Photosynthetic and Production of Urochloa ruziziensis Inoculated with Azospirillum brasilense under Drought

Abstract

Aims: The objective of this study was to evaluate the photosynthetic activity and production of Urochloa ruziziensis when inoculated with Azospirillum brasilense in the presence and absence of drought. Study Design:  Randomized block design and factorial 2x2. Methodology: The first factor was the presence or absence of seed inoculation with A. brasilense strains AbV5 + AbV6; the second factor was the presence or absence of drought. The variables evaluated were: relative water content (RWC), soil gravimetric moisture, net assimilation rate of CO2, response in function of active photon flux density, apparent quantum efficiency, light compensation point, absolute integrity of membrane, damage to membranes, dry mass aborted leaves, and total dry mass of aerial part. Results: Results demonstrate that plants maintained in drought presented a reduction in all evaluated variables. Under conditions of drought the use of A. brasilense promoted smaller variations in RWC, net assimilation rate of CO2, apparent quantum efficiency, light compensation point, absolute integrity of membrane, and damage to membranes; no variations were observed for dry mass, aborted leaves or total dry mass of aerial part. Conclusion: The inoculation of U. ruziziensis seeds with A. brasilense mitigates drought damage in plant physiology, but it does not mitigate leaf losses or plant productivity.