A STUDY OF ANCESTRAL AND MODERN CANADIAN SPRING WHEATS

Abstract

Spring wheat cultivars (Triticum aestivum L.) representing a century of crop breeding effort were evaluated in three rain-fed environments to determine which yield-related traits have been altered over time. Plant height and the length of the vegetative growth phase were shortened during the pre-Thatcher era. Spikelet number has been reduced but kernel weight increased during the period of cultivar development discussed herein. Tiller production has changed little since the turn of the century while spike number has been reduced slightly in the post-Thatcher period. Harvest indices increased with the introduction of Thatcher, but neither that trait nor crop grain yield have undergone consistent improvements since the 1930s. A significant cultivar × environment interaction resulted from adverse environment having a greater negative impact on grain yield of the older cultivars Red Fife and Marquis relative to their descendents. HY320, representing a potential new market class (Canadian Prairie Spring), yielded 25% more than standard height cultivars due to a higher biological yield and harvest index. Crop and spike grain yields were associated with kernel number/spike (r = 0.78,0.75) and days to spike emergence (r = 0.50,0.55), suggesting that high grain yield in this material is a function of maturity-dependent kernel production. Future improvements in grain yield might result from selection for higher harvest index since the latter trait is positively correlated with yield (r = 0.63) but not associated with maturity (−0.17).Key words: Old cultivars, spring wheat, yield components, harvest index, cultivar × environment interaction