ICARDA annual report 2004

ICARDA Annual Report 2004
26
Project 1.6.
Forage Legume Germplasm Improvement for
Increased Feed Production and Systems Productivity
in Dry Areas
F
orage legumes are valued for their ability to provide highprotein
animal feed, while simultaneously maintaining or
improving soil fertility. In 2004, ICARDA developed new,
high-yielding lines of common vetch (Vicia spp.) whose pods do
not shatter when mature. Non-shattering lines will reduce harvesting
costs and seed prices—which will encourage farmers to plant
more vetch. Advances were also made in reducing the toxicity of
grass pea, a hardy, drought-resistant crop, which is an important
source of food and feed.
Human and livestock populations are growing rapidly in
CWANA. As a result, rangelands are being overgrazed, and farmers
are cropping more marginal land and abandoning their traditional
fallow–barley rotations in favor of continuous barley cropping.
All these practices are placing increasing pressure on the
agricultural resource base of the dry areas, and degrading farmers’
soil resources.
Expanding the area cultivated with vetches (Vicia spp.) and
chicklings (Lathyrus spp.) is a sustainable way of boosting food
and feed production, and increasing the number of animals the
land can support. Using these crops to interrupt barley monoculture,
or to produce crops on land usually left fallow in fallow–barley
rotations, improves the organic matter content and nitrogen
status of the soil. It also helps to control the diseases and pests
that affect continuous cereal rotations. Grown in this way, these
drought-tolerant feed legumes can provide grazing during winter
and early spring. They can also be harvested for hay in the spring
or carried to maturity to provide both seed and straw.
New non-shattering lines
of common vetch
Common vetch (Vicia sativa) is an
important forage legume in the dry
areas. However, its seed pods tend
to shatter when mature, making
them difficult to collect. Harvesting
techniques have been developed to
reduce the amount of seed lost as a
result of shattering, but these are
costly. As a result, common vetch
seed is expensive—which places a
financial burden on poor farmers,
as the crop has to be resown each
year.
To harvest as many seeds as
possible, farmers have to collect
them at exactly the right time and
avoid pod-shattering. But, the optimum
harvest time usually coincides
with the harvest of important
food legumes like lentil, which
farmers need to harvest first. This,
and the fact that the late harvest of
common vetch can cause serious
‘vetch weed’ problems in any cereal
crops grown after it, severely
restricts its usefulness in prevailing
farming systems.
These problems could be solved
by producing a variety that retains
its seed in pods at maturity. This
would greatly benefit farmers, as
common vetch could then be used
to improve cropping systems (i) by
being grown on land left fallow in
traditional cereal–fallow rotations
and (ii) by being used to interrupt
the continuous cropping of barley
in monoculture. In either case, it
would replenish soil fertility and
provide extra grazing.
ICARDA is now working to
improve seed retention in common
vetch through a breeding program
that will incorporate non-shattering
genes into promising existing lines
lacking this character. As part of
this program, researchers studied
variation in seed retention and the
nature of its genetic control.
Nine hundred accessions of common
vetch were assembled at
ICARDA from different areas and
screened for pod-shattering. Initially
plants were assessed visually under
normal field conditions in July and
August 2004, when intense summer
heat encourages pod-shattering.
Occurrences of pod-shattering were
scored using a scale of 0 to 5 (0 =
complete shattering; 5 = no shattering
in 95% of plants). Genotypes
with scores of 4 or 5 were then selected
and re-tested in a glasshouse, to
provide more heat and further
encourage pod-shattering.
Under both field and glasshouse
conditions, a high proportion of the
genotypes had shattering pods
(Table 3). However, highly desirable
non-shattering behavior was identified
in three wild mutant genotypes
which each scored 5. Unfortunately,
these also exhibited undesirable
traits, such as late flowering, late
maturity, dwarfing, low herbage
yields, and small seeds.