Establishment of ‘Hycrest’ Crested and T-21076 Thickspike Wheatgrasses in Three Environments

Introduced grass species such as standard crested wheatgrass [Agropyron desertorum (Fischer ex Link) Schultes] are most often used to revegetate degraded rangelands in the Inter mountain region of the western USA. Use of native grass species is rising because public land management policies increasingly favor plant materials representative of native flora. Our objective was to compare the population T-21076, a promising source of germplasm of the native thickspike wbeatgrass [Elymus lanceolatus subsp. lanceolatus (Scribner & Smith) Gould] [Syn-Elytrigia dasystachya (Hook.) A. Löve & D. Löve], with ‘Hycrest’ crested wheatgrass for forage yield, tiller number, and tiller weight during and after establishment. The relative importance of tiller number and tiller weight for forage yield production was compared using path coefficient analysis. Seedlings were transplanted from a greenhouse to three field environments corresponding to three moisture stress levels where six harvests were evaluated through two growing seasons. Tiller number was more affected by moisture stress than tiller weight. Forage yield production of the caespitose Hycrest was more stable under moisture stress than the rhizomatous T-21076. T-21076's forage yield depended mostly on tillering through rhizomatous spread, which was more sensitive to moisture stress than the tillering of Hyerest. Tiller weight of T-21076 was similar in all environments and was equal or lower than Hycrest's at all harvests. In contrast to T-21076, Hycrest's forage yield production relied primarily on tiller weight, a more stable trait than tiller number. Increases in Hycrest's tiller weight were able to partially compensate for reductions in its tiller number with increasing moisture stress. The advantages conferred by T.21076's rhizomatous spreading and resultant tillering are probably limited by their sensitivity to moisture stress. Contribution of the Utah Agric. Exp. Stn. Paper no. 4177.