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Plant sensitization with nitric oxide (NO) donors may improve the tolerance to abiotic stresses such as water deficit. Physalis angulata is a genetic resource growing in semiarid areas of Brazil, with the potential for fruit growing and medicinal uses. In this experiment sodium nitroprusside, a NO donor was sprayed at three concentrations (0, 50 and 100 µM) at 25 and 49 days after transplantation in well-watered plants and underwater deficit to evaluate the NO mitigating role. The gas exchange, photosynthetic pigments, water relations, growth and productivity parameters were evaluated. The water deficit negatively influenced most of the variables analyzed. However, the SNP spray was able to attenuate, reverse or act in the recovery of stress effects. There was an improvement in gas exchange, especially carbon assimilation, stomatal conductance and transpiration; as well as an increase in total chlorophyll content. The donated NO was able to influence the plant water status. Besides, it promoted an increase in growth parameters, especially in photoassimilates incorporation and yield. However, the NO supply to plants under well-watered conditions does not seem to affect the physiology parameters. The NO supply in micromolar concentrations can attenuate or even reverse the water deficit effects on this species, being an important tool for promoting tolerance to this abiotic stress

Nitrate reductase (NR) is the first enzyme in the nitrogen assimilation pathway. The determination of its activity requires modifications for each plant species. The goal of this work was to evaluate the variation of NR activity throughout the day and the optimization of assay conditions in foliar and radicular tissues of Physalis angulata. The analysis was done in plants cultivated in a hydroponic system at two months of age. The NR activity was based on the in vivo assay method. Enzyme activity was observed on leaf and root, indicating two sites of nitrate assimilation with a higher activity in the daylight in leaf. The NR activity in leaf was increased after 4h of luminosity. In the root, we observed a high activity during most of the day, especially in periods of higher solar radiation and temperature. To obtain the highest activity of NR in both tissues we suggest 1% n-propanol, 50mM of KNO3- in pH=7 phosphate buffer for 75 min incubation in water bath.