The development of water stress in Bromus tectorum and Poa secunda in the field

Technical Report · Sun Mar 01 04:00:00 EST 1987

OSTI ID:6906677

Link, S O; Downs, J L; Gee, G W

Field observations of the phenological development, root and shoot characteristics, and water relations with increasing water stress of Bromus tectorum and Poa secunda were compared. The phenological development of B. tectorum was 3 to 4 weeks behind that of P. secunda. The root/shoot ratio of B. tectorum was 4 to 5 times less than that of P secunda. The greatest rooting depth was 45 cm for B. tectorum and 35 cm for P. secunda. Most of the root mass was found in the top 10 cm of soil for both species. Water stress developed sooner and to a greater degree in P. secunda than in B. tectorum. Xylem water potential was lower in P. secunda than in B. tectorum and the difference increased through the season. Pre-dawn xylem water potential was highly correlated with maximal stomatal conductance in P. secunda. Hydraulic conductance was greater in B. tectorum than in P. secunda, and decreased as water stress increased through the season. Stomatal conductance and transpiration were greater for B. tectorum than for P. secunda. Midday stomatal closure occurred later in the season and to a lesser degree for B. tectorum than for P. secunda. 31 refs., 7 figs., 1 tab.

• Research Organization: Pacific Northwest Lab., Richland, WA (USA)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 6906677
• Report Number(s): PNL-SA-14779; ON: DE88013117
• Country of Publication: United States
• Language: English

Related Subjects

510100* -- Environment
Terrestrial-- Basic Studies-- (-1989)
54 ENVIRONMENTAL SCIENCES
BIOLOGICAL STRESS
COMPARATIVE EVALUATIONS
FIELD TESTS
GROWTH
OPENINGS
PHENOLOGY
PLANT GROWTH
PLANTS
ROOTS
STOMATA
TESTING
WATER REQUIREMENTS