C discrimination in corn grain can be used to separate and quantify yield losses due to water and nitrogen stresses

• Published in: Weed science Vol. 53; no. 1; pp. 23 - 29
• Main Authors: Clay, D.E, Clay, S.A, Lyon, D.J, Blumenthal, J.M
• Format: Journal Article
• Language: English
• Published: Weed Science Society of America 2005
• Subjects: C3 plants; C4 plants; Clay soils; Corn; crop losses; Dehydration; equations; Fall lines; fertilizer rates; field experimentation; grain yield; methodology; Nitrogen; Physiology, Chemistry, and Biochemistry; Plant competition; Plant density; Plants; Soil water; stable isotopes; Triticum aestivum; water stress; wheat; Zea mays; Nebraska
• DOI: 10.1614/WS-04-070R1
• EISSN: 1550-2759
• ISSN: 0043-1745

It is difficult to quantify the mechanism(s) responsible for competition-induced yield loss using traditional experimental techniques. A technique using yield and 13C discrimination (delta) for wheat, a C3 plant, has been developed to separate total yield loss (TYL) into yield loss due to N (YLNS) and water (YLWS) stresses. The objective of this research was to determine whether the delta approach could be used in corn, a C4 plant, to separate TYL into YLNS and yield loss due to a combination of water and light stresses (YLWLS). The field study had a factorial design using five corn densities and five N rates and was conducted in western Nebraska in 1999 and 2000. Relationships for YLNS and YLWLS with TYL were derived from only a portion of the yield and delta data collected in 1999 and validated based on the remaining data collected in 1999 and 2000. In 1999, 20 to 40% of TYL was due to YLWLS, whereas in 2000, a dry year, YLWLS accounted for 60 to 80% of the TYL. Results from using the delta-based approach were consistent with analysis of variance results. For example, calculated YLWLS values were related to measured YLWLS by the equation: calculated YLWLS = 19 + 0.91 (measured YLWLS) (r2 = 0.95; P < 0.01). The delta approach, based on a plant's physiological response to the environment, can be used to separate and quantify competition-induced YLNS and YLWLS in corn.