Dear Researchers,
I have tested the effects of applying ascorbate as a stress-ameliorative strategy for tomato plants. Although plants under stress could recover from the major phytotoxicity symptoms upon application of ascorbate, the treatment with ascorbate alone, which was supposed to serve only as a positive control, revealed that non-stressed plants actually suffered severe growth inhibition, in terms of biomass production, due to ascorbate application.
It goes against many reports that refer to ascorbate as a growth stimulator. Does anyone know if ascorbate interferes with aquaporins? Could it have induced water loss from tissues?
Hello Sofia Spormann , what concentration did you use? I had similar problems when testing high concentrations in radish plants, but these deleterious effects no longer appeared at concentrations below 2 mM
When do you apply this? It is probably not a good idea to apply it during the day in full sun. I would apply it early in the morning. Make sure the plants are well watered and not wilted. Applying in full sun will stress the plants even more, especially under water stress. Applying at night could increase fungal infections. Also, as has been said before, use a lower concentration.
Dear Sofia, the negative effect od asvorbate can be related to the excessive scavenging of ROS, such as H2O2, which are are also important signaling molecules in Plant Physiology. The reduced normal content of H2O2 can disrupt process such as stomatal closure leading to stressful condition. Therefore, it is important to previously evaluate the used concentration of AsA aiming to have positive effects on plants.
Thank you all for your answers! We've used a concentration of Ascorbate of 150 mg L-1 of culture media (plants grew in vitro). This was probably too much ascorbate and may indeed have affected the redox homeostasis, interfering with the signaling roles of ROS, such as H2O2...
150 mg l-1? wow!!! it is too much indeed!!! Working on seeds, a concentration of only 100 ug l-1 was already enough to prevent germination! Thus, try to adjust your method.
Well, in our case AsA did not prevent germination, nor did it affect early seedling development. I actually found a study on sweet pepper plants where the authors used 250 mg L-1 of exogenous AsA and it even acted as a growth stimulator (Sakr, M. T., El-Sarkassy, N. M., & Fuller, M. P. (2015). Minimization the effects of salt stress on sweet pepper plants by exogenous protectants application)
Clearly it is a species-dependent response! I wish you all the best in your studies!
Thank you Marcelo Pedrosa Gomes . Do you have any published paper regarding those effects of AsA (100 ug L-1) on preventing seed germination?
Dear Sofia:
Although the previous answers seem to clarify the situation I summarize a little: Ascorbate usually acts as a non-enzymatic antioxidant that can help control reversible damage that reactive oxygen species (derived from environmental stress) can generate. For unstressed plants, the application of amounts greater than a critical dose of ascorbate (dependent of each species) could have opposite effects, that is, generate stressful effects or prevent the development of normal processes. This material could be useful.
https://onlinelibrary.wiley.com/doi/abs/10.1002/9781119552154.ch5
Hi. A very good discussion. Please refer to this work "Elicitation: a new perspective into plant chemo-diversity and functional property"
I did the same work applying exogenous ascorbate on growing alfalfa seeds. The effects of ascorbate on sprout growth were similar to that of tap water but the application affected the biological activity of the sprouts. I think generally elicitor affect the growth of sprouts by just inducing the release of hormones that regulates the growth of seedlings.
Thank you very much, both Cristóbal José Lárez Velásquez and Simon Aloo for your attentive and elucidative answers. This information is very useful. Best wishes!
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