Divergent recurrent selection for seedling tiller number in Altai wildrye

Abstract

Seedling tiller number is a possible selection criterion to improve seedling establishment of Altai wildrye, Leymus angustus (Trin.) Pilger, an important grass for autumn grazing of beef cattle in semiarid environments. Forty‐two half‐sib families selected for high seedling tiller number (HTN) and eighteen half‐sib families selected for low seedling tiller number (LTN) by four cycles of divergent recurrent selection were compared with four controls, Altai wildrye cultivars Prairieland, Eejay and Pearl, and crested wheatgrass (Agropyron desertorum (Fisch. Ex Link) Schultes), cultivar Nordan, on dryland and irrigated sites at Swift Current, Saskatchewan, Canada. Seedling tiller count, seedling height, tiller weight and seedling dry‐matter yield (DMY) were determined on two plants per plot and DMY was determined for each plot for 2 years post‐establishment. HTN half‐sib families had more, lighter and shorter tillers than LTN half‐sib families. There was a negative correlation (r=–0·42, P < 0·01, n=60) between seedling DMY and tiller number. HTN half‐sib families had higher DMY in post‐establishment years at the dryland site only. Seedling tiller number in Altai wildrye may be related to DMY at sites at which resource availability delays seedling establishment, but selection for HTN will not increase seedling DMY owing to concomitant changes in carbon allocation.

Divergent Selection for Seedling Tiller Number in Big Bluestem and Switchgrass

“…They attributed this difference to larger leaves, tillers, and elongating stems of Emerald. This similar relationship has also been seen in tall fescue (Jones et al, 1979), perennial ryegrass (Cooper and Edwards, 1961; Edwards and Cooper, 1963), and Altai wildrye (Jefferson et al, 2001) genotypes or populations that differed in number of tillers per plant.…”

“…Low‐tillering lines had greater seedling dry matter than high‐tillering lines and the base population when grown under irrigated conditions. However, both selected lines had less seedling dry matter than the base population under dryland conditions (Jefferson et al, 2001).…”

“…The single tiller Cycle 2 populations had greater shoot weight per plant than the other populations for both species (Tables 2, 3). In Altai wildrye, with festicoid seedling morphology, half‐sib lines divergently selected for seedling tiller number were different in seedling dry weight (Jefferson et al, 2001). Low‐tillering lines had greater seedling dry matter than high‐tillering lines and the base population when grown under irrigated conditions.…”

“…Pilg.] successfully produced half‐sib lines that differed in seedling tiller number, seedling height, tiller weight, and seedling dry matter yield (Jefferson et al, 2001). High tillering half‐sib lines produced more dry matter yield per hectare in the second and third years after establishment than the low tillering half‐sib lines at the nonirrigated site, but were not different at the irrigated site.…”

Recurrent selection for wider seedling leaves increases early biomass and leaf area in wheat (Triticum aestivum L.)

“…Here genetic gains for vigour of up to 10% per cycle have been demonstrated across a range of species including pasture legumes ( Klos and Brummer, 2000 ; DeHaan et al , 2001 ) and various pasture grasses (e.g. Faulkner et al , 1982 ; Jefferson et al , 2001 ). Recurrent selection from pools representing diverse genetic sources has also been demonstrated for improved establishment in wheat ( Gul and Allan, 1976 ) and pearl millet ( Lynch, 1994 ), and for increased seedling growth of maize ( Mock and Bakri, 1976 ) and sorghum ( Bacon et al , 1986 ) in cool soils.…”