Temperature effects on regrowth of 3 rough fescue species

Abstract

Three species of rough fescue, alpine rough fescue (Festuca altaica Trin.), mountain rough fescue (F. campestris Rydb.), and plains rough fescue (F. hallii (Vasey) Piper) were grown for 12 weeks under 5 temperature regimes — 7:3, 12:8, 17:13, 22:18, and 27:23 degrees C — and defoliated 3 times to 3.5 cm at 4-weekly intervals in a growth cabinet study. Final plant dry mass and harvestable biomass production were greatest at 17:13 degrees C for alpine rough fescue and plains rough fescue, and at 12:8 degrees C for mountain rough fescue. Harvestable biomass plateaued or declined at the final harvest in all species for temperatures above 12:8 degrees C. Tiller numbers increased at successive harvests. Biomass per tiller declined markedly at the final harvest of alpine rough fescue at all temperatures. Regrowth in alpine rough fescue was markedly reduced at temperatures either above or below the optimum. The results indicate that mountain rough fescue and plains rough fescue are better able to regrow following defoliation at temperatures below or equal to their optima, than at temperatures above their optima. This provides greater understanding of field responses in both species where frequent defoliations are more deleterious after the April/May period when temperatures are above optimal.