Yield, growth development and grain characteristics of seven Quinoa (Chenopodium quinoa Willd.) genotypes grown in open-field production systems under hot-arid climatic conditions.

Quinoa is an important Andean crop that can play a strategic role in the development of degraded lands in hot arid regions due to its high nutritional value, genetic diversity and its high adaptability to stressful environments. The aim of this work was to evaluate the agronomic performance (growth development, grain yield and grain quality characteristics) of seven quinoa genotypes (Giza1, Sajama, Santa Maria, Q102, Q29, Q27 and Q18) cultivated under open field conditions in the Sahara Desert of Algeria. Using randomized complete block design (4 blocks), field trials were conducted during two cropping seasons (2017-2018 and 2018-2019) from November to April. The measured parameters included: plant height, number of panicles per plant, 1000-grain weight (TGW), grain yield (GYd), grain protein content (GPt), grain saponin content (GSC), and maturity indicators. The genotype effect was statistically the main source of variation in most parameters investigated as compared to the effect of cropping year. The Q102 genotype produced the highest GYd (2.87 t/ha) and GPt (16.7 g/100 g DM); and it required medium period (149 days) to reach harvest maturity as compared to other genotypes. The genotype Giza1 showed the lowest GYd and also low values for most of traits measured. However, it had the shortest harvest maturity (139 days) and the lowest GSC (0.62 g/100 g DM). The variety Santa Maria recorded the highest TGW (2.68 g), but it took 164 days to reach harvest maturity and it had high GSC (1.92 g/100 g DM). Though the best yield and grain quality characteristics were not reunited in single genotype, our findings showed that quinoa has multi-benefit potentials as a new crop for the arid agriculture in particular in hot-arid regions of North Africa.

Lithic cyanobacterial communities in the polyextreme Sahara Desert: implications for the search for the limits of life.

The hyperarid Sahara Desert presents extreme and persistent dry conditions with a limited number of hours during which the moisture availability, temperature and light allow phototrophic growth. Some cyanobacteria can live in these hostile conditions by seeking refuge under (hypolithic) or inside (endolithic) rocks, by colonizing porous spaces (cryptoendoliths) or fissures in stones (chasmoendoliths). Chroococcidiopsis spp. have been reported as the dominant or even the only phototrophs in these hot desert lithic communities. However, the results of this study reveal the high diversity of and variability in cyanobacteria among the sampled habitats in the Sahara Desert. The chasmoendolithic samples presented high coccoid cyanobacteria abundances, although the dominant cyanobacteria were distinct among different locations. A high predominance of a newly described cyanobacterium, Pseudoacaryochloris sahariense, was found in hard, compact, and more opaque stones with cryptoendolithic colonization. On the other hand, the hypolithic samples were dominated by filamentous, non-heterocystous cyanobacteria. Thermophysiological bioassays confirmed desiccation and extreme temperature tolerance as drivers in the cyanobacterial community composition of these lithic niches. The results of the present study provide key factors for understanding life strategies under polyextreme environmental conditions. The isolated strains, especially the newly described cyanobacterium P. sahariense, might represent suitable microorganisms in astrobiology studies aimed at investigating the limits of life.

Microenvironmental Conditions Drive the Differential Cyanobacterial Community Composition of Biocrusts from the Sahara Desert.

The Sahara Desert is characterized by extreme environmental conditions, which are a unique challenge for life. Cyanobacteria are key players in the colonization of bare soils and form assemblages with other microorganisms in the top millimetres, establishing biological soil crusts (biocrusts) that cover most soil surfaces in deserts, which have important roles in the functioning of drylands. However, knowledge of biocrusts from these extreme environments is limited. Therefore, to study cyanobacterial community composition in biocrusts from the Sahara Desert, we utilized a combination of methodologies in which taxonomic assignation, for next-generation sequencing of soil samples, was based on phylogenetic analysis (16S rRNA gene) in parallel with morphological identification of cyanobacteria in natural samples and isolates from certain locations. Two close locations that differed in microenvironmental conditions were analysed. One was a dry salt lake (a "chott"), and the other was an extension of sandy, slightly saline soil. Differences in cyanobacterial composition between the sites were found, with a clear dominance of Microcoleus spp. in the less saline site, while the chott presented a high abundance of heterocystous cyanobacteria as well as the filamentous non-heterocystous Pseudophormidium sp. and the unicellular cf. Acaryochloris. The cyanobacteria found in our study area, such as Microcoleus steenstrupii, Microcoleus vaginatus, Scytonema hyalinum, Tolypothrix distorta, and Calothrix sp., are also widely distributed in other geographic locations around the world, where the conditions are less severe. Our results, therefore, indicated that some cyanobacteria can cope with polyextreme conditions, as confirmed by bioassays, and can be considered extremotolerant, being able to live in a wide range of conditions.