Badii Gaaliche

Morphological and Pomological Diversity of Fig (Ficus carica L.) Cultivars in Northwest of Tunisia

The fig (Ficus carica L.) is one of the oldest fruit trees cultivated in Tunisia. Djebba region is located in the northwest of Tunisia. It is very famous by fig culture. Many specific fig genotypes are very appreciated locally and nationally. Taking into account these considerations, Djebba fig cultivars are subject of label products, namely, “Djebba figs.” This study was focused on fig germplasm characterization of 17 cultivars in Djebba region based on morphological and pomological traits. Results revealed a large variability within the local fig germplasms. The comprehensive analyses of all the data permitted to distinguish some particular genotypes as distinct cultivars, and groups of cultivars as polyclone varieties. It was possible to discriminate six distinct cultivars and two groups of multiclone varieties (Soltani and Thgagli) with different degrees of polymorphism. Hypotheses of homonymy and synonymy were suggested for some cultivars. The diversity is currently threatened by genetic erosion. Measure of conservation is necessary to be undertaken.

Assessment of Pollen Viability, Germination, and Tube Growth in Eight Tunisian Caprifig (Ficus carica L.) Cultivars

The evaluation of pollen viability and its germination capacity are two essential criteria for pollinator’s characterization. This study was carried out to evaluate pollen quality of eight caprifigs grown in the center-east and north-west of Tunisia. Two colorimetric tests 2,3,5-triphenyl tetrazolium chloride (TTC) and acetocarmine were used to estimate pollen viability. Germination rate and pollen tube growth in a culture medium containing 5% sucrose, 5 ppm boric acid (H3BO3) and 1% agar were registered after 24, 48, and 72 hours (H) of incubation. Results showed that the highest pollen viability rate (84%) was obtained by TTC test in caprifig Assafri, followed by Jrani (80.2%), Djebba 2 (77.8%), and Djebba 1 (73.6%). That of other caprifigs did not exceed 50% for the two tests. In all caprifig types, germination rate and pollen tube growth varied according to the incubation period. The highest percentage of germination (72%) and maximum pollen tube length (960 μm) were recorded after 72 H of incubation in caprifigs Assafri and Jrani, respectively. Among the caprifigs studied, four types (Assafri, Jrani, Djebba 1, and Djebba 2) appeared to be suitable pollinators with respect to the criteria investigated.

Nutritional Compounds in Figs from the Southern Mediterranean Region

Nutritive value of mature figs (Ficus carica L.) was investigated in five Tunisian cultivars, ‘Bouhouli’ (BHL) and ‘Zidi’ (ZD) (dark skin figs); ‘Thgagli’ (THG), ‘Bidhi’ (BD), and ‘Khedri’ (KHD) (yellow-green skin figs). Sugars, organic acids, fibres, and polyphenols were analysed in representative fruit samples from two distinct regions known to develop fig crops. Tunisian figs were characterized by predominance of glucose (6.30 g/100 g fresh weight) and fructose (5.10 g/100 g fresh weight). Citric acid (0.35 g/100 g fresh weight) was the major organic acid in all cultivars, almost three times higher than malic acid (0.13 g/100 g fresh weight). Average content of alcohol insoluble solids was 3.3 g/100 g FW. Four main polyphenols could be identified: two anthocyanins (cyanidin-3-glucoside; cyanidin-3-rutinoside), one flavonol (rutin), and one hydroxycinnamic acid (5-cafeoylquinic acid), revealed only in ‘BD’ samples. Cyanidin-3-rutinoside was the most abundant compound among all cultivars. Compared to common fruit, figs are among high sugar leveled fruit with significant dietary fibre content. Dark skin ‘ZD’ fruit were the most interesting figs with the highest concentration of sugars, organic acids, and polyphenols, especially cyanidin-3-rutinoside. This cultivar could be better advised for fresh consumption. However, the three lighter cultivars are more suitable for drying.

Relationship between pollination and cell wall properties in common fig fruit.

Most botanical types in fig Ficus carica require pollination to fulfil their development and ensure quality onset of the fruit. Cell wall behaviour and composition was followed in fig fruit in response to pollination during maturity. Figs, when ripe, soften drastically and lose of their firmness and cell wall cohesion. Pollination increased peel thickness, flesh thickness, fresh weight and dry matter content of the fruit. Alcohol insoluble solids (AIS), more concentrated in the flesh tissue, were not influenced by the lack of pollination. Concentrations in uronic acids were higher in the AIS of the peel than that of the flesh and differences were significant between pollinated and non-pollinated fruits. Pectin polymers in figs were high methylated (DM>50). The methylation degree (DM) increased more with pollination affecting textural properties of the fig receptacle. The major neutral sugars from the AIS were glucose (Glc) from cellulose followed by arabinose (Ara). No significant changes in neutral sugars content could be allocated to pollination. Pollination is essential in fruit enlargement and softening. Minor changes were determined in the cell wall composition of the fruit at maturity. Fertile seeds resulting from pollination may possibly take place in hormonal activity stimulating many related enzymes of the wall matrix depolymerisation in particular polygalacturonase (PG) and pectin methylesterase (PME).

Shoot Architecture and Morphology of Different Branch Orders in Fig Tree (Ficus carica L.)

ABSTRACT Tree architecture describes plant form by defining the spatial organization of different structures. Shoot branching is an important step in understanding the tree architecture. Such studies are required for analyzing phenotypic diversity of plant architecture. Because such studies are rare on fig trees, the architecture diversity among nine Tunisian fig cultivars grown in Chott-Mariem (center-east Tunisia) was explored. Quantitative morphological descriptors were noted on six annual shoots and studied during four yearly growth cycles, from 2007–10. Coding strategy was adopted for fig branch description. Branch growth characteristics, location, and distribution of axillary shoots were determined for three axis orders. Results showed a great variability of fig branches, particularly in terms of branching density and position, branching angle, and shoot dimensions. Shoot length was closely related to its architectural position in the branch, i.e., all low-order shoots in all cultivars had more growth than high-order shoots. The meso-basitony tendency was frequent. Thus, an architectural typology characterizing all cultivars was established and three principal groups were distinguished. The first one (Type I) with orthotropic branches located at the basal and median parts of the bearer axis had dense and continuous ramification. The second group (Type II) with a diffuse branching differed in lateral shoot distribution, and finally, the third group (Type III) had open and diffuse branching located on the basal zone of the carrier axis. This typology could be used in future genetic improvement programs of local fig trees in Tunisia.

Health status of the pear tree following the establishment of Fire blight in Northern Tunisia

ABSTRACT Pears have great importance in Tunisia for their desirable taste and commercial value. Until 2012, the pear cultivation was protected against fire blight by the application of a rigorous quarantine system. Fire blight, caused by Erwinia amylovora, was outbreak in Tunisia in the spring of 2012 and has spread rapidly through the most important pear growing regions destroying several hundred hectares of pear plantations. Therefore, the total pear production has decreased from 60,000 metric tons in 2011 to less than 20,000 metric tons in 2016. In this study, collected data of pear culture and surveys were carried out during four years (2012–2016) in the main pear growing areas to evaluate the current situation of the disease in the country particularly in the damaged regions of the lower valley of Medjerda (Manouba, Ben Arous, Bizerte, and Beja). Samples collected from symptomatic trees were processed for the isolation and identification of the causal agent using microbiological and molecular techniques. The results indicate that the disease had destroyed more than 5500 hectares among a total of 8400 hectares of pear plantations area. Both provinces Manouba and Ben Arous were the most affected by fire blight disease resulting in the eradication of 350 and 325 hectares of pear plantations, i.e., 100% and 98% of the total infected area, respectively. All control attempts, including sanitary measures, the application of mineral oil and copper, growth regulators and biological control have failed to limit the spread of the disease. The presence of pathogen in the prospected regions was confirmed by pathogenicity and molecular tests, which are compatible with the symptoms observed throughout the surveys. The pear cultivation in Tunisia is threatened by fire blight due to the restriction tolerance of the available varieties and the climatic conditions favoring the staggered flowering of the species. Quarantine measures must be implemented to prevent the spread of this disease in a new disease-free areas.