Revista Chilena de Historia Natural 76 (2): 219-233, 2003
RESEARCH ARTICLE
Leaf water parameters of wheat (Triticum aestivum L.) and their use in the
selection of drought resistant genotypes
The leaf water parameters ys (solute potential), RWC (relative water content) and OA (osmotic adjustment) characterize the
response of plants to water stress and presumably allow the identification of better adapted genotypes. These parameters, however,
are highly influenced by the environment what makes their analysis difficult. In this work we hypothesize that it is possible to
characterize and select drought resistant wheat genotypes based on the field value of the leaf water parameters using the appropriate
analytical techniques. Thirty one wheat (Triticum aestivum L.) genotypes were grown in two field trials, one irrigated and
one non-irrigated that received 218.3 mm of winter rain. The statistical design was a randomized complete block with two replicates.
Between 77 and 121 days after emergence (DC 41 to DC 77), five samplings of relative water content (RWC) and solute potential of
hydrated flag leaves (ysh) were made in each replication of each trial (10 observations per trial). The
replicates were sampled in alternate days with a 24-h interval between 12:00 and 14:00 h. During harvest, biomass, yield and yield
components were measured. The observations both of RWC and ysh were highly affected by environmental factors (ca. 80 % of the sum of squares)
while they were not correlated between replications within each trial. For analysis purpose, each observation was considered as
independent (10 observations for each leaf water parameter per genotype) and linear regressions were made of each leaf water
parameter value of each genotype on the mean of all the genotypes at the time of sampling. Each genotype was characterized by its
average value of leaf water parameter and the regression slope. The osmotic adjustment (OA) of each genotype was estimated by
utilizing different methodologies proposed in the literature. Two genotype selections were made, one using the slope and average of
ysh, RWC and OA, and one that considered the and average of ysh and RWC. The order of the genotypes of both selection criteria were then correlated
with orders established by the three methods of calculation of OA, this established that the order that considers the slope and the
average of ysh, RWC and OA, correlated with the order established by the three methodologies to
calculate OA. This points out that it is possible to use the slope criteria in the selection of genotypes that adjust osmotically. Leaf water
parameters RWC, ysh and OA were not correlated to yield. The slope of ysh was negatively related to yield pointing to a survival role of OA. It is concluded that it
is possible to select drought resistant genotypes using the mean and slope of ysh, RWC and OA by removing part of the environmental noise.
Key words:
wheat, leaf water
parameters, yield
