Agronomic performance of hard red spring wheat isolines sensitive and insensitive to photoperiod

An increasing number of western Canadian hard red spring wheat cultivars (Triticum aestivum L.) are photoperiod insensitive, in part, to accommodate short day winter nurseries within breeding programs. The objective of this study was to compare the agronomic performance of near-isogenic photoperiod sensitive (PS) and insensitive (PI) hard red spring wheat lines over 21 environments (1996-1998) to determine if insensitivity had an effect on agronomic performance. Eight PS and eight PI isogenic lines within each of three genetic backgrounds including AC Minto, CDC Makwa, and SWP5304 were evaluated. The dominant allele Ppd-D1 conferred insensitivity to PI lines. The experimental design was a randomized complete block design with three replications. Testing environments included Fort Vermillion AB (58degreesN), Dawson Creek, BC (55degreesN), Saskatoon, SK (52degreesN), Elrose, SK (51degreesN), Elgin, MB (49degreesN), Bozeman, MT (45degreesN), Ste. Foy, QC (46degreesN), Charlottetown, PE (46degreesN), Guelph, ON (43degreesN), and Akron, CO (40degreesN). Measurements were made on 11 traits including final leaf number, days to heading and maturity, plant height, grain yield, kernel weight, spikelets per spike (total, fertile, and sterile), seeds per spike, and yield per spike. Generally, PS lines were later in heading and maturity, taller, initiated more leaves and spikelet primordia, and 5% higher yielding. Genetic backgrounds differed significantly in all traits, except final leaf number and grain yield. Significant, noncrossover, photoperiod response type X genetic background interactions were observed only for fertile spikelets per spike and seeds per spike. Our results suggest that photoperiod sensitivity may be advantageous in the northern latitudes of North America.