Breeding Guayule: how far have we come and how far can we go?

Authors: RAY, DENNIS - University Of Arizona; TEETOR, VALERIE - University Of Arizona; Coffelt, Terry; Dierig, David; Thompson, Anson; JORGE, MARCAL - University Of Arizona; VEATCH-BLOHM, MARTIN - University Of Arizona; KEYS, ROY - University Of Arizona

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/15/2010
Publication Date: 9/19/2010
Citation: Ray, D.T., Teetor, V.H., Coffelt, T.A., Dierig, D.A., Thompson, A.E., Jorge, M.H., Veatch-Blohm, M.E., Keys, R.N. 2010. Breeding Guayule: how far have we come and how far can we go?. Meeting Abstract. AAIC 22nd Annual meeting, Fort Collins, CO. September 18-22, 2010. pp 47.

Interpretive Summary: Guayule lines from the 1940s yielded less than 350 lb rubber/acre/year. Using the available germplasm from this earlier era, guayule rubber yields have increased significantly, between 830 lb rubber/acre/year and 1,000 lb rubber/ acre, through the efforts of a few, but dedicated researchers. Improved guayule germplasm lines have been developed and released, and these lines are now grown worldwide and are available for further improvement in specific environments or for specific traits. Selection in guayule has been aided by the description of the components of yield and their relationships to rubber production, and the measurement of the heritability of these characters. In general, rubber content (%) is not correlated with rubber yield, and in fact is often negatively correlated. Fresh and dry weights, as well as other characters related to biomass production, are highly and consistently correlated to rubber yield. Heritability estimates for these traits, made in mature stands (2- to 3-year-old plants) by parent-progeny regressions, were essentially zero, but it has been shown since then that this is from the compounding of environmental effects over the years that a guayule plant is in the field. We now know that the greatest gains made from selections are by making selections in the first year of growth. We still need to improve many characters, and even though there are problems in working with guayule from a breeder’s point of view (perennial growth habit, rubber produced in response to cold, and reproduction by apomixis), improvements have and will continue to be made.

Technical Abstract: Guayule lines from the 1940s yielded less than 350 lb rubber/acre/year. Using the available germplasm from this earlier era, guayule rubber yields have increased significantly, between 830 lb rubber/acre/year and 1,000 lb rubber/ acre, through the efforts of a few, but dedicated researchers. Improved guayule germplasm lines have been developed and released, and these lines are now grown worldwide and are available for further improvement in specific environments or for specific traits. Selection in guayule has been aided by the description of the components of yield and their relationships to rubber production, and the measurement of the heritability of these characters. In general, rubber content (%) is not correlated with rubber yield, and in fact is often negatively correlated. Fresh and dry weights, as well as other characters related to biomass production, are highly and consistently correlated to rubber yield. Heritability estimates for these traits, made in mature stands (2- to 3-year-old plants) by parent-progeny regressions, were essentially zero, but it has been shown since then that this is from the compounding of environmental effects over the years that a guayule plant is in the field. We now know that the greatest gains made from selections are by making selections in the first year of growth. We still need to improve many characters, and even though there are problems in working with guayule from a breeder’s point of view (perennial growth habit, rubber produced in response to cold, and reproduction by apomixis), improvements have and will continue to be made.