Influence of post-harvest residue management and cultivar on tiller dynamics and seed yield in timothy

Abstract

Timothy (Phleum pratense L.) is a bunch-type cool season perennial grass species grown in Manitoba primarily for seed production. The objectives of this study were to determine the effect of post-harvest residue management (straw removal-SR, straw and stubble removal-SSR and fall burning-Burn) on tiller production, yield components and seed yield of five timothy cultivars (Basho, Climax, Goliath, Hokuo and Salvo), and to better understand the association between yield components and final seed yield in timothy crops grown in the dry subhumid region of the Canadian prairies. Two experiments were conducted over four production seasons at Arborg, MB and one production season at St. Claude, MB. Tiller number per m2 in spring (TS) and at harvest (THV) were measured in 1990 at St. Claude and in 1990 and 1991 at Arborg. Residue management (RM) treatment ranking for TS was Burn < SR < SSR, but tiller senescence and compensatory mechanisms resulted in equivalent THV values across all RM treatments. The number of seed-bearing tillers m−2 at harvest was also unaffected by RM. Seed yield was unaffected by RM in all instances, except at Arborg in 1989 where a significant RM × cultivar interaction was observed. The basis of the interaction was the greater sensitivity of Hokuo to the Burn treatment. Cultivar differences for seed yield were relatively consistent over years and between the two experiments, with Climax always ranking in the high yielding group and Salvo with the low yielding group. Based on analysis of yield components, it appeared that RM most affected early season growth (i.e. TS), while cultivar most affected later season growth (fertile tillers per unit area, seed yield per fertile tiller (SYFT)). Seed yield differences were most closely associated with SYFT (r2 = 0.97**) across cultivar treatments. Key words: Burning, straw removal, harvest index, yield components, forages