Carbon isotope discrimination association with yield and test weight of the Pacific Northwest adapted spring and winter wheat

Authors: SHRESTHA, SURYA - Washington State University; Garland-Campbell, Kimberly; Steber, Camille; HULBERT, SCOT - Washington State University

Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/2020
Publication Date: 6/16/2020
Citation: Shrestha, S.L., Garland Campbell, K.A., Steber, C.M., Hulbert, S.H. 2020. Carbon isotope discrimination association with yield and test weight of the Pacific Northwest adapted spring and winter wheat. Field Crops Research. Vol 3, Issue 1. https://doi.org/10.1002/agg2.20052.
DOI: https://doi.org/10.1002/agg2.20052

Interpretive Summary: Although wheat is more drought tolerant than other major US crops, increasing genetic drought tolerance is critical for Western US wheat production. Carbon isotope discrimination (CID) measures the water use efficiency based on stored carbon within a leaf. While CID is an indicator of water use efficiency at the leaf level, it is not necessarily in indicator of good grain-yield under water-limited growing conditions. The correlation between CID and grain-yield was examine over 13 envrionments in the U.S. Pacific Northwest. Only a weak correlation was found. Future work will need to examine if other physiological measurements will prove a better indicator of performance under drought.

Technical Abstract: Due to considerable influence of environment on yield, breeding for drought tolerance could benefit from focusing on selection of more heritable physiological traits, such as carbon isotope discrimination (as measured by delta, ') for indirectly assessing water use efficiency of wheat (Triticum aestivum L.). Spring and winter wheat cultivars from the Washington state extension trials were assayed for ' and these values were used to determine the relationships with performance in over 13 environments in the Pacific Northwest. The correlation coefficients of ' values between the wheat cultivars grown in different environments ranged from 0.11 to 0.73 for both spring and winter wheat. There was significant genotypic variation for ' in soft spring and hard winter wheat but not in hard spring and soft winter wheat. The ' values were poor indicators of yield for this set of wheat cultivars in most environments, although low values (better water use efficiency) were sometimes correlated with yield. A population of 165 hard spring wheat recombinant inbred lines derived from a cross between two hard spring wheat varieties that differed in water use efficiency was also screened in low rainfall dryland and irrigated environments. High yields in this recombinant inbred population were weakly correlated with high ' values, or low water use efficiency in most environments.