scholarly journals Simulating winter wheat shoot apex phenology

1992 ◽  
Vol 119 (1) ◽  
pp. 1-12 ◽  
Author(s):  
G. S. McMaster ◽  
W. W. Wilhelm ◽  
J. A. Morgan
Keyword(s):  
Winter Wheat ◽  
Great Plains ◽  
Shoot Apex ◽  
Cultural Practices ◽  
Seedling Emergence ◽  
Simulation Models ◽  
Climatic Conditions ◽  
Growth Stages ◽  
Developmental Sequence ◽  
Wheat Shoot

SummarySimulation models are heuristic tools for integrating diverse processes and help to increase our understanding of complex processes and systems. Models that predict crop development can serve as decision-support tools in crop management. This paper describes a phenology simulation model for the winter wheat shoot apex and reports validation and sensitivity analysis results.The complete developmental sequence of the winter wheat shoot apex is quantitatively outlined and correlated with commonly recognised phenological growth stages. The phyllochron is used to measure the thermal time between most phenological growth stages, thereby increasing the flexibility over the growing degree-day (GDD) and photothermal approaches. Nineteen site-years covering a range of climatic conditions, cultural practices and cultivars across the Central Great Plains, USA, are used to validate the model.Validation results show that the predicted phyllochron (108 GDD) agrees well with the observed phyllochron (107 GDD) for ten cultivars. Mean seedling emergence is predicted to within 2 days in almost all of the 19 site-years. The ability of the model to predict growth stages accurately increased successively from jointing to heading to maturity. Maturity is generally predicted to within 5 days of the observed day.After validation, recalibration of the phyllochron estimates between growth stages are provided, and corrections for mesic and xeric conditions are suggested. Further validation of the entire developmental sequence of the shoot apex is recommended.

Using transpiration to characterize plant height in winter wheat in different environments: A simulation study

1995 ◽  
Vol 75 (3) ◽  
pp. 583-587 ◽  
Author(s):  
A. Weiss ◽  
N. Budak ◽  
P. S. Baenziger
Keyword(s):  
Winter Wheat ◽  
Plant Height ◽  
Great Plains ◽  
Seedling Emergence ◽  
Wheat Plant ◽  
Triticum Aestivum L ◽  
Growth And Yield ◽  
Yield Model ◽  
Climatic Regions ◽  
Height Predictions

Winter wheat (Triticum aestivum L.) plant height is an important trait for the diverse environmental conditions found in the Great Plains. It has been related to seedling emergence, lodging, soil erosion, ease of harvest, crop residue and weed control. The hypothesis that transpiration, which integrates atmosphere, soil, and plant processes, could be used to characterize environmental effects on wheat plant height was tested in this research. Data from four commercial winter wheat cultivars (Arapahoe, TAM107, Vista, and Siouxland) and nine environments in Nebraska in 1992 and 1993 were used. The climatic regions represented in this study ranged from sub-humid to semiarid. To test our hypothesis, a spring wheat growth and yield model was modified to predict plant height development (modeled as a sigmoidal function of time) in winter wheat. Daily height increment was based on the ratio of actual to potential transpiration. The model was run for these four cultivars in eight environments. Data from the ninth environment was used to estimate maximum plant height for each cultivar; a necessary input into the model. Modeled plant height predictions were in good agreement with actual measurements for all environments (R2 = 0.80). Based on these results, we conclude that transpiration was a good indicator of environment for plant height development in winter wheat. Key words:Triticum aestivum L., plant height, transpiration, modeling

scholarly journals Phenological responses of wheat and barley to water and temperature: improving simulation models

2003 ◽  
Vol 141 (2) ◽  
pp. 129-147 ◽  
Author(s):  
G. S. McMASTER ◽  
W. W. WILHELM
Keyword(s):  
Water Stress ◽  
Air Temperature ◽  
Shoot Apex ◽  
Spring Wheat ◽  
Simulation Models ◽  
Thermal Time ◽  
Growth Stages ◽  
Wheat Cultivars ◽  
Winter Wheat Cultivars ◽  
General Response

Understanding and predicting small-grain cereal development is becoming increasingly important in enhancing management practices. Recent efforts to improve phenology submodels in crop simulations have focused on incorporating developmental responses to water stress and interpreting and understanding thermal time. The objectives of the present study were to evaluate data from three experiments to (a) determine the qualitative and quantitative response of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) to water stress and (b) ascertain where in space to measure temperature, to provide information required to improve phenological submodels. The first experiment tested the phenological responses of 12 winter wheat cultivars to water stress for two seasons at two sites. The second experiment tested the timing of water stress on spring barley phenological responses for 2 years. In a third experiment, soil near the shoot apex of field-grown spring wheat was heated to 3°C above ambient soil temperature for three planting dates in each of 2 years, to test whether it is better to use soil or air temperature in calculating thermal time. The general response of wheat and barley to water stress was to reach growth stages earlier (i.e. to hasten development). The most significant response was for the grain filling period. Water stress had little effect on jointing and flag leaf complete/booting growth stages. Thermal time to jointing was highly variable across locations. However, thermal time to subsequent growth stages was very consistent both within and across locations. The winter wheat cultivars tested followed this general response across site-years, but inconsistencies were found, suggesting a complicated genotype by environment (G×E) interaction that makes improving phenology submodels for all cultivars difficult. The G×E interaction was most prominent for anthesis (A) and maturity (M) growth stages. Results of heating the soil at the shoot apex depth were completely unexpected: heating the soil did not speed spring wheat phenological development. These results, and others cited, suggest caution in allocating effort and resources to measuring or estimating soil temperature rather than relying on readily available air temperature as a means of universally improving phenology submodels. These results help quantify the response of wheat to water stress and thermal time for improving crop simulation models and management.

scholarly journals Developmental sequences for simulating crop phenology for water-limiting conditions

2005 ◽  
Vol 56 (11) ◽  
pp. 1277 ◽  
Author(s):  
Gregory S. McMaster ◽  
W. W. Wilhelm ◽  
A. B. Frank
Keyword(s):  
Soil Water ◽  
Shoot Apex ◽  
Management Practices ◽  
Triticum Aestivum L ◽  
Growth Stages ◽  
Plant Responses ◽  
Environment Interaction ◽  
Developmental Sequence ◽  
Hordeum Vulgare L ◽  
Crop Phenology

The timing, duration, and pace of developmental events, or phenology, are among the many responses of plants to limited soil water. Understanding and predicting plant responses to availability of soil water are important in improving the efficacy of management practices. However, the first steps towards gaining this understanding, summarising the complete developmental sequence of the shoot apex and correlating the timing of these events, have rarely been reported. Also, the effect of water-limiting conditions on crop phenology and shoot apex development is variable. The objective of this paper is to present the developmental sequence of the wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), and corn (Zea mays L.) shoot apices and correlate events in these sequences with growth stages for both well-watered and water-limiting conditions. We note that phenological responses to water availability occur at 3 different scales: among crops, among cultivars of a crop, and among growth stages within a cultivar or crop. Clearly, genotype × environment interaction affects the accuracy of predicting phenology. However, the fact that plants develop in an orderly, predictable pattern allows a general foundation for synthesising the complete sequence of developmental events of the shoot apex and correlate these with growth stages when water is not limiting. These patterns and relationships are the foundation to build upon in quantifying our understanding of crop phenology under water-limiting environments.

scholarly journals Rice phenology and growth simulation using CERES-Rice model under the agro-climate of upper Brahmaputra valley of Assam

MAUSAM ◽  
2021 ◽  
Vol 67 (3) ◽  
pp. 591-598
Author(s):  
R. L. DEKA ◽  
R. HUSSAIN ◽  
K. K. SINGH ◽  
A. K. BAXLA ◽  
V. U. M. RAO ◽  
...  
Keyword(s):  
Field Experiments ◽  
Simulation Models ◽  
Rice Cultivar ◽  
Climatic Conditions ◽  
Strategic Decision ◽  
Growth Stages ◽  
Growth Simulation ◽  
Brahmaputra Valley ◽  
Agricultural Planning ◽  
Tactical Decisions

Crop growth simulation models, properly validated against experimental data have the potential for facilitating strategic decision making in agriculture. Such validated models can also make use of the information generated for site specific experiments and trials to other sites and for different time durations. For proper calibration and evaluation of crop simulation models, there is a need for collection of a comprehensive minimum set of data on soil, weather and crop management in all agronomic experiments. Keeping this in view, data from seven field experiments conducted at Jorhat (26° 47' N, 94°12' E; 87 m amsl) during 1998-2005 for long duration rice cultivar Ranjit grown under rainfed conditions were collected. Genetic coefficients required for running the CERES-Rice v4.5 model were derived and the performance of the model under the climate of upper Brahmaputra valley was evaluated. These results indicate that the CERES Rice v4.5 model is capable of estimating growth stages and grain yield of rice cultivar Ranjit in the climatic conditions of upper Brahmaputra valley with reasonable accuracy. Hence, the model have the potential for its use as a tool in making various strategic and tactical decisions related to agricultural planning in the state.

Ecological Characteristics of Three Winter Annual Grasses

1998 ◽  
Vol 12 (3) ◽  
pp. 478-483 ◽  
Author(s):  
R. L. Anderson
Keyword(s):  
Winter Wheat ◽  
Seed Production ◽  
Cultural Practices ◽  
Seedling Emergence ◽  
Cultural Control ◽  
Downy Brome ◽  
Jointed Goatgrass ◽  
Annual Grasses ◽  
Winter Annual ◽  
Feral Rye

Producers rely on cultural practices to manage downy brome, jointed goatgrass, and feral rye in winter wheat because there are no effective herbicides for in-crop control. This study characterized seedling emergence, growth, and development of these winter annual grasses, with the goal of suggesting or improving cultural control strategies. Feral rye seedlings emerged within 4 wk, whereas downy brome and jointed goatgrass seedlings emerged over a 10-wk period. Emergence patterns of these grasses suggest that delay of winter wheat planting may be effective in reducing feral rye densities, but this strategy most likely will be ineffective with downy brome or jointed goatgrass. Downy brome began anthesis 1 to 2 wk earlier than the other two grasses and winter wheat. Both downy brome and jointed goatgrass were shorter than winter wheat during the growing season, whereas feral rye was at least as tall as wheat. Producers mow infested wheat to prevent weed seed production, but this practice may not be effective with jointed goatgrass and downy brome because of their short stature and downy brome's earlier development. Conversely, mowing has potential in preventing feral rye seed production. The grasses produced between 340 and 770 seeds/ plant.

Weed Community Response to Crop Rotations in Western South Dakota

2007 ◽  
Vol 21 (1) ◽  
pp. 131-135 ◽  
Author(s):  
Randy L. Anderson ◽  
Clair E. Stymiest ◽  
Bruce A. Swan ◽  
John R. Rickertsen
Keyword(s):  
Winter Wheat ◽  
Great Plains ◽  
Weed Management ◽  
Seedling Emergence ◽  
Warm Season ◽  
Community Response ◽  
Crop Rotations ◽  
Integrated Weed Management ◽  
Downy Brome ◽  
Proso Millet

Producers in the semiarid Great Plains are exploring alternative crop rotations, with the goal of replacing winter wheat–fallow. In 1993, a study was established to compare performance of eight rotations comprised of various combinations with winter wheat (W), spring wheat (SW), dry pea (Pea), safflower (Saf), corn (C), sunflower (Sun), proso millet (M), or fallow (F). After 8 years, we characterized weed communities by recording seedling emergence in each rotation. Seventeen species were observed, with downy brome, kochia, horseweed, and stinkgrass comprising 87% of the community. Rotations with the least number of weed seedlings were W–F and SW–W–C–Sun; in comparison, weed density was six-fold higher in W–M. Density of downy brome and kochia was highest in W–M compared with other rotations, whereas stinkgrass and green foxtail were prominent in proso millet of the W–M and W–C–M rotations. Horseweed established readily in safflower and dry pea. In the semiarid Great Plains, designing rotations in a cycle of four that includes cool- and warm-season crops can be a key component of integrated weed management.

Downy Brome (Bromus tectorum) Emergence Variability in a Semiarid Region

1996 ◽  
Vol 10 (4) ◽  
pp. 750-753 ◽  
Author(s):  
R. L. Anderson
Keyword(s):  
Winter Wheat ◽  
Great Plains ◽  
Wind Erosion ◽  
Bromus Tectorum ◽  
Control Strategies ◽  
Seedling Emergence ◽  
Plant Diseases ◽  
Semiarid Region ◽  
Downy Brome ◽  
Wheat Stubble

This study characterized seedling emergence of downy brome from August to early December over a 6-yr period. Seedlings were counted weekly in quadrats established in winter wheat stubble at Akron, CO. Seedling emergence varied among years, which was caused by erratic seasonal precipitation. Producers delay planting of winter wheat to reduce downy brome density in the crop, but in only 1 yr out of 6 would producers have benefited from this control strategy. Furthermore, delayed planting has negative crop consequences: less grain yield and more susceptibility to plant diseases and wind erosion because of less fall plant growth. Because fall precipitation is erratic in the semiarid Great Plains, other control strategies, such as nitrogen placement and increased seeding rates of winter wheat, would be more effective for downy brome management, yet not detrimental to winter wheat production.

Seasonal changes in the position of the shoot apex of winter wheat and spring barley in relation to the soil surface

1978 ◽  
Vol 91 (1) ◽  
pp. 245-248 ◽  
Author(s):  
R. K. M. Hay
Keyword(s):  
Winter Wheat ◽  
Soil Properties ◽  
Shoot Apex ◽  
Seasonal Changes ◽  
Leaf Growth ◽  
Spring Barley ◽  
Soil Surface ◽  
Growth Stages ◽  
Field Investigations ◽  
Crop Development

In many field investigations of cereal growth, stages of crop development may be described adequately using the Feekes scale (Large, 1954) or the more recent decimal code (Zadoks, Chang & Konzak, 1974). For example, the onset of stem extension (Feekes stage 6; decimal code 31) is frequently taken as a field indication of the switch from vegetative to reproductive growth. However, in investigations of the influence of soil properties, especially temperature, on shoot apex and leaf growth, it is important to know (a) the position of the apex below the soil surface during the early stages of development and (b) the timing of the rise of the apex above the soil surface.

Characterizing Weed Communities Among Various Rotations in Central South Dakota

2007 ◽  
Vol 21 (1) ◽  
pp. 76-79 ◽  
Author(s):  
Randy L. Anderson ◽  
Dwayne L. Beck
Keyword(s):  
Winter Wheat ◽  
Great Plains ◽  
Seedling Emergence ◽  
Warm Season ◽  
Downy Brome ◽  
Redroot Pigweed ◽  
Alternative Crop ◽  
Weed Communities ◽  
Green Foxtail ◽  
Central South

Producers in the Great Plains are exploring alternative crop rotations with the goal of reducing the use of fallow. In 1990, a study was established with no-till practices to compare eight rotations comprising various combinations of winter wheat (W), spring wheat (SW), corn (C), chickpea (CP), dry pea (Pea), soybean (SB), or fallow (F). After 12 yr, we characterized weed communities by recording seedling emergence in each rotation. Downy brome, cheat, redroot pigweed, and green foxtail were the most common weeds observed. Weed community density was highest for W–CP, being 13-fold greater than with Pea–W–C–SB. Downy brome and cheat were rarely observed in rotations where winter wheat was grown only once every 3 or 4 yr; in contrast, density of the brome species was 75-fold greater in W–CP. Warm-season weeds were also affected by rotation design; density of redroot pigweed and green foxtail was sixfold greater in W–C–CP compared with Pea–W–C–SB or W–F. One rotation design that was especially favorable for low weed density was arranging crops in a cycle of four, with two cool-season crops followed by two warm-season crops.

Cultural Practices in Wheat (Triticum aestivum), on Weeds in Subsequent Fallow and Sorghum (Sorghum bicolor)

Weed Science ◽  
1995 ◽  
Vol 43 (3) ◽  
pp. 434-444 ◽  
Author(s):  
Gail A. Wicks ◽  
Duane A. Martin ◽  
Garold W. Mahnken
Keyword(s):  
Winter Wheat ◽  
Grain Yield ◽  
Cultural Practices ◽  
Growth Stages ◽  
Annual Grass ◽  
Wheat Grain ◽  
Grain Yields ◽  
Herbicide Treatments ◽  
Urea Ammonium Nitrate ◽  
Different Growth Stages

The effect of herbicide and urea-ammonium nitrate (UAN) combinations on winter wheat injury in absence of noncompetitive weeds and weed control during a winter wheat-fallow and a winter wheat-sorghum-fallow rotation were investigated. Winter wheat was planted at different dates to obtain different growth stages for spraying in the spring. Winter wheat produced greater grain yields when planted Sept. 15 or Sept. 25, 1987, 1988, and 1989 vs. Sept. 1 at North Platte, NE, while at Sidney, NE, grain yield was higher in wheat planted on Sept. 10 or Sept. 20, 1988, compared to Aug. 26. Spring-applied UAN increased grain yield on wheat planted Sept. 10 compared to no UAN in 1988–89 at Sidney, but not in 1987–88, while at North Platte, grain yields were not affected by UAN. At Sidney 2,4-D ester at 0.6 kg ae ha−1, 2,4-D amine plus dicamba at 0.3 plus 0.1 kg ae ha−1, metsulfuron at 0.007 kg ai ha−1plus 0.25% nonionic surfactant (NIS), and metsulfuron plus 2,4-D ester at 0.007 plus 0.3 kg ha−1plus NIS decreased grain yields compared to one handweeding. At North Platte in 1988–89, when UAN was applied with 2,4-D ester, 2,4-D amine plus dicamba, or metsulfuron plus 2,4-D plus NIS grain yields were reduced compared to the handweeded check on wheat planted Sept. 15. Occasionally, metsulfuron plus 2,4-D ester plus NIS treated wheat yielded less grain than metsulfuron plus NIS treated wheat. One or more herbicide treatments reduced wheat grain yields 4 of 15 application dates. Crop injury was related to growth stage and health of winter wheat when treatments were applied. Wheat under stress was more susceptible to herbicide damage than healthy wheat. Metsulfuron and metsulfuron plus 2,4-D controlled kochia, tumble thistle, and redroot pigweed better after wheat harvest than 2,4-D or 2,4-D plus dicamba at North Platte, but allowed summer annual grass weeds to grow. Yields of grain sorghum planted after a 10-mo fallow period were higher following winter wheat treated with three of four herbicides than the handweeded treatment.

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