TITLE:
Effect of Varying Temperature Regime on Phyllochron in Four Warm-Season Pasture Grasses
AUTHORS:
Paul W. Bartholomew
KEYWORDS:
Phyllochron, Base Temperature, Warm-Season Grass
JOURNAL NAME:
Agricultural Sciences,
Vol.5 No.11,
September
25,
2014
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.