ادمه مطلب (3)
Current Issue:
January-February 2009
Abstract 21 of 3۲
INTEGRATED AGRICULTURAL SYSTEMS
Linking Wisconsin Dairy and Grain Farms via Manure Transfer for Corn Production
a Dep. of Agronomy, Univ. of Wisconsin, 1575 Linden Dr., Madison, WI 53706
b Massachusetts Association of Conservation Districts, 52 Boyden Rd., Holden, MA 01520
c Michael Fields Agricultural Institute, W2493 County Rd. ES, East Troy, WI 53120
d Agstat, 6394 Grandview Rd., Verona, WI 53593
* Corresponding author (gsanford@wisc.edu ).
One relatively under-used manure management strategy employed by dairy farmers is to transport and apply manure onto the fields of nearby grain farmers. While this system offers advantages to both parties, little of the existing research on manure management has been conducted on grain farms. As part of an effort to link grain and livestock farms in southern Wisconsin, 20 on-farm trials were conducted to study the agronomic and environmental effects of including manure in cash-grain rotations. Manure was applied at a rate of approximately 107 m3 ha–1 as slurry (11,000 gal acre–1) or 54 Mg ha–1 (24 ton acre–1) as a solid. Across-site analysis indicated that the manured treatment increased corn (Zea mays L.) yields significantly (alpha = 0.05), by 0.5 Mg ha–1 (11.5 vs. 11.0 Mg ha–1), with 67 kg ha–1 less purchased fertilizer N during the 3 yr of this study. However, there were environmental concerns: (i) Early fall manure spreading significantly increased fall nitrate (NO3) levels in the manured plots (175 vs. 87 kg NO3–N ha–1); (ii) Following corn harvest, fall NO3 levels were fairly low and equivalent between treatments with the exception of three sites where manuring resulted in significantly higher NO3–N; and (iii) Soil tests following corn harvest indicated a significant increase in soil test phosphorus (STP) on the manured plots. These results indicate that dairy manure can reduce fertilizer inputs although there is a risk of NO3–N leaching and P accumulation. Informal interviews were conducted with farmer-participants following this study to asses current manure use.
Abbreviations: BLUP, best linear unbiased predictors • FC, farmers' check • GDD, growing degree days • M, manure + supplemental fertilizer • PSNT, presidedress soil nitrate test • RCBD, randomized complete block design • RHA, rolling herd average • SFAL, Soil and Forage Analysis Laboratory • SPAL, Soil and Plant Analysis Laboratory • STK, soil test potassium • STP, soil test phosphorus
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Received for publication April 21, 2008.
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INTEGRATED AGRICULTURAL SYSTEMS
Rotational and Cover Crop Determinants of Soil Structural Stability and Carbon in a Potato System
Dep. of Crop and Soil Sciences, Michigan State Univ., Kellogg Biological Station, East Lansing, MI 48824-1325
* Corresponding author (snapp@msu.edu ).
Understanding processes that ameliorate structural degradation in sandy soils is particularly important in intensively managed potato (Solanum tuberosum L.) systems. Seven 2-yr potato rotation systems were evaluated over 3 yr in an irrigated field trial comparing winter management systems bare (B) and cover crops: rye (Secale cereale L.; R), rye-hairy vetch (Vicia villosa Roth; RV) mixture and red clover (Trifolium pratense L.; C). Crops rotated with potatoes (P) were snap bean (Phaseolus vulgaris (L.); SB), wheat (Triticum aestivum L.; W) and sweet corn (Zea mays L.; SC). The systems consisted of: S1 PBSBB; S2 PRSBR; S3 PRSCB; S4 PWWR; S5 PWWCC; S6 PRVSBRV; and S7 PRVSCRV, both entry points evaluated each year. Carbon inputs above- and belowground were measured and systems grouped as low (S1 and S4), medium (S2 and S6), and high (S5, S3 and S7): 1.2, 2.0, and 2.8 Mg C ha–1, respectively. Response variables included water stable aggregate (WSA) size fractions, macroaggregates (
0.25 mm) and microaggregates (<0.25 mm), mean weight diameter (MWD), soil C, nitrogen mineralization potential (NMP), and potato tuber yield. Systems with SC contributed twofold higher biomass than rotations with W or SB, and the presence of RC contributed higher amounts of carbon (1.2 Mg ha–1) compared to R (0.7 Mg ha–1). Only the entry year influenced macroaggregates in 2001; both entry year and cropping system influenced aggregate size classes in 2004. Over 3 yr the macro-WSAs declined by 13%, except for high carbon input systems. Residue C input was a moderate predictor of total soil C (31% of variability explained), whereas macro- and micro-WSAs were predictors of soil C, accounting for 58 and 72% of observed variability, respectively. Low levels of aggregation were observed in this sandy soil and the modest amounts of C inputs from winter cover crops posed a challenge to detecting treatment effects, which was in part overcome by georeferencing, to improve precision of sampling over time.
Abbreviations: B, winter management systems bare • C, clover • CEC, cation exchange capacity • MWD, mean weight diameter • NMP, nitrogen mineralization potential • P, potatoes • PEI, Prince Edward Island • R, rye • RV, rye-hairy vetch • SB, snap bean • SC, sweet corn • SOC, soil organic carbon • W, wheat • WSA, water stable aggregate
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Received for publication May 28, 2008.
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AGROFORESTRY
Effect of Loblolly Pine Root Pruning on Alley Cropped Herbage Production and Tree Growth
a Dale Bumpers Small Farms Research Center, USDA-ARS, 6883 S. State Hwy. 23, Booneville, AR 72927
b USDA-ARS, Appalachian Farming Systems Research Center, 1224 Airport Rd., Beaver, WV 25813
* Corresponding author (David.Burner@ars.usda.gov ).
Tillage to disrupt (prune) tree roots is an intensive practice which could improve herbage productivity at the crop–tree interface by reducing competition for water. We compared tillage effects on 9- to 11-yr-old loblolly pine (Pinus taeda L.) growth and herbage yields of annual ryegrass (Lolium multiflorum Lam.) and pearl millet [Pennisetum glaucum (L.) R. Br.] on a fragipan soil in Arkansas. Alley crops were rotationally grown in a 9.7-m wide alley (main plot) between bordering trees on one of three tillage treatments: control (surface tillage), rip followed by surface tillage, and trench plus root barrier followed by surface tillage. Topsoil water in May through September, herbage mass, and nutritive value were measured for each crop for 2 or 3 yr in three subplots systematically arrayed (north, middle, and south) across the alley. Diameter at breast height (DBH, measured 1.3 m above soil surface) and height of border trees were measured annually. Trenching resulted in a more uniform distribution of topsoil water among subplots compared to the other tillage treatments. Annual ryegrass yield did not show a tillage response, but pearl millet yielded more herbage in the rip (6760 kg ha–1 in 2003) and trench (3300 kg ha–1 in 2005) than the control treatment (4990 and 1260 kg ha–1 for 2003 and 2005, respectively). Ripping and trenching significantly reduced loblolly pine DBH and height compared to the control. Similarly configured alley cropping practices probably have little potential for annual herbage production even with root pruning.
Abbreviations: DBH, diameter breast height • IVDMD, in vitro dry matter digestibility • PAR, photosynthetically active radiation • TNC, total nonstructural carbohydrates
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Received for publication May 28, 2008.
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AGROCLIMATOLOGY
Canopy Gas Exchange Measurements of Cotton in an Open System
a USDA-ARS, Plant Stress and Water Conservation Laboratory, 302 West I-20, Big Spring, TX, 79720
b USDA-ARS, Plant Stress and Water Conservation Laboratory, 3810 4th Street, Lubbock, TX 79415
* Corresponding author (Jeff.Baker@ars.usda.gov ).
A portable, open transparent chamber system for measuring canopy gas exchanges was developed and tested. Differentials between incoming and outgoing atmospheric H2O and CO2 concentrations were used to calculate canopy transpiration (E) and net assimilation (A) at 10-s intervals using solenoid valve actuated sample lines connected to an infrared gas analyzer. A programmable data logger controlled fan speed and air flow rate to control daytime chamber air temperature to within 0.5°C of ambient air temperature. To validate the mass balance equations used to calculate E, the chamber was positioned over sealed soil potted cotton (Gossypium hirsutum L.) plants which were placed on a weighing scale. A second scale was used to measure E of cotton plants outside the chamber to quantify potential chamber effects. A wide range of crop canopy leaf areas and soil water contents were created with greenhouse-grown plants for these comparisons. Data analysis indicated agreement between chamber E measurements and the internal weighing scale (R2 = 0.93), as well as comparison between the internal and external scales (R2 = 0.88) across wide ranges of soil water contents and canopy leaf area. Transpiration ranged from near zero at night to 900 g (H2O) h–1 during the day. Bias estimates of E for chamber vs. internal scale and the internal vs. external scale were –6.0 and 4.6 g (H2O) h–1. With minor chamber effect, the chamber accurately estimates E for many field applications such as comparison of canopy gas exchanges and water use efficiencies among irrigation treatments.
Abbreviations: A, canopy net assimilation • BREB, Eddy Correlation and Bowen Ratio Energy Balance • CETA, Canopy EvapoTranspiration and Assimilation chamber • E, canopy transpiration • ET, evapotranspiration • IRGA, infrared gas analyzer • NEE, net ecosystem exchange • PAR, photosynthetically active radiation • SPAR, Soil-Plant-Atmosphere-Research chamber
1 Mention of this or other proprietary products is for the convenience of the readers only, and does not constitute endorsement or preferential treatment of these products by USDA-ARS.
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Received for publication July 3, 2008.
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AGROCLIMATOLOGY
Impact of Planting Date and Hybrid on Early Growth of Sweet Corn
Dep. of Biological and Agricultural Engineering, The Univ. of Georgia, 1109 Experiment St., Griffin, GA 30223-1797
* Corresponding author (axelg2@uga.edu ).
Sweet corn (Zea mays L. var. rugosa) is a warm-weather crop that is grown in most of the United States. Normally, it is planted over an extended planting window to provide a continuous supply for the fresh market. However, this planting window exposes the crop to various stresses and weather risks. The objective of this study was to determine the effect of planting date on early growth of sweet corn with different maturities for different environmental conditions in Georgia, USA. Three yellow sweet corn genotypes, including a full homozygous sugar enhanced (se), a super sweet (sh2), and a standard or normal (su), were compared in 2004, 2005, and 2006 in two locations in Georgia. The experiment consisted of one planting date in 2004, six in 2005, and four planting dates under two water regimes in 2006. Plant growth variables that were measured included leaf area index (LAI), canopy height, and aboveground biomass from emergence to the beginning of tasseling. The growth rate as a function of thermal time (TT) was used to determine the impact of planting date on growth of sweet corn. A base temperature (Tb) of 6.6°C for the three genotypes, obtained from experimental data, was used. Days to emergence varied from 4 to 12 for the warmest and coolest growing seasons, respectively. The growth of the three sweet corn genotypes showed a clear response to planting dates as LAI, canopy height, and aboveground biomass and the individual plant components, including stem, sheath, and leaves were significantly (P < 0.05) different at the beginning of tasseling. For all experiments, the longer the maturity group, the higher the total aboveground biomass. Significant differences (P < 0.05) for growth rate were found between planting dates, genotypes, plant components and their interactions. The short-season hybrid tended to have a faster overall plant growth rate of all individual plant components during the warmer seasons. In contrast, the mid- and full-season hybrids tended to have a higher growth rate during the cooler seasons. For rainfed conditions, the short-season hybrid had higher leaf and sheath growth rates than the mid- and full-season hybrids, resulting in a higher stem growth rate. These results indicate that the effect of planting date on early growth of sweet corn is of significance, as it may lead to identification of an optimum planting window for this crop.
Abbreviations: BRF, Bledsoe Research Farm • LAI, leaf area index • se, sugar enhanced • SIRP, C.M. Stripling Irrigation Research Park • sh2, super sweet • su, standard • Tb, base temperature • TT, thermal time
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Received for publication December 10, 2007.
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BIOFUELS
Improving the Fermentation Characteristics of Corn through Agronomic and Processing Practices
Plant Sci. Dep., South Dakota State Univ., Brookings, SD 57007-1096
* Corresponding author (Graig.Reicks@SDstate.edu ).
This study determined the influence of corn (Zea mays L.) hybrids, N availability, grain harvest moisture, and drying temperatures on dry-mill ethanol production. Six hybrids, ranging from 92 to 108 d in relative maturity (RM), were planted at two locations over 2 yr. One of four N fertilizer treatments were applied. Grain was hand-harvested at grain moistures of 20 and 25%. Grain was dried to about 15% moisture at either 25, 38, 52, or 60°C in 2003, and 38, 66, 75, or 93°C in 2004. Ethanol was measured after grain was subjected to a small-scale bench fermentation process. Grain yield increased at all four site-years as available N increased to the recommended N application rate. Relative ethanol concentration was generally not affected by normal N fertilizer rates. Significant reductions in relative ethanol concentration occurred at the both the highest and lowest N rates in one-of-four site years. Hybrids designated as high fermentable starch (HS) by the company did not necessarily yield more ethanol than other hybrids. Ethanol concentration was reduced by 0.3% at Brookings for grain that was subjected to a killing frost. Ethanol concentration generally did not differ between grain dried at 38 and 52°C in 2003. Ethanol from grain harvested at 25% moisture and dried at 25°C was 0.1 to 0.3% lower than when grain was dried at 38 or 52°C. Drying temperatures of 25 to 52°C had no influence on relative ethanol concentration when the grain was harvested at 20% moisture. However, ethanol concentration was lowered 0.1 to 0.4% when drying temperature increased to 93°C in 2004. These results suggest that producers should apply the recommended N rates for maximum economic yield, plant adapted hybrids, and dry corn grain between 38 and 52°C to maximize relative ethanol concentration.
Abbreviations: HS, high fermentable grain starch • R4, growth stage of corn when kernels are considered a dough consistency • RM, relative maturity
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Received for publication December 13, 2007.
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MANURE
Dairy Cattle Manure Improves Soil Productivity in Low Residue Rotation Systems
a Université Laval. Pavillon Paul Comtois. Département des Sols et Génie Agroalimentaire. Québec, QC. G1K 7P4. Canada
b Agriculture et Agroalimentaire Canada. 2560 Boul. Hochelaga. Québec, QC, G1V 2J3 Canada
c Institut de Recherche et de Développement en Agroenvironnement (IRDA). 2700, Rue Einstein. Québec, QC, G1P 3W8 Canada
* Corresponding author (judith.nyiraneza.1@ulaval.ca ).
Mineral fertilizer alone may not sustain soil productivity in cropping systems that return little crop residues to the soil, unless additional organic residues and/or manure is applied regularly to the soil. The objective of the present study was to assess the long-term effects of mineral fertilization (No fertilizer, PK, and NPK) and manure addition (0 and 20 Mg ha–1 yr–1) on soil physical and chemical properties and crop yields in a cereal rotation with removal of crop residues. After 28 yr, soil organic carbon (SOC) declined by –0.25 g C kg–1 yr–1 and total nitrogen (TN) by –0.025 g N kg–1 yr–1 with balanced mineral fertilization (NPK, no manure), comparable to the control (no manure, no fertilizer). In addition, mean weight diameter (MWD) of water-stable aggregates was lower with balanced mineral fertilization than in the control. In contrast, long-term application of manure significantly increased water-stable macroaggregates, potentially mineralizable nitrogen (PMN), and soil preseeding NO3–N levels. Corn yield and N uptake were increased by mineral fertilization compared to the control, and manure application increased corn yield by 89 and 87% and corn N uptake by 110 and 79% in 2005 and 2006, respectively. Increased corn yield in manured plots was attributed to the residual manure-derived nutrients and to improved soil properties. Mineral fertilizer alone could not sustain soil productivity in intensive low-residues cropping systems.
Abbreviations: FA, fulvic acids • HA, humic acids • MWD, mean weight diameter • NHF, nonhumified fraction • PMN, potentially mineralizable nitrogen • SOC, soil organic carbon • SOM, soil organic matter
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Received for publication April 4, 2008.
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MANURE
Zonejection: Conservation Tillage Manure Nutrient Delivery System
a Agric. & Agri-Food Canada, Southern Crop Protection & Food Res. Cent., 1391 Sandford St., London, ON, Canada N5V 4T3
b Agric. & Agri-Food Canada, Southern Crop Protection & Food Res. Cent., Delhi, ON, Canada, N4B 2W9
* Corresponding author (ballb@agr.gc.ca ).
Manure application in minimum till (MT) systems is a challenge worthy of attention because residue cover is a keystone for environmental protection. To develop a system combining zone tillage and manure application into one operation (zonejection), two experiments were conducted. In Exp. 1, liquid swine manure (LSM) was applied in fall or spring for two site years (A, B). In Exp. 2, LSM was zone-applied either all preplant (PP) or split between preplant and sidedress (SP) for three site years (C, D, E). In both experiments, dietrich (DMI), vibro shank (VS), or subsurface deposition (SSD) applied the LSM, corn (Zea mays L.) was seeded in the manured zone, and NO3–N movement was monitored. Nutrients were supplied by inorganic fertilizer (IF) in control treatments under conventional till (CT), no till (NT), and zone till (ZT). With fall-applied LSM, after a mild winter, more N was lost from the soil–plant system (i.e., 35 kg ha–1 soil NO3–N) than after a cold winter with snow cover (18 kg ha–1), and corn grain yield was reduced (by 1.2 Mg ha–1), even though supplemental fertilizer N was sidedressed. In Exp. 2, with LSM zoned all PP or SP, grain yield and N use efficiency were comparable to that with IF, except when double the crop N requirement was zoned all PP (Site D). Planting into a zone of concentrated LSM (3.4 S m–1) reduced grain yield when the LSM was injected by VS. With careful management, zonejection allows efficient utilization of manure nutrients while preserving residue cover.
Abbreviations: ANR, apparent N recovery • CT, conventional till • DMI, dietrich • IF, inorganic fertilizer • LSM, liquid swine manure • MT, minimum till • NT, no till • PHSN, post-harvest soil nitrate • PP, manure applied all preplant • PSNT, presidedress nitrate test • SD, sidedress • SP, manure split between preplant and sidedress • SSD, subsurface deposition • UAN, urea ammonium nitrate • VS, vibro shank • ZT, zone till
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Received for publication July 8, 2008.
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SPATIAL VARIABILITY
Nondestructive Measurement of Grapevine Leaf Area by Ground Normalized Difference Vegetation Index
a ECAV, UMR EGFV, Institut des Sciences de la Vigne et du Vin de Bordeaux, Domaine INRA de la Grande Ferrade, BP 81, 33883 Villenave d'Ornon Cedex, France
b Chateau Couhins, Chemin de la Gravette, BP 81, 33883 Villenave d'Ornon Cedex, France
* Corresponding author (drissirachid@yahoo.fr ).
Vine leaf area index has a great impact on berry quality. This study was conducted to determine whether vine leaf area index could be estimated, and mapped through normalized difference vegetation index (NDVI) ground-based measurements. The NDVI measurements were performed using a Greenseeker (N-Tech Industires, Ukiah, CA and Oklahoma State Univ., Stillwater), pointed sideways at the vertical shoot positioned vines [Vitis vinifera (L.)] at Bordeaux, France. Canopy gap fraction and vertical leaf area index (VLAI) measurements were also performed. Plot NDVI maps were obtained by linking the GreenSeeker to a GPS during measurements. The NDVI delivered by the sensor was sensitive to the variations of vertical leaf area index and gap fraction of the canopy, that is, vine vigor. The GreenSeeker was successfully used to carry out a follow-up of the foliar growth of the vine, but with many precautions. The maps obtained showed relative variations of vigor at an intraplot level, enabling access to relevant information for better vineyard management.
Abbreviations: LAI, leaf area index • NDVI, normalized difference vegetation index • PW, pruning weight • VLAI, vertical leaf area index
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Received for publication May 17, 2007.
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REMOTE SENSING
Optimization of Crop Canopy Sensor Placement for Measuring Nitrogen Status in Corn
a Dep. of Agronomy & Horticulture, Univ. of Nebraska, Lincoln, NE 68583
b Dep. of Biological Systems Engineering, Univ. of Nebraska, Lincoln, NE 68583
c USDA-ARS, Agroecosystem Mgmt. Res. Unit, Lincoln, NE 68583
d formerly USDA-ARS, Agroecosystem Mgmt. Res. Unit, Lincoln, NE 68583
* Corresponding author (droberts2@unl.edu ).
Active canopy sensors can be used to assess corn (Zea mays L.) N status and direct spatially-variable in-season N application. The goal of this study was to determine optimal sensor spacing for controlling whole- and/or split-boom N application scenarios for a hypothetical 24-row applicator. Sensor readings were collected from 24 consecutive rows at eight cornfields during vegetative growth in 2007 and 2008, and readings were converted to chlorophyll index (CI) values. A base map of measured CI values was created using square pixels equal to row spacing for each site (0.91 or 0.76 m in size). Sensor placement and boom section scenarios were evaluated using MSE (mean squared error) of calculated CI maps vs. the base CI map. Scenarios ranged from one sensor, one variable-rate to 24 sensors, 24 variable-rates for the hypothetical 24-row applicator. The greatest reduction in MSE from the one variable-rate scenario was obtained with 2 to 3 sensors estimating average CI for the entire boom width, unless each row was individually sensed. In every field, more accurate prediction of CI was obtained by averaging sensor readings across the entire 24 rows rather than predicting CI for more than two consecutive rows using only one sensor in each section. Because of the nature of spatial variability in CI, some fields may benefit from an increased number of sensors and/or boom sections equipped with 2 to 3 sensors each.
Abbreviations: CI, chlorophyll index • MSE, mean squared error • NUE, nitrogen use efficiency • NIR, near-infrared
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Received for publication August 30, 2008.
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NOTES & UNIQUE PHENOMENA
Methods for Creating Stomatal Impressions Directly onto Archivable Slides
a USDA-ARS, 3810 4th Street, Lubbock, TX 79415-3397
b USDA-ARS, Cropping Systems Research Laboratory, Big Spring, TX 79720-0013
* Corresponding author (dennis.gitz@ars.usda.gov ).
Stomatal density has been shown to be a primary determinant of crop yield, water use efficiency, and limitation to CO2 assimilation rate. Widely used methods of assessing stomatal density sample relatively small regions of the leaf, are labor intensive, or do not yield stable archivable samples for revisiting samples. We describe several methods of producing such epidermal impressions that yield samples large enough to generate stomatal density maps across entire leaf surfaces.
Abbreviations: CA, cellulose acetate • CAB, cellulose acetate butyrate • MeCl2, methylene chloride • MEK, methylethyl ketone • PMMA, polymethyl methacrylate • PVC, polyvinyl chloride
1 Mention of this or other proprietary products is for the convenience of the readers only, and does not constitute endorsement or preferential treatment of these products.
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Received for publication May 2, 2008.
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NOTES & UNIQUE PHENOMENA
Occurrence and Proposed Cause of Hollow Husk in Maize
University of Illinois, Crop Science Dep., 1201 W. Gregory Dr. Urbana, IL 61801
* Corresponding author (fbelow@illinois.edu ).
In 2007, a maize (Zea mays L.) ear abnormality that we term here as "hollow husk" occurred in research trials designed to alter the level or the sensing of plant ethylene. The unique experimental conditions of 2007 enabled us to document the occurrence of hollow husk and propose a physiological mechanism for its cause. Ears exhibiting hollow husk have normal appearing husks that feel hollow due to an abrupt cessation in ear development and a concomitant lack of silk emergence. Hollow husk occurred when the foliage of actively growing plants was sprayed before the VT growth stage with a chemical treatment that should either lower the level of plant ethylene (a strobilurin fungicide), or one that should decrease the plant's sensitivity to ethylene (1-MCP). An attempt to increase ethylene status (via ethephon) led to virtually no hollow husk symptoms. The percentage of plants exhibiting hollow husk symptoms depended on the hybrid, the stage of plant growth when sprayed, and the combination of management conditions that promoted plant growth. Plants sprayed at V15 generally exhibited greater symptoms than those sprayed at V11, and hollow husk successively increased with increases in N supply and decreased with increases in plant population. Based on our data, we speculate that hollow husk is a physiological ear abnormality related to a perturbation in the level or the sensitivity of the plant to ethylene.
Abbreviations: 1-MCP, 1-methylcyclopropene • ACC, 1-aminocyclopropane-1-carboxylic acid • a.i., active ingredient • DKC, DeKalb • DOY, day of year • R, reproductive • UTC, untreated control • V, vegetative
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Received for publication May 9, 2008.
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