Revue internationale d'écologie méditerranéenne International ...

180
◆ A. ABBAD, A. EL-HADRAMI & A. BENCHAABANE
INTRODUCTION
The fodder plants, which are susceptible to develop
spontaneously in conditions of saltiness and edaphical
aridity, raised a particular interest during recent years
(Choukr-Allah, 1996). Among these plants, the saltbush
Atriplex halimus had a great importance in Mediterranean
regions. The species is a xerohalophyte, native of arid and
semi-arid Mediterranean regions. Its palatability and its
satisfactory appetability make it a very appreciated fodder
to camels, ovines and caprines essentially in drought
seasons (Kinet et al., 1998). Its ligneous wood constitutes
a very interesting energizing source. Endowed with an
important aerial biomass and a complex root system, The
species represent an efficient and relatively little expensive
tool in the rehabilitation of degraded lands and in fighting
against erosion and desertification (Le Houérou, 1992;
Wills et al., 1990; Chisci et al., 1991). Considering these
qualities, several studies have been achieved on these species
essentially with genetic (Haddioui & Baaziz, 2001)
as well as ecophysiological aspects (Zid & Boukhris,
1977; Ben Ahmed et al., 1995; Hdadou, 1996). Little
information are available on the phenological behaviour
and the action of certain environmental factors on the
distribution and the installation of the various phenological
stages at the species. Phenological data represent
a very important topic concerning the programs of the
degraded land restoration. It has been shown that the
content in nitrogenous matters, which represent one of a
major criterion of a fodder value, is variable according to
the different phenological stages of the species (Boudet
& Rivière, 1968; Frank & Hofman, 1989).
In this perspective, an analysis of the phenological and
phenotypic behaviour of the clones of the three natural
populations of Atriplex halimus subjected to two mode of
treatment (irrigated and non irrigated treatment) has been
achieved. In this phenological survey, particular attention
Stations Lat. N. Long. W Altitude
(m)
Mean annual
rainfall
(mm)
Table 1. Climatic characteristics of the surveyed stations.*
has been given to the flowering (male and female flower
production) and the fruiting (weight of the produced
seeds, infestation and immature seed rates). Other phenotypic
parameters have also been studied.
MATERIALS AND METHODS
In an aridity gradient along an axis north-west southeast
orientation, we sampled three stations: a littoral semi
arid station (Sidi Bouzid station in the region of Safi), a
semi continental arid station (Marrakech station) and a
continental Saharan station (Idelssen station in the region
of Ouarzazate) (fig. 1). The climatic characteristics of the
three stations are reported in the table 1. At each station,
a natural population of Atriplex halimus was sampled. In
March 1999 we sampled randomly 10 plants, from each
population, from which we took six cuttings per plant.
Cuttings were treated with indole-butyric acid (4 g l -1 )
and placed in a greenhouse at the National Institute of
Agronomic Researches of Marrakech for rhizogenesis.
The choice of the classic cuttings aims at preserving the
genetic identity of every population (Gorenflot, 1994).
After two months, the shoots (individuals) have been
transplanted into polyethylene bags containing 2 part
sands and 1 part peat and placed in a shade house for
acclimatization. In September, the young individuals were
transplanted into common garden in Marrakech. Half the
individuals (cuttings) of each clone were assigned to a
non-irrigated portion of the garden while the other half
were irrigated. Within a treatment individuals were placed
at random. At each portion of the garden, we have 30
individuals (3 cuttings per plant / population). Individuals
in the irrigated treatment were irrigated at a rate 5 liters
/ individuals once per week for the duration of the experiment.
In the non-irrigated treatment, individuals were
M (°C) m (°C) M-m (°C)
HR % Mean annual
evaporation
max min (mm)
Sidi Bouzid (Safi ) 32° 18’ 9° 15’ 15 353 29,7 8,4 21,3 80 70 1800
Marrakech 31° 37’ 8° 02’ 470 242 38,3 4,5 33,8 73 30 2700
Idelssen (Ouarzazate) 30° 56’ 6°54’ 1135 115 39,4 1,0 38,4 - - -
* Abreviations: Lat. N: latitude north ; Long. W: longitude west ; M: Average temperature of the warmest month ; m: Average temperature of the coldest month,
M – m: Thermic amplitude ; HR: maximal (max) and minimal (min) relative humidity.
ecologia mediterranea, tome 29, fascicule 2, 2003