Chamaerops humilis L. var. argentea André (Arecaceae)

Chamaerops humilis L. var. argentea André (Arecaceae)

Nadjat Médjati 1 , Okkacha Hasnaoui , Nouria Hachemi 2, 3 1 , Brahim Babali 1 and Mohammed Bouazza 1, 3 1. Department of Ecology and Environment, Abou Bakr Belkaïd University, Tlemcen 13000, Algeria 2. Department of Biology, Dr Tahar Moulay University, Saïda 20000, Algeria 3. Ecological and Natural Ecosystem Managements Laboratory, University of Tlemcen, Tlemcen 13000, Algeria

Received: November 26, 2012 / Accepted: January 24, 2013 / Published: May 30, 2013.

Abstract: The regeneration conditions of Chamaerops humilis L. (Arecaceae), has been threatened by a strong tegumentary inhibition of its seeds. In this study, the authors have analyzed the germination behavior of the species to plan subsequently for protection and sustainable use of this natural resource through synchronization and homogenization of germination. In this context and to optimize Chamaerops humilis seeds germination, to overcome and to remove the obstacle of tegumentary inhibition, the treatments by soaking

in distilled water, manual, mechanical and chemical scarification (H 2 SO 4 ), have been applied to the seeds of Chamaerops humilis freshly harvested in the Beni Snous area (Tlemcen Mountain, Algeria). The seeds germination without treatment (control) has been represented by a good germination capacity (72%) and a significantly longer duration of germination (46 days). Soaking in distilled water does not seem to have a significant effect on the rate and duration of seeds germination compared to dry seeds (P ≥ 0.05). The manual scarification has clearly improved the germination capacity of these species (92%), and a change wed has been seen in the germination duration (16 days). However, mechanical scarification of seeds gave only low germination rate (42%). Seeds treatment with sulfuric acid has been found to affect the rate of germination, but this effect is varied depending on the concentration of the acid. Overall, the germination percentage has changed from 77% to 92%. The optimal value of 92% corresponds to a concentration of 96%.

Key words: Chamaerops humilis L., Arecaceae, tegumentary inhibition, germination, scarification.

1. Introduction  smaller diversity of palms among the tropics in the world. One of the kinds of palm trees found in Africa is

According to some sources, the Arecaceae the Chamaerops. Knowing that humilis species is a represents the third family of plants, mostly used after single found in the Mediterranean, more exactly in the grasses and legumes [1]. They are a family of globally southwest part of Mediterranean [4, 5]. In the west of significant socio-economic plants. The family includes Algeria, Chamaerops humilis L. has been represented Arecaceae palm trees as an economical important mainly by argentea variety that occupies a prominent source of both agricultural produce and as components place in its abundance dominance; it also enters in the in ornamental landscaping projects [2]. Its species are building structure and architecture of many plant scattered close to the equator mainly line within the groups. It participates with other species plant limits of 44°N and 44°18 ′S [3]. Almost all kinds are associations that give them the appearance of many restricted to three tropical continents (Africa, America matorrals and preforest [6]. The role of Chamaerops and Asia). According to Johnson [1], Africa has the humilis utility has been reported by several authors, in

Corresponding author: Nadjat Medjati, Ph.D. candidate, addition to its potential use in the regeneration of research fields: ecology and plant biotechnology. E-mail: najah400@hotmail.fr. vegetation cover in arid and its application as an

Study of Behavior Germination and Essays the Removing Tegumentary Inhibition of Seeds

of Chamaerops humilis L. var. argentea André (Arecaceae)

ornamental in warm seaside regions. This palm has Chamaerops humilis in a growth chamber maintained traditionally been used for other purposes [7-11]. The

at 25 °C. The optimal temperature for germination of adult leaves of plant were used in basketry to make

Chamaerops humilis seeds is between 20 °C and 30 °C mats, baskets carry and brushes. The young closed

leaves, treated with sulfur to make them soft and supple

2.2.2 Pretreatment

to be used for finer work [12]. For all experiments, the seeds have been disinfected However, the climatic conditions experienced in the

for a few minutes in sodium hypochlorite 1% followed western of Algeria more particularly in Tlemcen region,

by 3 rinses with distilled water to avoid the risk of combined the proliferation of anthropozoogenic action

contamination by fungi in particular. Then, they have bring a continual regression to plant germ plasm.

been placed in plastic Petri dishes of 9 cm diameter Nevertheless, this taxon has been threatened in some

lined with two layers of filter paper soaked with 5 cm 3 parts of the region [6]. In addition, the slow growth of

of distilled water. Each trial included 100 seeds, this palm can delay production because it has been

divided into 5 replicates of 20 seeds. estimated to require 2 to 3 months to germinate [6, 13,

To determine the optimal conditions for germination, 14]. Pretreatments intended to lift any tegumentary

several germination tests have been made by subjecting inhibitions were applied to seeds of Chamaerops

seeds to various pretreatments:

humilis which has low germination percentages as  The soaking in distilled water for 24, 48 and 96 h, reported in Hasnaoui et al. [6, 14] and Merlo et al. [12].

this is not only improves the absorption of water [16] Especially, increasing the rate of germination, shorten

but also eliminates seeds germination inhibitors [17]. the germination delay and highlight the value of each

 The scarification, superficial incision of the hard pretreatment with the objective of protection and

epicarp to allow gas exchange and water imbibitions sustainable use of this natural resource through

[18-20]. It has been carried out in three different ways: synchronization and homogenization of germination.

manual, mechanical and chemical. (1) The manual scarification, thus it has used a razor blade, removing

2. Material and Methods

part of the fleshy epicarp, until endosperm becomes

2.1 Plant Material visible (Fig. 1). (2) Mechanical scarification, which is the same process but much in faster which seeds are

The seeds used in this study have been collected in placed in an electric mixer for 2 to 3 min. (3) The September 2011 on the feet of Chamaerops humilis in chemical scarification, this process involves immersing Beni Snous area (mountain of Tlemcen- Algeria). Then the seeds in H 2 SO 4 at different concentrations 10%, have been carefully selected after morphological 30%, 50%, 70% and 96% for 5 min. sorting of selected seeds to be reddish brown; the color After each test, the seeds were washed with distilled attested to the physiological maturity of seeds. This water several times. For each of these treatments, the indicator of seeds maturity has also been evaluated by results have been compared with a control with which the flotation test. This latter consists of plunging the

seeds in water for 24 h, the good seeds immerse while the dead seeds float.

2.2 Methods

2.2.1 Condition of Germination Germination tests have been conducted in the

laboratory on freshly harvested and shelled seeds of

Fig. 1 Position of manual scarification.

Study of Behavior Germination and Essays the Removing Tegumentary Inhibition of Seeds

of Chamaerops humilis L. var. argentea André (Arecaceae)

the germination capacity, the latency time or germination delay, duration and speed of germination.

3.1 The Influence of Soaking in Distilled Water The variations capacity of Chamaerops humilis

germination during two months has been based on different soaking duration in distilled water display in Fig. 2. It has showed that the germination rate, latency time and duration of germination did not vary significantly. However, these applied soaking have

Fig. 2 Influence of soaking in distilled water on the

accelerated the speed of germination compared to dry

evolution of germination of Chamaerops humilis seeds.

seeds (control). These latter, take 42 days for 50% of

the seeds do not undergo any pretreatment. The the seeds of Chamaerops humilis have sprouted. follow-up testing has been spread over two months,

While soaking for periods of 24, 48 and 96 h, the counting germinated seeds where the radical pierced

germination speed is 29, 32 and 30 days respectively the seeds coat is done every day.

(Table 1). Thus the analysis of variance (ANOVA) The results of statistical analysis were performed by

shows a non-significant effect of these soaking in using data-processing software Minitab15; analysis of

distilled water on seeds germination (P ≥ 0.05). variance and followed by mean comparison to

3.2 Influence of Scarification

Turkey’s test at 5% were carried out. The scarification (manual, mechanical and chemical)

3. Results

of Chamaerops humilis seeds gave the results recorded The criteria and germination parameters defined by

in Table 2 and illustrated in Fig. 3. These results have Événari [21] and Côme [22] have been used to express

showed that the scarification razor blade has improved the results in terms of the rate of germination or incur

markedly the germination capacity of the species

Table 1 Comparison of rate, delay, duration and speed of germination of Chamaerops humilis seed for each soaking in

distilled water. Treatments

Germination rate (%) Germination delay (days) Germination duration (days) Germination speed (days) Control 72 15

Soaking in distilled water:

24 h 71 12 43 29.00 48 h

70 12 43 32.00 96 h

Table 2 Comparison of rates, delays, durations and speeds of Chamaerops humilis germination for different means of

scarification. Treatments

Germination rate (%) Germination delay (days) Germination duration (days) Germination speed (days) Control 72

15 46 42.00 Scarification

Manual 92 9 16 18.00 Mechanical

Chemical (H 2 SO 4 ) 10%

Study of Behavior Germination and Essays the Removing Tegumentary Inhibition of Seeds

of Chamaerops humilis L. var. argentea André (Arecaceae)

changed from 77% to 92%. The optimal value of 92% corresponds to a concentration of 96% (Table 2). The

analysis of variance (ANOVA) showed a highly significant effect of sulfuric acid on germination (P ≤ 0.05).

4. Discussion

The seeds coat of Chamaerops humilis has a typical Arecaceae anatomical structure which results in a strong tegumentary inhibition of germination. These husks also induce heterogeneous nucleation and

dispersed. However, it should be noted that the

Fig. 3 Influence of manual and mechanical scarification on

the evolution of the rate of germination of Chamaerops humilis.

impermeability of the seeds coat would also be an asset because it would protect them from rapid germination

under little or no favor seedling establishment [23-26]. The seeds of Chamaerops humilis studied present a varied germination behavior under the nature of the

applied treatment. The results obtained highlight the

role of each pregerminatif treatment to remove this tegumentary inhibition. The germination of Chamaerops humilis untreated spans the first 46 days after germination. The staggering in time of seeds germination is a strategy of adaptation of species to the high variation in rainfall [27]. The high germination percentage (72%) of untreated seeds of Chamaerops

Fig. 4 Evolution of germination capacity of Chamaerops

humilis seems to be linked to their moisture original

humilis seeds depending on concentration functions of

content. The results are similar to those of Gomes et al.

[28] who found a decrease in germination percentage (92%), the speed germination and its duration.

sulfuric acid (H 2 SO 4 ).

with low humidity. Same as Martins et al. [29] who However, the mechanical scarification of seeds gave

showed that the germination percentage decrease in low germination rate (42%). In addition, data analysis

proportion to the humidity with Archontophoenix manual and mechanical scarification have a shortened

Alexandrae seeds. It is important to remember that the seeds latency time compared to non-scarified seeds.

big seeds and recent harvest plays a significant role in However, data from Fig. 4 illustrate the effect of

the success of germination, but it should have a

sufficient time, soaking it in distilled water seems not capacity of Chamaerops humilis for 5 min, show that

increasing concentrations of H 2 SO 4 on the germination

to have softened the seeds coats of Chamaerops treatment with sulfuric acid is found to affect the rate of

humilis [6]. This is due to the fact that soaking in germination, but this effect is varied depending on the

distilled water has no influence on the apparent of concentration of the acid. Indeed, increasing germination rate, where the envelopes tegumentary concentrations of the latter (10%, 30%, 50%, 70% and

keep its original hardness and constituting a barrier to 96%) had a positive effect. Germination percentage has

germination. However, soaking in water is one of the

Study of Behavior Germination and Essays the Removing Tegumentary Inhibition of Seeds

of Chamaerops humilis L. var. argentea André (Arecaceae)

treatments used in some studies on seeds germination literature is explained by their initial moisture content. of palms to remove dormancy [30-32]. Manual

However, it should be noted that the physiological scarification should have the effect of causing the rapid

phenomena accompanying the germination depend on imbibitions seeds coat and water intake in the reserves

both on the intrinsic characteristics of the seeds. The which allows quick exit of the radicle and the onset of

comparative study of the ability to germinate seeds metabolic reactions of the embryo and cotyledons [33],

Chamaerops humilis showed that the scarification of that allowed reaching a germination capacity of 92% in

seeds with a razor blade, as well as their immersion in

16 days. According to Cavanagh [34] this method 96% sulfuric acid proved pretreatments most effective. allows you to bring the best of germination capacity of

In addition, it will be necessary to check that the seeds, although it is very hard for significant quantities

treatment with sulfuric acid has no effect on the of seeds [35]. However, mechanical scarification of

depressive effect of Chamaerops humilis seeds and seeds has appeared to be detrimental to seeds

evaluate various periods of soaking the optimal time germination, it has exposed the embryo and cotyledons

treatment. However, germination tests to undertake water logged and proteins rot and parasites [33]. This is

periodic remain to be defined through long-term perhaps what explains the low germination rate (42%)

studies in order to test the viability and germination of seeds germinated at this level. The positive results

capacity of seeds according to the time after harvest. confirm the role of sulfuric acid on germination of

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