PERFORMANCE OF DURUM WHEAT VARIETIES (TRITICUM DURUM Desf.) UNDER CONVENTIONAL AND ORGANIC AGRICULTURE

Field experiments were conducted for four years to determine the effects of organic and conventional systems and fourteen varieties (nine old and five improved) on growth, yield and quality of durum wheat crop. The experiments conducted at two sites (low semi-arid and higher semi-arid) were laid out in a split-plot design with four replicates. Studied parameters included (i) grain yield, (ii) technological and nutritional quality of the whole grain, dry matter, specific weight, proteins, amino acids, mineral content, gluten and baking strength. Results of the agronomic traits indicated that grain yield is on the average lower under organic cultivation compared to conventional methods (2.32 and 2.98 t/ha SEM=0.18 qx/ha respectively). However, varieties performance under this environment changed in dry year. Data analysis indicated high production potential of some varieties such as Khiar, Ben Bechir and INRAT69 (2.47, 2.46 and 2.44 t/ha respectively) under organic farming method. INRAT69 was found stable for grain yield under organic farming with low coefficient of variation (33 %) and a linear regression coefficient close to one (bi=0.94). Khiar and Ben Bechir varieties, identified for organic cultivation, were unstable. Results of the technological and nutritional quality were influenced by the cultivation method. The organic method affected positively proline contents (1.154 vs 1.146 g/100g of FM) and cystéine (0.216 vs 0.186 g/100g of FM) and gluten index which is responsible for the rheological properties of dough (64.73 vs 61.46 %). Contrary to the organic method, grain protein content is better in the conventional method (13.9 vs 13.5 %/MF, ESM=0.008 %/MF). Organic cultivation of INRAT69 variety was found to be associated with high nutritional and technological quality parameters such us grain weight, dry matter, total amino acids content and gluten index. Regardless of the cultivation method, results showed that old varieties Badri, Jnah Khortifa and Hamira have high protein and total amino acids content (> 16 %/FM and > 14.5 g/100g FM, respectively). These varieties should be considered by breeders in selection and breeding programs of durum wheat for organic farming. Based on these results, only INRAT69 variety could be potentially used in organic agriculture not only because its stable yield, but also because of its higher technological and nutritional quality. This variety could also be adapted for manufacturing organic pasta and couscous

Morphological evaluation of Tunisian garlic (Allium sativum L.) landraces for growth and yield traits

Purpose: Despite the significance of garlic as a food product and high annual income, until now there are no local commercialized Tunisian cultivars with registered names, which lead to the lack of recommended varieties of high yielding. This work is aimed to create the first garlic gene bank collection in Tunisia, evaluate the variation, identify yield related traits and structure genetic diversity among them. Research method: Thirty six local garlic landraces from the main production regions of Tunisia were collected and recorded in the National Gene Bank of Tunisia database, then grown in a gene bank field for multiplication. The phenotypic diversity was conducted on the basis of fourteen quantitative characteristics add to flowering ability. Findings: High diversity among Tunisian garlic landraces was detected. The bulb weight and bulb diameter explain the most significant variation of the yield. The cluster analysis sorted the 36 genotypes into three main groups as cluster 1 (11 accessions), cluster 2 (20 accessions), and cluster 3 (5 accessions). However, the grouping of genotypes did not correspond with their geographic origin. The highest genetic distance was reported between NGBTUN442 and NGBTUN452, however NGBTUN429 and NGBTUN434 found to be most similar with the lowest dissimilarity. Research limitation: Morphological traits need to be investigated overtime. Originality/Value: This study is interesting since it presents the first creation of the garlic gene bank in Tunisia. The results will provide basis information for the efficient use of the local garlic germplasm and help breeders to easily select out the desirable materials

Agro-morphological markers and organo-sulphur compounds to assess diversity in Tunisian garlic landraces

International audienceThis work is aimed at studying diversity of 31 garlic landraces from Tunisia and structuring this diversity. It helped at establishing correlations between content of organo-sulphur compounds and agro-morphological characteristics. For this purpose the quantitative variability of five organo-sulphur compounds, namely: alliin, isoalliin, glutamyl allyl cysteine (GluAlCs), isoglutamyl allyl cysteine (isoGlu- AlCs) and allicin is studied. The diversity of the accessions for number of leaves per plant, the pseudostem length, dry weight of bulb, weight of one clove, weight of one bulb, bulb diameter, number of cloves in one bulb, the yield and number of days to dormancy release, is assessed. Particular correlations related to the yield and to the organo-sulphur compounds were demonstrated. Genetic diversity was assessed between and within accessions using statistical analyses including coefficients of variation, one way analysis of variance, hierarchical cluster analysis (HCA) and principal component analysis (PCA). Significant agro-morphological traits and organo-sulphur contents variations were found between accessions, except for the number of days for dormancy release (DDR). There is no correlation between total measured organo-sulphur compounds and any of the agro-morphological characteristics. The yield is highly influenced by the following characteristics: weight of the clove, the weight and the diameter of the bulb, the number of leaves per plant and the stem length. Total variance was well described by the first three PCA axes which represent 80.57% of the variance. The PCA and HCA distinguished two major groups of garlic. Clustering does not correspond to the geographical origin but it distinguishes clearly between coloured and light coloured accessions

First report of garlic viruses A, B and C on garlic (Allium sativum L.) in Tunisia

Mite-borne viruses belonging to the genus Allexivirus (family Alphaflexiviridae) commonly occur on garlic in many parts of the world. There are usually asymptomatic and cause small damage to the plants, but often occur in mixed infection with potyviruses and carlaviruses, with synergistic effects reducing crop quality and leading to higher losses (Taglienti et al. 2017). Their occurrence on Tunisian garlic crops was studied here in the same garlic germplasm collection mentioned in a previous first report (Ayed et al. 2019). Leaf samples from a total of 66 garlic accessions were tested by DAS-ELISA using specific antibodies (DSMZ, Germany) against garlic virus A (GarV-A), garlic virus B (GarV-B) and garlic virus C (GarV-C). These serological tests showed individual virus incidence of respectively 56.4%, 67.7% and 10%. Our findings corroborate with the results of Chodorska et al (2012). In order to confirm the presence of these viruses, RT-PCR assays were performed using total RNAs extracted using two silica-capture extraction procedures according to Foissac et al (2005) and specific primers targeting the coat protein genes of the various viruses. These primers, designed for the present study are (GarV-A-F: 5' YCTYTTCTCHYTDGCHTGGACYTG 3' and GarV-A-R: 5' RCCYTTCCTAGACCARTTRGCRGG 3' for GarV-A; GarV-B-F: 5' TGGGCYTGYTACCACAAYGGATC 3' and GarV-B-R 5' TCTGCGCGVGTGGADACCATRTT 3' for GarV-B; GarV-C-F: 5' ARGAYCTYTTYTCMCTYGCRTGGGC 3' and GarV-C-R: 5' GGAGGYTCRTGAATYTGTTGTTG 3' for GarV-C). The viruses were detected by a two-step RT-PCR as described by Marais et al (2015). PCRs consisted of one cycle at 95 °C for 5 min; followed by 40 cycles of denaturation at 95 °C for 45 s, annealing at 45 °C for 45 s, and elongation at 72 °C for 45s; and a final extension step at 72 °C for 10 min. Products of the expected size (214 bp for GarV-A, 363 bp for GarV-B and 439 bp for GarV-C) were amplified from 58 (88%), 47 (71%) and 56 (85%) accessions, respectively. Forty three samples (65%) were co-infected by the three viruses. Higher numbers of positives revealed by RT-PCR especially in the case of GarV-C may reflect the higher sensitivity and efficiency of this technique compared to ELISA. Direct sequencing of selected amplicons of the expected size obtained for GarV-A, -B, and -C Tunisian isolates was performed and the sequences submitted to GenBank, validating the specificity of the three RT-PCR assays. The two sequenced GarV-A isolates (MK599147 and MN995836) shared 98% nucleotide (nt) sequence identity with each other, and 93-94% identity with the closest isolate in GenBank, the “G118” isolate from China (MN059320). The three sequenced GarV-B isolates (MN995829 to MN995831) shared 88-98% nt identity with each other. For “GarV-B 18.1” (MN995830) and “GarV-B 36.2” (MN995831) the closest isolate was “1109.1” (JX682828) from Spain (92-93% nt identity). For “GarVB 17.2” (MN995829), the closest isolate was “B-Sp-3” (LC97167) from Spain (90% nt identity). The sequenced GarV-C isolate (MN995834) showed the highest sequence nt identity (93%) with the “GarV-9” isolate (HQ724848) from Spain. To our knowledge this is the first report of the presence of GarV-A, -B and -C in Tunisia. The presence of these allexiviruses may pose a threat to the preservation of the Tunisian garlic germplasm and, more broadly, to garlic production in Tunisia. For this reason, the scrupulous identification of viruses occurring in garlic plants will help to use the appropriate strategy to decrease viral incidence in garlic growing area

Clotting and Proteolytic Activity of Freeze-Dried Crude Extracts Obtained from Wild Thistles <i>Cynara humilis</i> L. and <i>Onopordum platylepis</i> Murb.

The rising interest in finding alternatives to animal rennet in cheese production has led to studying the technological feasibility of using and exploiting new species of herbaceous plants. In this research work, and for the first time, freeze-dried extracts from Cynara humilis L. (CH) and Onopordum platylepis Murb. (OP) were studied for mineral and protein content, and their clotting and proteolytic activity were compared to those of Cynara cardunculus L. (CC). The effect of extract concentration (5–40 mg extract/mL), temperature (20–85 °C), pH (5–8), and CaCl2 concentration (5–70 mM) on the milk clotting activity (MCA) of CC, CH and OP extracts was evaluated. The MCA values were significantly higher in CC at the same extract concentration. The extract that showed the most significant increase in clotting activity due to increased temperature was OP, with maximum activity at 70 °C. The pH value for maximum milk clotting was 5.0 for both CC and CH, whereas, in the case of OP, the pH value was 5.5. CaCl2 enhanced the clotting capacity of the extracts, particularly for OP and CH. Furthermore, proteolytic activity (PA) and the hydrolysis rate increased with increasing time and enzyme concentration, with CC being the extract that achieved the highest caseinolytic activity

Effect of Planting Density in Two Thistle Species Used for Vegetable Rennet Production in Marginal Mediterranean Areas

In Mediterranean cropping systems, it is important to utilize marginal lands for the cultivation of non-food crops. Spontaneous thistle genera such as Cynara cardunculus L. and Onopordum tauricum Willd. are native to southern Europe. Previous research has focused on their spontaneous growth in the environment or ability to supply biofuel. The aim of this study was to identify the effect of two different planting densities on the flower differentiation, vegetable rennet production and weed control of O. tauricum Willd. and C. cardunculus L. in rainfed unfertilized Mediterranean cropping systems. The results showed that plant density influenced most of the biomass parameters for O. tauricum Willd. but no significant differences were observed for C. cardunculus L. Higher densities of both species were beneficial for weed control. We recommend the use of C. cardunculus L. and O. tauricum Willd. as suitable species for vegetable rennet production in Mediterranean organic cropping systems

Effect of Planting Density in Two Thistle Species Used for Vegetable Rennet Production in Marginal Mediterranean Areas

In Mediterranean cropping systems, it is important to utilize marginal lands for the cultivation of non-food crops. Spontaneous thistle genera such as Cynara cardunculus L. and Onopordum tauricum Willd. are native to southern Europe. Previous research has focused on their spontaneous growth in the environment or ability to supply biofuel. The aim of this study was to identify the effect of two different planting densities on the flower differentiation, vegetable rennet production and weed control of O. tauricum Willd. and C. cardunculus L. in rainfed unfertilized Mediterranean cropping systems. The results showed that plant density influenced most of the biomass parameters for O. tauricum Willd. but no significant differences were observed for C. cardunculus L. Higher densities of both species were beneficial for weed control. We recommend the use of C. cardunculus L. and O. tauricum Willd. as suitable species for vegetable rennet production in Mediterranean organic cropping systems