Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/3/1997
Publication Date: N/A
Citation: Interpretive Summary: Water is a major limiting factor for production of forages for pastures, hay, and rangelands in the semiarid Northern Great Plains. An increase in plant water-use efficiency (WUE) would enhance forage supply for livestock. Conventional breeding methods are efficient but slow. Carbon isotope discrimination has been proposed as a technique for selecting plants with greater (WUE), but chemical analysis is expensive. This study evaluated carbon isotope discrimination (CID), tissue ash concentration, and canopy temperature on half-sib families from genetically broad-based populations of diploid crested wheatgrass, tetraploid crested wheatgrass, and western wheatgrass to determine the utility of using ash and canopy temperature as alternative criteria to CID for selecting plants with high WUE. Relatively high correlations between CID, ash, and canopy temperature for tetraploid crested wheatgrass indicate that ash and canopy temperature could possibly be useful as alternative traits to CID in selecting for enhanced WUE in tetraploid crested wheatgrass families. Canopy temperature may be useful for selecting for improved WUE in diploid crested wheatgrass; however, correlations with CID were somewhat lower than for tetraploid crested wheatgrass. Neither ash nor canopy temperature would be an acceptable selection criteria for selecting for enhanced WUE in western wheaatgrass. Developing germplasm with improved WUE should increase forage production for hay and pastures, and sustainability of seeded forages.
Technical Abstract: Water is the main factor limiting forage production in the semiarid Northern Great Plains. Development of selection criteria suited to screening populations for water-use efficiency (WUE) are needed. This study evaluated carbon isotope discrimination (CID), tissue ash concentration, and canopy temperature of populations of diploid crested wheatgrass, tetraploid crested wheatgrass, and western wheatgrass to determine the utility of using ash and canopy temperature as alternative criteria to CID for selecting plants with high WUE. Tissue ash, canopy temperature, and CID were measured on half-sib families from genetically broad-based populations of each species. Sufficient genetic variation was present for CID and ash among families to suggest use of these traits as criteria for selecting plants with higher WUE. Correlations between ash and CID were greatest for tetraploid crested wheatgrass and least for western wheatgrass. Correlation of canopy temperature with CID was significant for tetraploid crested wheatgrass both years and for diploid crested wheatgrass in 1993, but neither year for western wheatgrass. Ash and CID were moderately heritable in all three grass populations, indicating that both traits are under genetic control and could be altered through breeding. Using ash and canopy temperature as criteria for selecting plants with greater WUE would provide a relatively low-cost, simple approach to develop cultivars with improved WUE.