Js. Ebdon et al., STABILITY OF EVAPOTRANSPIRATION RATES IN KENTUCKY BLUEGRASS CULTIVARSACROSS LOW AND HIGH EVAPORATIVE ENVIRONMENTS, Crop science, 38(1), 1998, pp. 135-142
In an effort to conserve water applied to irrigated turfgrass sites, i
t is important to assess the potential for water conservation among tu
rfgrass germplasm. Turfgrass can respond differently in evapotranspira
tion (ET) rate as climatic conditions change, The objective of this st
udy was to investigate the interaction between the ET response of 61 K
entucky bluegrass (Pen pratensis L., KBG) cultivars (evaluated under c
ontrolled environment) and three equally spaced, evaporative environme
nts (temperatures 25, 30, and 35 degrees C, corresponding to 1.263, 1.
664, and 2.261 kPa vapor pressure deficit, VPD, respectively), There w
as a significant interaction (P less than or equal to 0.001) in ET rat
e between the 61 cultivars and the three evaporative environments, Sim
ple linear regression models and AMMI (additive main effect and multip
licative interaction) models were used in interpreting cultivar-enviro
nment interactions, There was wide variation in cultivar mean ET (5.36
-6.82 mm d(-1)), in stability of cultivar ET ranking, and sensitivity
to evaporative environment characterized by cultivar stability, Cultiv
ar stability (regression coefficients) varied by as much as 60% in the
change in ET rate, from 1.13 to 3.16 mm d(-1) kPa(-1). The AMMI model
revealed that the high evaporative environment (2.261 kPa VPD) intera
cted with cultivars in a direction opposite to 1.263 and 1.661 kPa env
ironments indicating that relative ET rankings of cultivars are the mo
st variable between diverse evaporative environments. Compared with or
dinary analysis of variance (ANOVA), AMMI was more effective in detect
ing and interpreting interaction, This study indicated that (i) breedi
ng for water conserving I(BG may have limited impact for reducing irri
gation requirements because most of the variation in ET (87%) is due t
o environment and not to the plant's pedigree, and (ii) recommendation
s for use of specific cultivars may be difficult because of inconsiste
nt water use patterns and intraspecies variation in KEG that were obse
rved in response to diverse evaporative environments that are typical
of field conditions.