PLANT EXPLORATION TO COLLECT WILD HELIANTHUS NIVEUS SUBSPECIES FOR SUNFLOWER IMPROVEMENT

Authors: Seiler, Gerald; Gulya Jr, Thomas; MAREK, LAURA - IOWA STATE UNIVERSITY; KNAUF, CHRIS - USDI-BLM, EL CENTRO, CA

Submitted to: Proceedings Sunflower Research Workshop
Publication Type: Proceedings
Publication Acceptance Date: 3/10/2006
Publication Date: 3/13/2006
Citation: Seiler, G.J., Gulya Jr, T.J., Marek, L.F., Knauf, C. 2006. Plant exploration to collect wild Helianthus niveus subspecies for sunflower improvement. 28th Sunflower Research Workshop, January 11-12, 2006, Fargo, ND. Available: http://www.sunflowernsa.com/research/research-workshop/documents/Seiler_Helianthus_06.pdf

Interpretive Summary: The sunflower genus Helianthus comprises 51 species (14 annual and 37 perennial), all native to North America. The narrow genetic base of cultivated sunflower has been broadened by the infusion of genes from the wild species, which have provided a continued source of agronomic traits for crop improvement. Unusually high fall and winter rainfalls, in some desert southwest areas had up to five times its normal precipitation, producing a desert flora not observed for many years, affording us the rare opportunity to collect desert sunflowers during the winter of 2005. The objective of this exploration was to collect seeds (> 2,000 seeds per population) from as many populations as possible of dune sunflower in California, gray desert sunflower in Arizona, and showy sunflower in Baja, California, and make them available for future research and improvement of cultivated sunflower. The exploration for desert sunflowers took place from February 26 through March 5, 2005, covering 1,350 miles in southern California and adjacent Arizona. The seven-day exploration resulted in the collection of seed from nine populations. Five populations of the perennial dune sunflower were collected from the Algodones Dunes of California. Four populations of the annual gray desert sunflower were also collected, one population from the Yuma dunes, which was the western most distribution for this subspecies, and three from the Cabeza Prieta National Wildlife Refugee in the Pinta Sands area of Arizona which is the northernmost extension of the Gran Desierto of Sonora Mexico. Perennial dune sunflower survives and thrives in shifting sand dunes with annual precipitation of 2 inches could be of value for cultivated sunflower, which is often grown in arid areas. No seed of perennial showy sunflower was collected from Baja California. These populations were only observed because the U.S. currently does not have an agreement with Mexico to collect and distribute germplasm. The low seed set per head, few flowering heads, and the immaturity of the seed in the heads at the time of collection did not allow for the collection of an adequate seed samples for distribution from the populations. Additional seeds will have to be collected over time to obtain an adequate amount of seed, or the seed collected will have to be increased through regeneration using bees as pollinators. The somewhat better seed set in the gray desert sunflower from the Yuma area permitted the collection of 3,500 seeds. Two of three populations collected from the Pinta Sands had 2,200 and 3,400 seeds. This will be adequate for seed distribution. Future collections of dune sunflower will have to concentrate on collecting a larger number of heads with more mature seeds to reach the 2,000 seed level required for placement in the NPGS sunflower germplasm collection for distribution.

Technical Abstract: The narrow genetic base of cultivated sunflower has been broadened by the infusion of genes from the wild species, which have provided a continued source of agronomic traits for crop improvement. The genus Helianthus comprises 51 species (14 annual and 37 perennial), all native to North America. One of the species, H. niveus, contains three subspecies, two perennial and one annual. Dune sunflower, Helianthus niveus ssp. tephrodes, is a perennial species found in the Grand Desierto, Sonora, Mexico, and has been identified in several localities in the Algodones Dunes, Imperial County, California. Gray desert sunflower, H. niveus ssp. canescens, is an annual or rarely perennial sunflower species in sandy soils of southeastern New Mexico and western Texas, west to southern California and northern Mexico. Showy sunflower, Helianthus niveus ssp. niveus, is a perennial species occurring on the west coast of Baja California from Sensal to Santa Margarita, where it is found in disturbed sites on sand dunes. Unusually high fall and winter rainfalls, in some areas up to five-times normal precipitation, produced a desert flora not observed for many years, affording us the rare opportunity to collect these desert sunflowers during the winter of 2005. The objective of this exploration was to collect seeds (> 2,000 seeds per population) from as many populations as possible of H. niveus ssp. tephrodes, H. niveus ssp. niveus, and H. niveus ssp. canescens and make them available for future research and improvement of cultivated sunflower. The exploration for desert sunflowers took place from February 26 through March 5, 2005, covering 1,350 miles in southern California and adjacent Arizona. The seven-day exploration resulted in the collection of seed from nine populations. Five populations of dune sunflower were collected from the Algodones Dunes of California. Four populations of gray desert sunflower were also collected, one population from the Yuma dunes, which was the western most distribution for this subspecies, and three from the Cabeza Prieta National Wildlife Refugee in the Pinta Sands area of Arizona which is the northernmost extension of the Gran Desierto of Sonora Mexico. Perennial dune sunflower survives and thrives in shifting sand dunes with annual precipitation of 2 inches could be of value for cultivated sunflower, which is often grown in arid areas. The number of seeds per head averaged only one in the perennial dune sunflower. The low seed set could be due to the lack of pollinators or low self-compatibility, insect/rodent predation, or the perennial habit. The low number of seeds per head could also be due to the immaturity of the seed at the time of collection. The number of seeds per head was higher, with five seeds per head in the annual gray desert sunflower. No seed of perennial showy sunflower was collected from Baja California. These populations were only observed because the U.S. currently does not have an agreement with Mexico to collect and distribute germplasm. The low seed set per head and the few flowering heads of dune sunflower did not allow for the adequate collection of seeds for distribution from the populations. Additional seeds will have to be collected over time to obtain an adequate amount of seed, or the seed collected will have to be increased through regeneration using bees as pollinators. The somewhat better seed set in the gray desert sunflower from the Yuma area permitted the collection of 3,500 seeds. Two of three populations collected from the Pinta Sands had 2,200 and 3,400 seeds. This will be adequate for seed distribution. No seeds of showy sunflower were collected from the Baja region. These populations were only observed due to restrictions by Mexico on seed distribution. Future collections of dune sunflower will have to concentrate on collecting a larger number of heads with more mature seed