Low soil nutrient availability does not decrease post-drought recovery of Brachiaria Mavuno

Changes in the availability of soil nutrients may modify plant drought tolerance and post-drought recovery potential. In this study, we aimed to evaluate how soil nutrient availability changes the response of the tropical forage species Brachiaria Mavuno to drought and post-drought recovery and unravel the physiological adjustments that are involved in plant recovery. Plants were grown in two conditions of soil nutrient availability: low nutrient (LN) and high nutrient (HN) and were submitted to a drought cycle followed by a recovery period. We measured leaf gas exchange, stable carbon isotopic discrimination, PSII performance, leaf water status, and biomass production during the experiment. Since the beginning of the experiment, we observed that plants at LN had lower transpiration rates than plants at HN. Therefore, soil moisture decreasing rates were higher at HN plots. Water stress decreased photosynthesis, and PSII performance. Gas exchange and PSII performance data indicated that well-watered LN plants acclimated to conditions of LN. After the recovery, LN and HN plants submitted to the drought cycle fully recovered gas exchange and photosynthetic parameters. We concluded that an adequate soil nutrient availability is not essential to ensure plant recovery from drought. In fact, our data suggest that Brachiaria Mavuno maintain its capacity to tolerate drought conditions and fully recover from a drought cycle even at poor soils due to a switch in drought tolerance strategies. (AU)