BACKGROUND The current climate change scenario may affect the water availability of the soil, impacting the agricultural sector. Thus, the planting of safflower (Carthamus tinctorius L.), due to its potential for cultivation under drought during the off-season in Brazil, has increased, mainly due to its high potential for biofuel production. There are several reports about the potential of low doses of glyphosate to promote plant growth and development (hormesis). Despite the concept of glyphosate hormesis being well established, little is known if there is any mitigating effect on plants under water deficit conditions. The hypothesis raised is that low doses of glyphosate promote water stress tolerance during the growth and reproductive phases of C. tinctorius exposed to different water regimes. RESULTS In both water regimes, with and without deficiency, growth of plants treated with low doses of glyphosate increased, reaching a maximum stimulus amplitude of around 131% of the control. However, plants under water deficit required lower doses to achieve maximum growth and development. They maintained photosynthetic rates at the level of well-watered plants, as they had reduced stomatal conductance and transpiration, showing a gain in plant height and leaf area at the same level of the control plants. CONCLUSIONS Low doses of glyphosate can act as mitigators of water deficit in C. tinctorius, allowing plants to maintain metabolism, reaching levels close to plants without water stress, as observed for plant height and leaf area. Our findings indicate that there are even greater implications for the understanding of glyphosate hormesis in plants under drought conditions, given the current climate change scenario. This article is protected by copyright. All rights reserved.
Jania Claudia Camilo Dos Santos, Dayane Mércia Ribeiro da Silva, Deoclecio Jardim Amorim
Pest management science