Guidelines for Comparisons among Different Maize Maturity Rating Systems

Dwyer, L. M.; Stewart, Donald C.; Carrigan, L. L.; L., B.; Neave, Peter; Balchin, D.

doi:10.2134/agronj1999.916946x

Cited by 58 publications

(43 citation statements)

References 6 publications

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“…We found that population densities of 100 000 plants ha -1 or greater often were required to maximize whole-plant yield with these earlier-maturing hybrids under Alberta con- Irrigation water applied (mm) 330 225 z Accumulated corn heat units according to Dwyer et al (1999). y Long-term averages were determined from the years 1972 to 2002.…”

Section: Resultsmentioning

confidence: 99%

Influence of population density, row spacing and hybrid on forage corn yield and nutritive value in a cool-season environment

Baron¹,

Najda²,

Stevenson³

2006

Can. J. Plant Sci.

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. 2006. Influence of population density, row spacing and hybrid on forage corn yield and nutritive value in a cool-season environment. Can. J. Plant Sci. 86: 1131-1138. Increasing yield for silage and grazing in cool, short-season areas may be possible by planting corn (Zea mays L.) at high population densities and at narrow row spacing. The objective was to determine how population density (75 000, 100 000, and 125 000 plants ha -1 ) and row spacing (standard: 76 cm and narrow: 38 cm) affected whole-plant yield, yield-related parameters, and nutritive value of two corn hybrids grown at Brooks and Lacombe, Alberta during 2 yr. The hybrids (Pioneer 39F45 and 39N03) were rated at 2000 Ontario corn heat units (CHU). Trial, hybrid, population density and row spacing interacted to influence whole-plant yield. Population density had a greater impact on whole-plant yield than row spacing and hybrid choice. Generally, yield leveled off at 100 000 plants ha -1 when the interaction of all effects was considered. Leaf area index (LAI) and whole-plant yield at this density were 2.68 and 12.0 Mg ha -1 , respectively. Narrow compared with standard row spacing had positive effects on whole-plant yield of one hybrid, but not the other and improved LAI at 75 000 plants ha -1 , but not at the other plant densities. Increasing plant density and reducing row spacing had only minor effects on whole-plant nutritive value. Growing corn in narrow rows to accommodate prevalent planting equipment should have no adverse effects on whole-plant corn production in short-season areas of Canada. However, when considering changes in corn management to maximize whole-plant yield narrow row spacing is not as important as achieving a plant density of approximately 100 000 plants ha -1 . L'étude devait établir comment la densité du peuplement (75 000, 100 000 et 125 000 plants par hectare) et l'écartement des rangs (normal, 75 cm, et réduit, 38 cm) affectent le rendement en plants entiers, les paramètres du rendement et la valeur nutritive de deux hybrides cultivés à Brooks et à Lacombe (Alberta) pendant deux ans. Les deux variétés utilisées (Pioneer 39F45 et 39N03) étaient cotées à 2 000 unités thermiques du maïs. L'essai, la variété, la densité du peuplement et l'écartement des rangs interagissent pour modifier le rendement en plants entiers. La densité du peuplement agit plus sur ce facteur que l'écartement des rangs et le choix du cultivar. En général, quand on prend en compte les différents effets et leur interaction, on constate un plafonnement du rendement à 100 000 plants par hectare. À cette densité, l'indice foliaire et le rendement en plants entiers s'établissent respectivement à 2,68 et à 12,0 Mg par hectare. L'écartement réduit a eu une incidence positive sur le rendement en plants entiers d'une variété mais pas sur celui de l'autre cultivar. L'indice foliaire était également supérieur à la densité de 75 000 plants par hectare, mais pas aux autres densités. Accroître la densité de peuplement et rapprocher les rangs n'ont qu'une inciden...

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Section: Resultsmentioning

confidence: 99%

Influence of population density, row spacing and hybrid on forage corn yield and nutritive value in a cool-season environment

Baron¹,

Najda²,

Stevenson³

2006

Can. J. Plant Sci.

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“…Soil moisture was never limiting at either location. To relate CHU accumulation to other thermal unit maturity rating systems see Dwyer et al (1999).…”

Section: Climate and Maturitymentioning

confidence: 99%

Winter weathering effects on corn grown for grazing in a short-season area

Baron¹,

Najda²,

McCartney³

et al. 2003

Can. J. Plant Sci.

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G. W. 2003. Winter weathering effects on corn grown for grazing in a short-season area. Can. J. Plant Sci. 83: 333-341. Winter grazing can reduce over-winter feeding costs of beef cows and, recently, the selection and marketing of corn (Zea mays L.) varieties for grazing has increased the interest of Alberta beef producers. The objective of this study was to compare grazing corn varieties with early conventional corn hybrids for winter grazing potential. Five corn varieties (one grazing, one short-stature and three conventional types) were compared for whole-plant yield and forage quality at Lacombe and Brooks, AB, at four harvest times (two in September, one in December and one in January), in each of 2 yr. Forage quality analyses were in vitro digestible organic matter (IVDOM), neutral (NDF) and acid detergent fiber (ADF) and crude protein concentration. Averaged over varieties and years, yield decreased (P ≤ 0.05) by 13% between September and January at Lacombe, and by 39 and 16% at Brooks in 1999 and 2000, respectively. At Brooks, yield losses from September to January, averaged over years were 38 to 18% for a grazing and a conventional variety, respectively. At Lacombe, IVDOM concentration declined (P ≤ 0.05) by 6.3 and 3.6% between September and January during 1999 and 2000, respectively; NDF concentration increased (P ≤ 0.05) by 10% over the same interval for both years. At Lacombe there were no differences among varieties for nutritive value by January harvests. Trends for reduced forage quality with harvest were not clear at Brooks but the grazing-type variety had higher (P ≤ 0.05) NDF and ADF concentrations than the other varieties after the first harvest. In general, projected energy and crude protein concentrations of corn during winter exceeded minimum requirements and were adequate, respectively, for non-lactating, pregnant beef cows. Grazing and short stature corn varieties were not superior to early conventional corn genotypes for winter grazing potential. Thus, choice of variety for winter grazing should be made on the basis of cost of production and early maturity. ) pour la paissance a éveillé l'intérêt des producteurs de boeuf de l'Alberta. L'étude devait comparer le potentiel de paissance hivernal de ces variétés à celui d'hybrides ordinaires. Les auteurs ont comparé le rendement global de la plante et la qualité du fourrage de cinq variétés (une destinée à la paissance, une naine et trois ordinaires) à Lacombe et à Brooks (Alberta) pendant deux ans, à quatre périodes de récolte (deux en septembre, une en décembre et la dernière en janvier). Pour déterminer la qualité du fourrage, ils ont dosé la concentration de matière organique digestible in vitro (IVDOM), la quantité de fibres au détergent neutre (NDF) et acide (ADF) et la teneur en protéines. Une fois la moyenne pour les variétés et les deux années établie, on constate que le rendement a diminué (P ≤ 0,05) de 13 % entre septembre et janvier à Lacombe, contre 39 % et 16 % en 1999 et 2000, respectivement, à Brooks. Après calcul de la moy...

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“…They include simple heat units based on the accumulation of daily mean temperatures above a certain threshold temperature during growing period (Wiggans 1956, Brown 1960, Wang 1960, Baskerville & Emin 1969, Chen 1973. Others are: the sum of effective temperatures (Chirkov 1965, Gordeev et al 2006; effective degrees (Gilmore & Rogers 1958); the accumulated heat unit (Mederski et al 1973); growing degree units (Darby & Lauer 2002); P-days, which is a heat unit for the growth and development of potatoes (Sands et al 1979); corn heat units, used to define the relationship between temperature and the development of corn hybrids (Smith et al 1982, Bootsma 1994, Dwyer et al 1999, Bootsma et al 2004; the general thermal index, developed from statistically fitted maize development temperature response functions for the vegetative and grain-filling periods (Dwyer et al 1999); and photothermal units (McMaster & Smika 1988).There have been other approaches. One method calculates sums of positive temperatures over a period above a given threshold temperature (T base ), referred to as active temperatures for the growth period starting from the date of the onset of spring (e.g.…”

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confidence: 99%

Analysis of growing degree-days as a climate impact indicator in a region with extreme annual air temperature amplitude

Grigorieva¹,

Matzarakis²,

Freitas³

2010

Clim. Res.

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We used the concept of growing degree-days (GDD) as a measure of the agricultural potential of climate on a regional scale in the southern part of the Russian Far East, the climate of which is characterized by thermal extremes. Daily maximum and minimum air temperatures were used to calculate GDD at 17 locations using threshold base air temperatures of 0, 5, 10 and 15°C, with a high-temperature threshold cut-off of 30°C. GDD increased from north to south in the study area, but the mean GDD varied considerably from one location to another. Marginal thermal conditions were observed in the north, both in the elevated areas and in the coastal regions. There was a high correlation between GDD and mean monthly temperature for the growing season from May to September (T59), such that the latter can be used as a proxy for GDD, which has implications for agricultural management. GDD and T59 had an upward trend over the period for the study region as a whole. The most significant upward trend was observed for GDD0, while results for GDD15 exhibit little or no trend.KEY WORDS: Growing degree-days · Climate change · Spatial and temporal analysis · Russian Far East · Climate and agriculture · Agro-climate indices · Biologically active temperature Resale or republication not permitted without written consent of the publisherClim Res 42: [143][144][145][146][147][148][149][150][151][152][153][154] 2010 climatic indices used to quantify the rate of development of crops have evolved from this. They include simple heat units based on the accumulation of daily mean temperatures above a certain threshold temperature during growing period (Wiggans 1956, Brown 1960, Wang 1960, Baskerville & Emin 1969, Chen 1973. Others are: the sum of effective temperatures (Chirkov 1965, Gordeev et al. 2006; effective degrees (Gilmore & Rogers 1958); the accumulated heat unit (Mederski et al. 1973); growing degree units (Darby & Lauer 2002); P-days, which is a heat unit for the growth and development of potatoes (Sands et al. 1979); corn heat units, used to define the relationship between temperature and the development of corn hybrids (Smith et al. 1982, Bootsma 1994, Dwyer et al. 1999, Bootsma et al. 2004; the general thermal index, developed from statistically fitted maize development temperature response functions for the vegetative and grain-filling periods (Dwyer et al. 1999); and photothermal units (McMaster & Smika 1988).There have been other approaches. One method calculates sums of positive temperatures over a period above a given threshold temperature (T base ), referred to as active temperatures for the growth period starting from the date of the onset of spring (e.g. Davitaya 1965, Kelchevskaya 1971, Karing et al. 1999, Gordeev et al. 2006. The sum of biologically active temperatures (T ac ) is given as:( 1) where T i is mean daily temperature (°C) and i = 1, 2…n is the number of days with mean temperature above the respective threshold or base temperature (T base ), marking the start of the growing season (Table 1). The ...

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Guidelines for Comparisons among Different Maize Maturity Rating Systems

Cited by 58 publications

References 6 publications

Influence of population density, row spacing and hybrid on forage corn yield and nutritive value in a cool-season environment

Influence of population density, row spacing and hybrid on forage corn yield and nutritive value in a cool-season environment

Winter weathering effects on corn grown for grazing in a short-season area

Analysis of growing degree-days as a climate impact indicator in a region with extreme annual air temperature amplitude

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