Native Wildflower Seed Production With

Limited Subsurface Drip Irrigation

 

Clinton C. Shock, Erik B. G. Feibert, and Lamont D. Saunders Malheur Experiment Station
Oregon State University
Ontario, OR

 

Nancy Shaw
U.S. Forest Service
Rocky Mountain Research Station
Boise, ID

 

 

Introduction

 

Native wildflower seed is needed to restore rangelands of the Intermountain West. Commercial seed production is necessary to provide the quantity of seed needed for restoration efforts.  A major limitation to economically viable commercial production of native wildflower (forb) seed is stable and consistent seed productivity over years.  Variations in spring rainfall and soil moisture result in highly unpredictable water stress at flowering, seed set, and seed development, which for other seed crops is known to compromise seed yield and quality.

 

Native wildflower plants are often not competitive with crop weeds in cultivated fields, which also limits seed production.  Both sprinkler and furrow irrigation could provide supplemental water for seed production, but these irrigation systems risk further encouraging weeds.  Also, sprinkler and furrow irrigation can lead to the loss of plant stand and seed production due to fungal pathogens.  By burying drip tapes at 12-inch depth and avoiding wetting of the soil surface, we hope to assure flowering and seed set without encouraging weeds or opportunistic diseases.  This trial tested the effects of three irrigation intensities on the seed yield of 13 native forb species.

 

Materials and Methods

 

Plant Establishment

 

Seed of the seven Intermountain West forb species (the first seven species in Table 1) was received in late November in 2004 from the Rocky Mountain Research Station ( Boise, ID).  The plan was to plant the seed in the fall of 2004, but due to excessive rainfall in October, the ground preparation was not completed and planting was postponed to early 2005.  To ensure germination the seed was submitted to a cold stratification treatment.  The seed was soaked overnight in distilled water on January 26, 2004, after which the water was drained and the seed soaked for 20 min. in a 10 percent by volume solution of 13 percent bleach in distilled water.  The water was drained and the seed placed in a thin layer in plastic containers.  The plastic containers had lids with holes drilled to allow air movement.  These containers were placed in a cooler set at approximately 34°F.  Every few days the seed was mixed and, if necessary, distilled water added to maintain seed moist.  In late February, seed of Lomatium grayi and L. triternatum had started sprouting.  

 

In late February, 2005 drip tape (T-Tape TSX 515-16-340) was buried at 12-inch depth between two rows (30-inch rows) of a Nyssa silt loam with a pH of 8.3 and 1.1 percent organic matter.  The drip tape was buried in alternating inter-row spaces (5 ft. apart).  The flow rate for the drip tape was 0.34 gal/min./100 ft. at 8 psi with emitters spaced 16 inches apart, resulting in a water application rate of 0.066 inch/hour.

On March 3, seed of all species (Table 1) was planted in 30-inch rows using a custom-made plot grain drill with disk openers.  All seed was planted at 20-30 seeds/ft. of row.  The Eriogonum umbellatum and the Penstemon spp. were planted at 0.25-inch depth and the Lomatium spp. at 0.5-inch depth.  The trial was irrigated with a minisprinkler system (R10 Turbo Rotator, Nelson Irrigation Corp., Walla Walla, WA) for even stand establishment from March 4 to April 29.  Risers were spaced 25 ft. apart along the flexible polyethylene hose laterals that were spaced 30 ft. apart and the water application rate was 0.10 inch/hour.  A total of 1.72 inches of water was applied with the minisprinkler system. Eriogonum umbellatum, Lomatium triternatum, and L. grayi started emerging on March 29.  All other species except L. dissectum emerged by late April.  Starting June 24, the field was irrigated with the drip system.  A total of 3.73 inches of water was applied with the drip system from June 24 to July 7.  Thereafter the field was not irrigated. 

 

Plant stands for Eriogonum umbellatum, Penstemon spp., Lomatium triternatum, and L. grayi were uneven.  Lomatium dissectum did not emerge.  None of the species flowered in 2005.  In early October, 2005 more seed was received from the Rocky Mountain Research Station for replanting. The blank lengths of row were replanted by hand in the Eriogonum umbellatum and Penstemon plots.  Entire row lengths were replanted using the planter in the Lomatium plots.  The seed was replanted on October 26, 2005.  In the spring of 2006, plant stand of the replanted species was excellent, except for P. deustus.

 

On April 11, 2006 seed of three globemallow species (Sphaeralcea parvifolia, S. grossulariifolia, S. coccinea), two prairie clover species (Dalea searlsiae, D. ornata), and basalt milkvetch (Astragalus filipes) was planted at 30 seeds/ft. of row.  The field was sprinkler irrigated until emergence.  Emergence was poor.  In late August of 2006 seed of the three globemallow species was harvested by hand.  On November 9, 2006 the six forbs were flailed.  On November 10, 2006 the six forbs were replanted.  On November 11, the Penstemon deustus plots were replanted at 30 seeds/ft. of row. 

Table 1.  Forb species planted at the Malheur Experiment Station, Oregon State University, Ontario, OR (U.S. Department of Agriculture, Natural Resources Conservation Service. 2009).

Species

Common names

Eriogonum umbellatum

Sulfur-flower buckwheat

Penstemon acuminatus

Sharpleaf penstemon, sand-dune penstemon

Penstemon deustus

Scabland penstemon, hot-rock penstemon

Penstemon speciosus

Royal penstemon, sagebrush penstemon

Lomatium dissectum

Fernleaf biscuitroot

Lomatium triternatum

Nineleaf biscuitroot, nineleaf desert parsley

Lomatium grayi

Gray’s biscuitroot, Gray’s lomatium

Sphaeralcea parvifolia

Smallflower globemallow

Sphaeralcea grossulariifolia

Gooseberryleaf globemallow

Sphaeralcea coccinea

Scarlet globemallow, red globemallow

Dalea searlsiae

Searls’ prairie clover

Dalea ornata

Western prairie clover

Astragalus filipes

Basalt milkvetch

 

Irrigation for Seed Production

 

In April, 2006 the field was divided into 30-ft-long plots.  Each plot contained four rows each of Eriogonum umbellatum, P. acuminatus, P. speciosus, P. deustus, L. dissectum, L. triternatum, and L. grayi.  The experimental design was a randomized complete block with four replicates.  The three irrigation treatments were a nonirrigated check, 1 inch per irrigation, and 2 inches per irrigation.  Each treatment received four irrigations that were applied approximately every 2 weeks starting with flowering of the forbs.  The amount of water applied to each treatment was measured by a water meter and recorded after each irrigation to ensure correct water applications. 

 

In March, 2007 the drip-irrigation system was modified to allow separate irrigation of the species due to different growth habits.  The three Lomatium spp. were irrigated together and Penstemon deustus and P. speciosus were irrigated together, but separately from the others. Penstemon acuminatus and Eriogonum umbellatum were irrigated individually.  In early April, 2007 the three globemallow species, two prairie clover species, and basalt milkvetch were divided into plots with a drip-irrigation system to allow the same irrigation treatments that were received by the other forbs.  

 

Irrigation dates can be found in Table 2(a and b).  In 2007, irrigation treatments were inadvertently continued after the four irrigations were applied, as in 2006.  Irrigation treatments for all species were continued until the last irrigation on June 24 in 2007. 

 

Soil volumetric water content was measured by neutron probe.  The neutron probe was calibrated by taking soil samples and probe readings at 8-, 20-, and 32-inch depths during installation of the access tubes.  The soil water content was determined volumetrically from the soil samples and regressed against the neutron probe readings, separately for each soil depth.  The regression equations were then used to transform the neutron probe readings during the season into volumetric soil water content.

 

Flowering, Harvesting, and Seed Cleaning

 

Flowering dates for each species are found in Table 2(a and b).  The Eriogonum umbellatum and Penstemon spp. plots produced seed in 2006, probably because they had emerged in the spring of 2005.  The plant stand for P. deustus was too poor to result in reliable seed yield estimates.  Replanting of P. deustus in the fall of 2006 did not result in adequate plant stand in the spring of 2007.  Each year, the middle two rows of each plot were harvested when seed of each species was mature (Table 2(a and b)) using the methods listed in Table 3. 

Eriogonum umbellatum seeds did not separate from the flowering structures in the combine; the unthreshed seed was taken to the U.S. Forest Service Lucky Peak Nursery ( Boise, ID) and run through a dewinger to separate seed.  The seed was further cleaned in a small clipper seed cleaner. 

 

Penstemon deustus seed pods were too hard to be opened in the combine; the unthreshed seed was precleaned in a small clipper seed cleaner and then seed pods were broken manually by rubbing the pods on a ribbed rubber mat.  The seed was then cleaned again in the small clipper seed cleaner

 

Penstemon acuminatus and P. speciosus were threshed in the combine and the seed was further cleaned using a small clipper seed cleaner

.

Cultural Practices in 2006

 

On October 27, 2006, 50 lb. phosphorus (P)/acre and 2 lb. zinc (Zn)/acre were injected through the drip tape to all plots of Eriogonum umbellatum, Penstemon spp., and Lomatium spp.  On November 11, 100 lb. nitrogen (N)/acre as urea was broadcast to all Lomatium plots.  On November 17, all plots of Eriogonum umbellatum, Penstemon spp. (except P. deustus), and Lomatium spp. had Prowl® at 1 lb. ai/acre broadcast on the soil surface.  Irrigations for all species were initiated on May 19 and terminated on June 30.  Harvesting and seed cleaning methods for each species are listed in Table 3.

 

Cultural Practices in 2007

 

Penstemon acuminatus and P. speciosus were sprayed with Aza-Direct® at 0.0062 lb. ai/acre on May 14 and May 29 for lygus bug control.  All plots of Sphaeralcea were flailed on November 8, 2007.  Irrigations for each species were initiated and terminated on different dates (Table 2a).  Harvesting and seed cleaning methods for each species are listed in Table 3.

 

Cultural Practices in 2008

 

On November 9, 2007 and on April 15, 2008 Prowl at 1 lb. ai/acre was broadcast on all plots for weed control. 

 

Capture® 2EC at 0.1lb ai/acre was sprayed on all plots of Penstemon acuminatus and P. speciosus on May 20 for lygus bug control. 

Irrigations for each species were initiated and terminated on different dates (Table 2).  Harvesting and seed cleaning methods for each species are listed in Table 3.

 

Cultural Practices in 2009

 

On March18, Prowl at 1 lb. ai/acre and Volunteer® at 8 oz./acre were broadcast on all plots for weed control.  On April 9, 50 lb. N/acre and 10 lb. P/acre were applied through the drip irrigation system to the three Lomatium species.

 

Irrigations for each species were initiated and terminated on different dates (Table 2b).  Harvesting and seed cleaning methods for each species are listed in Table 3.


Table 2a. Native forb flowering, irrigation, and seed harvest dates by species in 2006, 2007, and 2008, Malheur Experiment Station, Oregon State University, Ontario, OR.

 

 

              Flowering             

 

Irrigation

 

Species

start

peak

end

 

start

end

Harvest

 

2006

Eriogonum umbellatum

19-May

 

 20-Jul

 

19-May

30-Jun

   3-Aug

Penstemon acuminatus

 2-May

10-May

19-May

 

19-May

30-Jun

  7-Jul

Penstemon deustus

10-May

19-May

30-May

 

19-May

30-Jun

   4-Aug

Penstemon speciosus

10-May

19-May

30-May

 

19-May

30-Jun

13-Jul

Lomatium dissectum

 

 

 

 

19-May

30-Jun

 

Lomatium triternatum

 

 

 

 

19-May

30-Jun

 

Lomatium grayi

 

 

 

 

19-May

30-Jun

 

Sphaeralcea parvifolia

 

 

 

 

 

 

 

S. grossulariifolia

 

 

 

 

 

 

 

Sphaeralcea coccinea

 

 

 

 

 

 

 

Dalea searlsiae

 

 

 

 

 

 

 

Dalea ornata

 

 

 

 

 

 

 

 

2007

Eriogonum umbellatum

25-May

 

 25-Jul

 

  2-May

24-Jun

31-Jul

Penstemon acuminatus

19-Apr

 

 25-May

 

19-Apr

24-Jun

9-Jul

Penstemon deustus

 5-May

25-May

25-Jun

 

19-Apr

24-Jun

 

Penstemon speciosus

 5-May

25-May

25-Jun

 

19-Apr

24-Jun

23-Jul

Lomatium dissectum

 

 

 

 

5-Apr

24-Jun

 

Lomatium triternatum

25-Apr

 

 1-Jun

 

5-Apr

24-Jun

29-Jun, 16-Jul

Lomatium grayi

  5-Apr

 

10-May

 

5-Apr

24-Jun

30-May, 29-Jun

Sphaeralcea parvifolia

  5-May

25-May

 

 

16-May

24-Jun

20-Jun, 10-Jul, 13-Aug

S. grossulariifolia

  5-May

25-May

 

 

16-May

24-Jun

20-Jun, 10-Jul, 13-Aug

Sphaeralcea coccinea

 5-May

25-May

 

 

16-May

24-Jun

20-Jun, 10-Jul, 13-Aug

Dalea searlsiae

 

 

 

 

 

 

20-Jun, 10-Jul

Dalea ornata

 

 

 

 

 

 

20-Jun, 10-Jul

 

2008

Eriogonum umbellatum

5-Jun

19-Jun

20-Jul

 

15-May

24-Jun

24-Jul

Penstemon acuminatus

29-Apr

 

5-Jun

 

29-Apr

11-Jun

11-Jul

Penstemon deustus

5-May

 

20-Jun

 

29-Apr

11-Jun

 

Penstemon speciosus

5-May

 

20-Jun

 

29-Apr

11-Jun

17-Jul

Lomatium dissectum

 

 

 

 

10-Apr

29-May

 

Lomatium triternatum

25-Apr

 

 5-Jun

 

10-Apr

29-May

3-Jul

Lomatium grayi

25-Mar

 

15-May

 

10-Apr

29-May

30-May, 19-Jun

Sphaeralcea parvifolia

5-May

 

15-Jun

 

15-May

24-Jun

21-Jul

S. grossulariifolia

5-May

 

15-Jun

 

15-May

24-Jun

21-Jul

Sphaeralcea coccinea

5-May

 

15-Jun

 

15-May

24-Jun

21-Jul

Dalea searlsiae

 

19-Jun

 

 

 

 

 

Dalea ornata

 

19-Jun

 

 

 

 

 

 

Table 2b. Native forb flowering, irrigation, and seed harvest dates by species in 2009, Malheur Experiment Station, Oregon State University, Ontario, OR.

 

 

Flowering

 

Irrigation

 

Species

start

peak

end

 

start

end

Harvest

Eriogonum umbellatum

31-May

 

15-Jul

 

19-May

24-Jun

28-Jul

Penstemon acuminatus

2-May

 

10-Jun

 

8-May

12-Jun

10-Jul

Penstemon deustus

 

 

 

 

19-May

24-Jun

 

Penstemon speciosus

14-May

 

20-Jun

 

19-May

24-Jun

10-Jul

Lomatium dissectum

10-Apr

 

 7-May

 

20-Apr

28-May

16-Jun

Lomatium triternatum

10-Apr

7-May

1-Jun

 

20-Apr

28-May

26-Jun

Lomatium grayi

10-Mar

 

7-May

 

20-Apr

28-May

16-Jun

Sphaeralcea parvifolia

1-May

 

10-Jun

 

22-May

24-Jun

14-Jul

S. grossulariifolia

1-May

 

10-Jun

 

22-May

24-Jun

14-Jul

Sphaeralcea coccinea

1-May

 

10-Jun

 

22-May

24-Jun

14-Jul

 

 

 

Table 3. Native forb seed harvest and cleaning by species, Malheur Experiment Station, Oregon State University, Ontario, OR.

 

Species

Number of harvests/year

Harvest method

Pre- cleaning

Threshing method

Cleaning method

Eriogonum umbellatum

1

combinea

none

dewingerb

mechanicalc

Penstemon acuminatus

1

combined

none

combine

mechanicalc

Penstemon deustus

1

combinea

mechanicalc

hande

mechanicalc

Penstemon speciosusf

1

combined

none

combine

mechanicalc

Lomatium dissectum

1

hand

hand

none

mechanicalc

Lomatium triternatum

1 – 2

hand

hand

none

mechanicalc

Lomatium grayi

1 – 2

hand

hand

none

mechanicalc

Sphaeralcea parvifolia

1 – 3

hand or combined

none

combine

none

Sphaeralcea grossulariifolia

1 – 3

hand or combined

none

combine

none

Sphaeralcea coccinea

1 – 3

hand or combined

none

combine

none

Dalea searlsiae

0 or 2

hand

none

dewinger

mechanicalc

Dalea ornate

0 or 2

hand

none

dewinger

mechanicalc

 

a Wintersteiger Nurserymaster small-plot combine with dry bean concave.

b Specialized seed-threshing machine at USDA Lucky Peak Nursery. In 2007, 2008, and 2009 an adjustable hand-driven corn grinder was used to thresh seed.

cClipper seed cleaner.

d Wintersteiger Nurserymaster small-plot combine with alfalfa seed concave. For the Sphaeralcea species, flailing in the fall of 2007 resulted in more compact growth and one combine harvest in 2008 and 2009.

e Hard seed pods were broken by rubbing against a ribbed rubber mat.

f Harvested by hand in 2007 and 2009 due to poor seed set.

 

 

Results and Discussion

 

The soil volumetric water content responded to the irrigation treatments (Figs. 1-6).

 

Flowering and Seed Set

 

Emergence for the two prairie clover (Dalea) species in the spring of 2007 was again poor.  Emergence for Penstemon deustus and Astragalus filipes was extremely poor; A. filipes produced negligible amounts of seed in 2007.

 

Penstemon acuminatus and P. speciosus had poor seed set in 2007, partly due to a heavy lygus bug infestation that was not adequately controlled by the applied insecticides.  In the Treasure Valley, the first hatch of lygus bugs occurs when 250 degree days (52°F base) are accumulated.  Data collected by an AgriMet weather station adjacent to the field indicate that the first lygus bug hatch occurred on May 14 in 2006, on May 1 in 2007, and on May 18 in 2008.  Penstemon acuminatus and P. speciosus start flowering in early May.  The earlier lygus bug hatch in 2007 probably resulted in harmful levels of lygus bugs present during a larger part of the Penstemon flowering period than in 2006 or 2008.  Poor seed set for P. acuminatus and P. speciosus in 2007 also was related to poor vegetative growth compared to 2006 and 2008.  In 2009, all plots of P. acuminatus and P. speciosus again showed poor vegetative growth and seed set.  Root rot affected all plots of P. acuminatus in 2009, killing all plants in two of the four plots of the wettest treatment (2 inches per irrigation).

 

The three Sphaeralcea species (globemallow) showed a long flowering period (early May through September) in 2007.  Multiple harvests were necessary because the seed falls out of the capsules once they are mature.  The flailing of the three Sphaeralcea species in the fall of 2007 and 2008 resulted in a more concentrated flowering in 2008 and 2009, which allowed one mechanical harvest.  Precipitation in June of 2009 (2.27 inches) was substantially higher than average (0.76 inches).  A rust infected all plots of the Sphaeralcea species in June, causing substantial leaf loss and reduced vegetative growth.

 

Seed Yields

 

In 2006, seed yield of Eriogonum umbellatum increased with increasing water application, up to 8 inches, the highest amount tested (Table 4, Fig. 7).  In 2007-2009 seed yield showed a quadratic response to irrigation rate. Seed yields were maximized by 8.1 inches, 7.2 inches, and 6.9 inches of water applied in 2007, 2008, and 2009, respectively.  Averaged over 4 years, seed yield of E. umbellatum increased with increasing water applied up to 8 inches, the highest amount tested (Fig. 7).

 

There was no significant difference in seed yield between irrigation treatments for Penstemon acuminatus in 2006 (Table 4).  Precipitation from March through June was 6.4 inches in 2006.  The 64-year average precipitation from March through June is 3.6 inches.  The wet weather in 2006 could have attenuated the effects of the irrigation treatments.  In 2007 and 2008, seed yield showed a quadratic response to irrigation rate. Seed yields were maximized by 4.0 and 8.5 inches of water applied in 2007 and 2008, respectively.  In 2009, there was no significant difference in seed yield between treatments.  However, due to root rot affecting all plots in 2009, the results are compromised.

 

In 2006-2009 seed yield of P. speciosus showed a quadratic response to irrigation rate (Fig. 8).  Seed yields were maximized by 4.3, 4.2, 5.0, and 4.3 inches of water applied in 2006, 2007, 2008, and 2009, respectively.  Averaged over 4 years, seed yield of P. speciosus was maximized by 4.9 inches of irrigation.

 

There was no significant difference in seed yield between irrigation treatments for P. deustus in 2006 or 2007.  Both the replanting of the low stand areas in October 2005 and the replanting of the whole area in October 2006 resulted in very poor emergence and in plots with very low and uneven stands.

 

Lomatium triternatum showed a trend for increasing seed yield with increasing irrigation rate in 2007 (Table 4).  The highest irrigation rate resulted in significantly higher seed yield than the nonirrigated check.  Seed yields of L. triternatum were substantially higher in 2008 and 2009.  In 2008 and 2009, seed yields of L. triternatum showed a quadratic response to irrigation rate (Table 4, Fig. 9).  Seed yields were maximized by 8.4 and 5.4 inches of water applied in 2008 and 2009, respectively.  Averaged over 3 years, seed yield of L. triternatum was maximized by 6.7 inches of irrigation.

 

Lomatium grayi showed a trend for increasing seed yield with increasing irrigation rate in 2007 (Table 4).  The highest irrigation rate resulted in significantly higher seed yield than the nonirrigated check.  Seed yields of L. grayi were substantially higher in 2008 and 2009, than in 2007.  In 2008, seed yields of L. grayi showed a quadratic response to irrigation rate (Table 4, Fig. 10).  Seed yields were maximized by 6.9 inches of water applied in 2008.  In 2009, seed yield showed a linear response to irrigation rate.  Seed yield with the 4-inch irrigation rate was significantly higher than with the nonirrigated check, but the 8-inch irrigation rate did not result in a significant increase above the 4-inch rate.  Averaged over 3 years, seed yield of L. grayi was maximized by 7.4 inches of irrigation.

 

Lomatium dissectum had very poor vegetative growth in 2006-2008, and produced only very small amounts of flowers in 2008.  In 2009, vegetative growth and flowering for L. dissectum were higher.  Seed yield of L. dissectum showed a linear response to irrigation rate in 2009 (Table 4, Fig. 11).  Seed yield with the 4-inch irrigation rate was significantly higher than with the nonirrigated check, but the 8-inch irrigation rate did not result in a significant increase above the 4-inch rate.  

 

In 2007-2009, there was no significant difference in seed yield among irrigation treatments for the three Sphaeralcea species (Table 4).  Seed yields for S. parvifolia and S. grossularifolia were lower in 2008 and 2009 than in 2007. 

 

In 2007, there was no significant difference in seed yield among irrigation treatments for the two Dalea species, with D. ornata having the highest seed yield.  Emergence for the two Dalea species was poor, and plots had poor and uneven stands.  The stand of the two Dalea species declined and was too poor for seed harvest in 2008.  The two Dalea species were replanted in the fall of 2008, but emergence was again poor and stands were not adequate for seed harvest in 2009.

 

Conclusions

 

Subsurface drip irrigation systems are being tested for native seed production because they have two potential strategic advantages, a) low water use, and b) the buried drip tape provides water to the plants at depth, precluding stimulation of weed seed germination on the soil surface and keeping water away from native plant tissues that are not adapted to a wet environment. 

 

Knowledge about native forb seed production would help make commercial production of this seed feasible.  Irrigation methods are being developed at the Oregon State University Malheur Experiment Station to help assure reliable seed production with reasonably high seed yields.  Growers need to have economic return on their seed plantings, but forbs may not produce seed every year.  Due to the arid environment, supplemental irrigation may be often required for successful flowering and seed set because soil water reserves may be exhausted before seed formation.  The total irrigation water requirements for these arid-land species has been shown to be low, but it varied by species. 

 

References

USDA, National Resource Conservation Service. 2009. The PLANTS Database (http://plants.usda.gov, 13 March 2009). National Plant Data Center, Baton Rouge, LA 70874-4490 USA .


Table 4. Native forb seed yield response to irrigation rate (inches/season) in 2006-2009. Malheur Experiment Station, Oregon State University, Ontario, OR, 2009.

Species 2006   2007   2008   2009
  0 inches 4 inches 8 inches LSD (0.05)   0 inches 4 inches 8 inches LSD (0.05)   0 inches 4 inches 8 inches LSD (0.05)   0 inches 4 inches 8 inches LSD (0.05)
------------------------------------------------------------------- lb./acre ---------------------------------------------------------------
Eriogonum umbellatuma 155.3 214.4 371.6 92.9 79.6 164.8 193.8 79.8 121.3 221.5 245.2 51.7 132.3 223.0 240.1 67.4
Penstemon acuminatusa 538.4 611.1 544.0 NS 19.3 50.1 19.1 25.5b 56.2 150.7 187.1 79.0 20.7 12.5 11.6 NS
Penstemon deustusc 1246d 1201d 1069d NS 120.3 187.7 148.3 NS ----- very poor stand ---- ----- very poor stand ----
Penstemon speciosusa 163.5 346.2 213.6 134.3 2.5 9.3 5.3 4.7b 94.0 367.0 276.5 179.6 6.8 16.1 9.0 6.0b
Lomatium dissectume ---- no flowering ---- ---- no flowering ---- -- very little flowering -- 66.0 322.8 431.4 233.7b
Lomatium triternatume ---- no flowering ---- 2.3 17.5 26.7 16.9b 195.3 1060.9 1386.9 410.0 181.6 780.1 676.1 177.0
Lomatium grayie ---- no flowering ---- 36.1 88.3 131.9 77.7b 393.3 1287.0 1444.9 141.0 359.9 579.8 686.5 208.4
Sphaeralcea parvifoliaf 1062.6 850.7 957.9 NS 436.2 569.1 544.7 NS 285.9 406.1 433.3 NS
Sphaeralcea grossularifoliaf 442.6 324.8 351.9 NS 275.3 183.3 178.7 NS 270.7 298.9 327.0 NS
Sphaeralcea coccineaf 279.8 262.1 310.3 NS 298.7 304.1 205.2 NS 332.2 172.1 263.3 NS
Dalea searlsiaef 11.5 10.2 16.4 NS ----- very poor stand ---- ----- very poor stand ----
Dalea ornataf           47.4 27.3 55.6 NS   ----- very poor stand ----     ----- very poor stand ----  

a planted March, 2005, areas of low stand replanted by hand in October 2005.

 bLSD (0.10).

 cplanted March, 2005, areas of low stand replanted by hand in October 2005 and whole area replanted in October 2006. Yields in 2006 are based on small areas with adequate stand. Yields in 2007 are based on whole area of very poor and uneven stand.

 dbased on small areas with good plant stands in 2006.

e planted March, 2005, whole area replanted in October 2005.

f planted spring 2006, whole area replanted in November 2006.


Figure 1. Soil volumetric water content for Eriogonum umbellatum over time in 2009.  Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths.  Irrigations started on May 19 and ended on June 24.  Arrows denote irrigations. E. umbellatum was harvested on July 28 (day 209).  Malheur Experiment Station, Oregon State University, Ontario, OR, 2009.

 

 

Figure 2.  Soil volumetric water content for Penstemon acuminatus over time in 2009.  Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Irrigations started on May 8 and ended on June 12.  Arrows denote irrigations. P. acuminatus was harvested on July 10 (day 191). Malheur Experiment Station, Oregon State University, Ontario, OR, 2009.

 

 

 

Figure 3.  Soil volumetric water content for Penstemon speciosus over time in 2009.  Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths.  Irrigations started on May 19 and ended on June 24. Arrows denote irrigations. P. speciosus was harvested on July 10 (day 191).  Malheur Experiment Station, Oregon State University, Ontario, OR, 2009.

 

 

 

Figure 4.  Soil volumetric water content for Lomatium triternatum over time in 2009.  Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Irrigations started on April 20 and ended on May 28. Arrows denote irrigations. L. triternatum was harvested on June 26 (day 177).  Malheur Experiment Station, Oregon State University, Ontario, OR, 2009.

 

 

 

 

Figure 5.  Soil volumetric water content for Lomatium grayi over time in 2009.  Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Irrigations started on April 20 and ended on May 28. Arrows denote irrigations. L. grayi was harvested on June 16 (day 167).  Malheur Experiment Station, Oregon State University, Ontario, OR, 2009.

 

 

 

Figure 6.  Soil volumetric water content for Lomatium dissectum over time in 2009.  Soil volumetric water content is the combined average at the 8-, 20-, and 32-inch depths. Irrigations started on April 20 and ended on May 28. Arrows denote irrigations. L. dissectum was harvested on June 16 (day 167).  Malheur Experiment Station, Oregon State University, Ontario, OR, 2009.

 

Figure 7.  Average annual Eriogonum umbellatum seed yield response to irrigation water applied in 2009 and averaged over 4 years, Malheur Experiment Station, Oregon State University, Ontario, OR, 2009.

 

 

 

Figure 8.  Penstemon speciosus seed yield response to irrigation water applied in 2009 and averaged over 4 years, Malheur Experiment Station, Oregon State University, Ontario, OR, 2009.

 

 

 

Figure 9.  Annual and 3-year average Lomatium triternatum seed yield response to irrigation water applied, Malheur Experiment Station, Oregon State University, Ontario, OR, 2009.

 

 

 

Figure 10.  Annual and 3-year average Lomatium grayi seed yield response to irrigation water applied, Malheur Experiment Station, Oregon State University, Ontario OR, 2009.

 

 

 

 

Figure 11.  Lomatium dissectum seed yield response to irrigation water applied in 2009, Malheur Experiment Station, Oregon State University, Ontario OR, 2009.