Soil Water Use by Diploid and Tetraploid Russian Wildrye
- A. B. Frank * and
- J. D. Berdahl
Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski] is an important cool-season forage grass for the Northern Great Plains, but it exhibits poor seedling vigor. Tetraploid (2n=4x=28) plants have improved seedling vigor over diploid (2n=2x=14) plants, but data is lacking on plant-soil-water relations. Objectives of this research were to compare water-use efficiency (WUE), evapotranspiration (ET), roofing activity, and water extraction in relation to Haun stage for diploid and tetraploid Russian wildrye. A diploid and tetraploid entry were evaluated for 3 yr under two water treatments (50 and 150% of monthly average precipitation for 1 April to 1 November) and two fertilizer rates (10 and 134 kg N ha−1) in a rain shelter. The soil was a Parshall fine sandy loam (Coarse-loamy, mixed, superactive, frigid Pachic Haplustoll). Cumulative ET averaged across the 50 and 150% water treatments was 138 and 141 mm for the diploid and tetraploid, respectively. Rate of root activity progression was linear with Haun to the 1.2-m depth and ranged from 0.148 to 0.163 m per Haun stage for the diploid and tetraploid, respectively, at 50% water. Forage yield of the tetraploid was greater than the diploid at the 50%, but not at the 150% water treatment. Water-use efficiency was higher for the tetraploid (3.8 g kg−1) than the diploid (3.1 g kg−1) at the 50% water treatment, but at 150% water the entries were not different. Overall, the tetraploid entry exhibited a more favorable WUE and other soil water relations than did the diploid entry.
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