Title:

Water Use of Bluegrass Seed Under Different Residue Management Systems

Objectives:

a. Determine the springtime crop water use of bluegrass seed for the following factors:
   i. aggressive/ nonaggressive cultivars
   ii. thermal/nonthermal residue management.

b. Determine the ET/yield relationship for bluegrass seed during the spring for:
   i. aggressive/non-aggressive cultivars.

c. Measure water stress response in bluegrass for aggressive/non-aggressive cultivars through differences in tillering, plant water potential, dry mater, and seed yield.

d. Measure the soil nutrient status (P, K, C, and S) and the soil N and plant N uptake and partitioning in the plant/soil system under different irrigation treatments. (with S. Griffith)

Investigator: Dr. Alan Mitchell, Assistant Professor,
OSU Central Oregon Agricultural Research Center (COARC) Madras, OR

Cooperators:

Dr. Stephen Griffith, Plant Physiologist, USDA-ARS-NFSPRC
Dr. Thomas G. Chastain, OSU Dept. of Crop and Soil Science
Dr. John Hammel, University of Idaho

Abstract of 1995 Progress

Bluegrass phytomass and seed yield response to water stress were studied in a preliminary experiment with six irrigation levels. Yield continued to increase for the highest irrigation treatment, and was attributed to less water stress (lower soil water tension) in the final days after irrigation ceased. Bluegrass seed water use for 1995 was 12.6 inches, and was similar to the water use estimates from the Bureau of Reclamation's AgriMet weather network. With this information, we are in a position to investigate irrigation in late June that appears to influence yield. This fall 1995, we have established an experimental plot with aggressive and non-aggressive cultivars. The design is a double line-source sprinkler with space to conduct nested experiments on nitrogen fertility and residue removal.

Justification

Water allocation for agricultural use is a matter of increasing concern in the arid Northwest. Because high quality bluegrass seed is produced in arid regions on both irrigated and rain-fed land, it is important to document the crop water use of bluegrass necessary to produce optimal seed yield. None of the past estimates agree! In non-irrigated regions it is important to investigate how seed yield responds to rainfall under the new thermal management. It is also important to investigate the relationship between yield and crop water use to better manage irrigation.