The importance of phosphate solubilizing rhizobacteria (PSB) has been well-document as an option for enhancing sustainable agriculture. As a particular group of plant growth promoting rhizobacteria (PGPR), PSB play an important role in the soil phosphorus cycle, increasing the bioavailability for growth and plant development. This study analyses the plant growth promoting effects of 5 strains (BN0009, BN0013, BN0015, BN0024, and BN0035) out of 180 isolated from Jarava frigida (Phil.) F.Rojas (Poaceae), a native grass from the Andean Atacama desert from North of Chile. The five bacterial isolated (BN strains) were identified as non-pathogenic Erwinia sp. and show a high phosphate solubilization capacity for Ca(PO4) ranging from 608.9 to 781.4 mg/L. Strains IAA production varies between 23.5 and 35.9 mg/L, siderophores, phosphatase (alkaline and acid) production was also observed, but none of the five isolated presented antagonism against plant pathogens Botrytis sp. and Sclerotinia sp. All isolates enhanced seed germination in Lactuca sativa and Solanum lycopersicum (excepting BN009). Additionally, all strains stimulated the early root elongation and seedling development in lettuce and tomato. Pot experiments displayed that BN0015, BN0024, and BN0035 significantly promote plant growth regarding root and leaf area, root and leaf weight, as well as leaf number compared with non-treated plants. In a field experiment with lettuce and two fertilization treatments (50 and 100% of the recommended crop fertilization), BN0024 application improved crop productivity compared to respective control. P content in plants with bacterial inoculations increased significantly compared to control in either fertilization treatment, suggesting an improved nutrient uptake. Also, lettuce with 50% fertilization and inoculation with BN0024 equate productivity with the control 100% fertilization. Finally, we discuss these results in the context of applicability to enhance the agroecosystem productivity in arid and semiarid zones.

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There are endemic cacti species in the North of Chile with edible fruits and a fledgling productive potential, with unknown degree diversity. Low diversity compromises the ability of populations to evolve and reduces their chances of survival under environmental changes. Copao (Eulychnia acida Phil.), a cactus endemic to Chile that grows in the Coquimbo Region (30º S lat) and able to bear fruit in water stress conditions, were morphologically characterized using descriptors of other columnar cacti at three different locations where it usually grows wild. Five inter simple sequence repeat (ISSR) primers, which were reported for other cacti that produced replicable and informative amplifications, were selected for the genetic characterization. Statistical analysis was performed to describe the diversity of this species and morphological and genetic results compared each other. High variation was observed between and within the evaluated populations for parameters of central tendency, dispersion, and univariate statistical analysis of the morphological traits. Principal component analysis showed that 73% of the population variation at the three locations could be explained by the first three principal components with 34%, 22%, and 17% of the observed variation, respectively. The five ISSR primers generated 7 to 11 polymorphic bands with a band range between 100 and 1517 bp. The polymorphic information content (PIC) averaged 0.75, which suggests high diversity between and within populations. Consensus of 85% existed between the selected descriptors and the ISSR markers, which points them out as suitable tools to analyze diversity in this species.K e y w o r d s : C o p a o , d e s c r i p t o r s , g e n e r a l i z e d procrustes analysis (GPA), genetic and morphological characterization, inter simple sequence repeat (ISSR).