Author(s)

Paul W. Bartholomew^*

USDA-ARS Grazinglands Research Laboratory, El Reno, OK, USA.

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 (T_base) 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 T_base 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 T_base. 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.

Phyllochron, Base Temperature, Warm-Season Grass

Bartholomew, P. (2014) Effect of Varying Temperature Regime on Phyllochron in Four Warm-Season Pasture Grasses. Agricultural Sciences, 5, 1000-1006. doi: 10.4236/as.2014.511108.