poster - International Conference of Agricultural Engineering

Morphological responses of Eucalyptus grandis seedlings
submitted to different water stress levels during hardening
Magali R. Silva 1* , Antonio C. Nogueira 2 , Carlos M. de Carvalho 1 , Danilo Simões 1
1 Universidade Estadual Paulista - Sector of Forestry Sciences, Postbox 237, Postcode
18610-307 - Botucatu, Sao Paulo, Brazil.
2
Universidade Federal do Paraná - Sector of Agricultural Sciences - Av. Pref. Lothário
Meissner, 900, Postcode 80210-170 - Jardim Botânico - Curitiba - Parana – Brazil
*Corresponding author. E.mail: magaliribeiro@fca.unesp.br
Abstract
Water stress, one form of seedling hardening, provokes morphological, physiological and
nutritional alterations in the plant that influence its capacity to resist adverse field conditions
and thus their quality. However, there are still some problems as to the manner of applying
water stress since irrigation of forest seedlings, most markedly during the hardening phase,
is done in a highly empirical manner in which only visual examination determines the
moment and conduct of the irrigation (time and frequency). In this sense the present study
aimed to verify the morphological responses of Eucalyptus grandis seedlings when submitted
to different water stress levels during the hardening phase. The seedlings were produced in
50 cm 3 plastic tubes with substrate based on pine bark and vermiculite. Until the 69th day, all
seedlings experienced the same conditions. Starting on the 70th day, for a 30-day period, the
seedlings received differentiated water managements that constituted the different
treatments, which were chosen from results from the curve of tension-retention of water by
the substrate, characterized as: T1 seedlings without suffering water deficit, in other words,
permanently subirrigated, and T2, T3, T4 and T5 seedlings irrigated when reaching a tension
of water retention at the substrate of -50, -100, -500 and -1500 KPa, respectively. The data
were submitted to variance analysis and significant effects evaluated by Tukey’s test at 95%
probability. The data revealed that the greatest seedling height was obtained under
continuous subirrigation, which differed statistically from the other treatments. Both the
greatest and least water stress produced statistically similar values for stem diameter and
root dry mass. The highest shoot dry masses resulted from treatments with less water stress.
Although the seedlings submitted to subirrigation continued to present greater height, the
leaves were more widely spaced along the stem and presented smaller size resulting in leaf
areas similar to seedlings submitted to greater water stress. The seedlings with greater water
stress presented the lightest specific leaf weights. It is concluded that water management
influenced the quality of Eucalyptus grandis seedlings given the alterations in morphological
characteristics, although the greatest differences have occurred in seedlings produced under
continuous subirrigation during the hardening phase.
Key words: nursery, quality, water management, irrigation, subirrigation.
1. Introduction
The quality of the seedlings is one of the key factors for obtaining stands of high
productivity. This quality is expressed by morphological, physiological and nutritional