water stress. FINAL REPORT to. GRAPE AND WINE RESEARCH & DEVELOPMENT CORPORATION. Research Organisation: The University of Adelaide.
Night-time transpiration / refill in grapevines as their capacity to recover from water stress.
FINAL REPORT to GRAPE AND WINE RESEARCH & DEVELOPMENT CORPORATION
Project Number: GWT 1011
Research Organisation: The University of Adelaide Principal Investigator: Dr. Sigfredo Fuentes Date: 20th June 2011
Table 1. 2. 3. 4. 5. 6. 7.
Abstract Executive summary Background Project aims and performance targets Results/Discussion Outcome / Conclusion Cited literature
1. Abstract: This project partially financed a trip to Italy mainly to attend a conference in Volterra (8th International Workshop on Sap Flow sensors). After the conference, trips were made to Padova, Legnaro and Conegliano to visit researchers and The University of Padova. In Conegliano a visit to wineries and the Prosecco area helped to have a snapshot view about viticultural practices in the region. Nocturnal refill/transpiration is gaining importance in viticultural research, since it is linked to reductions in water use efficiency (transpiration uncoupled to photosynthesis) and refill plays an important role in recovery from water stress, cavitation, berry shrivel and bunch dehydration. Understanding night-time transpiration/refill processes will enable to fine tune irrigation strategies and varietal selection for a sustainable viticulture in Australia within a future climate change scenario. 2. Executive summary: Latest research on nocturnal sap flow and night-time transpiration in grapevines were presented at the 8th International Symposium of Sap Flow in Volterra Italy. Specifically two papers were presented with the help of this grant, one in grapevines and the second in Almonds. The trip was used also to establish potential research collaborations between scientists from Italy and The University of Adelaide working in micrometeorology and plant physiology in viticulture to understand the energy, water and CO2 balances in commercial vineyards. Collaborations with scientists from Chile also resulted in the visit of Dr Carlos Poblete Echeverria to The University of Adelaide in September 2011. 3. Background: Nocturnal transpiration in plant species have been reported since 2007 (Caird et al., 2007) and specifically for grapevines (Rogiers et al., 2009). Our group has been researching nocturnal water uptake and the partitioning between refill and transpiration using sap flow sensors (Heat-pulse compensated) and gas exchange measurements at night-time. The varieties studied since 2009 have been: Country Australia (Benalla VIC; Richmond NSW) Australia (Adelaide, SA) Spain (Mallorca)
Cabernet Sauvignon Tempranillo, Malvasia, Cabernet Sauvignon, Pinot Noir, Grenache,
Manto Negro, Escursac. Merlot
The papers presented at the 8th International Workshop of sap Flow (Volterra) are the first in-depth research of nocturnal processes using sensitive sap flow sensors, gas exchange methods and stem water potential as ground-truth. Nocturnal water uptake by grapevines account for up to 40% compared to diurnal transpiration (Rogiers et al. 2010). These values of transpiration need to be taken into account for whole vine water use and water use efficiency studies, since night-time transpiration is not coupled to photosynthesis; therefore it reduces grapevine water use efficiency. Characterisation of night-time transpiration/refill is part of a wider international project between Australia and colleagues in Chile and Spain. The GWRDC climate change workshop (October 2010) has identified the necessity for rapid and accurate ways to estimate spatio-temporal changes in plant water status, yield prediction and the characterisation of nocturnal transpiration/refill for grapevines to achieve a sustainable industry in future climate change scenarios. Therefore, this project aligns with Program 5a of the GWRDC R&D-Plan and particularly Sub-Program 4a and 5a. 4. Project Aims and Performance targets: Modification from original application: The initial project was presented with the inclusion of a visit to Dr. Luca Mercenaro from The University of Sassari in Sardinia – Italy. However, this needed to be changed due to travel by Dr Mercenaro to Davis, California, USA at the same time for a period of 6 months. The project aims were: • • •
To present novel results in night-time sap flow and night-time transpiration / refill of grapevines of anisohydric, near-anisohydric and isohydric behaviours. To obtain feedback from the international scientific community to be included in peer-reviewed publications. To visit The University of Padova and CRA-VIT (Italy) and establish potential collaborations with The University of Adelaide.
The performance targets were: Output
1. Paper to be submitted to The Australian Journal of Grape and Wine Research 2. Paper to be submitted to Plant Cell and Environment 3. Paper to be submitted to Agricultural Water
One paper submitted to a peer-reviewed Oct 2011 scientific journal. One paper to be submitted to a high impact Nov-Dec journal. 2011 One paper on nocturnal water uptake in Nov 2011 Almonds to be submitted to peer-review.
Management 4. Grapegrower and winemaker article (Communication of results) 5. Establish research collaboration
One paper submitted to the grape grower Dec 2011 community in Australia. Visit to Australia from Chile Visit to Australia from Spain Visits planned for 2011-12 to Spain
Sept 2011 Jan 2012 May 2012
5. Results/Discussion International Workshop on Sap Flow sensors: There were very interesting papers presented at the International workshop on sap flow that dealt with low flow sensors. These are critical to achieve accurate constant measurements of nocturnal water uptake by grapevines. 5.1. Low and reverse flow sensors: One particular paper entitled: “Improving heat pulse methods to extend sap flow measurements range including reverse flows” also presented results on reverse flow, which are important to assess hydraulic redistribution within grapevines. The authors were: Rafael Romero (1), Steve Green (2), Ivan Garcia (1), Jose Luis Muriel (1), Brent Clothier (2); (1) Dept Recursos Naturales y Produccion Ecologica, IFAPA, Sevilla, Spain (2) Sustainable Production – Systems Modelling group, Plant and Food Research, Palmerston North, New Zealand. “Heat pulse methods are typically not suitable for the measurement of both very high and very low sap flows and few methods are able to measure reverse flow. In our work we have analysed two new methods that potentially extend the measurement range. Both methods can be utilized by modifying the analysis algorithm and adjusting the probe positions for common heat pulse methods, with no change to existing equipment. The first method we will refer to as the Symmetrical Gradient method (HP-SG). It consists of averaging the temperature difference signal of two probes (mean_deltaT) that are equidistant from the heater. The second method we will refer to as the Symmetrical Derivative method (HPSD). It uses the same symmetrical probe configuration. However, the analysis is based on the maximum rate of change of the temperature difference curve (i.e. the derivative, deltaT_prime). Computer modelling is used to show that these two indicators (mean_deltaT and deltaT_prime) are proportional to the heat pulse velocity across a wide range of positive and negative flows. Hence, both metrics can be used to determine the actual sap flux density with acceptable measurement errors and good measurement sensitivity. We present results from field experiments on a Willow tree (Salix alba L.) that were set up to compare our new methods against other heat pulse techniques. We will show that both HP-SG and HP-SD can provide reliable data across a very wide range of flows. We are currently working on other field experiments to further refine out use of HP-SG and HP-SD to estimate tree transpiration and even observe sap flow in roots.” 5.2. Miniature sap flow sensors:
Also, results using miniature sap flow sensors were presented in the conference. These sensors were used to monitor water flow in flowers and small organs. These kinds of measurements are very important to study water dynamics in bunches and berries. Monitoring these flows could give great insights in the nocturnal water refill and transpiration role in berry shrivel and bunch dehydration for susceptible varieties, such as Shiraz, Cabernet Sauvignon and Merlot. The specific paper was entitled: “Determining the water dynamics of flowering using miniature sap flow sensors”, from Adam B. Roddy, Todd E. Dawson. Department of Integrative Biology, University of California, Berkeley, CA, USA. Angiosperms dominate ecosystems globally, and for the vast majority, flowering is vital to successful reproduction. Despite this importance, the physiology of flowering per se and subsequent fruiting in wild plants has received little attention; yet understanding the water relations of flowers may help reinterpret our views of the costs of reproduction and reproductive phenology. Here we apply a new implementation of the heat ratio method (Burgess et al. 2000, Marshall 1958) designed for small diameter stems (Clearwater et al. 2009) to measure the water requirements of flowering and how water transport to developing flowers and fruits varies throughout their development. We rely upon empirical calibration of sensors and estimation of transpirational fluxes from temperature ratios using in situ gas exchange measurements and anatomical measurements. We will present data on a variety of tropical plants, including: the tropical understory tree, Hybanthus prunifolius (Violaceae), the liana Clitoria javitensis (Fabaceae), and the shrub Annona acuminata (Annonaceae). Preliminary results suggest that sap flow dynamics of reproductive organs are notably complex, sometimes showing bidirectional flow and nocturnal sap flow. These patterns are likely related to the dynamics of how water and carbon flow to and from flowers and fruits via the xylem and phloem. 5.3. Papers presented as a results of this project: The two papers presented in this conference were: 5.3.1). Night-time response to diurnal anisohydric and isohydric behaviour of grapevines (Vitis vinifera L.): characterisation of nocturnal water uptake as recovery capacity from diurnal water stress Fuentes S.A. (1), Collins M.J.B (2), Escalona J.C (3), De Bei R.A (1), Medrano H.C. (3), Tyerman S.A(1) (1) Plant Research Centre. University of Adelaide, Waite Campus, PMB 1 Glen Osmond, 5064, SA, Australia (2) CSIRO Plant Industries, PO Box 350, Glen Osmond, South Australia, 5064, Australia (3) Group of Plant Biology Research in Mediterranean Conditions. University of Baleares Islands. Spain Nocturnal sap flow corresponds to nocturnal stem and organs recharge and nocturnal transpiration. The working hypothesis was that night-time partitioning between refill and transpiration depends on the capacity of vines to recover from water stress from the previous day. To test this hypothesis, the compensated heatpulse sap flow method (cHP) was tested on anisohydric (field-conditions) and near
anisohydric grapevines (pots) (var. Shiraz, Cabernet Sauvignon, respectively) under partial root-zone drying (PRD) and deficit irrigation (DI) trials. Other vine water status monitoring methods used were midday stem water potential (Ψs) and nocturnal gas exchange for the var. Tempranillo on pots (anisohydric) under control and DI treatments. Results showed that Shiraz vines under PRD treatments were able to maintain an almost constant day-time water status and night-time refill capacity throughout the season, independently of atmospheric demand, which could indicate better stomatal control and a more isohydric-like behaviour (Collins et al. 2010). Furthermore, SN was significantly correlated to midday Ψs obtained from the day before for all varieties under PRD and DI trials. Two zones of night-time behaviour within the parabolic Ψs vs SN relationship were identified: i) non-water stress conditions (0 < Ψs < -1.2 MPa) characterised mainly by night-time transpiration and ii) water stress conditions (-1.2 MPa < Ψs < -1.2 MPa), characterised by minimal night-time transpiration and more xylem and organs refill. 5.3.2). Nocturnal sap flow of field-grown Almond trees and their response to water stress Mahalakshmi Mahadevan (1), Sigfredo Fuentes (2), Mark Skewes (1), Jim Cox (1) (1) South Australian Research and Development Institute. GPO Box 397. Adelaide, SA 5001. Australia (2) The University of Adelaide, Plant Research Centre. Waite Campus, PMB 1 Glen Osmond, 5064, SA, Australia Important water losses at night-time were registered in an Almond tree trial in Berri, South Australia in the season 2009-10. To quantify nocturnal tree water uptake (Sn), two sets of sap flow sensors (heat-pulse compensated) were installed per tree in the north-east (NE) and south-west (SW) sides of the trunk for three trees per treatment. The treatments were 100% ETc and 60% ETc with daily irrigations at the peak atmospheric demand period (Dec – Jan). Nocturnal water uptake by trees were in the order of 20% and 15%, compared to diurnal, for the 100% ETc and 60% ETc treatments respectively. Night-time water uptake was correlated to plant water stress from the previous day measured as midday stem water potential (Ψs) and also correlated to nocturnal VPD. The later, indicating that nocturnal transpiration (En) was significant for both treatments. Differences in Sn were registered by the NE and SW sensors only for the 60% ETc treatment, being less Sn for the NE side. This is consistent with the sun path in the area, with the NE side with maximum direct solar incidence on the canopy, and lower leaf water potentials (Ψl) for that side resulting in less leaf stomata conductance. More research need to be conducted to reduce Sn in the form of transpiration, since it is not coupled with photosynthesis, hence reducing water use efficiency (WUE). According to our results, reductions of water application up to 60% ETc contributed to increase WUE and reduce Sn and therefore En. 5.4. Night-time sap flow and reduction of cavitation: This was a very interesting paper that showed data to support the hypothesis that nocturnal water refill and transpiration helps to reduce and remove gas from the xylem produce by cavitation. The paper was entitled: “Nighttime sap flow removes
air from plant hydraulic systems”, by H. Jochen Schenk, Susana Espino Department of Biological Science, California State University Fullerton, California, USA. Evidence has accumulated in recent years that transpiration and sap flow during the night are important fluxes in the water balance of many ecosystems and some horticultural systems, especially in dry environments. Here we show that nocturnal sap flow plays a crucial role in removing air from plant hydraulic systems and allowing refilling of embolized vessels. In the North American desert shrub Encelia farinosa (Asteraceae), embolism repair occurs at night while stomata are open, the plants are transpiring, and water potentials negative. Experimental inhibition of nighttime transpiration by bagging of leaves was found to inhibit embolism repair. These findings show that, at least in this species, a transpiration stream is required for embolism repair under negative pressure. Measurements of air flow into artificially created embolisms in the wood revealed that air from these embolisms dissolved into the flowing xylem sap. It is hypothesized that air from refilling xylem conduits diffuses through pit membranes into the transpiration stream of functioning conduits. This happens while temperatures decline during the night, causing gas solubility in xylem sap to increase. Nighttime transpiration appears to be required to move air-saturated sap towards the leaves before temperatures increase again during the next morning, which would cause gas solubility to decrease and air to come out of solution. Nighttime transpiration thus is explained as playing a vital role in the nocturnal recovery from drought-stress experienced during the day.
5.5. Visit to The University of Padova: At Padova, the visit consisted in meetings with Prof. Andrea Pitacco and Dr Franco Meggio from the Facolta di Agraria (Universita degli Studi di Padova). Prof. Pitacco and Dr Meggio are involved in micrometeorological research in grapevines to study the energy, water and CO2 balances of grapevines in the field. They use a variety of instrumentation ranging from Eddy covariance systems, automatic meteorological stations and gas exchange analysers for field conditions. The meeting with these Italian colleagues was very productive and we agreed to have exchange of expertise and to establish a collaboration strategy for data collection and analysis. They were very interested with the data analysis techniques developed by our group, specially in regards to infrared thermography for canopies and digital cover photography analysis to obtain canopy architectural parameters, such as leaf area index, canopy cover and porosity, which are critical to upscale any measurement to the vineyard scale. Part of this collaboration will be a visit by Prof Pitacco and Dr Meggio bringing an Eddy covariance system to be installed in one of the vineyards in which we are conducting research (values at AUD$ 70,000). The advantage in working with this group is the seasonality between Europe and Australia, making possible the travel with instrumentation to potentiate research within a year (effectively two seasons). At the time of my visit, I was able to give one seminar to other colleagues and researchers from the University of Padova and one class to pre-graduate students.
The seminar was entitled “State of the art in instrumentation used for viticultural research and climate change”. In this talk I reported about the advances made from two years of research using novel instrumentation and methodologies of analysis. These talks have gathered high interest among international researchers and have allowed numerous contacts and potential collaborations. The techniques covered in my presentation ranges from: •
The use of infrared thermography to obtain grapevine stress indices automatically using a novel analysis program developed in MATLAB®
The use of Near Infrared Spectroscopy to obtain stem water potential in grapevines
Monitoring 2D and 3D soil wetting and nutrient patterns using a novel analysis program and capacitance soil moisture sensors within the rootzone.
The use of sap flow sensors to measure diurnal and nocturnal water uptake dynamics and hydraulic redistribution of water when using partial root-zone drying.
The use of remote controlled and automated vehicles (robots) to assess different plant water status and growth parameters from grapevines in vineyards. This system allows high intensity measurements and mapping of data to detect zones of interest within a vineyard.
Use of novel instrumentation in high temperature trials using undercanopy semi-passive heating systems.
Berry cell death and shrivel studies using fluorescent microscopy, novel image analysis techniques and statistical methods using MATLAB® programming.
5.6. Visit to Conegliano and the Prosseco area: Conegliano is located around 45 minutes from Padova. I visited the CRA-VIT, specifically Dr Diego Tomassi’s group. Part of the visit was going to the Prosecco area (picture at the front of this report). I was amazed with the cultivation of local varieties in terraces, without any irrigation and in slopes that reached 80%. I presented a seminar to research scientists from the centre, which attracted great interest and extended with question time and discussions to more than 2.5 hours. Dr Tomassi’s group has a great interest in collaborating with our group and we talked about a potential visit to Adelaide early in 2012. 6. Outcome/Conclusion: Papers presented at the conference in Volterra:
Two papers were presented at the conference, from where important feedbacks were gathered to include it in two papers to be published in peer-reviewed journals with the following titles: 1. Night-time response to diurnal anisohydric and isohydric behaviour of grapevines (Vitis vinifera. L.): characterisation of nocturnal water uptake as recovery capacity from diurnal water stress. For Plant, Cell and Environment. 2. Nocturnal sap flow of field-grown Almond trees and their response to water stress. For Agricultural Water management. Collaborations established thanks to this visit: This trip was successful also in establishing collaborative work between the University of Adelaide and the following institutions: • • • •
The University of Padova (A. Prof. Andrea Pitacco; Dr. Franco Meggio). Centro di Ricercar per la Viticoltura CRA-VIT (Dr. Diego Tomasi) The University of Talca - Chile (Prof. Samuel Ortega-Farias; Dr. Carlos Poblete). Massey University – New Zealand (AgResearch) (Dr. Steve Green).
A tentative collaboration program was outlined and colleagues from Italy and Chile are currently applying for funding to come to Australia in October to March of the season 2011-12. A visit to The University of Adelaide by Dr Carlos Poblete Echeverria from the University of Adelaide was made in September –October 2011. Collaborative work was done in the analysis of sap flow data and canopy architecture parameters obtained using a novel automated cover photography technique (Fuentes et al., 2008). Three drafts were completed for publication in 2012. Seminars presented: Three seminars were presented in Italy, two of them at The University of Padova (Legnaro) for reserachers and students, respectively. The last seminar was presented in Cogneliano to The Centro di Ricerca per la Viticoltura, Conegliano. Research collaborations were established with international scientists from Italy, Chile and New Zealand in viticulture to investigate energy, water and CO2 balances and nocturnal transpiration in grapevines. Papers submitted and in progress as result of this project: A paper was submitted to The Australian Journal of Grape and Wine Research entitled: “Responses of leaf night respiration and transpiration to water stress in Vitis vinifera L. by JOSÉ MARIANO ESCALONA†*, SIGFREDO FUENTES†† MAGDALENA TOMÀS†*, SEBASTIÀ MARTORELL†, JAUME FLEXAS† AND HIPÓLITO MEDRANO†. †Research Group in Plant Biology under Mediterranean conditions. Department of Biology. Balearic Island University (UIB). Ctra. Valldemossa km 7,5 07122 Palma de Mallorca. Spain ††Plant Research
Centre. School of Agriculture, Food and Wine. University of Adelaide. PMB1, Glen Osmond SA. 5064. Australia. A paper will be submitted to Plant, Cell and Environment in December 2011 entitled: “Night-time responses to diurnal anisohydric and isohydric behaviour of grapevines (Vitis vinifera. L.): characterisation of night-time water uptake as recovery capacity of vines from diurnal water stress Two draft papers were drafted as a result of the visit by Dr Poblete-Echeverria: “Spatio-temporal estimation of leaf area index (LAI) from grapevine canopies using a novel cover photography and video analysis method” to be presented to The Journal of Experimental Botany and “Increased accuracy of leaf area index (LAI) estimation by digital photography using a variable light extinction coefficient for apple orchards” to be presented to the Journal of Agricultural and Forest Meteorology. A communication paper is being prepared to describe the latest results in nighttime transpiration/refill for grapevines to be presented to The Australian and New Zealand Grapegrower and Winemaker. 7. Cited literature Caird, M.A., Richards, J.H. and Donovan, L.A., 2007. Nighttime Stomatal Conductance and Transpiration in C3 and C4 Plants. Plant Physiol., 143(1): 4-10. Fuentes, S., Palmer, A.R., Taylor, D., Zeppel, M., Whitley, R. and Eamus, D., 2008. An automated procedure for estimating the leaf area index (LAI) of woodland ecosystems using digital imagery, MATLAB programming and its application to an examination of the relationship between remotely sensed and field measurements of LAI. Functional Plant Biology, 35(10): 10701079. Rogiers, S.Y., Greer, D.H., Hutton, R.J. and Landsberg, J.J., 2009. Does nighttime transpiration contribute to anisohydric behaviour in a Vitis vinifera cultivar? Journal of Experimental Botany, 60(13): 3751-3763.