Changes in primordia and fertile florets in hexaploid triticale selected disruptively for spikelet fertility.

GUIDOBALDI, HA; MAICH, RH

Annual Wheat Newsletter

Kansas State University

Lugar: Kansas, EEUU; Año: 2001 vol. 47 p. 19 - 19

Fertility in triticale (number of seeds/spikelet) is a characteristic with a direct response to selection and a low heritability. The degree of fertility has been observed as an indirect response to previously determined ontogenic stages, such as the number and weight of seeds per spike, biological yield, harvest index, and seeds and spikes per sq. m. In wheat, changes in the number of seeds and reproductive structures of the spike have been studied widely. However, some evidence indicates that the progress in not homogeneous. Different genetic progress has been observed in the middle of the spike, especially with respect to the number of seeds per spikelet. We analyzed families of wheat with progressive microevolutionary differences. We found differences in the number of fertile florets in the middle and lower thirds of the spike and in the lower one-third for the primordial florets. Meiotic index (percentage of tetrads without micronucleus) is another triticale characteristic that has been studied in relation to its effect on the spike and spikelet fertility. A direct response to selection and an indirect response to the number of seeds per spike and spikelet were shown. The aim of our triticale research was to establish if disruptive selection for spikelet fertility and meiotic index caused an indirect response in previously determined ontogenic stages (number of primordia and fertile florets).