Abstract:
The increasing scarcity and competition for irrigation water demands for adoption of
innovative practices that increase efficient water use. In the context of improving water
use efficiency, there is a growing interest in deficit irrigation which provides a means of
reducing water consumption while minimizing adverse effects on yield. A field experiment
was conducted at Haramaya University to investigate the effects of deficit irrigation and
straw mulch levels on yield components, yield and water use efficiency of hot pepper
(Capsicum annuum L). The experiment was laid out in a randomized complete block
design in factorial arrangement with three levels of irrigation (100%, 75% and 50% of
ETc) and four levels of straw mulch (0, 3, 6 and 9 tonnes of vetiver grass straw per ha) in
three replications. The output of CROPWAT model indicated that the highest seasonal
water requirement of hot pepper was 275.66 mm at 100% ETc, while the lowest was
137.83 mm at 50% ETc. The analysis of variance revealed that the interaction effects of
deficit irrigation and straw mulch levels on growth (p < 0.05) and yield (p < 0.01)
parameters were significant. The highest marketable yield (12.36 t/ha) was obtained from
an experimental plot treated with combined application of 100% ETc and 6 t/ha straw
mulch, while the lowest (4.66 t/ha) was obtained from plots that received 50% ETc
irrigation and no mulch. Water use efficiency was also highly significantly (p<0.01)
influenced by the interaction effects of deficit irrigation and straw mulch levels, with the
highest (6.65 kg/m3
) and the lowest (3.25 kg/m3
) values recorded from the plots that
received 50% ETc irrigation and 9 t/ha straw mulch, and 100% ETc irrigation and no
mulch, respectively. The Partial budget analysis revealed that combined application of
75% ETc irrigation and 6 t/ha straw mulch is the most attractive management in economic
terms since it gave the highest net benefit. Therefore, in terms of marketable hot pepper
yield, economically attractive and water use efficiency, irrigating with 75% ETc combined
with 6 t/ha straw mulch can be recommended for profitable production of hot pepper in
the study area and others with similar agroecology.
