Response of mature olive trees to switching from

conventional to drip irrigation in dry area of Morocco-

Assessment of fruit and oil quality and composition

Abderaouf El Antari(1,*), Lhassane Sikaoui(1), Abdelaziz Bouizgaren(1),

Mohammed Karrou(2), Hakim Boulal(2), Mohammed Idrissi(1), Yamna

Ouguas(1), Vinay Nangia(3), Theib Oweis(3)

(1) INRA, CRRA Marrakech, BP 533 Morocco

(2) ICARDA, Rabat, Morocco

(3) ICARDA, Amman, Jordan

In Morocco, the area of irrigated olive trees increased in the last decades to reach 35% of a total of around one

million hectares.

Most of this irrigated area is cultivated under traditional inefficient surface irrigation system.

To overcome this inefficiency of water use, new saving irrigation methods such as drip irrigation have been

promoted by the Government.

The objective of this research is to study the response of mature olive trees to switching from conventional to drip

irrigation.

For this purpose :

A trial was conducted in a 36-years old irrigated olive orchard (var. Picholine marocaine) at the Tessaout

experiment station of INRA Marrakech characterized by a

hot and dry summer Mediterranean climate.

Five treatments are tested : T1= Flood irrigation (farmers use) T2= Minimum tillage with drip irrigation (100% x ETc)

T3= Minimum tillage with drip irrigation (70% x ETc)

T4= Deep tillage with drip irrigation (100% x ETc)

T5= Deep tillage with drip irrigation (70% x ETc)

Estimated fruit yield under the five studied treatments.

Olive average weight under the five studied treatments.

Maturity index of olives under the five studied treatments

Treatments Maturity index

T1 (Flood irrigation) 2.2 b

T2 (Min Till 100 % ETc) 3.04 a

T3 (Min Till 70 % ETc) 2.87 a

T4 (Deep till 100 % ETc ) 2.94 a

T5 (Deep till 70 % ETc ) 2.69 a

Oil yield (Kg/Ha) of olives under studied treatments

Treatments Maturity index

Oil yield

(Kg/Ha)

T1 (Flood irrigation) 2.2 b 1244,0

T2 (Min Till 100 % ETc) 3.04 a 1531,4

T3 (Min Till 70 % ETc) 2.87 a 1607,0

Treatments Viscosity (%)

Color index

L* a* b*

T1 (Flood irrigation) 3.27 ab 69.79 -6.58 46.77

T2 (Min Till 100 % ETc) 3.44 ab 54.68 -3.02 28.19

T3 (Min Till 70 % ETc) 3.82 b 59.82 0.14 15.02

T4 (Deep till 100 % ETc ) 3.72 ab 38.62 -0.03 23.75

T5 (Deep till 70 % ETc ) 3.16 a 36.23 0.18 21.94

Viscosity and color index of olive oils obtained under studied treatments.

Treatments E232 E270

Oil

bitterness

Total poly-phenols

(ppm)

T1 (Flood irrigation) 1.41 0.106 0.900 292.46

T2 (Min Till 100 % ETc) 1.56 0.091 0.540 236.96

T3 (Min Till 70 % ETc) 1.60 0.103 0.510 222.83

T4 (Deep till 100 % ETc ) 1.54 0.087 0.464 183.80

T5 (Deep till 70 % ETc ) 1.43 0.092 0.554 201.97

Specific extinction, bitterness and total poly-phenols of

olive oils obtained under studied treatments.

Treatments

C16:0 C16:1 C18:0 C18:1 C18:2 C18:3 Mono/Poly

T1 (Flood irrigation)

9.83 0.57 2.62 74.05 11.31 0.97 6.10

T2 (Min Till 100 %

ETc)

9.85 0.57 2.83 73.38 11.82 0.95 5.87

T3 (Min Till 70 %

ETc)

10.14 0.62 2.47 73.78 11.33 1.00 6.13

T4 (Deep till 100 %

ETc )

9.86 0.57 1.81 75.02 11.10 0.99 6.29

T5 (Deep till 70 %

ETc )

9.77 0.57 2.21 75.67 10.11 0.98 6.91

Mayor fatty acids content of olive oils obtained

under studied treatments

Sensoriel profils of positif attributs under

deficit and full irrigation

Specific aromatic profils under deficit and

full irrigation

Hedonic test

The organoleptic quality of extracted olive oils was tested

by 60 farmers in a hedonic test :

80% of participants had appreciated and prefered oil produced under deficit irrigation.

Conclusion 1/2

highest olive fruit yield and fruit olive weight were obtained under deep tillage and deficit irrigation.

maturity index was shown no significant effect between minimum and deep tillage, and between full and deficit irrigation

olive oils from the various treatments were quite viscous and the higher values were obtained under minimum tillage with deficit drip

irrigation (T3).

No significant effect of oil color index was noted between studied treatments

The specific extinction values indicated that olive oils obtained under all studied treatments had a high potential stability

Conclusion 2/2

the high values of total phenols content and bitterness were obtained with flood irrigation treatment (T1).

The composition of the total fatty acids of olive oils did not show significant differences among studied treatments.

sensory evaluation of olive oil indicated that under deficit irrigation (70% x ETc), the expression of sensorial positive attributes was more

intense and the specific aromas were clear with a good expression,

harmony and complexity of attributes.

80% of participants in hedonic test had appreciated and preferred oil produced under deficit irrigation

Thank you