Table 4).

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Protein increased by 12% relative to the treated check in kernels treated with nicosulfuron plus

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isoxadifen-ethyl, whereas all other treatments increased protein content between 4 to 8% Both

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fiber types (acid detergent fiber, neutral detergent fiber), P, Mg, K, Mn, and Zn were increased

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by 14 to 51% with the nicosulfuron plus isoxadifen-ethyl treatment. No treatments increased

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copper or sodium in sweet corn kernels, and only the nicosulfuron plus mesotrione plus

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isoxadifen-ethyl treatment increased calcium levels (100%). Zn, Mg, Cu, and Fe are limiting

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nutrients in cereal crops, especially in areas where these crops are a primary source of nutrition

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for the population of that region.32 Moreover, the 67% increase of Fe from the nicosulfuron plus

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isoxadifen-ethyl treated plants should be further highlighted, as Fe deficiency is one of the most

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common nutrient deficiencies in the world. A deficiency in Fe can lead to anemia and other

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severe health conditions. Iron deficiency is most often observed in women and is particularly

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concerning during pregnancy.33

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3.4 Sugar and Antioxidants Kernals from all treatments contained the same amount of total sugars, except the

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nicosulfuron alone treatment, which increased total sugar content by 16% (Table 5). Fructose

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and glucose levels were increased by applications of topramezone, nicosulfuron plus isoxadifen-

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ethyl, and topramezone plus nicosulfuron plus isoxadifen-ethyl. These increases in the

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monosaccharides fructose and glucose tended to be offset by decreases in the disaccharides

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maltose or sucrose. Fructose is the sweetest of the natural sugars and any increase should

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increase the perceived sweetness of the sweet corn, especially considering the offset decrease in

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maltose or sucrose.34 Sweetness and tenderness are the two qualities most associated with

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improving the eating quality of sweet corn.35 However, increases in fructose, while potentially

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beneficial from a sweetness perspective, may be negative from a human health perspective as

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fructose is not digested in the same manner as other sugars and higher concentrations of fructose

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in the human diet is linked to obesity, diabetes, hypertension, and heart disease.36 There were no

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significant differences between any of the treatments for carotenoid content.

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Mesotrione, topramezone, nicosulfuron and isoxadifen-ethyl are all currently registered for pre- or postemergence applications to various types of corn. Data from our studies demonstrated

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increased concentrations of nutritionally important fatty acids, protein, amino acids, fiber, sugar

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and minerals in sweet corn genotypes through applications of HPPD-inhibiting and ALS-

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inhibiting herbicides and the safener isoxadifen-ethyl. The key question is: what mechanism

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leads to these increases? In general, corn rapidly metabolizes herbicides like mesotrione into

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non-herbicidal byproducts. Moreover, corn can rapidly outgrow sensitivity in the form of leaf

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tissue bleaching, which results from suppression of carotenoid biosynthesis following application

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of mesotrione to sensitive varieties.At the time of harvest, no mesotrione residues were found in

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sweet corn kernels.17 In addition, field corn hybrids rapidly metabolize nicosulfuron; however,

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sweet corn varieties can be much more sensitive.37 When applied with safeners, like isoxadifen-

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ethyl, 84% of nicosulfuron is metabolized in a few of days.38 These herbicides are applied just

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weeks after corn emergence and are degraded in plants within days of application. That being

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said, how do these herbicides affect the nutrient content of sweet corn kernels harvested

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approximately 2 months after application?

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The most interesting and impactful treatment from these studies was nicosulfuron plus

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isoxadifen-ethyl. Safeners are believed to enhance enzyme activity that results in conjugating

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and detoxifying xenobiotics such as herbicides.12 The safener isoxadifen-ethyl has multiple

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impacts in the metabolism of xenobiotics in corn plants. First, isoxadifen-ethyl upregulates

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certain cytochrome P450 monooxygenases that appear to be the primary mechanism by which it

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detoxifies herbicides like nicosulfuron.39 Second, it can upregulate glutathione S-transferases.40

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Overexpression of glutathione S-transferases improves stress tolerance in plants.41 If we assume

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plant growth requires upregulation of key plant processes, then this may help explain some of the

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responses noted with the mixture of nicosulfuron plus isoxadifen-ethyl. However, if this is the

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case, then why do the three-way mixtures of HPPD plus nicosulfuron plus isoxadifen-ethyl

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provide less pronounced improvements in sweet corn kernel nutrient content? Also, if the

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safener is so critical in helping with these nutrient increases, then why do we observe increases

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in total sugars, some mineral elements, neutral detergent fiber, key amino acids, and behenic acid

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with applications of nicosulfuron, mesotrione, or topramezone applied without isoxadifen-ethyl

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(Tables 3,4, and 5) These dramatic increases that result from various applications of specific

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herbicides with or without isoxadifen, highlight the complexity of the pathways and mechanisms

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involved in these nutritional changes.

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Another partial explanation for the increases nutrient content may be related to the increases

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in mineral elements concentrations observed in this study. Several of the herbicide treatments in

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our studies stimulated uptake of mineral elements from soil (Table 4). The uptake of certain

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mineral elements may be increased in corn under stress. The stress in our studies most likely

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was induced in reaction to the herbicide treatments. Although the degree of corn injury

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following herbicide treatment was modest in these studies, this stress was only measured visually

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at a fixed point in time, and the total stress from these herbicides may not have been captured

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thoroughly via a subjective rating. Corn placed under stress can increase uptake of Fe, Mg, Mn,

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Cu, and N from the soil.42 In addition, increases in mineral element concentrations have the

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potential to enhance biochemical processes that impact the synthesis of many nutrients. For

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example, increases in Fe content in pea (Pisum sativum L.) seedlings causedto have more

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unsaturated fatty acids.43 The nicosulfuron plus isoxadifen-ethyl treatment in our studies

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displayed the highest levels of iron content and similarly altered the ratios of fatty acids in the

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corn kernels leading to increases in unsaturated fatty acids (Table 3 and 4). Also, deficiencies in

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Mg, Mn, and Fe in alfalfa (Medicage sativa L.) have led to decreases in the production of key

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amino acids.44 The aforementioned mineral elements were increased by the nicosulfuron plus

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isoxadifen-ethyl treatment in our studies, and most amino acids evaluated were also increased by

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this treatment.

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The concept of herbicides increasing certain nutrients (e.g., carotenoid, antioxidants) was

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documented previously at the University of Tennessee.17 Our studies concluded that many

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different, seemingly unconnected, plant processes can be changed in the presence of herbicides

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and isoxadifen-ethyl. These results again highlight the complex biochemical and physiological

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mechanisms activated when multiple herbicides or herbicides plus safeners such as isoxadifen-

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ethyl are applied to crops like sweet corn. These interactions could be further elucidated through

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transcriptome and metabolomics studies to uncover the exact sequence of activities that occur

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following application until harvest. More comprehensive experiments should focus on multiple

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variety trials and include additional corn herbicide safeners, such as cyprosulfamide across

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multiple additional states with different soil types and climatic conditions. Additionally, taste

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panel tests should be developed for assessing the impact of safener plus herbicide treatments on

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the taste of sweet corn. Calcium and sugar content can both impact flavor; thus, coupling specific

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plant genetics with key herbicides and safeners may improve or modify not only the nutritional

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content but also the taste of sweet corn or other fruits, vegetables, and grains.35,45,46 These results

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may help create a novel subfield in agriculture where pesticide application strategies are not only

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evaluated for their ability to control pests, but for their potential to enhance crop nutrition and

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taste.

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Page 20 of 26

Table 1. Percent Injury and yield for ‘Incredible’ sweet corn (Zea mays L. var rugosa) following applications of carotenoid and amino acid biosynthesis inhibitors applied alone and in mixtures with the Photosystem II inhibitors atrazine. Injurya Herbicide treatmentb

Rate g ai/ha

7 DAT

Yield 14 DAT

————— % —————

———————kg/ha———————

Nicosulfuron

35

5a

7 ab

7689 a

Mesotrione

105

5a

8a

6747 a

Topramezone

18

5a

4 ab

7847 a

35 + 13

4a

5 ab

9002 a

35 +

5a

4 ab

7868 a

4a

8a

8418 a

3a

0b

9437 a

Nicosulfuron + Isoxadifen-ethyl Nicosulfuron + Topramezone + Isoxadifen-ethyl Nicosulfuron+ Mesotrione+

18 + 13 35 + 105 + 13

Isoxadifen-ethyl Treated checkc

---

a

No study by treatment interaction occurred for percent visual injury ratings of sweet corn or for sweet corn yield, therefore these data were pooled over studies.

b

All treatments (including the treated check) included atrazine at 560 g ai/ha plus an adjuvant of 1% v/v crop oil concentrate.

c

Treated check was not included in the statistical analysis.

20


Page 21 of 26


Table 2. Percent increase in concentrations of key amino acids for ‘Incredible’ sweet corn (Zea mays L. var. rugose) following applications of carotenoid and amino acid biosynthesis inhibitors applied alone and in mixtures with the Photosystem II inhibitors atrazine. Amino Acidsa Total Aspartic Herbicide treatmentb

Rate

Amino

Glutamic Threonine

Acid

Proline

Glycine

Cysteine

Alanine

Valine

Methionine

Isoleucine

Leucine

Lysine

Acid

Acids ———————————————— % increase ———————————————

g ai/ha Nicosulfuron

35

-1 d

-4 c

2c

-2 c

-7 d

-4 b

0 cd

1 ab

0c

0a

0c

0c

1b

Mesotrione

105

6 abc

7 ab

16 a

6 ab

9a

4 ab

6b

4 ab

7 abc

2a

6 abc

6 abc

12 b

Topramezone

18

7 ab

6 ab

12 ab

6 abc

6 ab

4 ab

3 bc

8a

9 ab

8a

10 ab

8 ab

10 b

35 + 13

10 a

12 a

12 ab

10 a

10 a

9a

12 a

1 ab

13 a

4a

14 a

12 a

28 a

Nicosulfuron +

35 +

1 bcd

3 abc

3c

2 abc

3 cb

4 ab

-3 d

6 ab

-1 c

8a

0c

1 bc

6b

Topramezone +

18 +

Isoxadifen-ethyl

13 2 bcd

-1 bc

7 bc

1 bc

4 cb

0b

2 bcd

0b

5 abc

4a

3 bc

4 bc

6b

0 cd

0 bc

0c

0 bc

0c

0b

0 cd

0b

0 bc

0a

0c

0c

0b

Nicosulfuron + Isoxadifen-ethyl

Nicosulfuron+

35 +

Mesotrione+

105 +

Isoxadifen-ethyl c

Treated check

13 ---

a

No study by treatment interaction occurred for any amino acid data, therefore these data were pooled over studies.

b


c


21



Page 22 of 26

Table 3. Percent increase in concentrations of key fatty acids for ‘Incredible’ sweet corn (Zea mays L. var. rugosa) following applications of carotenoid and amino acid biosynthesis inhibitors applied alone and in mixtures with the Photosystem II inhibitors atrazine. Fatty Acids (by saturation grouping)

Fatty Acids (individual) Alpha-

Total Total

Total Mono-

Total Poly-

Myristoleic

Palmitic

Stearic

Oleic

Linoleic

Herbicide treatmentb

Rate

Fatty

Unsaturated

Unsaturated

Acid

Acid

Acid

Acid

Acid

Behenic

Acid

acid

(C20:0)

(C22:0)

Acid

Fatty Acids

Arachidic Linoleic

Saturated

Fatty Acids

Fatty Acids

(C14:1)

(C16:0)

(C18:0)

(C18:1)

(C18:2) (C18:3)

Acids

—————————————— % increase ———————————-


35

13 ab

12 ab

15 ab

12 ab

-50 a

12 ab

10 a

16 ab

12 ab

10 ab

17 a

13 ab

Mesotrione

105

11 ab

7 ab

9 ab

12 ab

-21 a

9 ab

1a

10 ab

13 ab

15 ab

10 ab

13 ab

Topramezone

18

9 ab

9 ab

10 ab

9 ab

0a

8b

6a

11 ab

9 ab

7b

10 ab

23 a

35 + 13

36 a

30 a

28 a

44 a

-43 a

33 a

11 a

29 a

44 a

44 a

20 a

25 a

Nicosulfuron +

35 +

11 ab

10 ab

16 ab

9 ab

7a

9 ab

12 a

16 ab

9 ab

8 ab

17 a

13 ab

Topramezone +

18 +

Isoxadifen-ethyl

13 10 ab

6b

14 ab

8b

0a

7b

5a

14 ab

8 ab

8 ab

13 ab

23 a

0b

0b

0b

0b

0a

0b

0a

0b

0b

0b

0b

0b


Nicosulfuron+

35 +

Mesotrione+

105 +

Isoxadifen-ethyl c

Treated check

13 ---

22


Page 23 of 26


a

No study by treatment interaction occurred for any fatty acid data, therefore these data were pooled over studies.

b


c


23



Page 24 of 26

Table 4. Percent increase in concentrations of proteins, acid detergent fiber (ADF), neutral detergent fiber (NDF), and key minerals for Incredible’ sweet corn (Zea mays L. var. rugose) following applications of carotenoid and amino acid biosynthesis inhibitors applied alone and in mixtures with the Photosystem II inhibitors atrazine. Proteins, Acid Detergent Fiber, Neutral Detergent Fiber, and Mineralsa Herbicide treatmentb

Rate

Proteins

ADF

NDF

Ca

P

Mg

K

Na

Fe

Mn

Zn

Cu

———————————————— % increase ———————————————


35

7 bc

9b

4c

0b

6 bc

14 bc

1 bc

21 a

14 b

33 b

2b

0a

Mesotrione

105

6 bcd

10 b

13 b

0b

12 ab

20 b

12 ab

21 a

21 b

25 bc

16 b

0a

Topramezone

18

8b

2b

7 bc

0b

8 ab

13 bc

6 bc

29 a

23 b

38 b

4b

0a

35 + 13

12 a

30 a

21 a

0b

14 a

41 a

18 a

21 a

31 ab

42 b

51 a

0a

Nicosulfuron +

35 +

5 cd

8b

7 bc

0b

8 ab

27 ab

5bc

36 a

67 a

75 a

14 b

0a

Topramezone +

18 +

Isoxadifen-ethyl

13 4d

13 b

7 bc

100 a

8 ab

20 b

3 bc

0a

26 b

38 b

9b

0a

0e

0b

0c

0b

0c

0c

0c

0a

0b

0c

0b

0a


Nicosulfuron+

35 +

Mesotrione+

105 +

Isoxadifen-ethyl c

Treated check

13 ---

a

No study by treatment interaction occurred for any protein, fiber, or mineral element data, therefore these data were pooled over studies.

b


c


24


Page 25 of 26


Table 5. Percent increase in concentrations of key sugars and antioxidants for Incredible’ sweet corn (Zea mays L. var. rugose) following applications of carotenoid and amino acid biosynthesis inhibitors applied alone and in mixtures with the Photosystem II inhibitors atrazine. Sugars

Antioxidants Gamma-

Herbicide treatmentb

Rate

Total Sugars

Fructose

Glucose

Maltose

Sucrose

Lutein

Zeaxanthin

antheraxanthin tocopherol

———————————————— % ———————————————


35

16 a

48 ab

35 ab

23 a

-4 ab

9a

9a

15 a

1 ab

Mesotrione

105

-4 c

18 ab

19 ab

15 ab

-32 c

17 a

1a

14 a

5a

Topramezone

18

10 ab

63 a

40 a

8 bc

-18 bc

0a

-8 a

23 a

8a

35 + 13

10 ab

68 a

43 a

-15 d

-15 abc

0a

-2 a

19 a

-3 ab

Nicosulfuron +

35 +

11 ab

63 a

42 a

8 bc

-21 bc

2a

-5 a

49 a

-10 b

Topramezone +

18 +

Isoxadifen-ethyl

13 9 ab

31 ab

23 ab

4c

2a

7a

-1 a

21 a

0 ab

0 bc

0b

0b

0c

0a

0a

0a

0a

0 ab


Nicosulfuron+

35 +

Mesotrione+

105 +

Isoxadifen-ethyl c

Treated check

13 ---

a

No study by treatment interaction occurred for any sugar or antioxidant data, therefore these data were pooled over studies.

b


c


25



338x190mm (96 x 96 DPI)


Page 26 of 26

Several Pesticides Influence the Nutritional Content of Sweet Corn

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