Characterization of Corn (<i>Zea mays</i> L.) Canopies from Measurements of Individual Plants<sup>1</sup>

Daynard, T. B.

doi:10.2134/agronj1971.00021962006300010041x

Cited by 12 publications

(3 citation statements)

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“…The leaves of a corn plant are mainly distributed in a single vertical plane as a consequence of a distichous structure (Daynard 1971). Once the first two leaves of a corn seedling emerge, they define a plane that should contain the rest of the leaves of a corn plant.…”

Section: Experiments 2: Leaf Azimuthmentioning

confidence: 99%

Red–far-red ratio of reflected light: a hypothesis of why early-season weed control is important in corn

Rajcan

Chandler

Swanton³

2004

Weed Science

119

124

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A plant's ability to detect and adjust morphologically to changes in light quality (red–far-red [R:FR] ratio) is one mechanism by which a crop plant responds to weeds. To test this hypothesis, two experiments were conducted where corn was grown in growth cabinets under different light environments. First, to determine the effect of R:FR ratio on corn growth and development, treatments of high R:FR (1.37) and low R:FR (0.67) ratio were compared. These were established by planting corn in pots and then placing trays of either turface (a baked clay medium with high R:FR) or commercial grass sod (low R:FR) on each side of a row of corn pots. Grass sod was used to simulate low-growing weeds. The low R:FR sod treatment resulted in corn plants which were taller, had larger leaves, and greater shoot–root ratio than plants growing in the high R:FR turface treatment. In the second experiment, the effect of R:FR ratio on corn leaf azimuth position was examined. This was accomplished by adding a third treatment where each corn row had sod placed on one side and turface on the other. The proportion of leaves in four azimuthal classes was recorded. In the presence of sod, the proportion of leaves perpendicular to the corn row decreased, and this altered the proportion of leaves in other classes. Therefore, corn seedlings detected changes in light quality caused by the presence of sod (which simulated low-growing weeds) and responded by adjusting carbon allocation and leaf orientation to optimize the interception of light quantity and quality. These results support our hypothesis that low-lying vegetation can alter the growth of corn seedlings before competition for resources occurs. This change in growth may help explain the importance of early-season weed control in corn.

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Section: Experiments 2: Leaf Azimuthmentioning

confidence: 99%

Red–far-red ratio of reflected light: a hypothesis of why early-season weed control is important in corn

Rajcan

Chandler

Swanton³

2004

Weed Science

119

124

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“…leaf area and angles were assumed to vary only with height. More recent measurements by Daynard (1971), Prévot et al (1991) and Stewart and Dwyer (1993) clearly show that two-dimensional aspects of the shape of maize plants can be important, i.e. leaf area can vary across the row.…”

Section: Crop Architecturementioning

confidence: 95%

Aspects of maize modelling in eastern Canada

Stewart¹,

Dwyer²,

Reid³

1998

Can. J. Soil. Sci.

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L. M. 1998. Aspects of maize modelling in eastern Canada. Can. J. Soil Sci. 78: 421-429. Maize (Zea mays L.) is a crop of growing importance in Eastern Canada. Modelling the temperature effects on pheno-logical development, crop architecture and disease infection in maize contributes to the development of well-adapted, early-maturing varieties. Details of modelling these three aspects of maize growth were presented. The first focussed on quantifying the effect of air or soil temperature on maize phenological development. Crop growth was divided into two periods: vegetative (planting to silking) and grain filling (silking to maturity). A third period (planting to emergence) was separated within the vegetative period. Heat unit systems based on daily temperature response functions were developed to produce the most consistent heat unit sums for each period. The best fits of these functions were determined by minimizing standard deviations and coefficients of variation of these sums for each thermal period over locations and years. Calculated temperature response functions estimated thermal periods more consistently than growing degree days (GDD) for all three periods. The largest improvement was made in the silk-ing to maturity period. The second aspect was a study of crop architecture. Methods were developed to mathematically characterize the structure of a canopy in terms of leaf area and leaf angle distributions with crop height and across the row. These calculations, in turn, were input to a soil-plant-atmosphere model to calculate interception of photosynthetically active radiation (PAR). Model calculations of PAR interception compared well with measurements for a range of plant types and plant population densities (R 2 =0.76). The third aspect was quantifying growth of Fusarium in maize. Differential equations were used to relate Fusarium rates of growth in maize ears to air temperature, relative humidity and precipitation. Integration of these equations over time produced quantitative estimates of fungal infection. Model calculations were compared to visual ratings of fungal infection for two Fusarium species over three years (R 2 =0.92). In each of the three aspects of this study, modelling tested our understanding of the processes involved and the dominant factors controlling these processes. Thus, modelling was an integral part of the scientific approach, synthesizing experimental data in a quantitative conceptual framework and identifying dominant factors and parameters which required additional focussed experimental evaluation., L. M. et Reid, L. M. 1998. Aspects de la modélisation de la culture du maïs dans l'est du Canada. Can. J. Soil Sci. 78: 421-429. Le maïs (Zea mays L.) est une culture qui prend de plus en plus d'importance dans l'est du Canada. La modélisation des effets de la température sur la phénologie, sur l'architecture du couvert cultural et sur la pathologie favorise la création de variétés précoces, bien adaptées. Nous décrivons ici les détails de modélisation de ces trois aspects de l...

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“…The maximum leaf-area index of 5.6 is due to very strong tiller development. Daynard (1971) reported a leaf-area index for corn >5, but, normally, the maximum values for corn crops on which micrometeorological studies have been done have not exceeded 4.5 (Brown and Covey, 1966;Impens and Lemeur, 1969). It is assumed that the index did not change significantly during the experiment.…”

Section: Boundary-layermentioning

confidence: 99%

Diurnal variation in net radiation depletion within a corn crop

McCaughey

Davies

1974

Boundary-Layer Meteorol

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The estimation of net radiation within a mature sweet corn canopy is examined using measurements of net radiation at one level above and three levels within the canopy during seven days in 1969. It is shown that Beer's Law, with a constant extinction coefficient, cannot be used to estimate hourly net radiation within the canopy. Functions of zenith angle and relative solar azimuth are incorporated into the model to account for the diurnal variation of optical density. These modifications, which are based on the characteristics of the crop, allow a constant extinction coefficient to be used to calculate hourly net radiation to an acceptable level of accuracy.

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Characterization of Corn (Zea mays L.) Canopies from Measurements of Individual Plants¹

Cited by 12 publications

References 0 publications

Red–far-red ratio of reflected light: a hypothesis of why early-season weed control is important in corn

Red–far-red ratio of reflected light: a hypothesis of why early-season weed control is important in corn

Aspects of maize modelling in eastern Canada

Diurnal variation in net radiation depletion within a corn crop

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Characterization of Corn (Zea mays L.) Canopies from Measurements of Individual Plants1

Cited by 12 publications

References 0 publications

Red–far-red ratio of reflected light: a hypothesis of why early-season weed control is important in corn

Red–far-red ratio of reflected light: a hypothesis of why early-season weed control is important in corn

Aspects of maize modelling in eastern Canada

Diurnal variation in net radiation depletion within a corn crop

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Product

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Characterization of Corn (Zea mays L.) Canopies from Measurements of Individual Plants¹