Digital Commons Network^™

Agronomic Responses Of Corn Hybrids From Different Eras To Deficit And Adequate Levels Of Water And Nitrogen, Patrick M. O'Neill, J.F. Shanahan, James S. Schepers, Bob Caldwell

Department of Agronomy and Horticulture: Faculty Publications

Maintaining current high yields of corn (Zea mays L.) grown in the USA poses an environmental threat due to continued overuse of water and N inputs. To reduce overreliance on inputs, future corn breeding efforts should focus on improving tolerance of corn to water and N stresses, utilizing appropriate tolerance mechanisms. The objective of this study was to identify appropriate mechanisms by characterizing agronomic responses of 12 hybrids from three different eras (‘B73 x Mo17’ from 1970s and three early 1990s and eight late 1990s Pioneer brand hybrids) to varying water and N supply. This was done by growing …

Land Rehabilitation And Maintenance Equipment Sources, Heidi Howard, Shannon Mcdowell, Amanda Breon, John A. Guretzky, Bradley Tadlock

Department of Agronomy and Horticulture: Faculty Publications

Military training can often be destructive to the environment. Environmental impacts associated with heavy training include soil compaction, soil erosion, siltation of waterways and wetlands, increased threat of flooding, loss of wildlife habitat, declining biodiversity, and invasion by noxious weeds. Planning and implementing land rehabilitation projects generally involves some soil movement, establishment of vegetation, stabilization and hardening of sites, etc. Procurement of appropriate heavy equipment and other specialized equipment is sometimes a difficult task that involves obtaining multiple vendors, especially when procuring equipment for rental, lease, or purchase. This report and associated database were created to help land managers easily …

Sources Of Plant Materials For Land Rehabilitation, Heidi Howard, John A. Guretzky, Brandy Koch, Shannon Mcdowell, Steven Warren, Gwyn L. Howard

Department of Agronomy and Horticulture: Faculty Publications

Military training often results in environmental degradation that has negative impacts on future training missions. The U.S. Army Construction Engineering Research Laboratory (CERL) conceptualized the Army’s Integrated Training Area Management (ITAM) program in response to the concerns expressed by military land managers and trainers over the declining condition of training and testing lands. ITAM has evolved to include land condition and trend analysis (LCTA), environmental awareness (EA), training requirements integration (TRI), and land rehabilitation and maintenance (LRAM). The need for LRAM has increased dramatically over the past decade. Among the many difficulties faced in planning and implementing a land rehabilitation …

Interactions Among Western Ragweed And Other Sandhills Species After Drought, Patrick E. Reece, Joe E. Brummer, Brian K. Northup, Ann E. Koehler, Lowell E. Moser

Department of Agronomy and Horticulture: Faculty Publications

Interannual differences in yield and species composition of herbaceous vegetation on semiarid rangelands are common and often related to variations in precipitation regime. Interspecific interactions that occur after drought-induced population fluxes of western ragweed (Ambrosia psilostachya D.C.) were evaluated by removing western ragweed or associated species from 1-m² quadrats at weekly intervals beginning in early May, June, or July 1991 or 1992 on high-seral sandhills prairie in Nebraska. The composite of peak standing crops for ragweed and each group of associated species was 77% greater during May–October 1991 (2 252 kg•ha^-1) compared with 1992 (1 275 …

Temporal Origin Of Nitrogen In The Grain Of Irrigated Rice In The Dry Season: The Outcome Of Uptake, Cycling, Senescence And Competition Studied Using A 15N-Point Placement Technique, J. E. Sheehy, M. Mnzava, Kenneth G. Cassman, P. L. Mitchell, P. Pablico, R. P. Robles, H. P. Samonte, J. S. Lales, A. B. Ferrer

Department of Agronomy and Horticulture: Faculty Publications

It is often suggested that nitrogen absorbed in the vegetative stage of growth acts as a “reservoir” to supply the shortfall in demand during grain filling. The main objective of the work described in this paper was to investigate how effectively nitrogen absorbed at different stages of the growing season was retained and used for grain growth. The total nitrogen in the grain is the integral of the product of the total nitrogen absorbed at any instant and the eventual allocation of a fraction of that nitrogen to the grain. A point-placement technique was used to deliver small amounts of …

Growth And Yield Of Snap Beans As Affected By Wind Protection And Microclimate Changes Due To Shelterbelts And Planting Dates, Laurie Hodges, Mohd Nazip Suratman, James R. Brandle, Kenneth G. Hubbard

Department of Agronomy and Horticulture: Faculty Publications

The effects of wind protection on growth and total and marketahle yields of snap bean (Phaseolus vulgaris L.) planted at 2-week intervals through the 1994 and 1995 growing seasons were examined. Research was conducted under nonirrigated conditions at the Shelterbelt Research Area, Univ, of Nebraska Agricultural Research and Development Center (ARDC) near Mead. 'Strike' (white-seeded) and 'Rushmore' (dark-seeded) were planted in locations sheltered from wind stress hy tree windbreaks (shelterbelts) and in locations exposed to normal winds using a randomized complete-block design with a split-split plot arrangement of treatments. Air temperature, soil temperature, humidity, wind speed, and wind direction …

Rice Yields Decline With Higher Night Temperature From Global Warming, Shaobing Peng, Jianliang Huang, John Sheehy, Rebecca C. Laza, Romeo M. Visperas, Xuhua Zhong, Grace S. Centeno, Gurdev S. Khush, Kenneth G. Cassman

Department of Agronomy and Horticulture: Faculty Publications

The impact of projected global warming on crop yields has been evaluated by indirect methods using simulation models. Direct studies on the effects of observed climate change on crop growth and yield could provide more accurate information for assessing the impact of climate change on crop production. We analyzed weather data at the International Rice Research Institute Farm from 1979 to 2003 to examine temperature trends and the relationship between rice yield and temperature by using data from irrigated field experiments conducted at the International Rice Research Institute Farm from 1992 to 2003. Here we report that annual mean maximum …

Nitrogen Mineralization From Humic Acid Fractions In Rice Soils Depends On Degree Of Humification, Bao Ve Nguyen, D. C. Olk, Kenneth G. Cassman

Department of Agronomy and Horticulture: Faculty Publications

Although the chemical nature of soil organic matter (SOM) is thought to affect the mineralization rate of N bound in SOM, little direct evidence exists for such effects. To test the hypothesis that the N mineralization rate is affected by the degree of SOM humification, we added equivalent amounts of humic acid (HA) N as either the labile mobile humic acid (MHA) fraction or the more humified cal- cium humate (CaHA) fraction to two lowland rice (Oryza sativa L.) soils, which were subsequently incubated under anaerobic conditions for 6 wk. The HA fractions had been chemically extracted from seven …

Characterization Of Humic Acid Fractions Improves Estimates Of Nitrogen Mineralization Kinetics For Lowland Rice Soils, Nguyen Bao Ve, D. C. Olk, Kenneth G. Cassman

Department of Agronomy and Horticulture: Faculty Publications

Nitrogen mineralization in irrigated lowland rice (Oryza sativa L.) soils is poorly predicted by total soil C and N. To improve its prediction, two humic acid fractions were extracted with NaOH from lowland rice soils of Vietnam and the Philippines to evaluate their influence on N mineralization kinetics during 84-d anaerobic incubations. Indicative of young organic matter, the mobile humic acid (MHA) fraction had a smaller C/N ratio and optical density at 465 nm (E₄) than did the calcium humate (CaHA) fraction, which was extracted after removal of polyvalent cations from the soil. Nitrogen contents of both …

A New Integrated Genetic Linkage Map Of The Soybean, Q.J. Song, L.F. Marek, R.C. Shoemaker, K.G. Lark, V.C. Concibido, X. Delannay, James E. Specht, P.B. Cregan

Department of Agronomy and Horticulture: Faculty Publications

A total of 391 simple sequence repeat (SSR) markers designed from genomic DNA libraries, 24 derived from existing GenBank genes or ESTs, and five derived from bacterial artificial chromosome (BAC) end sequences were developed. In contrast to SSRs derived from EST sequences, those derived from genomic libraries were a superior source of polymorphic markers, given that the mean number of tandem repeats in the former was significantly less than that of the latter (P<0.01). The 420 newly developed SSRs were mapped in one or more of five soybean mapping populations: ‘Minsoy’ × ‘Noir 1’, ‘Minsoy’ × ‘Archer’, ‘Archer’ × ‘Noir 1’, ‘Clark’ × ‘Harosoy’, and A81-356022 × PI468916. The JoinMap software package was used to combine the five maps into an integrated genetic map spanning 2,523.6 cM of Kosambi map distance across 20 linkage groups that contained 1,849 markers, including 1,015 SSRs, 709 RFLPs, 73 RAPDs, 24 classical traits, six AFLPs, ten isozymes, and 12 others. The number of new SSR markers added to each linkage group ranged from 12 to 29. In the integrated map, the ratio of SSR marker number to linkage group map distance did not differ among 18 of the 20 linkage groups; however, the SSRs were not uniformly spaced over a linkage group, clusters of SSRs with very limited recombination were frequently present. These clusters of SSRs may be indicative of gene-rich regions of soybean, as has been suggested by a number of recent studies, indicating the significant association of genes and SSRs. Development of SSR markers from map-referenced BAC clones was a very effective means of targeting markers to marker-scarce positions in the genome.

Stability Of The Allergenic Soybean Kunitz Trypsin Inhibitor, Robin Roychaudhuri, Gautam Sarath, Michael G. Zeece, John P. Markwell

Department of Agronomy and Horticulture: Faculty Publications

The soybean Kunitz trypsin inhibitor (SKTI) is a 21.5 kDa allergenic protein that belongs to the family of all antiparallel h-sheet proteins that are highly resistant to thermal and chemical denaturation. Spectroscopic and biochemical techniques such as circular dichroism (CD), ANS fluorescence and proteolysis were used to study its molecular structure under denaturing conditions such as acid and heat to which these allergens are commonly exposed during food processing. Reduction of native SKTI leads to its complete and rapid proteolysis by pepsin in simulated gastric fluid (SGF). Limited proteolysis with chymotrypsin during renaturation after heating showed that the native structure …

Hybrid-Maize—A Maize Simulation Model That Combines Two Crop Modeling Approaches, H. S. Yang, A. Dobermann, John L. Lindquist, Daniel T. Walters, Timothy J. Arkebauer, Kenneth G. Cassman

Department of Agronomy and Horticulture: Faculty Publications

A new maize (Zea mays L.) simulation model, Hybrid-Maize, was developed by combining the strengths of two modeling approaches: the growth and development functions in maize-specific models represented by CERES- Maize, and the mechanistic formulation of photosynthesis and respiration in generic crop models such as INTERCOM and WOFOST. It features temperature-driven maize phenological development, vertical canopy integration of photosynthesis, organ-specific growth respiration, and temperature-sensitive maintenance respiration. The inclusion of gross assimilation, growth respiration and maintenance respiration makes the Hybrid- Maize model potentially more responsive to changes in environmental conditions than models such as CERES-Maize. Hybrid-Maize also requires fewer genotype-specific …

Feasibility Of Site-Specific Management Of Corn Hybrids And Plant Densities In The Great Plains, J.F. Shanahan, Thomas A. Doerge, Jerry J. Johnson, Merle F. Vigil

Department of Agronomy and Horticulture: Faculty Publications

The goal of this research was to determine the potential for use of site-specific management of corn hybrids and plant densities in dryland landscapes of the Great Plains by determining (1) within-field yield variation, (2) yield response of different hybrids and plant densities to variability, and (3) landscape attributes associated with yield variation. This work was conducted on three adjacent fields in eastern Colorado during the 1997, -98, and -99 seasons. Treatments consisted of a combination of two hybrids (early and late maturity) and four plant densities (24,692, 37,037, 49,382 and 61,727 plants ha^-1) seeded in replicated long …

Agronomic Ufos, Thomas R. Sinclair, Kenneth G. Cassman

Department of Agronomy and Horticulture: Faculty Publications

Science is challenged from time-to-time by claims that are completely outside the usual boundaries of observation and experience. Reports of flying saucers (unidentified flying objects) and creationism’s counter to evolution are two examples that fall into this category. Credentialed scientists can themselves become the victims of such phenomena when their research results are not evaluated through anonymous peer review as part of publication. The cold fusion debacle of a few years ago is an example of such a bypass of peer evaluation.

Unfortunately, agronomic science is not immune to such problems, particularly as they relate to claims of miraculously high …

Appropriateness Of Management Zones For Characterizing Spatial Variability Of Soil Properties And Irrigated Corn Yields Across Years, Aaron R. Schepers, J.F. Shanahan, Mark A. Liebig, James S. Schepers, Sven Johnson, Ariovaldo Luchiari Jr.

Department of Agronomy and Horticulture: Faculty Publications

Recent precision-agriculture research has focused on use of management zones (MZ) as a method for variable application of inputs like N. The objectives of this study were to determine (i) if landscape attributes could be aggregated into MZthat characterize spatial varia- tion in soil chemical properties and corn yields and (ii) if temporal variability affects expression of yield spatial variability. This work was conducted on an irrigated cornfield near Gibbon, NE. Five landscape attributes, including a soil brightness image (red, green, and blue bands), elevation, and apparent electrical conductivity, were acquired for the field.Ageoreferenced soil-sampling scheme was used to determine …

Prediction Of Leaf/Stem Ratio Using Near-Infrared Reflectance Spectroscopy (Nirs): A Technical Note, Alexander J. Smart, Walter H. Schacht, Lowell E. Moser, Jerry D. Volesky

Department of Agronomy and Horticulture: Faculty Publications

Leaf/stem ratio of grass stands is an important factor affecting diet selection, quality, and forage intake. Determination of leaf/stem ratio involves a labor-intensive process of hand separating leaf and stem fractions. Our objectives in this study were to evaluate leaf/stem ratio prediction using near-infrared reflectance spectroscopy (NIRS) in monocultures of big bluestem (Andropogon gerardii Vitman), switch- grass (Panicum virgatum L.), intermediate wheatgrass [Thinopyrum intermedian (Host) Barkw. & D.R. Dewey], and smooth bromegrass (Bromus inermis Leyss.). Samples of each species were hand-clipped from monocultures at four locations throughout Nebraska in the 1997 and 1998 growing seasons. Ground …

Forage & Grazing Lands: Morphological Characteristics Of Big Bluestem And Switchgrass Plants Divergently Selected For Seedling Tiller Number, Alexander J. Smart, Lowell E. Moser, Kenneth P. Vogel

Department of Agronomy and Horticulture: Faculty Publications

Selection at the seedling stage in grass breeding would be useful if seedling traits were correlated to desired agronomic traits of mature plants. Objectives of this study were to determine if seedlings from big bluestem (Andropogon gerardii Vitman) and switchgrass (Panicumvirgatum L.) populations that differ genetically in seedling tiller num- ber differ in mature plant (i) morphological characteristics, (ii) forage yield managed by a three-cut harvest system or a single end-of-season harvest, and (iii) leaf elongation rate. Field experiments were conducted on a Kennebec silt loam soil (fine-silty, mixed, superactive, mesic Cumulic Hapludolls). In addition, greenhouse studies were …

Establishing Effects Of Application Of Swine Manure On Crop Leaf Damage To Growing Crops, Charles Shapiro, University Of Nebraska-Lincoln

Department of Agronomy and Horticulture: Faculty Publications

Swine manure from a below barn storage facility was applied to growing corn and soybeans to determine phytotoxic effects. The manure had an electrical conductivity of around 20 mmhos/cm and was diluted for treatment at full, half, quarter and none. The manure mixtures were applied at a rate of 0.5 in/acre using a procedure that wet the foliage three times in a 15-minute time span. Manure mixtures were applied at V7 and V14 for corn and V3 and R1 for soybeans. Phytotoxic effects were shown at the high rate for both crops, but soybeans were killed at the early application …

Expression Of A Putative Flavonoid 3'-Hydroxylase In Sorghum Mesocotyls Synthesizing 3-Deoxyanthocyanidin Phytoalexins, Jayanand Boddu, Catherine Svabek, Rajandeep Sekhon, Amanda Gevens, Ralph L. Nicholson, A. Daniel Jones, Jeffrey F. Pedersen, David L. Gustine, Surinder Chopra

Department of Agronomy and Horticulture: Faculty Publications

In sorghum, ingress of Cochliobolus heterostrophus stimulates the synthesis of 3-deoxyanthocyanidins that act as phytoalexins. Apigeninidin and luteolinidin are two major phytoalexins induced in the first 24 h after infection. In an attempt to understand genetic regulation of the biosynthesis of sorghum phytoalexins, we isolated a differentially expressed partial cDNA. Characterization and comparison showed that this cDNA sequence corresponds to a putative flavonoid 3’-hydroxylase. Full length sequence characterization allowed us to establish that the sorghum putative f3’h cDNA encodes a peptide of 517 amino acids that has domains conserved among cytochrome P450 proteins functioning in …

Random Amplified Polymorphic Dna (Rapd) Analysis Of Long-Term Cultured Hybrid Hazelnut, Mehmet Nuri Nas, Nedim Mutle, Paul Read

Department of Agronomy and Horticulture: Faculty Publications

RAPD and phenotypic analysis were conducted to assess clonal stability of hazelnuts generated from axillary buds cultured in vitro for long-term. The nuts produced on in vitro-propagated plants were indistinguishable from those of donor plants. With the exception of rare horizontal (plagiotropic) growth, all in vitro-propagated plants exhibited phenotypes similar to those of donor plants. RAPD analysis did not reveal any somaclonal variation between donor plants from which in vitro cultures were initiated and micropropogated plants (6-year cultures), and no somaclonal variation was detected among in vitro propogated plants. However, polymorphism (15.6%) was detected between the parent plant and its …

Heritability Of The Resistance To Potato Leafhopper In Dry Bean, J.W. Gonzales, Dermot P. Coyne, Dale T. Lindgren, D. Schaaf, Kent M. Eskridge

Department of Agronomy and Horticulture: Faculty Publications

The potato leafhopper (PLH), Empoasca fabae Harris is the most important Empoasca species attacking dry beans (Phaseolus vulgaris L.) in North America. The objective of this study was to determine the heritability (h²) of PLH injury based on parent-offspring regression analysis of F₃ means on individual F₂ plants derived from crosses of pinto 'Sierra' (resisant) x great northern 'Starlight' (susceptible), and black bean 'Tacarigua' (resistant) x 'Starlight' (susceptible). Low narrow-sense heritability values of 0.29 ± 0.06 ± 0.28 ± 0.10, respectively, were obtained for the above crosses. The low narrow-sense heritability estimates indicated large environmental …

In-Season Prediction Of Attainable Maize Yield Using The Hybrid-Maize Model, Achim R. Dobermann, Haishun Yang, Kenneth G. Cassman, Daniel T. Walters

Department of Agronomy and Horticulture: Faculty Publications

The Hybrid-Maize Model

Real-time Simulation and Yield Forecasting

Case Study 1: Irrigated Maize, Lincoln, Nebraska

Case Study 2: Rainfed Maize, Oliveros, Argentina

Case Study 3: Rainfed Maize, Mead, Nebraska

Conclusions

References

Test Of The Hybrid-Maize Model For Simulation Of Soil Moisture Dynamics And Maize Response To Water Deficit, Haishun S. Yang, Achim R. Dobermann, Kenneth G. Cassman, Kenneth G. Hubbard, Timothy J. Arkebauer, Shashi Verma, Daniel T. Walters

Department of Agronomy and Horticulture: Faculty Publications

The Hybrid-Maize model (Yang et al, 2004), which has been validated under optimal water conditions, was evaluated for its ability to simulate soil moisture dynamics in the root zone and effects of water deficits on maize development and final yields (Fig. 1). The experimental data for this evaluation were obtained from ongoing field studies of the Carbon Sequestration Program (CSP) at the University of Nebraska. The studies include three cropping systems, each located in a quarter-section field (57 ha), two of which are irrigated by central-pivots and the third is rainfed. One irrigated field is in continuous maize and the …

Plant Population And Fertilization Impacts On Irrigated Corn In Nebraska, Daniel T. Walters, Achim R. Dobermann

Department of Agronomy and Horticulture: Faculty Publications

Since 1999, a team of researchers at the University of Nebraska has been conducting studies to understand the yield potential of corn and soybeans and how management affects it. The crop model discussed in the previous article was a product of this team. The research compares continuous corn to a corn-soybean rotation and evaluates how plant population and nutrient management impact yield. In addition to determining productivity, the research involves an integrated assessment of profitability, input use efficiency, energy balance, and environmental consequences.

Distribution Of Legumes Along Gradients Of Slope And Soil Electrical Conductivity In Pastures, John A. Guretzky, Kenneth J. Moore, C. Lee Burras, E. Charles Brummer

Department of Agronomy and Horticulture: Faculty Publications

Legumes establish and persist on backslope landscape positions but fail on summits and toeslopes in southeastern Iowa pastures, suggesting that these pastures be managed site specifically. Visual delineation of landscape positions, however, can be difficult, and char- acterization of spatial variability through soil sampling is expensive. Creation of digital elevation models (DEM) and apparent soil electrical conductivity (EC_a) mapping are inexpensive alternatives to de- scribing field conditions. Our objective was to examine the relationships of DEM-derived slope, soil EC_a, and legume distribution in pastures.We examined these relationships across four 1.4-ha pastures. Each pasture was divided into …

Genotypic And Environmental Modification Of Asian Noodle Quality Of Hard Winter Wheats, Robert A. Graybosch, N. Ames, P. Stephen Baenziger, C. J. Peterson

Department of Agronomy and Horticulture: Faculty Publications

The relative effects of environment, genotype, and their interactions on the modification of Asian noodle quality attributes were assessed using 38 winter wheat (Triticum aestivum L.) cultivars and breeding lines grown in replicated trials at three Nebraska locations in harvest year 2000. Noodle color was determined in both white salted and yellow alkaline procedures, and noodle textural features were investigated by producing white salted noodles. Significant environmental, genotypic, and genotype-by-environment variation was observed for nearly all initial and 24-hr noodle color traits in both types of noodles. Significant genotypic effects were observed for several textural traits, while significant environmental …

Registration Of Npm-4, A Dwarf White Grain Pearl Millet Germplasm, J.F. Rajewski, D.J. Andrews, Ismail M. Dweikat

Department of Agronomy and Horticulture: Faculty Publications

Dwarf grain pearl millet [Pennisetum glucum (L.) R. Br.] germplasm NPM-4 (Reg. no. GP-37, PI 634545) was released in September 2003 by the Institute of Agriculture and Natural Resources, University of Nebraska, Lincoln, NE.

NPM-4 was derived from open-pollinated outcrosses of white grain inbred line 57028R1w grown in a 1998 Puerto Vallarta winter nursery. The source of the outcross pollen was from primarily genetically diverse, dwarf, early maturing, gray seeded lines being developed as parents for grain yield. Line 57028R₁w was derived from 89C57028R₁/3*90PV0121. Line 89C57028R₁ is gray-seeded, and line 90PV0121 has white seed. …

Application Of Sequence-Related Amplified Polymorphism Markers For Characterization Of Turfgrass Species, Hikmet Budak, Bob Shearman, Roch E. Gaussoin, Ismail M. Dweikat

Department of Agronomy and Horticulture: Faculty Publications

A simple marker technique called sequence-related amplified polymorphism (SRAP) provides a useful tool for estimation of genetic diversity and phenetic relationships in natural and domesticated populations. Previous studies and our initial screen show SRAP is highly polymorphic and more informative when compared to AFLP, RAPD and SSR markers. In this study, applicability of the SRAP markers to obtain an overview of genetic diversity and phenetic relationships resent among cool-season (C3) and warm-season (C4) turfgrass species and their relationship with other Gramineae species were tested. Phenetic trees based on genetic similarities (UPGMA, N-J) were consistent with known taxonomic relationships. In some …

Crop And Soil Productivity Response To Corn Residue Removal: A Literature Review, Wallace Wilhelm, J.M.F. Johnson, J. L. Hatfield, W.B. Voorhees, D.R. Linden

Department of Agronomy and Horticulture: Faculty Publications

Society is facing three related issues: over-reliance on imported fuel, increasing levels of greenhouse gases in the atmosphere, and producing sufficient food for a growing world population. The U.S. Department of Energy and private enterprise are developing technology necessary to use high-cellulose feedstock, such as crop residues, for ethanol production. Corn (Zea mays L.) residue can provide about 1.7 times more C than barley (Hordeum vulgare L.), oat (Avena sativa L.), sorghum [Sorghum bicolor (L.) Moench], soybean [Glycine max L.) Merr.], sunflower (Helianthus annuus L.), and wheat (Triticum aestivum L.) residues based on …

Predicting Phenological Development In Winter Wheat, Qingwu Xue, Albert Weiss, P. Stephen Baenziger

Department of Agronomy and Horticulture: Faculty Publications

Accurate prediction of phenological development is important in the winter wheat Triticum aestivum agroecosystem. From a practical perspective, applications of pesticides and fertilizers are carried out at specific phenological stages. In crop-simulation modeling, the prediction of yield components (kernel number and kernel weight) and wheat-grain yield relies on accurate prediction of phenology. In this study, a nonlinear multiplicative model by Wang & Engel (WE) for predicting phenological development in differing winter wheat cultivars was evaluated using data from a 3 yr field experiment. In the vegetative phase (emergence to anthesis) the daily development rate (r) was simulated based on the …