Abstract
The productivity of olive trees in arid and semi-arid environments is closely linked to irrigation. It is necessary to improve the efficiency of irrigation techniques to optimise the amount of olive fruit produced in relation to the volume of water used. Partial root-zone drying (PRD) is a water saving irrigation technique that theoretically allows the production of a root-to-shoot signal that modifies the physiology of the above-ground parts of the plant; specifically reducing stomatal conductance (gs) and improving water use efficiency (WUE). Partial root-zone drying has been successfully applied under field conditions to woody and non-woody crops; yet the few previous trials with olive trees have produced contrasting results. Thirty year-old olive trees (Olea europaea 'var. Chetoui') in a Tunisian grove were exposed to four treatments from May to October for three-years: 'control' plants received 100% of the potential evapotranspirative demand (ETc) applied to the whole root-zone; 'PRD100' were supplied with an identical volume of water to the control plants alternated between halves of the root-zone every ten-days; 'PRD50' were given 50% of ETc to half of the root-system, and; 'rain-fed' plants received no supplementary irrigation. Allowing part of the root-zone to dry resulted in reduced vegetative growth and lower yield: PRD100 decreased yield by ~47% during productive years. During the less productive years of the alternate bearing cycle, irrigation had no effect on yield; this suggests that withholding of water during 'off-years' may enhance the effectiveness of irrigation over a two-year cycle. The amount and quality of oil within the olive fruit was unaffected by the irrigation treatment. Photosynthesis declined in the PRD50 and rain-fed trees due to greater diffusive limitations and reduced biochemical uptake of CO2. Stomatal conductance and the foliar concentration of abscisic acid (ABA) were not altered by PRD100 irrigation, which may indicate the absence of a hormonal root-to-shoot signal. Rain-fed and PRD50 treatments induced increased stem water potential and increased foliar concentrations of ABA, proline and soluble sugars. The stomata of the olive trees were relatively insensitive to super-ambient increases in [CO2] and higher [ABA]. These characteristics of 'hydro-passive' stomatal behaviour indicate that the 'Chetoui' variety of olive tree used in this study lacks the physiological responses required for the successful exploitation of PRD techniques to increase yield and water productivity. Alternative irrigation techniques such as partial deficit irrigation may be more suitable for 'Chetoui' olive production.
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Claims 14
Claim · model-written summary
Partial root-zone drying reduced olive vegetative growth.
- Taxon
- olive trees
Olea europaeat0 - Treatment
- Allowing part of the root-zone to drye0
- Outcome
- vegetative growthe0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Allowing part of the root-zone to dry resulted in reduced vegetative growth and lower yield”
t0“olive trees (Olea europaea 'var. Chetoui')”
Claim · model-written summary
PRD100 decreased olive yield by about 47% in productive years.
- Taxon
- olive treesOlea europaeat0
- Treatment
- PRD100e0
- Outcome
- yielde0
- Direction
- decreasede0
- Value
- ~47%e0
- Qualifier
- productive yearse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PRD100 decreased yield by ~47% during productive years”
t0“olive trees (Olea europaea 'var. Chetoui')”
Claim · model-written summary
Irrigation had no effect on yield in less productive years.
- Taxon
- olive treesOlea europaeat0
- Treatment
- irrigatione0
- Outcome
- yielde0
- Direction
- no effecte0
- Qualifier
- less productive years of the alternate bearing cyclee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During the less productive years of the alternate bearing cycle, irrigation had no effect on yield”
t0“olive trees (Olea europaea 'var. Chetoui')”
Claim · model-written summary
Olive fruit oil amount and quality were unaffected by irrigation treatment.
- Taxon
- olive treesOlea europaeat0
- Treatment
- irrigation treatmente0
- Outcome
- amount and quality of oil within the olive fruite0
- Direction
- unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The amount and quality of oil within the olive fruit was unaffected by the irrigation treatment”
t0“olive trees (Olea europaea 'var. Chetoui')”
Claim · model-written summary
Photosynthesis declined in PRD50 olive trees.
- Taxon
- olive treesOlea europaeat0
- Treatment
- PRD50e0
- Outcome
- Photosynthesise0
- Direction
- declinede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Photosynthesis declined in the PRD50 and rain-fed trees due to greater diffusive limitations and reduced biochemical uptake of CO2”
t0“olive trees (Olea europaea 'var. Chetoui')”
Claim · model-written summary
Photosynthesis declined in rain-fed olive trees.
- Taxon
- olive treesOlea europaeat0
- Treatment
- rain-fede0
- Outcome
- Photosynthesise0
- Direction
- declinede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Photosynthesis declined in the PRD50 and rain-fed trees due to greater diffusive limitations and reduced biochemical uptake of CO2”
t0“olive trees (Olea europaea 'var. Chetoui')”
Claim · model-written summary
PRD100 did not alter stomatal conductance.
- Taxon
- olive treesOlea europaeat0
- Treatment
- PRD100 irrigatione0
- Outcome
- Stomatal conductancee0
- Direction
- not alterede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stomatal conductance and the foliar concentration of abscisic acid (ABA) were not altered by PRD100 irrigation”
t0“olive trees (Olea europaea 'var. Chetoui')”
Claim · model-written summary
PRD100 did not alter foliar ABA concentration.
- Taxon
- olive treesOlea europaeat0
- Treatment
- PRD100 irrigatione0
- Outcome
- foliar concentration of abscisic acid (ABA)e0
- Direction
- not alterede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stomatal conductance and the foliar concentration of abscisic acid (ABA) were not altered by PRD100 irrigation”
t0“olive trees (Olea europaea 'var. Chetoui')”
Claim · model-written summary
Rain-fed treatment increased stem water potential.
- Taxon
- olive treesOlea europaeat0
- Treatment
- Rain-fede0
- Outcome
- stem water potentiale0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rain-fed and PRD50 treatments induced increased stem water potential and increased foliar concentrations of ABA, proline and soluble sugars”
t0“olive trees (Olea europaea 'var. Chetoui')”
Claim · model-written summary
PRD50 increased stem water potential.
- Taxon
- olive treesOlea europaeat0
- Treatment
- PRD50e0
- Outcome
- stem water potentiale0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rain-fed and PRD50 treatments induced increased stem water potential and increased foliar concentrations of ABA, proline and soluble sugars”
t0“olive trees (Olea europaea 'var. Chetoui')”
Claim · model-written summary
Rain-fed treatment increased foliar concentrations of ABA, proline and soluble sugars.
- Taxon
- olive treesOlea europaeat0
- Treatment
- Rain-fede0
- Outcome
- foliar concentrations of ABA, proline and soluble sugarse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rain-fed and PRD50 treatments induced increased stem water potential and increased foliar concentrations of ABA, proline and soluble sugars”
t0“olive trees (Olea europaea 'var. Chetoui')”
Claim · model-written summary
PRD50 increased foliar concentrations of ABA, proline and soluble sugars.
- Taxon
- olive treesOlea europaeat0
- Treatment
- PRD50e0
- Outcome
- foliar concentrations of ABA, proline and soluble sugarse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rain-fed and PRD50 treatments induced increased stem water potential and increased foliar concentrations of ABA, proline and soluble sugars”
t0“olive trees (Olea europaea 'var. Chetoui')”
Claim · model-written summary
Olive stomata were relatively insensitive to elevated CO2 and ABA.
- Taxon
- olive treesOlea europaeae0
- Organ / stage
- stomatae0
- Outcome
- relatively insensitive to super-ambient increases in [CO2] and higher [ABA]e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The stomata of the olive trees were relatively insensitive to super-ambient increases in [CO2] and higher [ABA]”
Claim · model-written summary
Partial deficit irrigation may be more suitable for Chetoui olive production.
- Taxon
- oliveOlea europaeae0
- Material
- 'Chetoui'e0
- Outcome
- partial deficit irrigation may be more suitablee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Alternative irrigation techniques such as partial deficit irrigation may be more suitable for 'Chetoui' olive production”
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Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.