Productivity and Survival of Defoliated Wheatgrasses in the Rolling Plains of Texas

Abstract

In the Texas Rolling Plains, cool‐season perennial grasses may complement limited forage availability in March–May and October–December. In two experiments conducted at Vernon, TX, on a sandy loam soil (fine‐loamy, mixed, thermic Udic Paleustalfs), we evaluated productivity and persistence of crested [Agropyron cristatum (L.) Gaertn. × A. desertorum (Fisch. ex Link) J.A. Schultes], hybrid [Elytrigia repens (L.) Nevski × Pseudoroegneria spicata (Pursh) L‘ve], intermediate [Thinopyrum intermedium (Host) Barkworth & D.R. Dewey], pubescent [T. intermedium ssp. barbulatum (Schur) Barkw. & D.R. Dewey], and tall wheatgrass [T. ponticum (Podp.) Barkworth & D.R. Dewey] under combinations of 3‐ or 6‐wk defoliation frequency at 7.5‐ or 15‐cm. About 64% more herbage yield was harvested from all species at the 7.5‐ vs. 15‐cm defoliation height in the first, but only from crested, hybrid, and pubescent wheatgrass in the second growing season. Frequent defoliation increased herbage by 22% in Experiment A or 37% in Experiment B only in the first growing season. Tiller survival increased with frequent defoliation in intermediate wheatgrass by 33% in Experiment A and up to 70% in Experiment B, but decreased by 52% in hybrid and by 33% in pubescent wheatgrass in Experiment A, and up to 50% in Experiment B. Lower nighttime soil temperatures increased tiller survival during summer in swards defoliated at the 7.5‐ vs. 15‐cm height. Wheatgrass productivity increased under intensive or frequent defoliation in the first, but declined in several species in the subsequent growing season, making their potential to complement forage base limited.