poster - International Conference of Agricultural Engineering

evaluation, five central plants, amounting to 20 plants per treatment. The results were
subjected to analysis of variance. Variables significant at Test F were subjected to the Tukey
test at 5% probability.
3. Results and discussion
The water management affect with different intensities the morphological
characteristics of Eucalyptus grandis seedlings (Table 1). Only the seedlings without stress
treatment (T1) differed significantly from the others, with higher rates.
The fact that the height was similar among stress treatments it can be attributed to the
fact that during hardening, seedlings in tube have gone through the phase of rapid growth,
since the size of the pack and hence the amount of substrate and nutrients are limiting (Silva
et al., 2004). Therefore the seedlings that suffered water stress did not have higher growth
rates than those subjected to high stress.
Sasse et al. (1996) and Coopman et al. (2008) found a reduction of the height of
Eucalyptus globulus subjected to water stress and Lopes et al. (2007) found an increase in
height of of Eucalyptus grandis seedlings with increasing levels of irrigation.
The stem diameter was not associated with the level of applied stress as found by
Coopman et al. (2008) and different in Sasse et al. (1996) who concluded that diameter
growth rates were reduced by water stress.
The shoot dry masses, root dry masses and total dry masses had decreasing mean
inasmuch water stress levels increased. Although the root dry masses of T1, considering
only the root system contained in the tube (as seedlings are in constant contact with water,
the root system grew out of the tube), had statistically similar values to those subjected to
higher stress. These results confirm that the decrease of water promotes a slower growth
which reflects in the total dry matter produced.
The presence of water in the tissues of the leaves causes the stomatal cells to become
turgid for longer and open capturing light energy and carbon to photosynthesize. Coopman et
al. (2008) found a reduction in the biomass of leaf, stem and root of Eucalyptus globulus
seedlings when subjected to water stress. Lima et al. (2005) observed that the increase of
irrigation led to the linear increase in root biomass of Eucalyptus grandis seedlings.
The results of the leaf area of seedlings showed that water stress also affected leaf
area. In T1 it was observed that despite presenting greater height, the internodes were
higher, with the leaves more spaced out contributing for a less high leaf area than others.
The treatments with higher levels of stress (T4 and T5) showed the lowest values of leaf area
did not differing from each other.
Lopes et al. (2007) reported an increase in leaf area with increasing levels of irrigation.
Stoneman et al. (1994) and Coopman et al. (2008) found a reduction in leaf area of
Eucalyptus marginata and globulus respectively, when subjected to water stress.
The most stressed seedlings (T5) had the lowest specific leaf weight. Treatment 1
had the highest specific leaf weight and was statistically different from the other treatments.
Farrell et al. (1996) in his research on physiological and morphological responses of
seedlings of six clones of Eucalyptus camaldulensis grown in a greenhouse and subjected to
water stress treatments found that clones that produced a large number of leaves had leaves
with low specific weight, while clones that produced a few leaves had leaves with relatively
high specific weight.