Application and use of sulphuric acid pretreatment to improve seed germination of three acacia species

The experiments were led to study the effect of pretreatments and their duration on germination behavior of three Acacia species A. cyanophylla Lindl., A. farnesiana L. and A. decurrens Willd. by analyzing three parameters (GP: germination percentage; MGT: germination mean time (days) and GRI: germination rate index) for various times of incubation (5, 10 and 15 days) in Petri dishes. Pre-sowing treatment included immersion in concentrated sulphuric acid for 60, 90 and 120 minutes. The sowing in distilled water (Control) had no positive effect on the germination induction. Generally, the seed pretreatments were very useful to improve germination. Time of immersion significantly (P < 0.0001) affected GP, MGT and GRI in all species. Increasing the duration of sulphuric acid immersion (from 60 to 120 min) improved the germination percentages for A. cyanophylla and A. farnesiana seeds to (98% and 99%), respectively. However, increasing this duration had a negative effect on A. decurrens seed germination, reducing the final germination percentage from 97% at 60 minutes of immersion to 43% at 120 minutes

Chickpea Callus Histology Inoculated with Ascochyta RabieiBlight Causal Agent Spores

The objective of this research was to study the interaction between Ascochyta rabiei as a pathogen and its host, established through in vitro tissue culture using as a pathosystem chickpea Cicer arietinum callus inoculated with Ascochyta rabiei spores. A resistant chickpea genotype INRA 199 and a local cultivar Zouaoui were used. Murashige and Skoog, (1962) medium supplemented with 0.5 mg%252Fl of Naphthalene Acetic Acid (NAA) and 1 mg%252Fl of Benzyl Amino Purine (BAP) were used for the production of calluses used as a host. The histological study of calli inoculated with Ascocchyta rabiei spore suspension compared to the control showed two different reactions. In INRA199, the pathogen proliferation was slow and limited by the formation of an area where the cells accumulated phenolic compounds whereas in the cultivar Zouaoui the pathogen rapidly colonized the calli intercellular space and the number of formed pycnidia was high

Maximizing seed germination in five species of the genus Acacia (Fabaceae Mimosaceae)

Seeds of many tree-species possess a hard seed coat which is impervious to water. These seeds often take a long time to germinate, resulting in heterogeneity and a delay in seedlings development which is an inconvenience for reforestation success. The aim of the present work was to determine the possibilities to improve the germination of five leguminous trees of the genus Acacia that have been recorded in the arid and the desert region of Algeria using sulphuric acid. A duration of 30 min of immersion in sulphuric acid improved the seed germination up to 97.5% and 99% for A. albida and A. laeta, respectively. Increasing the time of immersion (from 30 to 90 min) improved the germination percentages for A. ehrenbergiana and A. seyal seeds to 92.5% and 93.7%, respectively. Increasing this duration to 120 min had a positive effect on A. tortilis seed germination, improving the final germination rate up to 97%. Understanding of seed Germination Requirements is very important for regeneration and successful tree establishment in forest nurseries as well as for direct plantation in arid and semi-arid lands

Effects of Nitrogen Fertilization on Mycorrhizal Infection, Nodulation and Growth of Phaseolus vulgaris L.

The common bean (Phaseolus vulgaris L.) has been the subject of a number of studies and has been described by many authors as a legume with low nitrogen fixing potential compared to other legume species. The first objective of this study is to assess the development and growth of P. vulgaris L. var. Djedida and its yield at different developmental stages (vegetative, flowering and fruiting), in the presence and absence of nitrogen fertilizer (Urea 46) in an arid climate and in a soil containing high level of CaCO3 and assimilable phosphorus. The second objective is to carry out a survey on nodulation, number of spores and mycorrhizal infection under these conditions. The results showed that the nitrogen fertilizer amendment is mainly significant (p< 0.0001) for various morphological parameters. Indeed, great improvement was observed on the majority of the morphological parameters with considerable percentages. However, no significant effect was reported for the roots length. In addition, a negligible number of nodules were obtained in the plot without fertilization and no significant effect on the number of spores was recorded. Furthermore, the effect of fertilization on the arbuscular intensity (a%, A%) and on mycorrhizal colonization (M%, m%) of the roots was found to be significant. The soil in the arid region of Biskra showed significant mycorrhizogenic potential, although the conditions in this region were not very favorable for their development, which could constitute an effective biological resource to improve the tolerance of host plants to biotic and abiotic constraints

Nodular bacterial endophyte diversity associated with native Acacia spp. in desert region of Algeria

Five species of Acacia (Acacia ehrenbergiana Hayne, A. nilotica (L.) Delile, A. seyal Delile, A. tortilis(Forssk.) Hayne and A. laeta Delile) indigenous to Tamanrasset (Algeria) were investigated for theirnodulation status and nodular endophytic diversity. A. ehrenbergiana showed the highest nodulationability across the different sites in this region, indicating the widespread occurrence of compatiblerhizobia in the soils. Altogether 81 strains were purified. Among this endophytic strain collection, onlyfour bacterial endophytes nodulated their respective host plants. On the basis of partial 16S rDNAsequencing, they were affiliated to Ensifer sp., Ensifer teranga, Mesorhizobium sp. and Rhizobium sp.Among the 79 non- symbiotic endophytes, 24 representative strains on the basis of PCR-RFLP profileobtained with MSPI enzyme digestion were characterized. They belonged to nine genera, namely: Paenibacillus, Ochrobactrum, Stenotrophomonas, Pseudomonas, Microbacterium, Rhizobium,Agrobacterium, Brevibacillus and Advenella. The isolated nodular endophytes in this study revealed astrong tolerance profile to salinity and high temperature. Principal component analysis confirmed thatno correlation was found between bacterial tolerance to a maximum temperature of growth and soildepth of sampling. This tolerance profile was distributed over the three levels of soil depth sampling:20, 40 and 60 cm. On the other hand, there was no relationship between in vitro tolerances of rhizobialstrains to NaCl and high temperature and corresponding edaphoclimatic characteristics of the samplingsites. This study is a contribution to nodular bacterial diversity knowledge of desert African Acaciaspecies growing in preserved ecosystems