of evapotranspiration and crop coefficients for bush okra (Corchorus
olitorius) in a sub-humid area of Nigeria
A. J. Odofin1*, J. A.
Oladiran2, J. A. Oladipo1 and E. P.
of Soil Science, Federal University of Technology, P. M. B.
65, Minna, Niger State, Nigeria.
of Crop Production, Federal University of Technology, P. M.
B. 65, Minna, Niger State, Nigeria.
Accepted 11 July, 2011
A two-year field experiment was carried out to determine
crop evapotranspiration (ETc) and crop coefficients (Kc) for
irrigated bush okra (Corchorus olitorius) at
Minna in a tropical sub-humid area of Nigeria between
February and April of 2008 and 2009. Eight 4 x 1 m check
basins were laid out in a randomized complete block design
with two treatments and four replications. The two common
local varieties of C. olitorius (Amugbadu and
Oniyaya) constituted the treatments. The soil moisture
depletion method was used to determine ETc while potential
evapotranspiration (ETp) was calculated on a daily basis
using Blaney-Morin-Nigeria (BMN) evapotranspiration model
developed for Nigerian environmental conditions. Kc values
were derived as dimensionless ratios of ETc to ETp on a
weekly basis. Across varieties and cropping periods, average
weekly ETc ranged from 2.0 to 6.8 mm day-1 while
seasonal ETc ranged from 326 to 374 mm, with Amugbadu
having significantly higher seasonal ETc (P≤0.01) in each
cropping period, presumably because of its spreading growth
habit. Weekly Kc values rose from a minimum of 0.38 at the
initial stage of crop growth to a peak value of 1.05 at the
mid-season stage and dropped to 0.40 at the end of the late
season stage. Closer spacing of Oniyaya, which has an
erect growth habit, is recommended in order to increase its
ground coverage, ETc and fresh leaf yield, under sole
Corchorus olitorius, Amugbadu, Oniyaya,
evapotranspiration, crop coefficients.