Aspectos ecofisiológicos de plântulas de Myracrodruon urundeuva Allemão (Anacardiaceae) inoculadas com Azospirillum lipoferum submetidas a estresses

Abstract

Environmental stresses limit the establishment and development of seedlings in arid and semi-arid climate environments. Inoculation of Plant Growth Promising Rhizobacteria (RPCPs) minimizes the adverse effects of stresses on cultivated plants. However, few studies have tested the inoculation of RPCP in native plants in semi-arid environments. The present work had as objective to evaluate the influences of the inoculation of Azospirillum lipoferum on the growth and the physiological responses of Myracrodruon urundeuva seedlings submitted to stress. The experiment was conducted at the Federal Rural University of Pernambuco, Serra Talhada Academic Unit in a nursery environment. The seeds were sanitized and inoculated with the rhizobacterium, with control treatment corresponding to the seeds that did not receive the inoculation. Three weeks after germination the seedlings were transplanted into 3.8 L vessels. The reduction of water replenishment was in accordance with the reference evapotranspiration (ET0). The treatments were: control (100% ET0), moderate stress (50% ET0) and severe stress (25% ET0). Evaluations were biometric and biomass, physiological (gas exchange, chlorophyll content), water potential, light curves of photosynthetic efficiency and evaluation of chlorophyll fluorescence were performed. Seedlings inoculated and under moderate water deficit treatments presented a 31% higher height in relation to seedlings without inoculum. Foliar biomass of inoculated seedlings and under severe water defict was 17% higher than seedlings without inoculum. The photosynthetic rates, stomatal conductance and transpiration presented higher averages for the seedlings under inoculation effect. The water potential of uninoculated and moderately deficit seedlings was 14% more negative than seedlings with inoculum. The light intensity curves for seedlings inoculated and under water defict showed higher values of photosynthesis, conductance and transpiration. The maximum fluorescence showed the highest mean values for inoculated seedlings of the water déficit control treatment and for the photochemical dissipation coefficient the inoculated seedlings of the severe water stress treatment were highlighted in relation to the seedlings without inoculum. Thus, the inoculation of RPCP in M. urundeuva presents itself as an alternative for the production of plants more tolerant to water defict, being an alternative for the use of these plants in the recovery of degraded areas.