Penstemon Seed Production and Stand Establishment

SUMMARY

I conducted this project to determine the effectiveness of direct-field seeding or using greenhouse starts to establish a field of Penstemon speciosus for seed production. I conducted the study over the 2004 and 2005 growing seasons, which resulted in greenhouse starts being the only way any stand of Penstemon speciosus was established.

I used four methods of cold stratification to start seed for greenhouse production of Penstemon speciosus; all except the hydrogen peroxide treatment proved equally effective at producing seedlings for transplantation to the field. The hydrogen peroxide treatment produced only one seedling and is not recommended for starting the seedlings. Germination, even in the greenhouse, was low and resulted in only 12.5% germination using seed that was 93.5% viable.

Despite the effectiveness of the herbicide Weed Block, weeds were still a significant problem around the base of the plants and on the perimeter of the Weed Block. Stand establishment costs were approximately $3.15 per plant. Despite some desirable qualities of Penstemon speciosus, more work is needed to make this crop economically viable.

OBJECTIVES

I conducted this project to test two ways to establish a native forb, Penstemon speciosus. In this project, I compared direct seeding to use of transplants started in a greenhouse for seed production. I also demonstrated whether Weed Block adequately controlled the weeds. I ultimately hoped to reach a realistic estimate of stand establishment costs.

METHODS AND RESULTS

To test direct seeding of Penstemon speciosus with use of starts for establishing a seed-producing stand, I laid a sheet of Weed Block (300 ft. by 12 ft.) in the field in December 2003. I laid three drip lines with emitters spaced 18 in. apart such that 600 plants could be established and irrigated with a drip system on top of the Weed Block, and cut holes in it at each emitter.

I divided the 600 emitters into 30 plots of 20 emitters each and marked the drip line with a piece of Ag Bag tape to delineate the boundaries of each plot. I randomly selected 15 of the plots for direct seeding with 20 seeds. I accomplished randomization by flipping a coin. The seeds were placed in the ground in December 2003 at a depth of approximately 1/8 in. We planted the seeds in December to allow for several months of cold stratification in the field.

I started another test for germination and establishment of greenhouse starts in the spring of 2004. I placed seeds on a piece of paper towel moistened with one of four treatments: 1) 0.5% gibberellic acid, 2) cool water, 3) boiled water and 4) 3% hydrogen peroxide solution.

I then placed seeds in a refrigerator with a temperature of approximately 45 degrees F for 60 days. I repeated each treatment six times and each replication had 20 seeds with 480 seeds stratified for the first test.

Wince germination was so low in the first test that I repeated it two more times, once in the summer and again in the fall. Neither the summer nor the fall test included the hydrogen peroxide treatment because almost no germination resulted. I also increased the number of replications to eight but remained with 20 seeds per replication.

Only one of the methods of establishing a stand of Penstemon speciosus resulted in established plants. Germination in the field was zero. Germination in the greenhouse was more successful but the overall cold stratification treatments were 12.5%.

When I started this project, I went with the assumption that cold stratification was necessary for germination in most penstemon species. By accident, I proved this true since the refrigerator I used did not maintain a temperature of 45 degrees F or lower for the summer test and no seedlings resulted from that test. I acquired a new refrigerator and the fall test did result in germination similar to the spring test.

I transplanted plants from the spring germination test to the field in September 2004. All but four of the 60 plants survived until the next spring to produce seed. In contrast, plants from the fall greenhouse test that I transplanted in May and June 2004 had a greater tendency to die. When I realized this, I stopped transplanting them. Instead, I am currently transplanting the rest of the fall 2004 greenhouse test to the field in the fall of 2005.

I estimate that it cost about $3.13 per plant to establish a stand for seed production. This does not include the costs of harvesting the crop, which was not within the scope of this project. From my observations of the form that many of the plants took, seed will have to be harvested by hand because many of the stalks were lying almost on the ground.

Besides the problem of penstemon seed production turning into a hand-labor intensive crop, I have found out that penstemon appear to be very susceptible to root rot. Some of the plants that established well in the field from the fall 2004 transplanting survived to produce seed but succumbed to root rot. I did not harvest seed from plants that died of root rot. Instead, I selectively harvested seed only on plants that were still alive at the time the seed was ripe. My plan is to plant the seed from plants that didn’t succumb to root rot in hopes of isolating resistance to root rot. I will plant transplants from the seed of those that didn’t succumb to root rot to locations where plants did succumb to see if they survive.

BENEFITS OR IMPACTS ON AGRICULTURE

I was told I wouldn’t get a crop using Weed Block; however, I had 60 plants that did produce seed and most are still alive. This fell short of my original goal of getting between 300 and 600 plants established. In the future, I could establish a better stand if I only use greenhouse starts that I transplant to the field.

Through observation from my yard, I’ve already lost Penstemon palmeri after only four years, but Penstemon eatonii is still alive. I’ve never planted Penstemon speciosus before so I have no idea how many years a stand of this species will produce before its time to plow it.

Useful information I discovered in this project includes:

1) The actual cost of establishing this stand ($3.15/plant including all the materials and handling from seed to transplantation into the field),
2) In spite of the effectiveness of Weed Block at controlling weeds between the rows, more weed control is still needed around the base of each plant and along the edges of the Weed Block,
3) Need for crop improvement such as finding strains that are root-rot resistant and
4) Potential other use of Penstemon speciosus as a perennial bedding plant.

PRODUCER ADOPTION

At the time I applied for this grant, there was tremendous interest in native seed as a potentially new crop to Nevada because of a shortage of seed for re-vegetating rangelands destroyed by fires. Now that most of that seed was purchased out of state and the rangelands have been reseeded, demand for native seed has dropped. The drop in demand for native seed has also dampened grower enthusiasm for starting any more fields of native seed of any species. Since the producer interest for getting into native seed production is very low, no one is thinking about adopting any production practices from my project. If in the future I can get the rest of the stand established and get sizeable yields of viable seed, some producers might consider adopting the practices I’ve tested in this project. Another consideration will be the actual price I get for the seed. If the price is not high enough to cover production costs and give me a reasonable margin of profit then no one will be convinced to try producing penstemon seed.

REACTIONS FROM PRODUCERS

Currently, interest in my project from other producers has been lacking because they don’t see a reliable market for native seed of any species. I am president of the Nevada Wildland Seed Producers Association, and many of the members are plowing under their fields of native grasses because companies are not purchasing it or the contracts from other buyers are not being honored. Only one potential buyer has expressed interest in purchasing Penstemon speciosus seed from me, but he is concerned pollinators specific to this species may not have been present in my field and the seed may not be viable.

RECOMMENDATIONS OR NEW HYPOTHESES

I can’t recommend this crop for producers until some improvements in the crop have taken place and the market for native seed is more stable. Among the improvements needed are:

1) Resistance to root rot,
2) Selecting plants that have more upright growth habit, making mechanical seed harvesting possible and making the plant more attractive to the nursery industry and
3) Finding better ways to get more of the seeds to germinate.

I recommend anyone daring to get into this crop consider starting with eight times as much seed as you think you will need because only about 12.5% of it will germinate even though 93.5% of it is viable. Any producer of this crop should have access to lots of hand labor. I also recommend that a future grower have a firm offer for the seed before planting. The latter recommendation may change if the market for native seed or native plants stabilizes and grows.

I wouldn’t consider directly seeding a field of this crop in Nevada because penstemon seed requires cool moist stratification, and winter soil moisture in Nevada is erratic and may result in no germination for many seasons.

Winter moisture should be a consideration for any native seed production where the seed requires cool moist stratification before germination will occur. To get around dry winter conditions, growers might consider using greenhouse starts but should also consider what price they will receive for the seed produced and how long the stand will last.

OUTREACH

I plan to write up the results of this project in a formal manner that can be published or presented at conferences.