Abstract
The present research aimed to evaluate the water dynamics of grapevines trained in Cordon and Guyot systems by coupling sap flow and trunk diameter measurements under Mediterranean climate conditions. The study was conducted in a vineyard with Touriga-Nacional located at the Douro Valley, Portugal, during 2017. The results showed daily trunk diameter fluctuations (TDFs), with the contraction, recovery and increment phases and higher sap flow (SF) rates at earlier stages. Under harsh pedoclimatic conditions, SF was reduced and TDF flattened. Rehydration and stomatal mechanisms were mostly associated with these responses. Guyot vines showed higher changes in TDF for the same SF values, whereas the TDFs of Cordon vines remained practically unchanged over maturation. Guyot vines generally showed increased values of cumulative increment and maximum daily trunk shrinkage. Although Guyot vines had a similar leaf area index (LAI), they showed higher SF/LAI ratios than Cordon vines. These results highlight the effect of the shorter length of the hydraulic pathways of the Guyot training system, in contrast to the higher trunk and the permanent horizontal branch (cordon) of the Cordon training system, indicating good adaptation to local pedoclimatic conditions. The study pointed to the complementary use of both techniques in the evaluation of grapevine water dynamics.
Highlights
IntroductionVitis vinifera is an environmentally sensitive species, mainly to climate and soil conditions [1].Radiative, thermal and water stresses, generally combined, are the main causes of reduced growth and yield of vineyards in Mediterranean winegrowing regions, under rain-fed conditions [2,3].these regions, characterized by long growing seasons, mild-warm temperatures and dry summers [4,5] are likely to face a greater and intensified number of abiotic events in the near future [6,7].Depending on the crop and variety, plants can control their water status by developing strategies to cope with critical conditions of atmospheric evaporative demand and soil water availability [8,9].Water redistribution within the plant has been identified as a crucial survival strategy [10,11]
The objectives of the present study were threefold: (i) to evaluate the daily and seasonal water dynamics of Touriga-Nacional grapevines trained in the Guyot and Cordon systems throughout the growing season, (ii) to assess their responses to water supply events and (iii) to appraise the joint use of sap flow and trunk diameter measurements
This study exposed the effect of the shorter length of the hydraulic pathways of the Guyot-trained vines, in contrast to the higher trunk and the permanent horizontal branch of the Cordon-trained vines, highlighting the adaptive potential of the Guyot training system to the hot and dry areas
Summary
Vitis vinifera is an environmentally sensitive species, mainly to climate and soil conditions [1].Radiative, thermal and water stresses, generally combined, are the main causes of reduced growth and yield of vineyards in Mediterranean winegrowing regions, under rain-fed conditions [2,3].these regions, characterized by long growing seasons, mild-warm temperatures and dry summers [4,5] are likely to face a greater and intensified number of abiotic events in the near future [6,7].Depending on the crop and variety, plants can control their water status by developing strategies to cope with critical conditions of atmospheric evaporative demand and soil water availability [8,9].Water redistribution within the plant has been identified as a crucial survival strategy [10,11]. Thermal and water stresses, generally combined, are the main causes of reduced growth and yield of vineyards in Mediterranean winegrowing regions, under rain-fed conditions [2,3]. These regions, characterized by long growing seasons, mild-warm temperatures and dry summers [4,5] are likely to face a greater and intensified number of abiotic events in the near future [6,7]. Depending on the crop and variety, plants can control their water status by developing strategies to cope with critical conditions of atmospheric evaporative demand and soil water availability [8,9]. The mechanism generally considered most important for plant survival in a hot and dry environment is stomatal control to reduce transpiration [3,4,12,13]
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