Abstract:
In the face of the prevailing
challenges of limited water for irrigated
agriculture, the knowledge of crop
coefficients for use in irrigation, and the yield
response to moisture stresses become
pertinent for developing strategies to improve
agricultural water productivity. Field
experiments were conducted to evaluate the
crop coefficients and yield response factors of
UC 82B tomato subjected to soil moisture
stresses on growth-stage basis. The irrigation
treatments investigated were: a full irrigation
(application of 100% ETo), and three soil
moisture deficit levels (20%, 40%, 60% ETo)
imposed at the vegetative, flowering and
maturity growth stages, in successions. The
mean crop coefficient (Kc) was highest (0.99)
during the mid-season under full irrigation,
and lowest (0.47) during the vegetative stage
under 60% ETo soil moisture deficit, while
the mean value across the entire crop growth
stage was 0.88. The yield response factors
(Ky) were 1.26 and 1.30 for the 2017/2018
and 2018/2019 seasons, respectively. The
mean Ky of was 1.28 for the entire growth
cycle, implying high sensitivity of the tomato
cultivar to water deficits, and that yield
reduction is proportionally larger when water
used is reduced because of stress. Full irrigation
at the maturity stage is recommended.
