- 1Instituto de Tecnologia Química e Biológica, Universidade NOVA de Lisboa Oeiras, Portugal.
- 2Trees
and Timber Institute, The National Research Council of ItalyFlorence,
Italy; Department of Plant, Soil and Environmental Sciences, University
of FlorenceFlorence, Italy.
- 3Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de Agronomia, Universidade de Lisboa Lisboa, Portugal.
- 4Instituto de Tecnologia Química e Biológica, Universidade NOVA de LisboaOeiras, Portugal; Faculdade de Ciências e Tecnologia, Universidade NOVA de LisboaCaparica, Portugal.
- 5Department
of Biology, Agriculture and Food Sciences, Institute for Sustainable
Plant Protection, The National Research Council of Italy Florence,
Italy.
- 6Instituto de Tecnologia Química e Biológica, Universidade NOVA de LisboaOeiras, Portugal; Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de Agronomia, Universidade de LisboaLisboa, Portugal.
Abstract
The
impact of water deficit on berry quality has been extensively
investigated during the last decades. Nonetheless, there is a scarcity
of knowledge on the performance of varieties exposed to a combination of
high temperatures/water stress during the growing season and under
vineyard conditions. The objective of this research was to investigate
the effects of two irrigation regimes, sustained deficit irrigation
(SDI, 30% ETc) and regulated deficit irrigation (RDI, 15% ETc)
and of two cluster positions within the canopy (east- and west-exposed
sides) on berry ripening in red Aragonez (Tempranillo) grapevines. The
study was undertaken for two successive years in a commercial vineyard
in South Portugal,
monitoring the following parameters: pre-dawn leaf water potential,
berry temperature, sugars, polyphenols, abscisic acid (ABA) and related
metabolites. Additionally, expression patterns for different transcripts
encoding for enzymes responsible for anthocyanin and ABA biosynthesis (VviUFGT, VvNCED1, VvβG1, VviHyd1, VviHyd2) were analyzed. In both years anthocyanin concentration was lower in RDI at the west side (RDIW- the hottest one) from véraison
onwards, suggesting that the most severe water stress conditions
exacerbated the negative impact of high temperature on anthocyanin. The
down-regulation of VviUFGT expression revealed a repression of
the anthocyanin synthesis in berries of RDIW, at early stages of berry
ripening. At full-maturation, anthocyanin degradation products were
detected, being highest at RDIW. This suggests that the negative impact
of water stress and high temperature on anthocyanins results from the
repression of biosynthesis at the onset of ripening and from degradation
at later stages. On the other hand, berries grown under SDI displayed a
higher content in phenolics than those under RDI, pointing out for the
attenuation of the negative temperature effects under SDI. Irrigation
regime and berry position had small effect on free-ABA concentration.
However, ABA catabolism/conjugation process and ABA biosynthetic pathway
were affected by water and heat stresses. This indicates the role of
ABA-GE and catabolites in berry ABA homeostasis under abiotic stresses.
Principal component analysis (PCA) showed that the strongest influence
in berry ripening is the deficit irrigation regime, while temperature is
an important variable determining the improvement or impairment of
berry quality by the deficit irrigation regime. In summary, this work
shows the interaction between irrigation regime and high temperature on
the control of berry ripening.
KEYWORDS:
ABA metabolism; anthocyanins; flavonols; heat stress Vitis vinifera; water stress
