Effect of soil water, nitrogen, and growing degree-days on morphological development of crested and western wheatgrass

Production of total forage dry matter is mainly a function of available soil water and soil nitrogen (N), whereas plant morphological development from spring greenup to anthesis is primarily controlled by air temperature. There is a lack of information on effects of soil water and soil N on plant morpholoical development. A study was conducted in a rain-out shelter at Mandan, North Dakota, over a 3-year period to determine the effect of 2 fertilizer N rates (11 and 110 kg N/ha) and 3 rates of applied water (50, 100, and 150% of long term April-November rainfall at Mandan, North Dakota) on morphological development of initial spring growth and fall regrowth of crested wheatgrass [Agropyron desertorum (Fisch.) Schult] and western wheatgrass [Pascopyrum smithii Rydb, (Love)]. Regression analysis of plant development stage with accumulated growing degree-days (GDD) was linear for both initial and regrowth forage. There were no differences in rate of plant development for the 3 rates of applied water or the 2 rates of N fertilizer. Initial growth forage of crested and western wheatgrass required 82 and 98 GDD to produce a leaf, respectively. Regrowth forage of crested wheatgrass required 372 and western wheatgrass 135 more GDD than initial growth to produce a leaf. These data confirm that plants develop primarily in response to air temperature and not added water or N, which enhances the utility of using the accumulation of GDD for predicting development of crested and western wheatgrass under different growing conditions. This information will be useful for predicting plant development of these species in growth models and for farmers and ranchers in predicting grazing readiness.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact lbry-journals@email.arizona.edu for further information.Migrated from OJS platform August 202