Abstract
The study was carried out to have a comprehensive view of the root system behavior of young olive trees cultivated under field conditions. The experiment involved irrigated trees (Olea europaea L., cv., Chétoui) cultivated at 6x6 m2 spacing in Mornag (36.5°N, 10.2°E), northern Tunisia. The way in which roots explore the soil volume during the first years after planting was explored through ‘in situ’ root system drawings and estimation of root densities. The relationship between canopy and root growth parameters was also investigated. The last section of this paper proposes a methodological approach for determining irrigation requirements of young olive trees and how water supply could be linked to the development of canopy and root system during the first years of cultivation when ground cover and the root system are not completely developed. Some agronomic applications were then deduced concerning water and fertilizers for such orchards. Results show that the main development of the olive root system occurs during the two to four first years of cultivation confining most roots (70%) to the top soil layers (20-40 cm). Maximum root densities were observed at this depth at a distance of 0.4 m from trunks. For young trees, water and fertilizers should be supplied at these depths and distances from trunk to allow easy and efficient root absorption. Obtained results also show a significant relationship between canopy and root areas which can be approximated by a linear model (r = 0.94). The root-canopy ratio estimated from their areas decreased rapidly beginning from the second year after planting, resulting from the establishment of competition between vegetative growth and fruiting. The optimum ratio root length/leaf canopy area of 2.3 km m-2 was found for the six-year-old tree indicating good equilibrium between the above and underground parts. The mathematical model developed on the basis of canopy cover and root extension allows precise esti- mation of water needs taking into account the actual root surface. However, while the canopy cover measurement was relatively easy to carry out, it was much more difficult to determine the surface covered by the root system. Results obtained in the present work also show an over-estimation of water needs when the FAO method is adopted to estimate the evapotranspiration of young trees.
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Claims 9
Claim · model-written summary
Most olive root development occurred in the first two to four years, with 70% of roots in the top 20-40 cm.
- Taxon
- olive
Olea europaeae0 - Organ / stage
- root systeme0
- Outcome
- most rootse0
- Value
- 70%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“main development of the olive root system occurs during the two to four first years of cultivation confining most roots (70%) to the top soil layers (20-40 cm)”
Claim · model-written summary
Maximum root density occurred at 20-40 cm depth and 0.4 m from trunks.
- Taxon
- oliveOlea europaeat0
- Outcome
- Maximum root densitiese0
- Value
- 0.4 me0
- Qualifier
- top soil layers (20-40 cm)e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Maximum root densities were observed at this depth at a distance of 0.4 m from trunks”
e1“top soil layers (20-40 cm)”
t0“olive trees”
Claim · model-written summary
Water and fertilizer should be supplied at the identified root depths and distances.
- Taxon
- oliveOlea europaeat0
- Outcome
- water and fertilizers should be supplied at these depths and distances from trunke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For young trees, water and fertilizers should be supplied at these depths and distances from trunk to allow easy and efficient root absorption”
t0“olive trees”
Claim · model-written summary
Canopy and root areas had a significant linear relationship with r = 0.94.
- Taxon
- oliveOlea europaeat0
- Organ / stage
- roote0
- Outcome
- relationship between canopy and root arease0
- Value
- r = 0.94e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“significant relationship between canopy and root areas which can be approximated by a linear model (r = 0.94)”
t0“olive trees”
Claim · model-written summary
The root-canopy area ratio decreased rapidly from the second year after planting.
- Taxon
- oliveOlea europaeat0
- Outcome
- root-canopy ratioe0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The root-canopy ratio estimated from their areas decreased rapidly beginning from the second year after planting”
t0“olive trees”
Claim · model-written summary
The optimum root length to leaf canopy area ratio was 2.3 km m-2 in a six-year-old tree.
- Taxon
- oliveOlea europaeat0
- Outcome
- ratio root length/leaf canopy areae0
- Value
- 2.3 km m-2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The optimum ratio root length/leaf canopy area of 2.3 km m-2 was found for the six-year-old tree”
t0“olive trees”
Claim · model-written summary
A canopy-cover and root-extension model permitted precise estimation of water needs.
- Taxon
- oliveOlea europaeat0
- Outcome
- precise esti- mation of water needse0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The mathematical model developed on the basis of canopy cover and root extension allows precise esti- mation of water needs taking into account the actual root surface”
t0“olive trees”
Claim · model-written summary
Canopy cover was easier to measure than root-covered surface.
- Taxon
- oliveOlea europaeat0
- Outcome
- canopy cover measuremente0
- Comparator
- surface covered by the root systeme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“while the canopy cover measurement was relatively easy to carry out, it was much more difficult to determine the surface covered by the root system”
t0“olive trees”
Claim · model-written summary
The FAO method overestimated water needs for young trees.
- Taxon
- oliveOlea europaeat0
- Outcome
- water needse0
- Direction
- over-estimatione0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“over-estimation of water needs when the FAO method is adopted to estimate the evapotranspiration of young trees”
t0“olive trees”