Impact of selective flame weeding on onion yield, pungency, flavonoid concentration, and weeds

Abstract Field experiments were conducted to evaluate the effects of multiple selective flame weeding treatments on onion ( Allium cepa L.). Onions were flamed between one and six times over the course of the season with a high (72 kg propane ha −1 ) or low (45 kg propane ha −1 ) propane dose. In each treatment, one subplot was hand-weeded in addition to flame treatment to remove differential weed effects, while the other received only the prescribed flame weeding regimen as weed control. Overall, control of broadleaf weeds was better than that of grass species. Broadleaf weed density and shoot mass were reduced as propane dose and the number of flame treatments increased. Grass density was reduced by 50% in all flamed treatments compared to the non-treated control, but no differences between flamed treatments were observed. Effects of flame treatments on grass shoot mass were minimal. Among weed-free treatments, onion was able to tolerate up to six flame treatments at either dose without a loss of yield. Treatments that received only flame weeding as weed control had total onion yields 37 and 80% of the weed-free flamed treatments in 2006 and 2007, respectively. Flame weeding treatments had little effect on the time to reach maturity, onion pungency, or quercetin concentration.

[1]  M. Olsson,et al.  Quercetin content in field-cured onions (Allium cepa L.): effects of cultivar, lifting time, and nitrogen fertilizer level. , 2006, Journal of agricultural and food chemistry.

[2]  S. Schwimmer,et al.  Enzymatic development of pyruvic acid in onion as a measure of pungency , 1961 .

[3]  D. Kopsell,et al.  Onion Cultivars Differ in Pungency and Bulb Quality Changes during Storage , 1997 .

[4]  J. Bornman,et al.  Differential flavonoid response to enhanced uv-b radiation in brassica napus , 1998 .

[5]  A. Christopoulos,et al.  Fitting Models to Biological Data Using Linear and Nonlinear Regression: A Practical Guide to Curve Fitting , 2004 .

[6]  C. Akoh,et al.  Flavonoids and antioxidant capacity of Georgia-grown Vidalia onions. , 2002, Journal of agricultural and food chemistry.

[7]  P. Seguin,et al.  Seeding date, row spacing, and weed effects on soybean isoflavone concentrations and other seed characteristics , 2006 .

[8]  Jae-Hoon Jeong,et al.  Effects of low dose quercetin: Cancer cell‐specific inhibition of cell cycle progression , 2009, Journal of cellular biochemistry.

[9]  B. Melander,et al.  Effects of cultural methods and physical weed control on intrarow weed numbers, manual weeding and marketable yield in direct‐sown leek and bulb onion , 2001 .

[10]  D. Schwarz,et al.  Distribution of quercetin-3,4′-O-diglucoside, quercetin-4′-O-monoglucoside, and quercetin in different parts of the onion bulb (Allium cepa L.) influenced by genotype , 2010 .

[11]  J. Ascard,et al.  Effects of flame weeding on weed species at different developmental stages. , 1995 .

[12]  Peter C. H. Hollman,et al.  Optimization of a quantitative HPLC determination of potentially anticarcinogenic flavonoids in vegetables and fruits , 1992 .

[13]  A. Datta,et al.  Tolerance of selected weed species to broadcast flaming at different growth stages , 2010 .

[14]  P. Seguin,et al.  Effects of Foliar Application of Elicitors on Red Clover Isoflavone Content , 2006 .

[15]  J. Schrezenmeir,et al.  Quercetin reduces systolic blood pressure and plasma oxidised low-density lipoprotein concentrations in overweight subjects with a high-cardiovascular disease risk phenotype: a double-blinded, placebo-controlled cross-over study , 2009, British Journal of Nutrition.

[16]  D. Barrett,et al.  Modified method for the determination of pyruvic acid with dinitrophenylhydrazine in the assessment of onion pungency , 2003 .

[17]  Akira Murakami,et al.  Multitargeted cancer prevention by quercetin. , 2008, Cancer letters.

[18]  D. Kopsell,et al.  Sequentially Reducing Sulfate Fertility During Onion Growth and Development Affects Bulb Flavor at Harvest , 2002 .

[19]  H. A. Stafford.  Roles of flavonoids in symbiotic and defense functions in legume roots , 2008, The Botanical Review.

[20]  B. Patil,et al.  Quantification of quercetin glycosides in 6 onion cultivars and comparisons of hydrolysis-HPLC and spectrophotometric methods in measuring total quercetin concentrations. , 2010, Journal of food science.

[21]  H. Schwartz,et al.  Yield and Growth Response of Onion to Simulated Storm Damage , 1994 .

[22]  K. A. Stewart,et al.  Weed Response to Flame Weeding at Different Developmental Stages , 2009, Weed Technology.

[23]  T. Coolong,et al.  Temperature Influences Flavor Intensity and Quality in 'Granex 33' Onion , 2003 .

[24]  Ramon C. Littell,et al.  SAS for Linear Models , 2002 .

[25]  Eun-ju Lee,et al.  Analytical methods of pyruvic acid and difference of pyruvic acid content in relation to bulb characteristics in onion. , 2009 .

[26]  B. Patil,et al.  Changes in quercetin concentration in onion (Allium cepa L.) owing to location, growth stage and soil type , 1995 .

[27]  A. J. Barr,et al.  SAS user's guide , 1979 .

[28]  Fredrik Fogelberg,et al.  Mechanical In-Row Weed Control in Transplanted and Direct-Sown Bulb Onions , 2008 .

[29]  Donald L. Smith,et al.  Foliar application of elicitors alters isoflavone concentrations and other seed characteristics of field-grown soybean , 2006 .