This study evaluated the influence of Azospirillum lipoferum on the growth of Myracroduon urundeuva (Anacardiaceae) plants under drought stress, by means of biometric, physical-chemical and biochemical parameters. The association of A. lipoferum with the roots of the plants provided increases of 30% root length, 50% root dry weight, 34% shoot dry weight and 10% soluble protein content. The inoculated plants still maintained 5% higher leaf water potential than those not inoculated and lower membrane damage. Furthermore, the inoculated plants shown less leaf fall and dark green leaves, confirmed by maintenance of the highest levels of chlorophyl a, b and total. On the other hand, superoxide dismutase activity was significantly lower in the inoculated plants, possibly due to the induction of a non-enzymatic protective feature. In this way, the inoculation of PGPR in M. urundeuva can be an alternative for the production of plants that are more tolerant to drought stress.

A B S T R A C TIn semi-arid environments, the plants are subject to stressful conditions due to high temperatures, light intensity and long drought, which are limiting for the establishment of seedlings. One way of minimizing stress is by inoculating rhizobacteria which promote plant growth (RPGP). The objective of this study was to evaluate the effectiveness of RPCP inoculation in the development of Myracrodruon urundeuva Allemão seedlings in different light conditions. Four treatments were applied: full sun with inoculum; full sun without inoculum; 70% shade with inoculum and 70% shade without inoculum. Data were collected biweekly for height, diameter, the number of leaves and leaf temperature (Tf). The vapor pressure deficit was determined by the temperature and humidity of the air. Parameters of leaf water potential, biomass, leaf area, specific leaf area and root area were evaluated. The seedlings presented higher growth under shading, demonstrating a mechanism to develop better in low light, and inoculation of the bacterium provided an increase in height and diameter of the seedlings, besides higher Tf on most days. The seedlings of the treatments in the sun invested more in radicular biomass, whereas in the shading they invested more in the aerial part. The water potential did not vary among the treatments, indicating that they adjusted to the submitted conditions. The use of RPGP is very promising, especially for the implantation of plant species in the recovery of degraded areas, as well as the condition of greater shading favors the initial stage of development of the seedlings.

Endophytic fungi (EF) colonize plant tissues without causing damage; this relationship brings benefits to both, including a greater resistance to environmental stresses, but the influence of genotypes and culture system in endophytic community is still unraveled. Thus, this work aimed to study EF from Sorghum bicolor and correlate to its genotypes submitted to different culture systems; their potential to produce antimicrobial compounds was also evaluated. To optimize the production of metabolites, four isolates were submitted to liquid medium and the crude extracts of different culture times were analyzed. EF of leaves of Qualimax and SF15 genotypes were isolated after superficial disinfection. Fungal identification was made using classical taxonomy. As results, the traditional system presented the lowest number EF isolates, while the minimum system showed the highest. The genera Aspergillus, Fusarium, Penicillium, Cladosporium, Curvularia and Syncephalastrum were found; Aspergillus spp. was pointed out as a predominant endophyte of genotype Qualimax. Among the 25 endophytes submitted antimicrobial activity assay in solid medium, 21 presented antibacterial activity against at least one bacterium with the highest inhibition zone of 29.3 mm of diameter against Staphylococcus aureus. All EF submitted to liquid medium kept the capacity to produce antibacterial metabolites. In conclusion, regardless of genotype and culture system, sorghum is colonized by different EF, mainly Aspergillus spp. EF from leaves of S. bicolor produce antibacterial compounds and their biotechnological applications can be explored in future.