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Studies of the inhibition of stomatal opening by naph-1-ylacetic acid and abscisic acid.
in Journal of Experimental Botany 35, 1410–1418 – DOI: https://doi.org/10.1093/jxb/35.10.1410 –
In contrast to the natural auxin IAA, NAA exerts effects which, in some respects, resemble those of ABA. The mode of action of NAA on the guard cells is, however, thought to be different from that of ABA.
When NAA and ABA are applied together, their combined action results in a greater reduction in stomatal aperture than would be predicted from their separate effects.