Abstract
Using accumulated temperature measures to predict plant development may provide guidance on timing of management practices to minimize competition between warm and cool-season components of mixed pastures. However, temperature and plant development relationships for warm-season pasture grasses common in the southern Great Plains of the USA have not been extensively studied. Under controlled environment conditions, base temperature (Tbase) values were determined for Big bluestem (Andropogon gerardii Vitman), Indiangrass (Sorghastrum nutans, (L.) Nash), Little bluestem (Schizachyrium scoparium (Michx) Nash) and, Sideoats grama (Bouteloua curtipendula (Michx) Torr). Measures of the accumulated temperature requirement for the phyllochron (leaf appearance interval) were made under a range of temperature regimes for these same species. Mean Tbase was 8.1°C and differences among species were not significant (P > 0.05). Within temperature regimes mainstem leaf appearance was closely and linearly related to accumulated temperature above Tbase. Increase of 7.5°C in night temperature increased phyllochron by a mean of 43%, but similar increase in day temperature only increased phyllochron by 16%. Phyllochron increased by 6.4°C leaf-1 for each 1°C increase in daily mean temperature within the range of 15.0°C to 22.5°C. If accumulated temperature measures are to monitor reliably the development of warm-season grasses, allowance must be made for changes in phyllochron as the growing season progresses.
Highlights
In the southern USA, cool- and warm-season grasses may be grown in mixtures of perennial species [1] or as aHow to cite this paper: Bartholomew, P.W. (2014) Effect of Varying Temperature Regime on Phyllochron in Four WarmSeason Pasture Grasses
Problems arising from competition in mixed pastures might be alleviated by adoption of management practices, such as timing of harvests or N fertilizer application, that reduce interference between warm and coolseason grasses, especially at times of year when conditions are suitable for active growth of both warm and coolseason species
Appropriate timing of field operations depends on knowledge of the growth and development status of the components of the mixed pasture, but this information may not be readily available because it requires frequent field observation of plant growth stage
Summary
In the southern USA, cool- and warm-season grasses may be grown in mixtures of perennial species [1] or as aHow to cite this paper: Bartholomew, P.W. (2014) Effect of Varying Temperature Regime on Phyllochron in Four WarmSeason Pasture Grasses. In the southern USA, cool- and warm-season grasses may be grown in mixtures of perennial species [1] or as a. Bartholomew sequence of annual species overseeded into a perennial base [2] [3], in order to extend the productive growing season. The expectation of increased annual production arising from a longer growing season is, frequently not fully realized because of competition between cool- and warm-season components of pasture that results in lower than expected aggregate productivity [4] or in reduced persistence of one or both components of the mixture [5]. Problems arising from competition in mixed pastures might be alleviated by adoption of management practices, such as timing of harvests or N fertilizer application, that reduce interference between warm and coolseason grasses, especially at times of year when conditions are suitable for active growth of both warm and coolseason species. An indirect method of monitoring the progress of pasture development that eliminates the need for time-consuming direct observation might be of value in support of pasture management decisions by farmers
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