ICARDA annual report 2004

ICARDA Annual Report 2004
42
Project 3.1.
Water Resource Conservation and Management
for Agricultural Production in Dry Areas
Legumes benefit from
supplemental irrigation
Lentil, chickpea, and faba bean are
the major cool-season food legumes
grown in CWANA. They provide
food and animal feed and restore
soil fertility. However, productivity
needs to be increased, as yields are
currently quite low: 0.8, 1.0, and 1.7
t/ha, on average, for lentil, chickpea,
and faba bean, respectively.
Because rainfall in the region is
low and variable, legume crops usually
suffer water stress during the
reproductive stage of development.
This leads to low yields and low productivity
per unit rainfall. Options
for improving and stabilizing rainfed
yields and water productivity were,
Theme 3
Natural Resource
Management
E
fficient management of water resources is especially
important in the dry areas of CWANA where water scarcity
is severe. ICARDA has tested new water-use-efficient irrigation
technologies to increase and stabilize the yields of strategic
cereal and legume crops. Results from four years of lentil, chickpea,
and faba bean trials showed that appropriate combinations
of planting date and deficit supplemental irrigation can substantially
increase yields and maximize the water-use efficiency of
these crops. In order to identify parameters to improve crop tolerance
to salinity, researchers assessed the relationship between
tolerance to drought and tolerance to salinity and identified different
mechanisms for each.
therefore, tested at ICARDA’s Tel
Hadya research station over four
years (1997/1998 to 2000/2001).
The trials involved various
planting dates (to help the crops
avoid terminal drought stress) and
different levels of supplemental
irrigation (SI). These levels were
‘full SI’, which completely satisfies
a crop’s water requirements, and
one-third and two-thirds of this
amount (deficit supplemental irrigation).
Researchers measured
grain and biomass yields and calculated
water-use efficiency (water
productivity): the yield per unit of
water used. This was expressed per
cubic meter of water (kg/m 3) or
per millimeter of water applied per
hectare 1kg/m 3 = 10 kg/ha-mm).
A supplemental irrigation trial of lentil at
Tel Hadya, Syria, 2003/04.
In the lentil trials, supplemental
irrigation increased biomass and
grain yields significantly. In
response to increases in the total
amount of water supplied (including
rain), grain yields increased linearly,
rising from 1.04 t/ha under
rainfed conditions to 1.81 t/ha
under full SI (Fig. 13). The same
was true for biomass yield, which
rose from 4.27 t/ha under rainfed
conditions to 6.2 t/ha under full SI.
Supplemental irrigation also
increased water productivity relative
to rainfed conditions.
Optimum water productivity—for
both grain (0.6 kg grain/m 3 water)
and biomass—occurred when only
two-thirds of the water required for
full SI was applied.
However, the study showed
that varying the sowing date did
not significantly affect lentil grain
yield (Fig. 13). In fact, sowing at the
traditional time (late December to
mid-January) gave the greatest
overall grain yield (1.6 t/ha).
Biomass yield, on the other hand,
was higher when lentil was sown
earlier, as was biomass water productivity.
In the case of grain, however,
water productivity under sup-