Tillering Relationships Between Spaced and Densely Sown Populations of Spring and Winter Wheat¹

Abstract

The relationship between tillering in space‐planted early generation populations and in close‐planted commercial‐type stands of wheat (Triticum aestivum L.) was investigated over a 5‐year period. The primary objective was to determine if this relationship is strong enough to justify selection for tillering type in spaced populations. Secondary objectives were to examine tillering‐ yield relationships and possible differences in tiller survival among wheat genotypes. Four winter and two spring wheat cultivars with known tillering differences in densely‐seeded stands maintained their relative rankings when grown in spaced plantings. However, when F5 plants selected for high or low tillering in spaced populations were subsequently grown in densely‐sown F6 plant‐rows, little relationship was observed between tillering characteristics in the two planting densities. In attempting to explain the divergent results it is theorized that tillering differences among the cultivars, which had exhibited these differences over many years and environments, were largely genetic and would, therefore, likely persist regardless of planting density. Conversely, we suspect that much of the tillering variation observed among the spaced F5 plants was non genetic and would lack consistency under dense seeding. The relationship between tillering in spaced and close plantings appears to be further complicated by the differential ability of genotypes to mature spike‐bearing tillers, as a percentage of total tillers initiated. The cultivars we studied veried widely in the efficiency with which they matured fertile tillers in dense plantings. In only two of eight crosses did we observe a significant association between degree of tillering in space‐planted F5's and in their densely‐seeded F6 plant‐rows. Consequently, tillering differences in space‐planted early generation wheat populations do not appear to provide a reliable selection criterion. We observed no consistency between grain yield and degree of tillering. Other yield components largely compensated for variation in tiller number, with kernels per spike having a greater effect than kernel weight.

Light quality effects on the appearance of tillers of different order in wheat (Triticum aestivum)

“…2). The latter is consistent with the poor tillering relationships between spaced and densely sown populations of spring and winter wheat (Dewey & Albrechtsen, 1985). The rate of leaf appearance was unaffected by the treatments (Fig.…”

Elevated growth redundancy and size inequality in spring wheat populations mulched with clear plastic film

“…Increasing the percentage of tillers that survive has been hypothesized as an approach for increasing yield of wheat plants. But some researchers have suggested that as high as 50-70 % abortive tillers in certain wheat cultivars (Dewey & Albrechtsen 1985) is a higher growth redundancy for spring wheat population for higher grain yield (Donald 1968;Kirby & Jones 1977). The present study was conducted to determine the effects of plastic film mulch on the degrees of growth redundancy (increased percentage of abortive tillers and decreased reproductive allocation) in two spring wheat cultivars, and to explore its mechanism in relation to size inequality and life-history strategies theory.…”

Dryland Wheat Domestication Changed the Development of Aboveground Architecture for a Well-Structured Canopy

“…Tillering in wheat is closely related to the production of nodal roots and hence affects the biomass size of root system [49]–[50]. This study showed that there was a continuous reduction in the number of tillers from diploid to tetraploid and further to hexaploid wheat.…”

“…During the domestication from tetraploid to hexaploid wheat, the biomass of root system was decreased, presumably because of a reduction in root number and root length at the level of individual plants [49] . Tillering in wheat is closely related to the production of nodal roots and hence affects the biomass size of root system [49] – [50] . This study showed that there was a continuous reduction in the number of tillers from diploid to tetraploid and further to hexaploid wheat.…”