Abstract
Vertical and horizontal expansion of irrigated agriculture to feed the increasing population has
contributed to excessive groundwater withdrawal and affected the availability of water in terms of
both quality and quantity. To sustain agricultural growth. strategic measures should be adopted to
and
vi
deficit treatment (treatment T,). From the evaluation of yield, irrigation amount, irrigation water
productivity, relative water savings, relative yield reduction, and maximum profit under limited
water resource condition, it can be concluded that when limited quantities of water is available,
preference should be miven to irrigate first at CRI if one irrigation is available) then at CRI and
was differences in relative yield reduction (6 - 2%). The highest relative yield reduction
associated with deficit at CRI, followed by tillering, and then booting-heading stage. The highest
net financial return from both land- and water-limiting condition was obtained from alternate
treatment having irrigation at early and booting-heading stages (T7) saved 39 % water coupled
with 16% yield reduction compared to well- irrigated plot. Marginal productivity of irrigation
water associated with treatment T10 and T7 was about two folds of the others. Within the single
deficit treatments (T to T) relative water savings were almost similar (27 - 31 %). but had
phases. Deficit irrigation effectively boosted water productivity. On average, the single irrigation
at early stage (T10) in addition to post-sowing irrigation saved about 68 % water in comparison to
well-irrigated plot (To) with a yield reduction of 19 %. Between two alternate deficit strategies,
The heading, and flowering-soft dough stages was 0.27, 0.21, 0.25, and 0.17, respectively.
sensitivity index (Ai, of Jensen model) for early, vegetative, booting-heading, and flowering-soft
dough phases was 0.35, 0.22, 0.31, and 0.14, respectively. A more sensitive growth stage had
higher yalue of 1 and therefore water supply is more important at early and booting-heading
a
years crop
between Ke values determined by various Elo metious. wnen tne varues were averagen
and methods, a ke value of 0.77, 1.17, 1.41, and 0.89 were found for early,
development, middle and late period, respectively. The yield response factor (ky) varied with the
growth phase and also among seasons. On average, the k, for early, maximum tillering, bootingearly,
1.62,
crop development, middle, and late period ranged from 0.54 to 0.96, 0.95 to 1.36, 1.2 to
and 0.68 to 1.05, respectively. The Penman-Monteith method resulted in relatively higher
ke value than those of other methods. Non-significant differences were observed by pair 'дс
uLan thi
test
alternate irrigation at CRI and booting -heading phase produced higher grain yield over the other
one; and this treatment produced statistically similar yield to those of single-deficit and no-deficit
treatments. This strategy showed the highest harvest ratio indicating higher proportional
accumulation of assimilates to grain. The crop coefficient (k.) under different ETo methods for
the
addition of irst increment of water at CRI stage. within all treatments, tne wel-irfigaled
treatment produced the highest grain yield. When compared within single-deficit treatments,
grain yield reduction was in the order to water deficit at phases: CRI> maximum tillering
booting - heading >flowering- soft dough. Within two deficit strategies, the treatment having
>
deficit treatment. The grain and straw yields were significantly affected by treatments.
Differences in grain and straw yield among the partial- and no-deficit treatments were small, and
statistically insignificant in most cases. The greatest effect on yield was observed with
ll iigotod
the
growth, nutrient uptake, plant height) adversely. Yield attributes were affected by deficit
irrigation treatments although they are not statistically significant in all cases. Differences in yield
attributes among the partial deficits (i.e. single stage or alternate stage deficits) and no deficit
treatments were small, but there was a sharp difference between partial or no deficit, and full
Irrigation treatments Were imposed in a randomized complete block (RCB) design covering
deficit, no deficit at all, single deficit at different stages, and alternate deficits. Water deficit
created by withholding irrigation at different growth stages. The results indicate that deficit
irrigation strategies affected all aspects of plant growth (leaf area index, chlorophyll content, root
was reduce water consumption while minimizing adverse effect on yield. The effect of deficit
irrigation on wheat yield was studied in three consecutive years (2002-03 to 2004-05) in field and
pot at the experimental farm of Bangladesh Institute of Nuclear Agriculture, Ishurdi. Ten