Nick E. Christians

Isolation and identification of root-inhibiting compounds from corn gluten hydrolysate

Interest has centered on the use of plantderived compounds as natural herbicides, and they are considered to represent an environmentally sound approach to weed control. Corn gluten hydrolysate, found to have a growth-regulating effect on the root system of germinating grass seeds, has been suggested as a natural herbicide. A protocol was developed to extract, isolate, and identify the root-inhibiting compounds from corn gluten hydrolysate aqueous solution and a perennial ryegrass (Lolium perenne L.). A Petri dish bioassay was used to test the root-inhibiting activity. Five bioactive dipeptides were isolated by using Sephadex G-15 gel filtration, solid-phase extraction, and C18 reversed-phase high-performance liquid chromatography procedures. The five dipeptides were glutaminyl-glutamine, alaninyl-asparagine, alaninyl-glutamine, glycinyl-alanine, and alaninyl-alanine. Their root-inhibiting activity on perennial ryegrass was demonstrated in Petri dish bioassays.

Herbicidal activity of hydrolyzed corn gluten meal on three grass species under controlled environments

US Patent No. 5,030,268 discloses that corn gluten meal, the protein fraction of corn (Zea mays L.) grain, can be used as a natural preemergence herbicide. However, corn gluten meal is insoluble in water, and this characteristic renders it difficult to apply as a herbicide. To seek a watersoluble material with more potent herbicidal activity, the phytotoxicity of various samples derived from corn gluten meal and other related crop materials were evaluated by using three different grass species under controlled environments. Greenhouse and growth chamber bioassays showed that the sample of enzymatically hydrolyzed corn gluten meal was more herbicidally active than the corn gluten itself and was highly water soluble. Gluten hydrolysate prepared with bacterial source proteinase had the greatest inhibitory activity to the root growth of germinating seeds. This water-soluble material derived from corn gluten meal had a growth-regulating effect on the root system and can be used as a natural herbicide.

Corn gluten meal - a natural preemergence herbicide: effect on vegetable seedling survival and weed cover.

Weeds are considered the most important pest group for farmers interested in lowering external inputs and avoiding synthetic chemical use. Corn gluten meal (CGM) is a natural preemergence weed control used in turfgrass, which reduces germination of many broadleaf and grass weeds. The objective of this study was to investigate weed cover and vegetable seedling survival in field plots when CGM is incorporated before planting. Three studies were conducted, with three replications for each study. Five rates of powdered CGM (0,100, 200, 300, and 400 g m –2 ) were weighed and incorporated into the top 5–8 cm of soil in recently disked 1.5-m by 2.7-m plots. Seeds of eight vegetables were each planted in rows 1.4 m long and 0.3 m apart. Seedling survival and percentage of weed cover were recorded for each plot. Corn gluten meal at rates of 100, 200, 300, and 400 g m –2 reduced mean weed cover by 50, 74, 84, and 82%, respectively, compared with the control. Seedling survival at 100 g CGM per m 2 was reduced by 67% for ‘Comanche’ onion, 35% for ‘Ruby Queen’ beet, 41% for ‘Red Baron’ radish, 71% for ‘Provider’ bean, 73% for ‘Scarlet Nantes’ carrot, 59% for ‘Maestro’ pea, and 68% for ‘Black Seeded Simpson’ lettuce, compared with the control. Seedling survival for ‘Daybreak’ sweet corn was not reduced by rates of 100 or 200 g CGM per m 2 , but was reduced by 26% at a rate of 300 g CGM per m 2 compared with the control. Because of the reduction in seedling survival at even the lowest rate of CGM (100 g m –2 ), direct seeding of these vegetables into soil into which CGM has been incorporated is not advisable. Using transplants may be an alternative that takes advantage of the herbicidal effects of CGM and the nitrogen it provides.

Movement of herbicides under two irrigation regimes applied to turfgrass

Abstract Our objective was to investigate the movement of the dimethylamine salt of (2,4-dichlorophenoxy) acetic acid (2,4-D), dicamba, and 2-(2-methyl-4-chlorophenoxy) propionic acid (MCPP), when applied to Kentucky bluegrass turf under both infrequent and frequent irrigation regimes. The turfgrass was established on 50-cm length and 20-cm diameter undisturbed soil columns of Nicollet (fine-loamy, mixed, mesic-Aquic Hapludolls) with intact macropores. The infrequent irrigation regime consisted of four 2.54-cm applications, and the frequent regime consisted of 16 0.64-cm applications. On average, the amounts of 2,4-D, dicamba, and MCPP recovered from the soil columns, and in the leachate, under the infrequent irrigation regime were 3.0, 22.4, and 1.1%, respectively. The average amounts of 2,4-D, dicamba, and MCPP recovered from soil columns, and in the leachate, under the frequent irrigation regime were 3.2, 6.3, and 2.3%, respectively. Average values of 1.9, 21.8, and 0.7% of the applied 2,4-D, dicamba, and MCPP, respectively, were measured in the leachate from the soil columns under infrequent irrigation, in contrast to 0.1, 3.4, and 0.2%, respectively, from the soil columns under frequent irrigation. We concluded that the frequency of irrigation can have an impact on the movement of these herbicides through soil profiles.

Bioactivity of a Pentapeptide Isolated from Corn Gluten Hydrolysate on Lolium perenne L.

Corn gluten hydrolysate (CGH) has been observed to inhibit root formation of germinating grass seeds and has the potential for use as a natural herbicide. Five dipeptides have been isolated from the aqueous solution of CGH and proved to have greater root-inhibiting activity than the crude extract of CGH. The objective of this study was to isolate and identify other biologically active compounds from CGH with herbicidal properties. A perennial ryegrass (Lolium perenne L.) Petri dish bioassay was used to test for the bioactivity. A pentapeptide, Leu-Ser-Pro-Ala-Gln, was isolated from CGH by using Sephadex G-15 gel filtration and two-step C18 reversed phase high performance liquid chromatography procedures. The compound suppressed growth of both the root and the shoot of germinating perennial ryegrass. It required 0.5 mg/mL of the pentapeptide to inhibit 50% of root length in the perennial ryegrass bioassay, and this compound is more active than any of the five dipeptides isolated previously from CGH.

COMPARING DISPERSIVITIES AND SOIL CHLORIDE CONCENTRATIONS OF TURFGRASS-COVERED UNDISTURBED AND DISTURBED SOIL COLUMNS

Research relating to soil leaching properties under turfgrass conditions has often been conducted on disturbed soils where macropore structure has been destroyed. The objective of this study was to compare the solute movement characteristics of undisturbed and disturbed soil columns covered with turfgrass. Dispersivities and chloride (Cl) breakthrough curves of undisturbed and disturbed soils were investigated. Soil columns were excavated into three sections after testing, for which the mean bulk density was 1.33 Mg M−3 for the undisturbed columns and 1.16 Mg m−3 for the disturbed columns. The dispersivity for the undisturbed columns was over three times greater than for the disturbed columns. Chloride concentration found in Layer 1 (0–6.7 cm), Layer 2 (6.7–13.4 cm), and Layer 3 (13.4–20.0 cm) were 2.8, 5.3, and 4.8 times higher, respectively, for the disturbed soils than for the undisturbed. Applying conclusions from solute movement studies using repacked columns covered with turfgrass to actual undisturbed field conditions could lead to errors in interpretation because of the effect of macropores.

Mesotrione controls creeping bentgrass (Agrostis stolonifera) in Kentucky bluegrass.

Creeping bentgrass creates a dense, high-quality playing surface on golf courses, but it often encroaches adjacent areas of Kentucky bluegrass. Mesotrione can control creeping bentgrass in Kentucky bluegrass, but more information is needed regarding the effect of herbicide rate and number of applications on creeping bentgrass control and the impact to Kentucky bluegrass. Field experiments were conducted to determine the effect of application rate and number of applications on creeping bentgrass control. One application of mesotrione controlled 7 to 43% of creeping bentgrass in Kentucky bluegrass, and two applications of mesotrione controlled 39 to 88% as rates increased from 70 to 1,120 g ai/ha. Gaps present in the canopy after the creeping bentgrass died reduced overall turfgrass quality 2 to 6 wk after treatment (WAT) before recovering. These data indicate the capability of mesotrione to selectively control creeping bentgrass while providing excellent safety to Kentucky bluegrass. Nomenclature: Mesotrione; creeping bentgrass, Agrostis stolonifera L. AGSST; Kentucky bluegrass, Poa pratensis L. POAPR.

Fate of amended urea in turfgrass biosystems

Abstract The fate of nitrogen (N) has been studied under several agronomic crops and agricultural profiles, but relatively little information has been collected from areas managed as turfgrass. The turfgrass industry has become the focus of environmental concerns in recent years and is often identified as a source of ground water contaminate. The objectives of this study were to: i) investigate the hydrology of 20‐cm diameter by 50‐cm deep undisturbed soil columns covered with a Kentucky bluegrass (Poa pratensis L.) turf under a heavy (one 2.54‐cm application) and a light (four 0.64‐cm applications) irrigation regime, and to ii) quantify the fate of 15N‐labeled urea when it is applied to an undisturbed soil columns having intact macropores. Clipping, verdure, and thatch/mat samples were taken from each column, and the soil was excavated in 10‐cm layers at the end of the 7‐day test period. A glass collection chamber was used to collect volatilized N and a plastic bag for leachate collection. All samples we...

Pendimethalin and corn gluten meal combinations to control turf weeds

Concerns over ground water contamination and other environmental issues have prompted research to reduce synthetic herbicide use. Corn (Zea mays L.) gluten meal, a by-product of wet milling, inhibits germination and the establishment of many annual and perennial weed species. Our objective in the field was to investigate crabgrass control (Digitaria spp.) in Kentucky Bluegrass (Poa pratensis L.) turf established on a Nicollet soil (fine-loamy, mixed, mesic Aquic Hapludoll). In the greenhouse, we investigated the control of large crabgrass [Digitaria sanguinalis (L.) Scop.] on the same soil with no turfgrass cover. Experiments were conducted with corn gluten meal at 0, 49, 98, and 147 g m -2 combined in a factorial arrangement with pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] at 0, 29, 59, 88, and 117 mg ai m -2 . The minimum label rate for pendimethalin is 176 mg ai m -2 . Field crabgrass control was improved by application of a sublethal rate of pendimethalin in addition to corn gluten meal. As the application rate of corn gluten meal increased from 49 to 147 g m -2 , the level of pendimethalin required to provide 75 to 85% control for 15 wk decreased from 88 to 29 mg aim -2 . There was no increase in crabgrass control in plots that received amounts of corn gluten meal and pendimethalin exceeding these combined rates.

Creeping bentgrass response to zinc in modified soil

Abstract Interpretations of soil zinc (Zn) tests for golf course greens vary among testing laboratories, with little information in the literature on which to base these interpretations. Our studies determined the effects of increasing fertilizer Zn on extractable soil Zn and tissue Zn levels for five creeping bentgrass (Agrostis palustris Huds.) cultivars, to investigate their potential for Zn toxicity. The effects of Zn concentrations up to 4000 mg/kg were investigated in three greenhouse studies on a potted soil mix of sand, Nicolett (fine‐loamy, mixed‐mesic, Aquic Hapludoll) soil, and Hypnum peat in an 8:1:1 ratio. ‘Penncross’ bentgrass was used in the first two studies, and ‘Penncross’, ‘Penneagle’, ‘Cobra’, ‘Emerald’, and ‘Prominent’ were compared in a third study. Mean DTPA‐extractable soil Zn concentrations increased from 0.6 mg/kg in the controls to 652 mg/kg in the pots treated with 4000‐mg Zn/kg soil. Tissue Zn concentrations increased from a low of 50 mg/kg for grass on the control pots to a h...