Studies of lodging, floral biology and breeding techniques in tef (Eragrostis tef )
Two aspects of the Ethiopian cereal tef (Eragrostis tef)
which relate to its improvement have been studied: lodging and
floral biology with special reference to hybridisation. Lodging
was examined in a large germplasm collection in Ethiopia. Several
types of lodging were recognised. Temporary lodging, from which
the plant makes a complete recovery, occurs before heading.
Permanent lodging, which occurs after heading, takes one of three
forms: bend-lodging, break-lodging and root-lodging. Only bendlodging
is widespread and of economic importance: losses are
estimated at seventeen per-cent. Lodging resistance is aS80ciated
with several interacting morphological characteristics
particularly plant height, length of panicle, peduncle and culm
and the diameter of culm.
The sequence of flowering in tef is a8 follows: flowering
commences at the top of the inflorescence and proceeds
basipetallYj flowering begins at the bottom of each spikelet and
proceeds acropetally. The timing of flowering is complex, making
it difficult to predict anthesis for any individual flower.
Anthesis is rapid: exsertion of the stamens and shedding of the
pollen takes less than five minutes and the pollen starts to
germinate on the stigma immediately.
In the presence of light, temperatures above 4°C do not
prevent flower opening while in the ab8ence of light,
temperatures above 4 °c inhibit flower opening and therefore
enable the breeder to control anthesis. Warm humid air helps to
delay the dehiscence of anthers of opening flowers by up to an
hour without affecting pollen viability.
Contrary to previous reports ethrel does not prevent
fertilization in tef and can be used as a male gametocide; it is
most effective when applied at the flag-leaf stage, though it is
phytotoxic at high concentrations. Dark treatment and hot water
treatment induced male sterility but produced other effects which
make them unsuitable for em,asculation.
A reliable and rapid method of screening seedlings for
hybridity has been developed utilizing anthocyanin production.
When pollen carrying the marker gene is used for crossing, only
hybrid progeny produce anthocyanin. This technique reduces
screening time from about three months (heading time) to less
than four days.