Phenotypic variations, heritability and correlations in dry biomass, rubber and resin production among guayule germplasm

Authors: Abdel-Haleem, Hussein; FOSTER, MIKE - Texas Agrilife Research; RAY, DENNIS - University Of Arizona; Coffelt, Terry

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/31/2017
Publication Date: 1/8/2018
Citation: Abdel-Haleem, H.A., Foster, M., Ray, D., Coffelt, T.A. 2018. Phenotypic variations, heritability and correlations in dry biomass, rubber and resin production among guayule germplasm. Industrial Crops and Products. 112:691-697. https://doi.org/10.1016/j.indcrop.2017.12.072.
DOI: https://doi.org/10.1016/j.indcrop.2017.12.072

Interpretive Summary: Among the more than 2000 plant species that produce rubber, guayule and Hevea are the two that have produced commercial grade natural rubber and latex. Based on its origin in Southern Texas and northern Mexico, guayule is a good candidate for the arid and semi-arid sustainable agricultural systems. Continued improvement of guayule for higher biomass, rubber and resin production, and high resistance to environmental stresses, are necessary to meet the demand of the guayule industry. Our results indicated that improved guayule germplasm had good genetic variability among and within the different growth stages (harvested plant age), where the dry biomass, rubber and resin production are the highest when plants were harvested after two years of growth. High heritability estimates for these traits suggest that selection is feasible in the first three years in general, and the highest after two years of growth as the plants reach maximum growth homogeneity with low competition among plants. Positive correlation coefficients among these traits suggest the possibility of selection for more than one trait at the same time, which could reduce the guayule breeding time and effort to produce superior germplasm.

Technical Abstract: Gauyaule (Parthenium argentatum Gray) originated in the Southern Texas and northern Mexico deserts, which suggests it as a good candidate for arid and semi-arid sustainable agricultural systems to produce natural rubber and industrial byproducts. Continued improvement of guayule for higher biomass, rubber and resin production, and high resistance to environmental stresses, are required and necessary to meet the demand of the guayule industry. The current study was conducted to evaluate the phenotypic variations in dry biomass, and rubber and resin content and production in eight improved guayule germplasm that were harvested after one, two, and three years of growth in seven environments. Our results indicated that improved guayule germplasm had good genetic variability among and within the different growth stages, where the biomass rubber and resin production are the highest when plants are harvested after two years of growth. Genotype effects were significant for these traits despite the environmental effects, suggests that testing genotypes in multiple environments in order to detect and select lines with the desired level of these traits is required. High heritability estimates of these traits suggest that selection is feasible in the first three years in general, and the best after two years when plants reached maximum growth homogeneity with low competition among plants in growing area. Positive correlation coefficients among these traits suggest the possibility of selection for more than one trait at a time, which could reduce guayule breeding time and efforts to meet different industrial demands such as rubber and byproducts in the same breeding programs.