Yield Stability of Hybrid vs. Pureline Hard Winter Wheats in Regional Performance Trials

Abstract

Hybrid hard winter wheats (Triticum aestivum L.) have shown superior grain yield potential in regional performance trials during the last decade. Evidence for enhanced yield stability, combined with enhanced yield potential, would facilitate wider acceptance of hybrid wheat by growers. Hybrid and pureline yield stability and environmental responsiveness were compared with the use of data from the Southern Regional Performance Nursery (SRPN), 1990 through 1995, and Agripro Standard Variety Trial (SVT), 1993 and 1994. Hybrid and pureline yields were regressed on an environmental index based on location mean yields for purelines, and response slope and deviations were calculated. Analyses were conducted separately for each nursery, as hybrid and pureline entries varied. Hybrids showed significantly higher mean yields compared with purelines and the yield advantage generally increased with increasing environmental yield potential. Average regression slope for hybrids was significantly higher (1.09–1.12) than for purelines (1.0) in the 1994 and 1995 SRPN and 1993 and 1994 SVT. Hybrid slopes were not significantly different from those for purelines in the 1990 through 1993 SRPN, where they ranged from 1.0 to 1.07. There was no crossover in yield response between hybrids and purelines at lower yield levels. Deviations from regression were of similar magnitude for hybrids and purelines. Confidence intervals for hybrid and pureline regressions generally overlapped throughout the observed yield ranges in the SRPN. In the 1993 and 1994 SVT, hybrid and pureline confidence intervals diverged as environmental yield potential increased. Compared with pureline cultivars, hybrid wheats have potential for enhanced mean yield and greater yield response to favorable environmental conditions with similar deviations from expected response.